Patent Publication Number: US-2021180033-A1

Title: Bacteria engineered to treat diseases associated with hyperammonemia

Description:
This application is a continuation of U.S. application Ser. No. 15/164,828, filed May 26, 2016; which continuation-in-part of U.S. application Ser. No. 14/960,333, filed Dec. 4, 2015; a continuation-in-part of PCT Application No. PCT/US2016/020530, filed Mar. 2, 2016; and claims the benefit of U.S. Provisional Application No. 62/173,710, filed Jun. 10, 2015; U.S. Provisional Application No. 62/173,706, filed Jun. 10, 2015; U.S. Provisional Application No. 62/183,935, filed Jun. 24, 2015; U.S. Provisional Application No. 62/184,811, filed Jun. 25, 2015; U.S. Provisional Application No. 62/184,770, filed Jun. 25, 2015; U.S. Provisional Application No. 62/248,805, filed Oct. 30, 2015; U.S. Provisional Application No. 62/256,041, filed Nov. 16, 2015; U.S. Provisional Application No. 62/256,039, filed Nov. 16, 2015; U.S. Provisional Application No. 62/256,048, filed Nov. 16, 2015; U.S. Provisional Application No. 62/263,329, filed Dec. 4, 2015; U.S. Provisional Application No. 62/291,468, filed Feb. 4, 2016; U.S. Provisional Application No. 62/277,654, filed Jan. 12, 2016; U.S. Provisional Application No. 62/150,508, filed Apr. 21, 2015; U.S. Provisional Application No. 62/103,513, filed Jan. 14, 2015; U.S. Provisional Application No. 62/087,854, filed Dec. 5, 2014; and U.S. Provisional Application No. 62/293,749, filed Feb. 10, 2016; which are incorporated herein by reference in their entirety to provide continuity of disclosure. 
    
    
     BACKGROUND 
     Ammonia is highly toxic and generated during metabolism in all organs (Walker, 2012). In mammals, the healthy liver protects the body from ammonia by converting ammonia to non-toxic molecules, e.g., urea or glutamine, and preventing excess amounts of ammonia from entering the systemic circulation. Hyperammonemia is characterized by the decreased detoxification and/or increased production of ammonia. In mammals, the urea cycle detoxifies ammonia by enzymatically converting ammonia into urea, which is then removed in the urine. Decreased ammonia detoxification may be caused by urea cycle disorders (UCDs) in which urea cycle enzymes are defective, such as argininosuccinic aciduria, arginase deficiency, carbamoylphosphate synthetase deficiency, citrullinemia, N-acetylglutamate synthetase deficiency, and ornithine transcarbamylase deficiency (Häberle et al., 2012). The National Urea Cycle Disorders Foundation estimates that the prevalence of UCDs is 1 in 8,500 births. In addition, several non-UCD disorders, such as hepatic encephalopathy, portosystemic shunting, and organic acid disorders, can also cause hyperammonemia. Hyperammonemia can produce neurological manifestations, e.g., seizures, ataxia, stroke-like lesions, coma, psychosis, vision loss, acute encephalopathy, cerebral edema, as well as vomiting, respiratory alkalosis, hypothermia, or death (Häberle et al., 2012; Häberle et al., 2013). 
     Ammonia is also a source of nitrogen for amino acids, which are synthesized by various biosynthesis pathways. For example, arginine biosynthesis converts glutamate, which comprises one nitrogen atom, to arginine, which comprises four nitrogen atoms. Intermediate metabolites formed in the arginine biosynthesis pathway, such as citrulline, also incorporate nitrogen. Thus, enhancement of arginine biosynthesis may be used to incorporate excess nitrogen in the body into non-toxic molecules in order to modulate or treat conditions associated with hyperammonemia. Likewise, histidine biosynthesis, methionine biosynthesis, lysine biosynthesis, asparagine biosynthesis, glutamine biosynthesis, and tryptophan biosynthesis are also capable of incorporating excess nitrogen, and enhancement of those pathways may be used to modulate or treat conditions associated with hyperammonemia. 
     Current therapies for hyperammonemia and UCDs aim to reduce ammonia excess, but are widely regarded as suboptimal (Nagamani et al., 2012; Hoffmann et al., 2013; Torres-Vega et al., 2014). Most UCD patients require substantially modified diets consisting of protein restriction. However, a low-protein diet must be carefully monitored; when protein intake is too restrictive, the body breaks down muscle and consequently produces ammonia. In addition, many patients require supplementation with ammonia scavenging drugs, such as sodium phenylbutyrate, sodium benzoate, and glycerol phenylbutyrate, and one or more of these drugs must be administered three to four times per day (Leonard, 2006; Diaz et al., 2013). Side effects of these drugs include nausea, vomiting, irritability, anorexia, and menstrual disturbance in females (Leonard, 2006). In children, the delivery of food and medication may require a gastrostomy tube surgically implanted in the stomach or a nasogastric tube manually inserted through the nose into the stomach. When these treatment options fail, a liver transplant may be required (National Urea Cycle Disorders Foundation). Thus, there is significant unmet need for effective, reliable, and/or long-term treatment for disorders associated with hyperammonemia, including urea cycle disorders. 
     The liver plays a central role in amino acid metabolism and protein synthesis and breakdown, as well as in several detoxification processes, notably those of end-products of intestinal metabolism, like ammonia. Liver dysfunction, resulting in hyperammonemia, may cause hepatic encephalopathy (HE), which disorder encompasses a spectrum of potentially reversible neuropsychiatric abnormalities observed in patients with liver dysfunction (after exclusion of unrelated neurologic and/or metabolic abnormalities). In HE, severe liver failure (e.g., cirrhosis) and/or portosystemic shunting of blood around the liver permit elevated arterial levels of ammonia to permeate the blood-brain barrier (Williams, 2006), resulting in altered brain function. 
     Ammonia accumulation in the brain leads to cognitive and motor disturbances, reduced cerebral perfusion, as well as oxidative stress-mediated injury to astrocytes, the brain cells capable of metabolizing ammonia. There is evidence to suggest that excess ammonia in the brain disrupts neurotransmission by altering levels of the predominant inhibitory neurotransmitter, γ-aminobutyric acid (GABA) (Ahboucha and Butterworth, 2004). Elevated cerebral manganese concentrations and manganese deposition have also been reported in the basal ganglia of cirrhosis patients, and are suspected to contribute to the clinical presentation of HE (Cash et al., 2010; Rivera-Mancia et al., 2012). General neurological manifestations of hyperammonemia include seizures, ataxia, stroke-like lesions, Parkinsonian symptoms (such as tremors), coma, psychosis, vision loss, acute encephalopathy, cerebral edema, as well as vomiting, respiratory alkalosis, hypothermia, or death (Häberle et al., 2012; Häberle et al., 2013). 
     Ammonia dysmetabolism cannot solely explain all the neurological changes that are seen in patients with HE. Sepsis is a well-known precipitating factor for HE. The systemic inflammatory response syndrome (SIRS) results from the release and circulation of proinflammatory cytokines and mediators. In patients with cirrhosis, SIRS may exacerbate the symptoms of HE, both in patients with minimal and overt HE in a process likely mediated by tumor necrosis factor (TNF) and interleukin-6 (IL6). Notably, enhanced production of reactive nitrogen species (RNS) and reactive oxygen species (ROS) occurs in cultured astrocytes that are exposed to ammonia, inflammatory cytokines, hyponatremia or benzodiazepines. 
     Hyperammonemia is also a prominent feature of Huntington&#39;s disease, an autosomal dominant disorder characterized by intranuclear/cytoplasmic aggregates and cell death in the brain (Chen et al., 2015; Chiang et al., 2007). In fact, hyperammonemia is a feature of several other disorders, as discussed herein, all of which can be treated by reducing the levels of ammonia. 
     Current therapies for hepatic encephalopathy, Huntington&#39;s disease, and other diseases and disorders associated with excess ammonia levels, are insufficient (Cash et al., 2010; Cordoba and Minguez, 2008; Shannon and Fraint, 2015). In Huntington&#39;s disease, the side effects of antipsychotic drugs (e.g., haloperidol, risperidone, quetiapine) and drugs administered to suppress involuntary movements (e.g., tetrabenazine, amantadine, levetiracetam, clonazepam) may worsen muscle rigidity and cognitive decline in patients (Mayo Clinic). Antibiotics directed to urease-producing bacteria were shown to have severe secondary effects, such as nephrotoxicity, especially if administered for long periods (Blanc et al., 1992; Berk and Chalmers, 1970). Protein restriction is also no longer a mainstay therapy, as it can favor protein degradation and poor nutritional status, and has been associated with increased mortality (Kondrup and Willer, 1997; Vaqero et al., 2003). Protein restriction is only appropriate for one third of cirrhotic patients with HE (Nguyen and Morgan, 2014). Thus, there is significant unmet need for effective, reliable, and/or long-term treatment for hepatic encephalopathy and Huntington&#39;s disease. 
     SUMMARY 
     The disclosure provides genetically engineered bacteria that are capable of reducing excess ammonia and converting ammonia and/or nitrogen into alternate byproducts. In certain embodiments, the genetically engineered bacteria reduce excess ammonia and convert ammonia and/or nitrogen into alternate byproducts. In certain embodiments, the genetically engineered bacteria are non-pathogenic and may be introduced into the gut in order to reduce toxic ammonia. As much as 70% of excess ammonia in a hyperammonemic patient accumulates in the gastrointestinal tract. Another aspect of the invention provides methods for selecting or targeting genetically engineered bacteria based on increased levels of ammonia and/or nitrogen consumption, or production of a non-toxic byproduct, e.g., arginine or citrulline. The invention also provides pharmaceutical compositions comprising the genetically engineered bacteria, and methods of modulating and treating disorders associated with hyperammonemia, e.g., urea cycle disorders and hepatic encephalopathy. 
     The disclosure also provides genetically engineered bacteria that are capable of reducing excess ammonia and other deleterious molecules, e.g., GABA, manganese. In certain embodiments, the genetically engineered bacteria reduce excess ammonia and convert ammonia and/or nitrogen into alternate byproducts. In certain embodiments, the genetically engineered bacteria are non-pathogenic and may be introduced into the gut in order to reduce toxic ammonia. In certain embodiments, the genetically engineered bacteria are capable of reducing excess ammonia and other deleterious molecules, e.g., GABA, manganese, and are also capable of producing one or more gut barrier enhancer molecules, e.g., one or more short chain fatty acid(s), such as butyrate. Another aspect of the disclosure provides methods for selecting or targeting genetically engineered bacteria based on increased levels of ammonia and/or nitrogen consumption, or production of a non-toxic byproduct, e.g., arginine or citrulline. The invention also provides pharmaceutical compositions comprising the genetically engineered bacteria, and methods of modulating and treating disorders associated with excess ammonia, including, for example, hepatic encephalopathy and Huntington&#39;s disease. 
     In some embodiments, the genetically engineered bacteria comprise one or more gene(s) or gene cassette(s) or circuit(s), containing one or more native or non-native component(s), which mediate one or more mechanisms of action. Additionally, one or more endogenous genes or regulatory regions within the bacterial chromosome may be mutated or deleted. The genetically engineered bacteria harbor these genes or gene cassettes or circuits on a plasmid or, alternatively, the genes/gene cassettes have been inserted into the chromosome at certain regions, where they do not interfere with essential gene expression. 
     These gene(s)/gene cassette(s) may be under the control of constitutive or inducible promoters. Exemplary inducible promoters described herein include oxygen level-dependent promoters (e.g., FNR-inducible promoter), promoters induced by HE-specific molecules or metabolites indicative of liver damage (e.g., bilirubin), promoters induced by inflammation or an inflammatory response (RNS, ROS promoters), and promoters induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose and tetracycline. 
     In addition, the engineered bacteria may further comprise one or more of more of the following: (1) one or more auxotrophies, such as any auxotrophies known in the art and provided herein, e.g., thyA auxotrophy, (2) one or more kill switch circuits, such as any of the kill-switches described herein or otherwise known in the art, (3) one or more antibiotic resistance circuits, (4) one or more transporters for importing biological molecules or substrates, such any of the transporters described herein or otherwise known in the art, (5) one or more secretion circuits, such as any of the secretion circuits described herein and otherwise known in the art, and (6) combinations of one or more of such additional circuits. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIGS. 1A and 1B  depict the state of the arginine regulon in one embodiment of an ArgR deletion bacterium of the invention under non-inducing ( FIG. 1A ) and inducing ( FIG. 1B ) conditions.  FIG. 1A  depicts relatively low arginine production under aerobic conditions due to arginine (“Arg” in oval) interacting with ArgA (squiggle  ) to inhibit (indicated by “X”) ArgA activity, while oxygen (O 2 ) prevents (indicated by “X”) FNR (dotted boxed FNR) from dimerizing and activating the FNR promoter (grey FNR box) and the argA fbr  gene under its control.  FIG. 1B  depicts up-regulated arginine production under anaerobic conditions due to FNR dimerizing (two dotted boxed FNRs) and inducing FNR promoter (grey FNR box)-mediated expression of ArgA fbr  (squiggle   above argA fbr ), which is resistant to inhibition by arginine. This overcomes (curved arrow) the inhibition of the wild-type ArgA caused by arginine (“Arg” in oval) interacting with ArgA (squiggle   above box depicting argA). Each gene in the arginine regulon is depicted by a rectangle containing the name of the gene. Each arrow adjacent to one or a cluster of rectangles depict the promoter responsible for driving transcription, in the direction of the arrow, of such gene(s). Heavier lines adjacent one or a series of rectangles depict ArgR binding sites, which are not utilized because of the ArgR deletion in this bacterium. Arrows above each rectangle depict the expression product of each gene. 
         FIGS. 2A and 2B  depict an alternate exemplary embodiment of the present invention.  FIG. 2A  depicts the embodiment under aerobic conditions where, in the presence of oxygen, the FNR proteins (FNR boxes) remain as monomers and are unable to bind to and activate the FNR promoter (“FNR”) which drives expression of the arginine feedback resistant argA fbr  gene. The wild-type ArgA protein is functional, but is susceptible to negative feedback inhibition by binding to arginine, thus keeping arginine levels at or below normal. All of the arginine repressor (ArgR) binding sites in the promoter regions of each arginine biosynthesis gene (argA, argE, argC, argB, argH, argD, argI, argG, carA, and carB) have been mutated (black bars; black “X”) to reduce or eliminate binding to ArgR.  FIG. 2B  depicts the same embodiment under anaerobic conditions where, in the absence of oxygen the FNR protein (FNR boxes) dimerizes and binds to and activates the FNR promoter (“FNR”). This drives expression of the arginine feedback resistant argA fbr  gene (black squiggle ( )=argA fbr  gene expression product), which is resistant to feedback inhibition by arginine (“Arg” in ovals). All of the arginine repressor (ArgR) binding sites in the promoter regions of each arginine biosynthetic gene (argA, argE, argC, argB, argH, argD, argI, argG, carA, and carB) have been mutated (black bars) to reduce or eliminate binding to ArgR (black “X”), thus preventing inhibition by an arginine-ArgR complex. This allows high level production of arginine. 
         FIG. 3  depicts another embodiment of the invention. In this embodiment, a construct comprising an ArgR binding site (black bar) in a promoter driving expression of the Tet repressor (TetR) from the tetR gene is linked to a second promoter comprising a TetR binding site (black bar between TetR and X) that drives expression of gene X. Under low arginine concentrations, TetR is expressed and inhibits the expression of gene X. At high arginine concentrations, ArgR associates with arginine and binds to the ArgR binding site, thereby inhibiting expression of TetR from the tetR gene. This, in turn, removes the inhibition by TetR allowing gene X expression (black squiggle ( )). 
         FIG. 4  depicts another embodiment of the invention. In this embodiment, a construct comprising an ArgR binding site (black bar) in a promoter driving expression of the Tet repressor (TetR) from the tetR gene is linked to a second promoter comprising a TetR binding site (black bar bound to TetR oval) that drives expression of green fluorescent protein (“GFP”). Under low arginine concentrations, TetR is expressed and inhibits the expression of GFP. At high arginine concentrations, ArgR associates with arginine and binds to the ArgR binding site, thereby inhibiting expression of TetR from the tetR gene. This, in turn, removes the inhibition by TetR allowing GFP expression. By mutating a host containing this construct, high arginine producers can be selected on the basis of GFP expression using fluorescence-activated cell sorting (“FACS”). 
         FIG. 5  depicts another embodiment of the invention. In this embodiment, a construct comprising an ArgR binding site (black bar bound by the ArgR-Arg complex) in a promoter driving expression of the Tet repressor (not shown) from the tetR gene is linked to a second promoter comprising a TetR binding site (black bar) that drives expression of an auxotrophic protein necessary for host survival (“AUX”). Under high arginine concentrations, the ArgR-arginine complex binds to the ArgR binding site, thereby inhibiting expression of TetR from the tetR gene. This, in turn, allows expression of AUX, allowing the host to survive. Under low arginine concentrations, TetR is expressed from the tetR gene and inhibits the expression of AUX, thus killing the host. The construct in  FIG. 5  enforces high arginine (“Arg”) production by making it necessary for host cell survival through its control of AUX expression. 
         FIG. 6  depicts a schematic diagram of the argA fbr  gene under the control of an exemplary FNR promoter (fnrS) fused to a strong ribosome binding site. 
         FIG. 7  depicts another schematic diagram of the argA fbr  gene under the control of an exemplary FNR promoter (nirB) fused to a strong ribosome binding site. Other regulatory elements may also be present. 
         FIG. 8  depicts a schematic diagram of the argA fbr  gene under the control of an exemplary FNR promoter (nirB) fused to a weak ribosome binding site. 
         FIGS. 9A and 9B  depict exemplary embodiments of a FNR-responsive promoter fused to a CRP binding site.  FIG. 9A  depicts a map of the FNR-CRP promoter region, with restriction sites shown in bold.  FIG. 9B  depicts a schematic diagram of the argA fbr  gene under the control of an exemplary FNR promoter (nirB promoter), fused to both a CRP binding site and a ribosome binding site. Other regulatory elements may also be present. 
         FIGS. 10A and 10B  depict alternate exemplary embodiments of a FNR-responsive promoter fused to a CRP binding site.  FIG. 10A  depicts a map of the FNR-CRP promoter region, with restriction shown in bold.  FIG. 10B  depicts a schematic diagram of the argA fbr  gene under the control of an exemplary FNR promoter (fnrS promoter), fused to both a CRP binding site and a ribosome binding site. 
         FIG. 11  depicts an exemplary embodiment of a constitutively expressed argG construct in  E. coli  Nissle. The constitutive promoter is BBa_J23100, boxed in gray. Restriction sites for use in cloning are in bold. 
         FIG. 12  depicts a map of the wild-type argG operon  E. coli  Nissle, and a constitutively expressing mutant thereof. ARG boxes are present in the wild-type operon, but absent from the mutant. ArgG is constitutively expressed under the control of the BBa_J23100 promoter. 
         FIG. 13  depicts a schematic diagram of an exemplary BAD promoter-driven argA fbr  construct. In this embodiment, the argA fbr  gene is inserted between the araC and araD genes. ArgA fbr  is flanked by a ribosome binding site, a FRT site, and one or more transcription terminator sequences. 
         FIG. 14  depicts an exemplary embodiment of an engineered bacterial strain deleted for the argR gene and expressing the feedback-resistant argA fbr  gene. In some embodiments, this strain further comprises one or more auxotrophic modifications on the chromosome. This strain is useful for the consumption of ammonia and the production of arginine. 
         FIG. 15  depicts an exemplary embodiment of an engineered bacterial strain deleted for the argR and argG genes, and expressing the feedback-resistant argA fbr  gene. In some embodiments, this strain further comprises one or more auxotrophic modifications on the chromosome. This strain is useful for the consumption of ammonia and the production of citrulline. 
         FIG. 16  depicts an exemplary embodiment of an engineered bacterial strain which lacks ArgR binding sites and expresses the feedback-resistant argA fbr  gene. In some embodiments, this strain further comprises one or more auxotrophic modifications on the chromosome. This strain is useful for the consumption of ammonia and the production of arginine. 
         FIG. 17  depicts an exemplary embodiment of an engineered bacterial strain which lacks ArgR binding sites in all of the arginine biosynthesis operons except for argG, and expresses the feedback-resistant argA fbr  gene. In some embodiments, this strain further comprises one or more auxotrophic modifications on the chromosome. This strain is useful for the consumption of ammonia and the production of citrulline. 
         FIG. 18  depicts a map of exemplary integration sites within the  E. coli  1917 Nissle chromosome. These sites indicate regions where circuit components may be inserted into the chromosome without interfering with essential gene expression. Backslashes (/) are used to show that the insertion will occur between divergently or convergently expressed genes. Insertions within biosynthetic genes, such as thyA, can be useful for creating nutrient auxotrophies. In some embodiments, an individual circuit component is inserted into more than one of the indicated sites. The malE/K site is circled. In some embodiments of the disclosure, FNR-ArgAfbr is inserted at the malEK locus. 
         FIG. 19  depicts three bacterial strains which constitutively express red fluorescent protein (RFP). In strains 1-3, the rfp gene has been inserted into different sites within the bacterial chromosome, and results in varying degrees of brightness under fluorescent light. Unmodified  E. coli  Nissle (strain 4) is non-fluorescent. 
         FIG. 20  depicts the gene organization of exemplary constructs of the disclosure. Non-limiting examples of strains comprising such a construct include SYN-UCD301 and SYN-UCD302. SYN-UCD301 comprises ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, Wild type ThyA, and Chloramphenicol resistance. 
         FIG. 21  depicts the gene organization of an exemplary construct of the disclosure. Non-limiting examples of strains comprising such a construct include SYN-UCD303, SYN-UCD306, SYN-UCD307, and SYN-UCD309. For example, SYN-UCD303 comprises ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and kanamycin resistance. 
         FIG. 22  depicts the gene organization of exemplary constructs of the disclosure. Non-limiting examples of strains comprising such a construct include SYN-UCD304, SYN-UCD305, SYN-UCD308, and SYN-UCD310. For example, SYN-UCD304 comprises ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, wild type ThyA, and no antibiotic resistance. SYN-UCD305 comprises ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and no antibiotic resistance. 
         FIG. 23  depicts a bar graph of in vitro arginine levels produced by streptomycin-resistant control Nissle (SYN-UCD103), SYN-UCD201, SYN-UCD202, and SYN-UCD203 under inducing (+ATC) and non-inducing (−ATC) conditions. SYN-UCD201 comprises ΔArgR and no argA fbr . SYN-UCD202 comprises ΔArgR and tetracycline-inducible argA fbr  on a high-copy plasmid. SYN-UCD203 comprises ΔArgR and tetracycline-driven argA fbr  on a low-copy plasmid. 
         FIG. 24  depicts a bar graph of in vitro levels of arginine and citrulline produced by streptomycin-resistant control Nissle (SYN-UCD103), SYN-UCD104, SYN-UCD204, and SYN-UCD105 under inducing conditions. SYN-UCD104 comprises wild-type ArgR, tetracycline-inducible argA fbr  on a low-copy plasmid, tetracycline-inducible argG, and mutations in each ARG box for each arginine biosynthesis operon except for argG. SYN-UCD204 comprises ArgR and argA fbr  expressed under the control of a tetracycline-inducible promoter on a low-copy plasmid. SYN-UCD105 comprises wild-type ArgR, tetracycline-inducible argA fbr  on a low-copy plasmid, constitutively expressed argG (BBa_J23100 constitutive promoter), and mutations in each ARG box for each arginine biosynthesis operon except for argG. 
         FIG. 25  depicts a bar graph of in vitro arginine levels produced by streptomycin-resistant Nissle (SYN-UCD103), SYN-UCD205, and SYN-UCD204 under inducing (+ATC) and non-inducing (−ATC) conditions, in the presence (+O 2 ) or absence (−O 2 ) of oxygen. SYN-UCD103 is a control Nissle construct. SYN-UCD205 comprises ArgR and argA fbr  expressed under the control of a FNR-inducible promoter on a low-copy plasmid. SYN204 comprises ΔArgR and argA fbr  expressed under the control of a tetracycline-inducible promoter on a low-copy plasmid. 
         FIG. 26  depicts a bar graph of in vitro ammonia levels in culture media from SYN-UCD101, SYN-UCD102, and blank controls at baseline, two hours, and four hours. Both SYN-UCD101 and SYN-UCD102 are capable of consuming ammonia in vitro. SYN-UCD101 comprises wild type ArgR, and wild type ThyA, and no ArgAFbr; SYN-UCD102 comprises wild type ArgR, tetracycline-inducible argAfbr on a low copy plasmid, and wild type ThyA. 
         FIG. 27  depicts a bar graph of in vitro ammonia levels in culture media from SYN-UCD202, SYN-UCD203, and blank controls at baseline, two hours, and four hours. Both SYN-UCD202 and SYN-UCD203 are capable of consuming ammonia in vitro. SYN-UCD202 and SYN-UCD203 both comprise ΔArgR, tetracycline-inducible argAfbr on a high-copy plasmid or low copy plasmid, respectively, Amp resistance, and wild type ThyA. 
         FIGS. 28A, 28B, and 28C  depict bar graphs of ammonia levels in hyperammonemic TAA mice.  FIG. 28A  depicts a bar graph of ammonia levels in hyperammonemic mice treated with unmodified control Nissle or SYN-UCD202, a genetically engineered strain in which the Arg repressor gene is deleted and the argA fbr  gene is under the control of a tetracycline-inducible promoter on a high-copy plasmid. A total of 96 mice were tested, and the error bars represent standard error. Blood ammonia (BA) levels in mice treated with SYN-UCD202 are lower than ammonia levels in mice treated with unmodified control Nissle at day 4 and day 5 (Nissle, BA=220 mM; SYN-UCD202, BA=105 mM; BA Nissle −BA SYN-UCD202 =115 mM; average blood volume=1.5 mL.  FIG. 28B  depicts a bar graph showing in vivo efficacy (ammonia consumption) of SYN-UCD204 in the TAA mouse model, relative to streptomycin-resistant control Nissle (SYN-UCD103) and vehicle-only controls.  FIG. 28C  depicts a bar graph of the percent change in blood ammonia concentration between 24-48 hours post-TAA treatment. 
         FIG. 29  depicts a bar graph of ammonia levels in hyperammonemic spf ash  mice. Fifty-six spf ash  mice were separated into four groups. Group 1 was fed normal chow, and groups 2-4 were fed 70% protein chow following an initial blood draw. Groups were gavaged twice daily, with water, streptomycin-resistant Nissle control (SYN-UCD103), or SYN-UCD204, and blood was drawn 4 hours following the first gavage. SYN-UCD204, comprising ΔArgR and argA fbr  expressed under the control of a tetracycline-inducible promoter on a low-copy plasmid, significantly reduced blood ammonia to levels below the hyperammonemia threshold. 
         FIG. 30  depicts a bar graph of ammonia levels in hyperammonemic spf ash  mice on a high protein diet. Mice were treated with SYN-UCD204 (comprising ΔArgR, PfnrS-ArgAfbr on a low-copy plasmid and wild type ThyA), SYN-UCD206 (comprising ΔArgR, PfnrS-ArgAfbr on a low-copy plasmid and ΔThyA) or water, then switched to high protein chow after 2 days. As seen in  FIG. 30 , at 48 hours after switch to high protein chow ammonia levels were reduced to a similar extent in both SYN-UCD205 and SYN-UCD206, indicating that ThyA auxotrophy does not have a significant effect on efficacy. 
         FIGS. 31A and 31B  depict bar graphs of ammonia levels in the media at various time points post anaerobic induction.  FIG. 31A  depicts a bar graph of the levels of arginine production of SYN-UCD205, SYN-UCD206, and SYN-UCD301 measured at 0, 30, 60, and 120 minutes.  FIG. 31B  depicts a bar graph of the levels of arginine production of SYN-UCD204 (comprising ΔArgR, PfnrS-ArgAfbr on a low-copy plasmid and wild type ThyA), SYN-UCD301, SYN-UCD302, and SYN-UCD303 (all three of which comprise an integrated FNR-ArgAfbr construct; SYN UCD301 comprises ΔArgR, and wtThyA; SYN 303 comprises ΔArgR, and ΔThyA). Results indicate that chromosomal integration of FNR ArgA fbr results in similar levels of arginine production as seen with the low copy plasmid strains expressing the same construct. 
         FIGS. 32A and 32B  depicts a bar graph of ammonia levels and a survival curve for hyperammonemic spf ash  mice on a normal (NC) or high protein (HP) diet. Two strains with an integrated copy of FNR-ArgAfbr, one with (SYN-UCD303) and one without a ThyA deletion (SYN-UCD301) were compared.  FIG. 32A  depicts a bar graph of ammonia levels in hyperammonemic spf ash  mice on a normal (NC) or high protein (HP) diet. Ammonia levels of spf-ash mice in a high protein diet were reduced in the SYN-UCD301 and SYN-UCD303 groups as compared to the H2O high protein diet control group. The observed reduction in ammonia levels was similar in both SYN-UCD301 and SYN-UCD303, indicating that ThyA auxotrophy does not have a significant effect on efficacy of SYN-UCD303.  FIG. 32B  depicts a survival curve of hyperammonemic spf ash  mice on a normal (NC) or high protein (HP) diet and shows that SYN-UCD301 and SYN-UCD303 displayed prolonged survival as compared to controls. 
         FIG. 33  depicts a graph of blood ammonia levels in an hyperammonemic spf ash  mice on a normal (NC) or high protein (HP) diet. For SYN-UCD303, doses of 1×10 7 , 1×10 8 , 1×10 9 , and 1×10 10  cells were administered daily over a time course of 12 days. Blood ammonia levels were measured on day 5. Both doses of 1×10 8  and 1×10 9  were sufficient to result in a significant reduction of blood ammonia levels in this model. SYN-UCD303 comprises ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and Kanamycin resistance. 
         FIG. 34  depicts a graph of Nissle residence in vivo. Streptomycin-resistant Nissle was administered to mice via oral gavage without antibiotic pre-treatment. Fecal pellets from six total mice were monitored post-administration to determine the amount of administered Nissle still residing within the mouse gastrointestinal tract. The bars represent the number of bacteria administered to the mice. The line represents the number of Nissle recovered from the fecal samples each day for 10 consecutive days. 
         FIGS. 35A, 35B, and 35C  depict bar graphs of bacterial residence in various compartments of the intestinal tract at 1, 4, 8, 12, 24, and 30 hours post gavage. Mice were treated with approximately 10 9  CFU, and at each timepoint, animals (n=4) were euthanized, and intestine, cecum, and colon were removed. The small intestine was cut into three sections, and the large intestine and colon each into two sections. Intestinal effluents gathered and CFUs in each compartment were determined by serial dilution plating.  FIG. 35A  depicts a bar graph of residence over time for SYN-UCD103 (streptomycin resistant Nissle).  FIG. 35B  depicts a bar graph residence over time for SYN-UCD106, comprising ΔArgR and ΔThyA and no ArgAfbr.  FIG. 35C  depicts a bar graph showing residence over time for SYN-UCD303, comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, and ΔThyA. 
         FIGS. 36A, 36B, and 36C  depict bar graphs of viable bacterial cells and arginine production. Cells were either incubated with 70% isopropanol or phosphate buffered saline (PBS) as a control for 1 hour with shaking. After treatment, the cells were mixed at specific ratios in M9 media supplemented with 0.5% glucose and 3 mM thymidine and incubated with shaking at 37 C for 2 hours. As seen in  FIGS. 36A and 36B , a greater ratio of isopropanol treated cells to untreated in a culture results in fewer CFUs as determined by plating, and lower levels of arginine production. Arginine production relative to amount of bacteria present remained constant across the various cultures ( FIG. 36C ). These results indicate that only viable bacteria are contributing to arginine production. 
         FIG. 37 . Depicts the number of bacteria quantified in fecal samples collected in a non-human primate toxicity study. Pharmacokinetics and pharmacodynamics resulting from administration of SYN-UCD107 (a kanamycin resistant Nissle) and SYN-UCD303 (comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and Kanamycin resistance) was compared over 50 days. Results indicate that under these dosing conditions, similar amounts of bacteria were recovered with the auxotroph SYN-UCD303 as control kanamycin resistant Nissle in the feces. Similar results have been observed in mice. 
         FIG. 38  depicts an exemplary synthetic genetic circuit for treating hepatic encephalopathy and other disorders characterized by hyperammonemia. In the ammonia conversion circuit, ammonia is taken up by a bacterium (e.g.,  E. coli  Nissle), converted to glutamate, and glutamate is subsequently metabolized to arginine. Arginine ultimately exits the bacterial cell. 
         FIG. 39  depicts one embodiment of the invention. In this embodiment, the genetically engineered bacteria comprise four exemplary circuits for the treatment of hepatic encephalopathy. In one circuit, ammonia is taken up by the bacterium, converted to glutamate, and glutamate is subsequently metabolized to arginine. Arginine ultimately exits the bacterial cell. In a second circuit, the GABA membrane transport protein (GabP) is expressed by the gabP gene, and facilitates GABA transport into the cell. In a third circuit, the bacterial manganese transport protein (MntH) is expressed by the mntH gene, and facilitates manganese transport into the cell. In a fourth circuit, expression of a butyrate gene cassette results in the production of butyrate, and release of this gut barrier enhancer molecule outside of the cell. In some embodiments, all four circuits are each under the control of the same inducible promoter. In other embodiments, the four circuits may be under the control of different inducible promoters. Exemplary inducible promoters include oxygen level-dependent promoters (e.g., FNR-inducible promoter), promoters induced by HE-specific molecules or metabolites indicative of liver damage (e.g., bilirubin), promoters induced by inflammation or an inflammatory response, and promoters induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose. 
         FIG. 40  depicts one embodiment of the invention. In this embodiment, the genetically engineered bacteria comprise two exemplary circuits for the treatment of hepatic encephalopathy. In one circuit, ammonia is taken up by the bacterium, converted to glutamate, and glutamate is subsequently metabolized to arginine. Arginine ultimately exits the bacterial cell. In a second circuit, the GABA membrane transport protein (GabP) is expressed by the gabP gene, and facilitates GABA transport into the cell. In some embodiments, both circuits are under the control of the same inducible promoter. In other embodiments, the two circuits may each be under the control of a different inducible promoter. Exemplary inducible promoters include oxygen level-dependent promoters (e.g., FNR-inducible promoter), promoters induced by HE-specific molecules or metabolites indicative of liver damage (e.g., bilirubin), promoters induced by inflammation or an inflammatory response, and promoters induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose. In other embodiments, the genetically engineered bacteria may further comprise an additional circuit for reducing the level of GABA, e.g., a circuit for metabolizing (catabolizing) GABA. 
         FIGS. 41A and 41B  depict the catabolism of GABA following uptake into genetically engineered bacteria comprising synthetic genetic circuits. In  FIG. 41A , upon entry into the cell, GABA is converted to succinyl semialdehyde by GABA α-ketoglutarate transaminase (GSST). Succinate-semialdehyde dehydrogenase (SSDH) then catalyzes the second and only other specific step in GABA catabolism, the oxidation of succinyl semialdehyde to succinate. Ultimately, succinate becomes a substrate for the citric acid (TCA) cycle. GOT (glutamate oxaloacetate transaminase) converts alpha-ketoglutarate to glutamate. In certain embodiments, the genetically engineered bacteria of the disclosure comprise a GABA consuming circuit including, but not limited to, one or more of GSST, SSDH, and GOT.  FIG. 41B  depicts a schematic representation of the GABA utilization pathway in  E. coli  Nissle. 
         FIG. 42  depicts one embodiment of the invention. In this embodiment, the genetically engineered bacteria comprise two exemplary circuits for the treatment of hepatic encephalopathy. In one circuit, ammonia is taken up by the bacterium, converted to glutamate, and glutamate is subsequently metabolized to arginine. Arginine ultimately exits the bacterial cell. In a second circuit, the bacterial manganese transport protein (MntH) is expressed by the mntH gene, and facilitates manganese transport into the cell. In some embodiments, both circuits are under the control of the same inducible promoter. In other embodiments, the two circuits may each be under the control of different inducible promoter. Exemplary inducible promoters include oxygen level-dependent promoters (e.g., FNR-inducible promoter), promoters induced by HE-specific molecules or metabolites indicative of liver damage (e.g., bilirubin), promoters induced by inflammation or an inflammatory response, and promoters induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose. 
         FIG. 43  depicts one embodiment of the invention. In this embodiment, the genetically engineered bacteria comprise two exemplary circuits for the treatment of hepatic encephalopathy. In one circuit, ammonia is taken up by the bacterium, converted to glutamate, and glutamate is subsequently metabolized to arginine. Arginine ultimately exits the bacterial cell. In a second circuit, expression of a butyrate gene cassette results in the production of butyrate, and release of this gut barrier enhancer molecule outside of the cell. In some embodiments, both circuits are under the control of the same inducible promoter. In other embodiments, the two circuits may each be under the control of different inducible promoter. Exemplary inducible promoters include oxygen level-dependent promoters (e.g., FNR-inducible promoter), promoters induced by HE-specific molecules or metabolites indicative of liver damage (e.g., bilirubin), promoters induced by inflammation or an inflammatory response, and promoters induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose. One or more of the butyrate cassettes described herein may be expressed by the genetically engineered bacteria comprising an arginine (and/or citrulline) producing circuit. 
         FIG. 44  depicts an exemplary schematic of the  E. coli  1917 Nissle chromosome comprising multiple mechanisms of action (MoAs). 
         FIG. 45  depicts an exemplary schematic of the  E. coli  1917 Nissle chromosome comprising multiple MoAs. In some embodiments, an ammonia conversion circuit, a butyrate production circuit, a GABA transport and/or a GABA metabolic circuit, and a manganese transport circuit are inserted at four or more different chromosomal insertion sites 
         FIGS. 46A and 46B  depict—an exemplary schematic of the  E. coli  1917 Nissle chromosome comprising multiple MoAs. In  FIG. 46A , an ammonia conversion circuit, a butyrate production circuit, and a GABA transport and/or GABA metabolic circuit are inserted at three different chromosomal insertion sites. In  FIG. 46B , an ammonia conversion circuit, a GABA transport and/or GABA metabolic circuit, and a manganese transport circuit are inserted at three or more different chromosomal insertion sites. 
         FIGS. 47A and 47B  depict—an exemplary schematic of the  E. coli  1917 Nissle chromosome comprising multiple MoAs. In  FIG. 47A , an ammonia conversion circuit, and a manganese transport circuit are inserted at two different chromosomal insertion sites. In  FIG. 47B , an ammonia conversion circuit, and a GABA transport and/or GABA metabolic circuit are inserted at two or more different chromosomal insertion sites. 
         FIG. 48A  depicts a metabolic pathway for butyrate production  FIGS. 48B and 48C  depict two schematics of two different butyrate producing circuits (found in SYN-UCD503 and SYN-UCD504), both under the control of a tetracycline inducible promoter.  FIG. 48D  depicts a schematic of a third butyrate gene cassette (found in SYN-UCD505) under the control of a tetracycline inducible promoter. SYN-UCD503 comprises a bdc2 butyrate cassette under control of tet promoter on a plasmid. A “bdc2 cassette” or “bdc2 butyrate cassette” refres to a butyrate producing cassette that comprises at least the following genes: bcd2, etfB3, etfA3, hbd, crt2, pbt, and buk genes. SYN-UCD504 comprises a ter butyrate cassette (ter gene replaces the bcd2, etfB3, and etfA3 genes) under control of tet promoter on a plasmid. A “ter cassette” or “ter butyrate cassette” refers to a butyrate producing cassete that comprises at least the following genes: ter, thiA1, hbd, crt2, pbt, buk. SYN-UCD505 comprises a tesB butyrate cassette (ter gene is present and tesB gene replaces the pbt gene and the buk gene) under control of tet promoter on a plasmid. A “tes or tesB cassette or “tes or tesB butyrate cassette” refers to a butyrate producing cassette that comprises at least ter, thiA1, hbd, crt2, and tesB genes. An alternative butyrate cassette of the disclosure comprises at least bcd2, etfB3, etfA3, thiA1, hbd, crt2, and tesB genes. In some embodiments, the tes or tesB cassette is under control of an inducible promoter other than tetracycline. Exemplary inducible promoters which may control the expression of the tesB cassette include oxygen level-dependent promoters (e.g., FNR-inducible promoter), promoters induced by HE-specific molecules or metabolites indicative of liver damage (e.g., bilirubin), promoters induced by inflammation or an inflammatory response (RNS, ROS promoters), and promoters induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose and tetracycline. 
         FIGS. 49A-F  depict the gene organization of exemplary engineered bacteria of the disclosure and their induction under anaerobic or inflammatory conditions for the production of butyrate.  FIGS. 49A and 49B  depict the gene organization of an exemplary recombinant bacterium of the invention and its induction under low-oxygen conditions.  FIG. 49A  depicts relatively low butyrate production under aerobic conditions in which oxygen (02) prevents (indicated by “X”) FNR (grey boxed “FNR”) from dimerizing and activating the FNR-responsive promoter (“FNR promoter”). Therefore, none of the butyrate biosynthesis enzymes (bcd2, etfB3, etfA3, thiA1, hbd, crt2, pbt, and buk; black boxes) is expressed.  FIG. 49B  depicts increased butyrate production under low-oxygen conditions due to FNR dimerizing (two grey boxed “FNR”s), binding to the FNR-responsive promoter, and inducing expression of the butyrate biosynthesis enzymes, which leads to the production of butyrate.  FIGS. 49C and 49D  depict the gene organization of an exemplary recombinant bacterium of the invention and its derepression in the presence of nitric oxide (NO). In  FIG. 49C , in the absence of NO, the NsrR transcription factor (gray circle, “NsrR”) binds to and represses a corresponding regulatory region. Therefore, none of the butyrate biosynthesis enzymes (bcd2, etfB3, etfA3, thiA1, hbd, crt2, pbt, buk; black boxes) is expressed. In  FIG. 49D , in the presence of NO, the NsrR transcription factor interacts with NO, and no longer binds to or represses the regulatory sequence. This leads to expression of the butyrate biosynthesis enzymes (indicated by gray arrows and black squiggles) and ultimately to the production of butyrate.  FIGS. 49E  and F depict the gene organization of an exemplary recombinant bacterium of the invention and its induction in the presence of H2O2. In  FIG. 49E , in the absence of H2O2, the OxyR transcription factor (gray circle, “OxyR”) binds to, but does not induce, the oxyS promoter. Therefore, none of the butyrate biosynthesis enzymes (bcd2, etfB3, etfA3, thiA1, hbd, crt2, pbt, buk; black boxes) is expressed. In  FIG. 49F , in the presence of H2O2, the OxyR transcription factor interacts with H2O2 and is then capable of inducing the oxyS promoter. This leads to expression of the butyrate biosynthesis enzymes (indicated by gray arrows and black squiggles) and ultimately to the production of butyrate. 
         FIGS. 50A-F  depict the gene organization of exemplary recombinant bacteria of the disclosure and their induction under anaerobic or inflammatory conditions for the production of butyrate.  FIGS. 50A and 50B  depict the gene organization of an exemplary recombinant bacterium of the invention and its induction under low-oxygen conditions.  FIG. 50A  depicts relatively low butyrate production under aerobic conditions in which oxygen (O 2 ) prevents (indicated by “X”) FNR (grey boxed “FNR”) from dimerizing and activating the FNR-responsive promoter (“FNR promoter”). Therefore, none of the butyrate biosynthesis enzymes (ter, thiA1, hbd, crt2, pbt, and buk; black boxes) is expressed.  FIG. 50B  depicts increased butyrate production under low-oxygen conditions due to FNR dimerizing (two grey boxed “FNR”s), binding to the FNR-responsive promoter, and inducing expression of the butyrate biosynthesis enzymes, which leads to the production of butyrate.  FIGS. 50C and 50D  depict the gene organization of another exemplary recombinant bacterium of the invention and its derepression in the presence of NO. In  FIG. 50C , in the absence of NO, the NsrR transcription factor (gray circle, “NsrR”) binds to and represses a corresponding regulatory region. Therefore, none of the butyrate biosynthesis enzymes (ter, thiA1, hbd, crt2, pbt, buk; black boxes) is expressed. In  FIG. 50D , in the presence of NO, the NsrR transcription factor interacts with NO, and no longer binds to or represses the regulatory sequence. This leads to expression of the butyrate biosynthesis enzymes (indicated by gray arrows and black squiggles) and ultimately to the production of butyrate.  FIGS. 50E and 50F  depict the gene organization of another exemplary recombinant bacterium of the invention and its induction in the presence of H 2 O 2 . In  FIG. 50E , in the absence of H 2 O 2 , the OxyR transcription factor (gray circle, “OxyR”) binds to, but does not induce, the oxyS promoter. Therefore, none of the butyrate biosynthesis enzymes (ter, thiA1, hbd, crt2, pbt, buk; black boxes) is expressed. In  FIG. 50F , in the presence of H 2 O 2 , the OxyR transcription factor interacts with H 2 O 2  and is then capable of inducing the oxyS promoter. This leads to expression of the butyrate biosynthesis enzymes (indicated by gray arrows and black squiggles) and ultimately to the production of butyrate. 
         FIGS. 51A and 51B  depict a graph of butyrate production using the circuits (SYN-UCD-503, SYN-UCD-504, SYN-UCD-505) shown in  FIGS. 48B-D . Cells were grown in M9 minimal media containing 0.2% glucose and induced with ATC at early log phase. As seen in  FIG. 51A , similar amounts of butyrate were produced for each construct under aerobic vs anaerobic conditions. The ter strain produces more butyrate overall. SYN-UCD503 comprises pLogic031 (bdc2 butyrate cassette under control of tet promoter on a plasmid) and SYN-UCD504 comprises pLogic046 (ter butyrate cassette under control of tet promoter on a plasmid).  FIG. 51B  depicts butyrate production of SYN-UCD504 (pLogic046 (ter butyrate cassette under control of tet promoter on a plasmid)) and SYN-UCD505 (a Nissle strain comprising plasmid pLOGIC046-delta pbt.buk/tesB+, an ATC-inducible ter-comprising butyrate construct with a deletion in the pbt-buk genes and their replacement with the tesB gene). The tesB construct results in greater butyrate production. 
         FIG. 52  depicts a graph of butyrate production using different butyrate-producing circuits comprising a nuoB gene deletion. Strains depicted are SYN-UCD503, SYN-UCD504, SYN-UCD510 (SYN-UCD510 is the same as SYN-UCD503 except that it further comprises a nuoB deletion), and SYN-UCD511 (SYN-UCD511 is the same as SYN-UCD504 except that it further comprises a nuoB deletion). The NuoB gene deletion results in greater levels of butyrate production as compared to a wild-type parent control in butyrate producing strains. NuoB is a main protein complex involved in the oxidation of NADH during respiratory growth. In some embodiments, preventing the coupling of NADH oxidation to electron transport increases the amount of NADH being used to support butyrate production. 
         FIG. 53A  depicts a schematic of a butyrate producing circuit under the control of an FNR promoter.  FIG. 53B  depicts a bar graph of anaerobic induction of butyrate production. FNR-responsive promoters were fused to butyrate cassettes containing either the bcd or ter circuits. Transformed cells were grown in LB to early log and placed in anaerobic chamber for 4 hours to induce expression of butyrate genes. Cells were washed and resuspended in minimal media w/ 0.5% glucose and incubated microaerobically to monitor butyrate production over time. SYN-UCD501 led to significant butyrate production under anaerobic conditions.  FIG. 53C  depicts SYN-UCD501 in the presence and absence of glucose and oxygen in vitro. SYN-UCD501 comprises pSC101 PydfZ-ter butyrate plasmid; SYN-UCD500 comprises pSC101 PydfZ-bcd butyrate plasmid; SYN-UCD506 comprises pSC101 nirB-bcd butyrate plasmid.  FIG. 53D  depicts levels of mouse lipocalin 2 and calprotectin quantified by ELISA using the fecal samples in an in vivo model of HE. SYN-UCD501 reduces inflammation and/or protects gut barrier function as compared to control SYN-UCD103. 
         FIGS. 54A and 54B  depict bar graphs showing in vitro arginine ( FIG. 54A ) and butyrate ( FIG. 54B ) production for (1) butyrate producing strain; (2) arginine producing strain (ammonia consuming strain), and (3) strain that produces butyrate and also consumes ammonia. SYN-UCD501 (butyrate producing strain comprising Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance)), and SYN-UCD305 (arginine producing/ammonia consuming strain comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, and ΔThyA, with no antibiotic resistance), and SYN-UCD601 (butyrate producing and arginine producing/ammonia consuming strain comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance)). The data show that SYN-UCD601 is able to produce similar levels of arginine as SYN-UCD305 and similar levels of butyrate as SYN-UCD501 in vitro. 
         FIGS. 55A and 55B  depict the gene organization of an exemplary engineered bacterium of the invention and its induction under low-oxygen conditions for the production of propionate.  FIG. 55A  depicts relatively low propionate production under aerobic conditions in which oxygen (O 2 ) prevents (indicated by “X”) FNR (grey boxed “FNR”) from dimerizing and activating the FNR-responsive promoter (“FNR promoter”). Therefore, none of the propionate biosynthesis enzymes (pct, lcdA, lcdB, lcdC, etfA, acre, acrC; black boxes) are expressed.  FIG. 55B  depicts increased propionate production under low-oxygen conditions due to FNR dimerizing (two grey boxed “FNR”s), binding to the FNR-responsive promoter, and inducing expression of the propionate biosynthesis enzymes, which leads to the production of propionate. 
         FIG. 56  depicts an exemplary propionate biosynthesis gene cassette. 
         FIGS. 57A, 57B and 57C  depict the gene organization of an exemplary engineered bacterium and its induction under low-oxygen conditions for the production of propionate.  FIG. 57A  depicts relatively low propionate production under aerobic conditions in which oxygen (O 2 ) prevents (indicated by “X”) FNR (grey boxed “FNR”) from dimerizing and activating the FNR-responsive promoter (“FNR promoter”). Therefore, none of the propionate biosynthesis enzymes (thrA, thrB, thrC, ilvA, aceE, aceF, lpd; black boxes) are expressed.  FIG. 57B  depicts increased propionate production under low-oxygen conditions due to FNR dimerizing (two grey boxed “FNR”s), binding to the FNR-responsive promoter, and inducing expression of the propionate biosynthesis enzymes, which leads to the production of propionate.  FIG. 57C  depicts an exemplary propionate biosynthesis gene cassette. 
         FIGS. 58A and 58B  depict the gene organization of an exemplary engineered bacterium of the invention and its induction under low-oxygen conditions for the production of propionate.  FIG. 58A  depicts relatively low propionate production under aerobic conditions in which oxygen (O 2 ) prevents (indicated by “X”) FNR (grey boxed “FNR”) from dimerizing and activating the FNR-responsive promoter (“FNR promoter”). Therefore, none of the propionate biosynthesis enzymes (thrA, thrB, thrC, ilvA, aceE, aceF, lpd, tesB; black boxes) are expressed.  FIG. 58B  depicts increased propionate production under low-oxygen conditions due to FNR dimerizing (two grey boxed “FNR”s), binding to the FNR-responsive promoter, and inducing expression of the propionate biosynthesis enzymes, which leads to the production of propionate. 
         FIG. 59  depicts an exemplary propionate biosynthesis gene cassette. 
         FIGS. 60A and 60B  depict diagrams of exemplary constructs which may be used to produce a positive feedback auxotroph and select for high arginine production.  FIG. 60A  depicts a map of the astC promoter driving expression of thyA.  FIG. 60B  depicts a schematic diagram of the thyA gene under the control of an astC promoter. The regulatory region comprises binding sites for CRP, ArgR, and RNA polymerase (RNAP), and may also comprise additional regulatory elements. 
         FIG. 61  depicts another exemplary embodiment of an engineered bacterial strain to target urea cycle disorder (UCD), via the conversion of ammonia to desired products, such as citrulline or arginine. The strain is deleted for the argR gene and expressing the feedback-resistant argAfbr gene. In some embodiments, this strain further comprises one or more auxotrophic modifications on the chromosome. The synthetic biotic engineered to target urea cycle disorder (UCD) also has the kill-switch embodiment described in  FIG. 65 . In this example, the Int recombinase and the Kid-Kis toxin-antitoxin system are used in a recombinant bacterial cell for treating UCD. The recombinant bacterial cell is engineered to consume excess ammonia to produce beneficial byproducts to improve patient outcomes. The recombinant bacterial cell also comprises a highly controllable kill switch to ensure safety. In response to a low oxygen environment (e.g., such as that found in the gut), the FNR promoter induces expression of the Int recombinase and also induces expression of the Kis anti-toxin. The Int recombinase causes the Kid toxin gene to flip into an activated conformation, but the presence of the accumulated Kis anti-toxin suppresses the activity of the expressed Kid toxin. In the presence of oxygen (e.g., outside the gut), expression of the anti-toxin is turned off. Since the toxin is constitutively expressed, it continues to accumulate and kills the bacterial cell. 
         FIG. 62  depicts one non-limiting embodiment of the disclosure, where an exogenous environmental condition or one or more environmental signals activates expression of a heterologous gene and at least one recombinase from an inducible promoter or inducible promoters. The recombinase then flips a toxin gene into an activated conformation, and the natural kinetics of the recombinase create a time delay in expression of the toxin, allowing the heterologous gene to be fully expressed. Once the toxin is expressed, it kills the cell. 
         FIG. 63  depicts another non-limiting embodiment of the disclosure, where an exogenous environmental condition or one or more environmental signals activates expression of a heterologous gene, an anti-toxin, and at least one recombinase from an inducible promoter or inducible promoters. The recombinase then flips a toxin gene into an activated conformation, but the presence of the accumulated anti-toxin suppresses the activity of the toxin. Once the exogenous environmental condition or cue(s) is no longer present, expression of the anti-toxin is turned off. The toxin is constitutively expressed, continues to accumulate, and kills the bacterial cell. 
         FIG. 64  depicts another non-limiting embodiment of the disclosure, where an exogenous environmental condition or one or more environmental signals activates expression of a heterologous gene and at least one recombinase from an inducible promoter or inducible promoters. The recombinase then flips at least one excision enzyme into an activated conformation. The at least one excision enzyme then excises one or more essential genes, leading to senescence, and eventual cell death. The natural kinetics of the recombinase and excision genes cause a time delay, the kinetics of which can be altered and optimized depending on the number and choice of essential genes to be excised, allowing cell death to occur within a matter of hours or days. The presence of multiple nested recombinases can be used to further control the timing of cell death. 
         FIG. 65  depicts a schematic of an activation-based kill switch, in which R is any inducible promoter, e.g., a FNR-responsive promoter. When the therapeutic is induced, the anti-toxin and recombinases are turned on, which results in the toxin being ‘flipped’ to the ON position after 4-6 hours, which results in a build-up of anti-toxin before the toxin is expressed. In absence of the inducing signal, only toxin is made and the cell dies. 
       Hyperammonemia can also contribute to other pathologies.  FIG. 66A  depicts another non-limiting embodiment of the disclosure, wherein the expression of a heterologous gene is activated by an exogenous environmental signal. In the absence of arabinose, the AraC transcription factor adopts a conformation that represses transcription. In the presence of arabinose, the AraC transcription factor undergoes a conformational change that allows it to bind to and activate the ParaBAD promoter (P araBAD ), which induces expression of the Tet repressor (TetR) and an anti-toxin. The anti-toxin builds up in the recombinant bacterial cell, while TetR prevents expression of a toxin (which is under the control of a promoter having a TetR binding site). However, when arabinose is not present, both the anti-toxin and TetR are not expressed. Since TetR is not present to repress expression of the toxin, the toxin is expressed and kills the cell.  FIG. 66A  also depicts another non-limiting embodiment of the disclosure, wherein the expression of an essential gene not found in the recombinant bacteria is activated by an exogenous environmental signal. In the absence of arabinose, the AraC transcription factor adopts a conformation that represses transcription of the essential gene under the control of the araBAD promoter and the bacterial cell cannot survive. In the presence of arabinose, the AraC transcription factor undergoes a conformational change that allows it to bind to and activate the araBAD promoter, which induces expression of the essential gene and maintains viability of the bacterial cell. 
         FIG. 66B  depicts a non-limiting embodiment of the disclosure, where an anti-toxin is expressed from a constitutive promoter, and expression of a heterologous gene is activated by an exogenous environmental signal. In the absence of arabinose, the AraC transcription factor adopts a conformation that represses transcription. In the presence of arabinose, the AraC transcription factor undergoes a conformational change that allows it to bind to and activate the araBAD promoter, which induces expression of TetR, thus preventing expression of a toxin. However, when arabinose is not present, TetR is not expressed, and the toxin is expressed, eventually overcoming the anti-toxin and killing the cell. The constitutive promoter regulating expression of the anti-toxin should be a weaker promoter than the promoter driving expression of the toxin. The araC gene is under the control of a constitutive promoter in this circuit.  FIG. 66C  depicts another non-limiting embodiment of the disclosure, wherein the expression of a heterologous gene is activated by an exogenous environmental signal. In the absence of arabinose, the AraC transcription factor adopts a conformation that represses transcription. In the presence of arabinose, the AraC transcription factor undergoes a conformational change that allows it to bind to and activate the araBAD promoter, which induces expression of the Tet repressor (TetR) and an anti-toxin. The anti-toxin builds up in the recombinant bacterial cell, while TetR prevents expression of a toxin (which is under the control of a promoter having a TetR binding site). However, when arabinose is not present, both the anti-toxin and TetR are not expressed. Since TetR is not present to repress expression of the toxin, the toxin is expressed and kills the cell. The araC gene is either under the control of a constitutive promoter or an inducible promoter (e.g., AraC promoter) in this circuit. 
         FIG. 67  depicts the use of GeneGuards as an engineered safety component. All engineered DNA is present on a plasmid which can be conditionally destroyed. See, e.g., Wright et al., “GeneGuard: A Modular Plasmid System Designed for Biosafety,” ACS Synthetic Biology (2015) 4: 307-316. 
         FIG. 68  depicts a one non-limiting embodiment of the disclosure, which comprises a plasmid stability system with a plasmid that produces both a short-lived anti-toxin and a long-lived toxin. When the cell loses the plasmid, the anti-toxin is no longer produced, and the toxin kills the cell. In one embodiment, the genetically engineered bacteria produce an equal amount of a Hok toxin and a short-lived Sok antitoxin. In the upper panel, the cell produces equal amounts of toxin and anti-toxin and is stable. In the center panel, the cell loses the plasmid and anti-toxin begins to decay. In the lower panel, the anti-toxin decays completely, and the cell dies. 
         FIG. 69  depicts a schematic of a secretion system based on the flagellar type III secretion in which an incomplete flagellum is used to secrete a therapeutic peptide of interest (star) by recombinantly fusing the peptide to an N-terminal flagellar secretion signal of a native flagellar component so that the intracellularly expressed chimeric peptide can be mobilized across the inner and outer membranes into the surrounding host environment. 
         FIG. 70  depicts a schematic of a type V secretion system for the extracellular production of recombinant proteins in which a therapeutic peptide (star) can be fused to an N-terminal secretion signal, a linker and the beta-domain of an autotransporter. In this system, the N-terminal signal sequence directs the protein to the SecA-YEG machinery which moves the protein across the inner membrane into the periplasm, followed by subsequent cleavage of the signal sequence. The beta-domain is recruited to the Bam complex where the beta-domain is folded and inserted into the outer membrane as a beta-barrel structure. The therapeutic peptide is then thread through the hollow pore of the beta-barrel structure ahead of the linker sequence. The therapeutic peptide is freed from the linker system by an autocatalytic cleavage or by targeting of a membrane-associated peptidase (scissors) to a complementary protease cut site in the linker. 
         FIG. 71  depicts a schematic of a type I secretion system, which translocates a passenger peptide directly from the cytoplasm to the extracellular space using HlyB (an ATP-binding cassette transporter); HlyD (a membrane fusion protein); and TolC (an outer membrane protein) which form a channel through both the inner and outer membranes. The secretion signal-containing C-terminal portion of HlyA is fused to the C-terminal portion of a therapeutic peptide (star) to mediate secretion of this peptide. 
         FIG. 72  depicts a schematic of the outer and inner membranes of a gram-negative bacterium, and several deletion targets for generating a leaky or destabilized outer membrane, thereby facilitating the translocation of a therapeutic polypeptides to the extracellular space, e.g., therapeutic polypeptides of eukaryotic origin containing disulphide bonds. Deactivating mutations of one or more genes encoding a protein that tethers the outer membrane to the peptidoglycan skeleton, e.g., lpp, ompC, ompA, ompF, tolA, toIB, pal, and/or one or more genes encoding a periplasmic protease, e.g., degS, degP, nlpI, generates a leaky phenotype. Combinations of mutations may synergistically enhance the leaky phenotype. 
         FIG. 73  depicts a modified type 3 secretion system (T3SS) to allow the bacteria to inject secreted therapeutic proteins into the gut lumen. An inducible promoter (small arrow, top), e.g. a FNR-inducible promoter, drives expression of the T3 secretion system gene cassette (3 large arrows, top) that produces the apparatus that secretes tagged peptides out of the cell. An inducible promoter (small arrow, bottom), e.g. a FNR-inducible promoter, drives expression of a regulatory factor, e.g. T7 polymerase, that then activates the expression of the tagged therapeutic peptide (hexagons). 
         FIG. 74  depicts an exemplary L-homoserine and L-methionine biosynthesis pathway. Circles indicate genes repressed by MetJ, and deletion of metJ leads to constitutive expression of these genes and activation of the pathway. 
         FIG. 75  depicts an exemplary histidine biosynthesis pathway. 
         FIG. 76  depicts an exemplary lysine biosynthesis pathway. 
         FIG. 77  depicts an exemplary asparagine biosynthesis pathway. 
         FIG. 78  depicts an exemplary glutamine biosynthesis pathway. 
         FIG. 79  depicts an exemplary tryptophan biosynthesis pathway. 
         FIG. 80  depicts a schematic of non-limiting processes for designing and producing the genetically engineered bacteria of the present disclosure. The step of “defining” comprises 1. Identification of diverse candidate approaches based on microbial physiology and disease biology; 2. Use of bioinformatics to determine candidate metabolic pathways; the use of prospective tools to determine performance targets required of optimized engineered synthetic biotics. The step of “designing” comprises the use of 1. Cutting-edge DNA assembly to enable combinatorial testing of pathway organization; 2. Mathematical models to predict pathway efficiency; 3. Internal stable of proprietary switches and parts to permit control and tuning of engineered circuits. The step of “Builing” comprises 1. Building core structures “chassies” 2. Stably integrating engineered circuits into optimal chromosomal locations for efficient expression; 3. Employing unique functional assays to assess genetic circuit fidelity and activity. The step of “integrating” comprises 1. Use of chromosomal markers, which enable monitoring of synthetic biotic localization and transit times in animal models; 2. Leveraging expert microbiome network and bioinformatics support to expand understanding of how specific disease states affect GI microbial flora and the behaviors of synthetic biotics in that environment; 3. Activating process development research and optimization in-house during the discovery phase, enabling rapid and seamless transition of development candidates to pre-clinical progression; Drawing upon extensive experience in specialized disease animal model refinement, which supports prudent, high quality testing of candidate synthetic biotics. 
         FIGS. 81A , B, C, D, and E depict a schematic of non-limiting manufacturing processes for upstream and downstream production of the genetically engineered bacteria of the present disclosure.  FIG. 81A  depicts the parameters for starter culture 1 (SC1): loop full—glycerol stock, duration overnight, temperature 37° C., shaking at 250 rpm.  FIG. 81B  depicts the parameters for starter culture 2 (SC2): 1/100 dilution from SC1, duration 1.5 hours, temperature 37° C., shaking at 250 rpm.  FIG. 81C  depicts the parameters for the production bioreactor: inoculum—SC2, temperature 37° C., pH set point 7.00, pH dead band 0.05, dissolved oxygen set point 50%, dissolved oxygen cascade agitation/gas FLO, agitation limits 300-1200 rpm, gas FLO limits 0.5-20 standard liters per minute, duration 24 hours.  FIG. 81D  depicts the parameters for harvest: centrifugation at speed 4000 rpm and duration 30 minutes, wash 1×10% glycerol/PBS, centrifugation, re-suspension 10% glycerol/PBS.  FIG. 81E  depicts the parameters for vial fill/storage: 1-2 mL aliquots, −80° C. 
         FIGS. 82A-C  depict ATC ( FIG. 82A ) or nitric oxide-inducible ( FIG. 82B ) reporter constructs. These constructs, when induced by their cognate inducer, lead to expression of GFP. Nissle cells harboring plasmids with either the control, ATC-inducible P tet -GFP reporter construct or the nitric oxide inducible P nsrR -GFP reporter construct induced across a range of concentrations. Promoter activity is expressed as relative florescence units.  FIG. 82C  depicts a schematic of the constructs. 
         FIG. 83  depicts a dot blot of bacteria harboring a plasmid expressing NsrR under control of a constitutive promoter and the reporter gene gfp (green fluorescent protein) under control of an NsrR-inducible promoter. DSS-treated mice serve as exemplary models for HE. As in HE subjects, the guts of mice are damaged by supplementing drinking water with 2-3% dextran sodium sulfate (DSS). Chemiluminescent is shown for NsrR-regulated promoters induced in DSS-treated mice. 
         FIG. 84  depicts butyrate production by genetically engineered Nissle comprising the pLogic031-nsrR-norB-butyrate construct (SYN-UCD507) or the pLogic046-nsrR-norB-butyrate construct (SYN-UCD508), which produce more butyrate as compared to wild-type Nissle. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The invention includes genetically engineered bacteria, pharmaceutical compositions thereof, and methods of modulating or treating disorders associated with hyperammonemia, e.g., urea cycle disorders, hepatic encephalopathy and other disorders associated with excess ammonia or elevated ammonia levels. The genetically engineered bacteria are capable of reducing excess ammonia, particularly under certain environmental conditions, such as those in the mammalian gut. In some embodiments, the genetically engineered bacteria reduce excess ammonia by incorporating excess nitrogen in the body into non-toxic molecules, e.g., arginine, citrulline, methionine, histidine, lysine, asparagine, glutamine, or tryptophan. In some embodiments, the genetically engineered bacteria reduce excess ammonia and also reduce one or more other toxic substances, e.g., GABA and/or manganese. In some embodiments, the genetically engineered bacteria reduce excess ammonia and also reduce GABA levels, e.g., by importing GABA and/or by metabolizing GABA. In some embodiments, the genetically engineered bacteria reduce excess ammonia and also reduce manganese levels, e.g., by importing manganese. The genetically engineered bacteria may additionally produce one or molecules that improve gut barrier function or otherwise alleviate a symptom of a disorder associated with elevated ammonia (e.g., UCDs, HE, etc). Thus, in any of the described embodiments, the genetically engineered bacteria may also produce one or molecules that improve gut barrier function or otherwise alleviate a symptom of a disorder associated with elevated ammonia. In some embodiments, the genetically engineered bacteria produce a short chain fatty acid, e.g., butyrate, propionate, and/or acetate. In some embodiments, the engineered bacteria reduce excess ammonia and produce one or molecules that improve gut barrier function or otherwise alleviate a symptom of a disorder associated with elevated ammonia, e.g., produce a short chain fatty acid, such as butyrate, propionate, and/or acetate. In some embodiments, the engineered bacteria reduce excess ammonia, reduce one or more other toxic substances, e.g., GABA and/or manganese, and produce one or molecules that improve gut barrier function or alleviate a symptom of a disorder associated with elevated ammonia, e.g., produce a short chain fatty acid, such as butyrate, propionate, and/or acetate. In some embodiments, the genetically engineered bacteria reduce excess ammonia, reduce GABA levels, e.g., by importing GABA and/or by metabolizing GABA, and produce one or molecules that improve gut barrier function or alleviate a symptom of a disorder associated with elevated ammonia, e.g., produce a short chain fatty acid, such as butyrate, propionate, and/or acetate. In some embodiments, the genetically engineered bacteria reduce excess ammonia, reduce manganese levels, e.g., by importing manganese, and produce one or molecules that improve gut barrier function or alleviate a symptom of a disorder associated with elevated ammonia, e.g., produce a short chain fatty acid, such as butyrate, propionate, and/or acetate. 
     In any of the described embodiments, the engineered bacteria may further comprise one or more of more of the following: (1) one or more auxotrophies, such as any auxotrophies known in the art and provided herein, e.g., thyA auxotrophy, (2) one or more kill switch circuits, such as any of the kill-switches described herein or otherwise known in the art, (3) one or more antibiotic resistance circuits, (4) one or more transporters for importing biological molecules or substrates, such any of the transporters described herein or otherwise known in the art, (5) one or more secretion circuits, such as any of the secretion circuits described herein and otherwise known in the art, and (6) combinations of one or more of such additional circuits. 
     In some embodiments, any one or more of the payload or therapeutic circuits (e.g., ammonia consuming, GABA reducing, manganese reducing, short chain fatty acid producing circuits) and/or any one or more of the additional circuits (e.g., auxotrophies, kill switch circuits, antibiotic resistance circuits, transporters, and secretion circuits) may be regulated by a constitutive promoter. In some embodiments, any one or more of the payload or therapeutic circuits (e.g., ammonia consuming, GABA reducing, manganese reducing, short chain fatty acid producing circuits) and/or any one or more of the additional circuits (e.g., auxotrophies, kill switch circuits, antibiotic resistance circuits, transporters, and secretion circuits) may be regulated by a tissue-specific promoter. In some embodiments, any one or more of the payload or therapeutic circuits (e.g., ammonia consuming, GABA reducing, manganese reducing, short chain fatty acid producing circuits) and/or any one or more of the additional circuits (e.g., auxotrophies, kill switch circuits, antibiotic resistance circuits, transporters, and secretion circuits) may be regulated by an inducible promoter. In some embodiments, any one or more of the payload or therapeutic circuits (e.g., ammonia consuming, GABA reducing, manganese reducing, short chain fatty acid producing circuits) and/or any one or more of the additional circuits (e.g., auxotrophies, kill switch circuits, antibiotic resistance circuits, transporters, and secretion circuits) may be regulated by an inducible promoter that is responsive to environmental conditions, factors, or cues, e.g., environmental conditions, factors, or cues found in the mammalian gut. Exemplary inducible promoters include oxygen level-dependent promoters (e.g., FNR-inducible promoter), promoters induced by HE-specific molecules or metabolites indicative of liver damage (e.g., bilirubin), promoters induced by inflammation or an inflammatory response (RNS, ROS promoters), and promoters induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose and tetracycline. 
     In some embodiments, any one or more of the payload or therapeutic circuits (e.g., ammonia consuming, GABA reducing, manganese reducing, short chain fatty acid producing circuits) and/or any one or more of the additional circuits (e.g., auxotrophies, kill switch circuits, antibiotic resistance circuits, transporters, and secretion circuits) may be present on one or more low copy or high copy plasmids. In some embodiments, any one or more of the payload or therapeutic circuits (e.g., ammonia consuming, GABA reducing, manganese reducing, short chain fatty acid producing circuits) and/or any one or more of the additional circuits (e.g., auxotrophies, kill switch circuits, antibiotic resistance circuits, transporters, and secretion circuits) may be integrated into the bacterial chromosome. In order that the disclosure may be more readily understood, certain terms are first defined. These definitions should be read in light of the remainder of the disclosure and as understood by a person of ordinary skill in the art. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art. Additional definitions are set forth throughout the detailed description. 
     “Hyperammonemia,” “hyperammonemic,” or “excess ammonia” is used to refer to increased concentrations of ammonia in the body. Hyperammonemia is caused by decreased detoxification and/or increased production of ammonia. Decreased detoxification may result from urea cycle disorders (UCDs), such as argininosuccinic aciduria, arginase deficiency, carbamoylphosphate synthetase deficiency, citrullinemia, N-acetylglutamate synthetase deficiency, and ornithine transcarbamylase deficiency; or from bypass of the liver, e.g., open ductus hepaticus; and/or deficiencies in glutamine synthetase (Hoffman et al., 2013; Häberle et al., 2013). Decreased detoxification may also result from liver disorders such as hepatic encephalopathy, acute liver failure, or chronic liver failure; and neurodegenerative disorders such as Huntington&#39;s disease (Chen et al., 2015; Chiang et al., 2007). Increased production of ammonia may result from infections, drugs, neurogenic bladder, and intestinal bacterial overgrowth (Häberle et al., 2013). Other disorders and conditions associated with hyperammonemia include, but are not limited to, liver disorders such as hepatic encephalopathy, acute liver failure, or chronic liver failure; organic acid disorders; isovaleric aciduria; 3-methylcrotonylglycinuria; methylmalonic acidemia; propionic aciduria; fatty acid oxidation defects; carnitine cycle defects; carnitine deficiency; β-oxidation deficiency; lysinuric protein intolerance; pyrroline-5-carboxylate synthetase deficiency; pyruvate carboxylase deficiency; ornithine aminotransferase deficiency; carbonic anhydrase deficiency; hyperinsulinism-hyperammonemia syndrome; mitochondrial disorders; valproate therapy; asparaginase therapy; total parenteral nutrition; cystoscopy with glycine-containing solutions; post-lung/bone marrow transplantation; portosystemic shunting; urinary tract infections; ureter dilation; multiple myeloma; and chemotherapy (Hoffman et al., 2013; Häberle et al., 2013; Pham et al., 2013; Lazier et al., 2014). In healthy subjects, plasma ammonia concentrations are typically less than about 50 μmol/L (Leonard, 2006). In some embodiments, a diagnostic signal of hyperammonemia is a plasma ammonia concentration of at least about 50 μmol/L, at least about 80 μmol/L, at least about 150 μmol/L, at least about 180 μmol/L, or at least about 200 μmol/L (Leonard, 2006; Hoffman et al., 2013; Häberle et al., 2013). 
     “Ammonia” is used to refer to gaseous ammonia (NH 3 ), ionic ammonia (NH 4   + ), or a mixture thereof. In bodily fluids, gaseous ammonia and ionic ammonium exist in equilibrium: 
       NH 3 +H + ↔NH 4   + 
 
     Some clinical laboratory tests analyze total ammonia (NH 3 +NH 4   + ) (Walker, 2012). In any embodiment of the invention, unless otherwise indicated, “ammonia” may refer to gaseous ammonia, ionic ammonia, and/or total ammonia. 
     “Detoxification” of ammonia is used to refer to the process or processes, natural or synthetic, by which toxic ammonia is removed and/or converted into one or more non-toxic molecules, including but not limited to: arginine, citrulline, methionine, histidine, lysine, asparagine, glutamine, tryptophan, or urea. The urea cycle, for example, enzymatically converts ammonia into urea for removal from the body in the urine. Because ammonia is a source of nitrogen for many amino acids, which are synthesized via numerous biochemical pathways, enhancement of one or more of those amino acid biosynthesis pathways may be used to incorporate excess nitrogen into non-toxic molecules. For example, arginine biosynthesis converts glutamate, which comprises one nitrogen atom, to arginine, which comprises four nitrogen atoms, thereby incorporating excess nitrogen into non-toxic molecules. In humans, arginine is not reabsorbed from the large intestine, and as a result, excess arginine in the large intestine is not considered to be harmful. Likewise, citrulline is not reabsorbed from the large intestine, and as a result, excess citrulline in the large intestine is not considered to be harmful. Arginine biosynthesis may also be modified to produce citrulline as an end product; citrulline comprises three nitrogen atoms and thus the modified pathway is also capable of incorporating excess nitrogen into non-toxic molecules. 
     “Arginine regulon,” “arginine biosynthesis regulon,” and “arg regulon” are used interchangeably to refer to the collection of operons in a given bacterial species that comprise the genes encoding the enzymes responsible for converting glutamate to arginine and/or intermediate metabolites, e.g., citrulline, in the arginine biosynthesis pathway. The arginine regulon also comprises operators, promoters, ARG boxes, and/or regulatory regions associated with those operons. The arginine regulon includes, but is not limited to, the operons encoding the arginine biosynthesis enzymes N-acetylglutamate synthetase, N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine am inotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, carbamoylphosphate synthase, operators thereof, promoters thereof, ARG boxes thereof, and/or regulatory regions thereof. In some embodiments, the arginine regulon comprises an operon encoding ornithine acetyltransferase and associated operators, promoters, ARG boxes, and/or regulatory regions, either in addition to or in lieu of N-acetylglutamate synthetase and/or N-acetylornithinase. In some embodiments, one or more operons or genes of the arginine regulon may be present on a plasmid in the bacterium. In some embodiments, a bacterium may comprise multiple copies of any gene or operon in the arginine regulon, wherein one or more copies may be mutated or otherwise altered as described herein. 
     One gene may encode one enzyme, e.g., N-acetylglutamate synthetase (argA). Two or more genes may encode distinct subunits of one enzyme, e.g., subunit A and subunit B of carbamoylphosphate synthase (carA and carB). In some bacteria, two or more genes may each independently encode the same enzyme, e.g., ornithine transcarbamylase (argF and argI). In some bacteria, the arginine regulon includes, but is not limited to, argA, encoding N-acetylglutamate synthetase; argB, encoding N-acetylglutamate kinase; argC, encoding N-acetylglutamylphosphate reductase; argD, encoding acetylornithine aminotransferase; argE, encoding N-acetylornithinase; argG, encoding argininosuccinate synthase; argH, encoding argininosuccinate lyase; one or both of argF and argI, each of which independently encodes ornithine transcarbamylase; carA, encoding the small subunit of carbamoylphosphate synthase; carB, encoding the large subunit of carbamoylphosphate synthase; operons thereof; operators thereof; promoters thereof; ARG boxes thereof; and/or regulatory regions thereof. In some embodiments, the arginine regulon comprises argJ, encoding ornithine acetyltransferase (either in addition to or in lieu of N-acetylglutamate synthetase and/or N-acetylornithinase), operons thereof, operators thereof, promoters thereof, ARG boxes thereof, and/or regulatory regions thereof. 
     “Arginine operon,” “arginine biosynthesis operon,” and “arg operon” are used interchangeably to refer to a cluster of one or more of the genes encoding arginine biosynthesis enzymes under the control of a shared regulatory region comprising at least one promoter and at least one ARG box. In some embodiments, the one or more genes are co-transcribed and/or co-translated. Any combination of the genes encoding the enzymes responsible for arginine biosynthesis may be organized, naturally or synthetically, into an operon. For example, in  B. subtilis , the genes encoding N-acetylglutamylphosphate reductase, N-acetylglutamate kinase, N-acetylornithinase, N-acetylglutamate kinase, acetylornithine am inotransferase, carbamoylphosphate synthase, and ornithine transcarbamylase are organized in a single operon, argCAEBD-carAB-argF (see, e.g., Table 2), under the control of a shared regulatory region comprising a promoter and ARG boxes. In  E. coli  K12 and Nissle, the genes encoding N-acetylornithinase, N-acetylglutamylphosphate reductase, N-acetylglutamate kinase, and argininosuccinate lyase are organized in two bipolar operons, argECBH. The operons encoding the enzymes responsible for arginine biosynthesis may be distributed at different loci across the chromosome. In unmodified bacteria, each operon may be repressed by arginine via ArgR. In some embodiments, arginine and/or intermediate byproduct production may be altered in the genetically engineered bacteria of the invention by modifying the expression of the enzymes encoded by the arginine biosynthesis operons as provided herein. Each arginine operon may be present on a plasmid or bacterial chromosome. In addition, multiple copies of any arginine operon, or a gene or regulatory region within an arginine operon, may be present in the bacterium, wherein one or more copies of the operon or gene or regulatory region may be mutated or otherwise altered as described herein. In some embodiments, the genetically engineered bacteria are engineered to comprise multiple copies of the same product (e.g., operon or gene or regulatory region) to enhance copy number or to comprise multiple different components of an operon performing multiple different functions. 
     “ARG box consensus sequence” refers to an ARG box nucleic acid sequence, the nucleic acids of which are known to occur with high frequency in one or more of the regulatory regions of argR, argA, argB, argC, argD, argE, argF, argG, argH, argI, argJ, carA, and/or carB. As described above, each arg operon comprises a regulatory region comprising at least one 18-nucleotide imperfect palindromic sequence, called an ARG box, that overlaps with the promoter and to which the repressor protein binds (Tian et al., 1992). The nucleotide sequences of the ARG boxes may vary for each operon, and the consensus ARG box sequence is A/T nTGAAT A/T A/T T/A T/A ATTCAn T/A (SEQ ID NO: 120) (Maas, 1994). The arginine repressor binds to one or more ARG boxes to actively inhibit the transcription of the arginine biosynthesis enzyme(s) that are operably linked to that one or more ARG boxes. 
     “Mutant arginine regulon” or “mutated arginine regulon” is used to refer to an arginine regulon comprising one or more nucleic acid mutations that reduce or eliminate arginine-mediated repression of each of the operons that encode the enzymes responsible for converting glutamate to arginine and/or an intermediate byproduct, e.g., citrulline, in the arginine biosynthesis pathway, such that the mutant arginine regulon produces more arginine and/or intermediate byproduct than an unmodified regulon from the same bacterial subtype under the same conditions. In some embodiments, the genetically engineered bacteria comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr , and a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for one or more of the operons that encode the arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, and carbamoylphosphate synthase, thereby derepressing the regulon and enhancing arginine and/or intermediate byproduct biosynthesis. In some embodiments, the genetically engineered bacteria comprise a mutant arginine repressor comprising one or more nucleic acid mutations such that arginine repressor function is decreased or inactive, or the genetically engineered bacteria do not have an arginine repressor (e.g., the arginine repressor gene has been deleted), resulting in derepression of the regulon and enhancement of arginine and/or intermediate byproduct biosynthesis. In some embodiments, the genetically engineered bacteria comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr , a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes, and/or a mutant or deleted arginine repressor. In some embodiments, the genetically engineered bacteria comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr  and a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes. In some embodiments, the genetically engineered bacteria comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr  and a mutant or deleted arginine repressor. In some embodiments, the mutant arginine regulon comprises an operon encoding wild-type N-acetylglutamate synthetase and one or more nucleic acid mutations in at least one ARG box for said operon. In some embodiments, the mutant arginine regulon comprises an operon encoding wild-type N-acetylglutamate synthetase and mutant or deleted arginine repressor. In some embodiments, the mutant arginine regulon comprises an operon encoding ornithine acetyltransferase (either in addition to or in lieu of N-acetylglutamate synthetase and/or N-acetylornithinase) and one or more nucleic acid mutations in at least one ARG box for said operon. 
     The ARG boxes overlap with the promoter in the regulatory region of each arginine biosynthesis operon. In the mutant arginine regulon, the regulatory region of one or more arginine biosynthesis operons is sufficiently mutated to disrupt the palindromic ARG box sequence and reduce ArgR binding, but still comprises sufficiently high homology to the promoter of the non-mutant regulatory region to be recognized as the native operon-specific promoter. The operon comprises at least one nucleic acid mutation in at least one ARG box such that ArgR binding to the ARG box and to the regulatory region of the operon is reduced or eliminated. In some embodiments, bases that are protected from DNA methylation and bases that are protected from hydroxyl radical attack during ArgR binding are the primary targets for mutations to disrupt ArgR binding (see, e.g., Table 3). The promoter of the mutated regulatory region retains sufficiently high homology to the promoter of the non-mutant regulatory region such that RNA polymerase binds to it with sufficient affinity to promote transcription of the operably linked arginine biosynthesis enzyme(s). In some embodiments, the G/C:A/T ratio of the promoter of the mutant differs by no more than 10% from the G/C:A/T ratio of the wild-type promoter. 
     In some embodiments, more than one ARG box may be present in a single operon. In one aspect of these embodiments, at least one of the ARG boxes in an operon is altered to produce the requisite reduced ArgR binding to the regulatory region of the operon. In an alternate aspect of these embodiments, each of the ARG boxes in an operon is altered to produce the requisite reduced ArgR binding to the regulatory region of the operon. 
     “Reduced” ArgR binding is used to refer to a reduction in repressor binding to an ARG box in an operon or a reduction in the total repressor binding to the regulatory region of said operon, as compared to repressor binding to an unmodified ARG box and regulatory region in bacteria of the same subtype under the same conditions. In some embodiments, ArgR binding to a mutant ARG box and regulatory region of an operon is at least about 50% lower, at least about 60% lower, at least about 70% lower, at least about 80% lower, at least about 90% lower, or at least about 95% lower than ArgR binding to an unmodified ARG box and regulatory region in bacteria of the same subtype under the same conditions. In some embodiments, reduced ArgR binding to a mutant ARG box and regulatory region results in at least about 1.5-fold, at least about 2-fold, at least about 10-fold, at least about 15-fold, at least about 20-fold, at least about 30-fold, at least about 50-fold, at least about 100-fold, at least about 200-fold, at least about 300-fold, at least about 400-fold, at least about 500-fold, at least about 600-fold, at least about 700-fold, at least about 800-fold, at least about 900-fold, at least about 1,000-fold, or at least about 1,500-fold increased mRNA expression of the one or more genes in the operon. 
     “ArgR” or “arginine repressor” is used to refer to a protein that is capable of suppressing arginine biosynthesis by regulating the transcription of arginine biosynthesis genes in the arginine regulon. When expression of the gene that encodes for the arginine repressor protein (“argR”) is increased in a wild-type bacterium, arginine biosynthesis is decreased. When expression of argR is decreased in a wild-type bacterium, or if argR is deleted or mutated to inactivate arginine repressor function, arginine biosynthesis is increased. 
     Bacteria that “lack any functional ArgR” and “ArgR deletion bacteria” are used to refer to bacteria in which each arginine repressor has significantly reduced or eliminated activity as compared to unmodified arginine repressor from bacteria of the same subtype under the same conditions. Reduced or eliminated arginine repressor activity can result in, for example, increased transcription of the arginine biosynthesis genes and/or increased concentrations of arginine and/or intermediate byproducts, e.g., citrulline. Bacteria in which arginine repressor activity is reduced or eliminated can be generated by modifying the bacterial argR gene or by modifying the transcription of the argR gene. For example, the chromosomal argR gene can be deleted, can be mutated, or the argR gene can be replaced with an argR gene that does not exhibit wild-type repressor activity. 
     “Operably linked” refers a nucleic acid sequence, e.g., a gene encoding feedback resistant ArgA, that is joined to a regulatory region sequence in a manner which allows expression of the nucleic acid sequence, e.g., acts in cis. 
     A regulatory region is a nucleic acid that can direct transcription of a gene of interest and may comprise promoter sequences, enhancer sequences, response elements, protein recognition sites, inducible elements, promoter control elements, protein binding sequences, 5′ and 3′ untranslated regions, transcriptional start sites, termination sequences, polyadenylation sequences, and introns. 
     An “inducible promoter” refers to a regulatory region that is operably linked to one or more genes, wherein expression of the gene(s) is increased in the presence of an inducer of said regulatory region. In some embodiments, the genetically engineered bacteria of the invention comprise an oxygen level-dependent promoter induced by low-oxygen, microaerobic, or anaerobic conditions. In some embodiments, the genetically engineered bacteria comprise a promoter induced by a molecule or metabolite, for example, a tissue-specific molecule or metabolite or a molecule or metabolite indicative of liver damage. In some embodiments, the metabolites may be gut specific. In some embodiments, the metabolite may be associated with hepatic encephalopathy, e.g., bilirubin. Non-limiting examples of molecules or metabolites include, e.g., bilirubin, aspartate aminotransferase, alanine aminotransferase, blood coagulation factors II, VII, IX, and X, alkaline phosphatase, gamma glutamyl transferase, hepatitis antigens and antibodies, alpha fetoprotein, anti-mitochondrial, smooth muscle, and anti-nuclear antibodies, iron, transferrin, ferritin, copper, ceruloplasmin, ammonia, and manganese in their blood and intestines. Promoters that respond to one of these molecules or their metabolites may be used in the genetically engineered bacteria provided herein. In some embodiments, the genetically engineered bacteria comprise a promoter induced by inflammation or an inflammatory response, e.g., RNS or ROS promoter. In some embodiments, the genetically engineered bacteria comprise a promoter induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose and tetracycline. 
     “Exogenous environmental condition(s)” refer to setting(s) or circumstance(s) under which the promoter described herein is induced. The phrase “exogenous environmental conditions” is meant to refer to the environmental conditions external to the engineered microorganism, but endogenous or native to the host subject environment. Thus, “exogenous” and “endogenous” may be used interchangeably to refer to environmental conditions in which the environmental conditions are endogenous to a mammalian body, but external or exogenous to an intact microorganism cell. In some embodiments, the exogenous environmental conditions are specific to the gut of a mammal. In some embodiments, the exogenous environmental conditions are specific to the upper gastrointestinal tract of a mammal. In some embodiments, the exogenous environmental conditions are specific to the lower gastrointestinal tract of a mammal. In some embodiments, the exogenous environmental conditions are specific to the small intestine of a mammal. In some embodiments, exogenous environmental conditions refer to the presence of molecules or metabolites that are specific to the mammalian gut in a healthy or disease state (e.g., HE). In some embodiments, the exogenous environmental conditions are low-oxygen, microaerobic, or anaerobic conditions, such as the environment of the mammalian gut. In some embodiments, exogenous environmental conditions are molecules or metabolites that are specific to the mammalian gut, e.g., propionate. In some embodiments, the exogenous environmental condition is a tissue-specific or disease-specific metabolite or molecule(s). In some embodiments, the exogenous environmental condition is a low-pH environment. In some embodiments, the genetically engineered microorganism of the disclosure comprises a pH-dependent promoter. In some embodiments, the genetically engineered microorganism of the disclosure comprise an oxygen level-dependent promoter. In some aspects, bacteria have evolved transcription factors that are capable of sensing oxygen levels. Different signaling pathways may be triggered by different oxygen levels and occur with different kinetics. 
     An “oxygen level-dependent promoter” or “oxygen level-dependent regulatory region” refers to a nucleic acid sequence to which one or more oxygen level-sensing transcription factors is capable of binding, wherein the binding and/or activation of the corresponding transcription factor activates downstream gene expression. 
     Examples of oxygen level-dependent transcription factors include, but are not limited to, FNR, ANR, and DNR. Corresponding FNR-responsive promoters, ANR-responsive promoters, and DNR-responsive promoters are known in the art (see, e.g., Castiglione et al., 2009; Eiglmeier et al., 1989; Galimand et al., 1991; Hasegawa et al., 1998; Hoeren et al., 1993; Salmon et al., 2003), and non-limiting examples are shown in Table 1. 
     In a non-limiting example, a promoter (PfnrS) was derived from the  E. coli  Nissle fumarate and nitrate reductase gene S (fnrS) that is known to be highly expressed under conditions of low or no environmental oxygen (Durand and Storz, 2010; Boysen et al, 2010). The PfnrS promoter is activated under anaerobic conditions by the global transcriptional regulator FNR that is naturally found in Nissle. Under anaerobic conditions, FNR forms a dimer and binds to specific sequences in the promoters of specific genes under its control, thereby activating their expression. However, under aerobic conditions, oxygen reacts with iron-sulfur clusters in FNR dimers and converts them to an inactive form. In this way, the PfnrS inducible promoter is adopted to modulate the expression of proteins or RNA. PfnrS is used interchangeably in this application as FNRS, fnrs, FNR, P-FNRS promoter and other such related designations to indicate the promoter PfnrS. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Examples of transcription factors and responsive  
               
               
                 genes and regulatory regions 
               
            
           
           
               
               
               
            
               
                   
                   
                 Exemplary responsive genes, 
               
               
                   
                 Transcription 
                 promoters, and/or regulatory 
               
               
                   
                 Factor 
                 regions: 
               
               
                   
                   
               
               
                   
                 FNR 
                 nirB, ydfZ, pdhR, focA, ndH, hlyE, 
               
               
                   
                   
                 narK, narX, narG, yfiD, tdcD 
               
               
                   
                 ANR 
                 arcDABC 
               
               
                   
                 DNR 
                 norb, norC 
               
               
                   
                   
               
            
           
         
       
     
     “Gut barrier function enhancer molecules” include, but are not limited to, short-chain fatty acids, butyrate, propionate, acetate, GLP-2, IL-10, IL-27, TGF-β1, TGF-β2, N-acylphosphatidylethanolamines (NAPEs), elafin (also called peptidase inhibitor 3 and SKALP), trefoil factor, melatonin, PGD2, kynurenic acid, and kynurenine. A gut barrier function enhancer molecule may be encoded by a single gene, e.g., elafin is encoded by the PI3 gene. Alternatively, a gut barrier function enhancer molecule may be synthesized by a biosynthetic pathway requiring multiple genes, e.g., butyrate. These molecules may also be referred to as therapeutic molecules. 
     As used herein, a “gene cassette” or “operon” encoding a biosynthetic pathway refers to the two or more genes that are required to produce a gut barrier function enhancer molecule, e.g., butyrate, propionate. In addition to encoding a set of genes capable of producing said molecule, the gene cassette or operon may also comprise additional transcription and translation elements, e.g., a ribosome binding site. 
     A “butyrogenic gene cassette,” “butyrate biosynthesis gene cassette,” and “butyrate operon” are used interchangeably to refer to a set of genes capable of producing butyrate in a biosynthetic pathway. Unmodified bacteria that are capable of producing butyrate via an endogenous butyrate biosynthesis pathway include, but are not limited to,  Clostridium, Peptoclostridium, Fusobacterium, Butyrivibrio, Eubacterium , and  Treponema , and these endogenous butyrate biosynthesis pathways may be a source of genes for the genetically engineered bacteria of the invention. The genetically engineered bacteria of the invention may comprise butyrate biosynthesis genes from a different species, strain, or substrain of bacteria, or a combination of butyrate biosynthesis genes from different species, strains, and/or substrains of bacteria. A butyrogenic gene cassette may comprise, for example, the eight genes of the butyrate production pathway from  Peptoclostridium difficile  (also called  Clostridium difficile ): bcd2, etfB3, etfA3, thiA1, hbd, crt2, pbt, and buk, which encode butyryl-CoA dehydrogenase subunit, electron transfer flavoprotein subunit beta, electron transfer flavoprotein subunit alpha, acetyl-CoA C-acetyltransferase, 3-hydroxybutyryl-CoA dehydrogenase, crotonase, phosphate butyryltransferase, and butyrate kinase, respectively (Aboulnaga et al., 2013). One or more of the butyrate biosynthesis genes may be functionally replaced or modified.  Peptoclostridium difficile  strain 630 and strain 1296 are both capable of producing butyrate, but comprise different nucleic acid sequences for etfA3, thiA1, hbd, crt2, pbt, and buk. A butyrogenic gene cassette may comprise bcd2, etfB3, etfA3, and thiA1 from  Peptoclostridium difficile  strain 630, and hbd, crt2, pbt, and buk from  Peptoclostridium difficile  strain 1296. Alternatively, a single gene from  Treponema denticola  (ter, encoding trans-2-enoynl-CoA reductase) is capable of functionally replacing all three of the bcd2, etfB3, and etfA3 genes from  Peptoclostridium difficile . Thus, a butyrogenic gene cassette may comprise thiA1, hbd, crt2, pbt, and buk from  Peptoclostridium difficile  and ter from  Treponema denticola . The butyrogenic gene cassette may comprise genes for the aerobic biosynthesis of butyrate and/or genes for the anaerobic or microaerobic biosynthesis of butyrate. 
     Likewise, a “propionate gene cassette” or “propionate operon” refers to a set of genes capable of producing propionate in a biosynthetic pathway. Unmodified bacteria that are capable of producing propionate via an endogenous propionate biosynthesis pathway include, but are not limited to,  Clostridium propionicum, Megasphaera elsdenii , and  Prevotella ruminicola , and these endogenous propionate biosynthesis pathways may be a source of genes for the genetically engineered bacteria of the invention. The genetically engineered bacteria of the invention may comprise propionate biosynthesis genes from a different species, strain, or substrain of bacteria, or a combination of propionate biosynthesis genes from different species, strains, and/or substrains of bacteria. In some embodiments, the propionate gene cassette comprises acrylate pathway propionate biosynthesis genes, e.g., pct, lcdA, lcdB, lcdC, etfA, acre, and acrC, which encode propionate CoA-transferase, lactoyl-CoA dehydratase A, lactoyl-CoA dehydratase B, lactoyl-CoA dehydratase C, electron transfer flavoprotein subunit A, acryloyl-CoA reductase B, and acryloyl-CoA reductase C, respectively (Hetzel et al., 2003, Selmer et al., 2002). In alternate embodiments, the propionate gene cassette comprises pyruvate pathway propionate biosynthesis genes (see, e.g., Tseng and Prather, 2012), e.g., thrA fbr , thrB, thrC, ilvA fbr , aceE, aceF, and lpd, which encode homoserine dehydrogenase 1, homoserine kinase, L-threonine synthase, L-threonine dehydratase, pyruvate dehydrogenase, dihydrolipoamide acetyltransferase, and dihydrolipoyl dehydrogenase, respectively. In some embodiments, the propionate gene cassette further comprises tesB, which encodes acyl-CoA thioesterase. The propionate gene cassette may comprise genes for the aerobic biosynthesis of propionate and/or genes for the anaerobic or microaerobic biosynthesis of propionate. One or more of the propionate biosynthesis genes may be functionally replaced or modified, e.g., codon optimized. 
     An “acetate gene cassette” or “acetate operon” refers to a set of genes capable of producing acetate in a biosynthetic pathway. Bacteria “synthesize acetate from a number of carbon and energy sources,” including a variety of substrates such as cellulose, lignin, and inorganic gases, and utilize different biosynthetic mechanisms and genes, which are known in the art (Ragsdale et al., 2008). Unmodified bacteria that are capable of producing acetate via an endogenous acetate biosynthesis pathway may be a source of acetate biosynthesis genes for the genetically engineered bacteria of the invention. The genetically engineered bacteria of the invention may comprise acetate biosynthesis genes from a different species, strain, or substrain of bacteria, or a combination of acetate biosynthesis genes from different species, strains, and/or substrains of bacteria.  Escherichia coli  are capable of consuming glucose and oxygen to produce acetate and carbon dioxide during aerobic growth (Kleman et al., 1994). Several bacteria, such as  Acetitomaculum, Acetoanaerobium, Acetohalobium, Acetonema, Balutia, Butyribacterium, Clostridium, Moorella, Oxobacter, Sporomusa , and  Thermoacetogenium , are acetogenic anaerobes that are capable of converting CO or CO 2 +H 2  into acetate, e.g., using the Wood-Ljungdahl pathway (Schiel-Bengelsdorf et al., 2012). Genes in the Wood-Ljungdahl pathway for various bacterial species are known in the art. The acetate gene cassette may comprise genes for the aerobic biosynthesis of acetate and/or genes for the anaerobic or microaerobic biosynthesis of acetate. One or more of the acetate biosynthesis genes may be functionally replaced or modified. 
     “GABA” and “γ-aminobutyric acid” are used to refer to the the predominant inhibitory neurotransmitter (C 4 H 9 NO 2 ) in the mammalian central nervous system. In humans, GABA is also directly responsible for regulating muscle tone. GABA is capable of activating the GABA A  receptor, which is part of a ligand-gated ion channel complex, as well as the GABA B  metabotropic G protein-coupled receptor. Neurons that produce GABA are known as “GABAergic” neurons, and activation of GABA receptors is described as GABAergic tone (i.e., increased activation of GABA receptors refers to increased GABAergic tone). 
     “GABA transporter” and “GabP” are used to refer to a membrane transport protein that is capable of transporting GABA into bacterial cells (see, e.g., Li et al., 2001). In  Escherichia coli , the gabP gene encodes a high-affinity GABA permease responsible for GABA transport (Li et al., 2001). In some embodiments, the GABA transporter is encoded by a gabP gene derived from a bacterial species, including but not limited to,  Bacillus subtilis  and  Escherichia coli . These endogenous GABA transporter genes may be a source of genes for the genetically engineered bacteria of the invention. Any suitable gene(s) encoding a GABA transporter may be used. 
     “Manganese” refers to a chemical element with the symbol “Mn” and atomic number 25. In biological systems, manganese is an essential trace metal and plays an important role in enzyme-mediated catalysis, but can also have deleterious effects. Cells maintain manganese under tight homeostatic control in order to avoid toxicity. Some disorders associated with hyperammonemia may also be characterized by elevated levels of manganese; manganese may contribute to disease pathogenesis (e.g., hepatic encephalopathy) (Rivera-Mancia et al., 2012). 
     “Manganese transporter” and “MntH” refer to a membrane transport protein that is capable of transporting manganese into bacterial cells (see, e.g., Jensen and Jensen, 2014). In  Escherichia coli , the mntH gene encodes a proton-stimulated, divalent metal cation uptake system involved in manganese transport (Porcheron et al., 2013). In some embodiments, the manganese transporter is encoded by a mntH gene derived from a bacterial species, including but not limited to,  Salmonella typhimurium, Shigella flexneri, Yersinia pestis , and  Escherichia coli . These endogenous manganese transporter genes may be a source of genes for the genetically engineered bacteria of the invention. Any suitable gene(s) encoding a manganese transporter may be used. 
     As used herein, a “non-native” nucleic acid sequence refers to a nucleic acid sequence not normally present in a bacterium, e.g., an extra copy of an endogenous sequence, or a heterologous sequence such as a sequence from a different species, strain, or substrain of bacteria, or a sequence that is modified and/or mutated as compared to the unmodified sequence from bacteria of the same subtype. In some embodiments, the non-native nucleic acid sequence is a synthetic, non-naturally occurring sequence (see, e.g., Purcell et al., 2013). The non-native nucleic acid sequence may be a regulatory region, a promoter, a gene, and/or one or more genes in gene cassette. In some embodiments, “non-native” refers to two or more nucleic acid sequences that are not found in the same relationship to each other in nature. The non-native nucleic acid sequence, e.g., gene or gene cassette, may be present on a plasmid or bacterial chromosome. In some embodiments, the genetically engineered bacteria of the invention comprise a gene cassette that is operably linked to a directly or indirectly inducible promoter that is not associated with said gene cassette in nature, e.g., a FNR-responsive promoter operably linked to a butyrogenic gene cassette, or an arginine production cassette. In addition, multiple copies of the gene, gene cassette, or regulatory region may be present in the bacterium, wherein one or more copies may be mutated or otherwise altered as described herein. In some embodiments, the genetically engineered bacteria are engineered to comprise multiple copies of the same non-native nucleic acid sequence, e.g., gene, gene cassette, or regulatory region, in order to enhance copy number or to comprise multiple different components of a gene cassette performing multiple different functions. 
     “Constitutive promoter” refers to a promoter that is capable of facilitating continuous transcription of a coding sequence or gene under its control and/or to which it is operably linked. Constitutive promoters and variants are well known in the art and include, but are not limited to, BBa_J23100, a constitutive  Escherichia coli  a promoter (e.g., an osmY promoter (International Genetically Engineered Machine (iGEM) Registry of Standard Biological Parts Name BBa_J45992; BBa_J45993)), a constitutive  Escherichia coli σ   32  promoter (e.g., htpG heat shock promoter (BBa_J45504)), a constitutive  Escherichia coli σ   70  promoter (e.g., lacq promoter (BBa_J54200; BBa_J56015),  E. coli  CreABCD phosphate sensing operon promoter (BBa_J64951), GlnRS promoter (BBa_K088007), lacZ promoter (BBa_K119000; BBa_K119001); M13K07 gene I promoter (BBa_M13101); M13K07 gene II promoter (BBa_M13102), M13K07 gene III promoter (BBa_M13103), M13K07 gene IV promoter (BBa_M13104), M13K07 gene V promoter (BBa_M13105), M13K07 gene VI promoter (BBa_M13106), M13K07 gene VIII promoter (BBa_M13108), M13110 (BBa_M13110)), a constitutive  Bacillus subtilis σ   A  promoter (e.g., promoter veg (BBa_K143013), promoter 43 (BBa_K143013), P liaG  (BBa_K823000), P lepA  (BBa_K823002), P veg  (BBa_K823003)), a constitutive  Bacillus subtilis σ   B  promoter (e.g., promoter ctc (BBa_K143010), promoter gsiB (BBa_K143011)), a  Salmonella  promoter (e.g., Pspv2 from  Salmonella  (BBa_K112706), Pspv from  Salmonella  (BBa_K112707)), a bacteriophage T7 promoter (e.g., T7 promoter (BBa_I712074; BBa_I719005; BBa_J34814; BBa_J64997; BBa_K113010; BBa_K113011; BBa_K113012; BBa_R0085; BBa_R0180; BBa_R0181; BBa_R0182; BBa_R0183; BBa_Z0251; BBa_Z0252; BBa_Z0253)), a bacteriophage SP6 promoter (e.g., SP6 promoter (BBa_J64998)), and functional fragments thereof. 
     As used herein, genetically engineered bacteria that “overproduce” arginine or an intermediate byproduct, e.g., citrulline, refer to bacteria that comprise a mutant arginine regulon. For example, the engineered bacteria may comprise a feedback resistant form of ArgA, and when the arginine feedback resistant ArgA is expressed, are capable of producing more arginine and/or intermediate byproduct than unmodified bacteria of the same subtype under the same conditions. The genetically engineered bacteria may alternatively or further comprise a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes. The genetically engineered bacteria may alternatively or further comprise a mutant or deleted arginine repressor. In some embodiments, the genetically engineered bacteria produce at least about 1.5-fold, at least about 2-fold, at least about 10-fold, at least about 15-fold, at least about 20-fold, at least about 30-fold, at least about 50-fold, at least about 100-fold, at least about 200-fold, at least about 300-fold, at least about 400-fold, at least about 500-fold, at least about 600-fold, at least about 700-fold, at least about 800-fold, at least about 900-fold, at least about 1,000-fold, or at least about 1,500-fold more arginine than unmodified bacteria of the same subtype under the same conditions. In some embodiments, the genetically engineered bacteria produce at least about 1.5-fold, at least about 2-fold, at least about 10-fold, at least about 15-fold, at least about 20-fold, at least about 30-fold, at least about 50-fold, at least about 100-fold, at least about 200-fold, at least about 300-fold, at least about 400-fold, at least about 500-fold, at least about 600-fold, at least about 700-fold, at least about 800-fold, at least about 900-fold, at least about 1,000-fold, or at least about 1,500-fold more citrulline or other intermediate byproduct than unmodified bacteria of the same subtype under the same conditions. In some embodiments, the mRNA transcript levels of one or more of the arginine biosynthesis genes in the genetically engineered bacteria are at least about 1.5-fold, at least about 2-fold, at least about 10-fold, at least about 15-fold, at least about 20-fold, at least about 30-fold, at least about 50-fold, at least about 100-fold, at least about 200-fold, at least about 300-fold, at least about 400-fold, at least about 500-fold, at least about 600-fold, at least about 700-fold, at least about 800-fold, at least about 900-fold, at least about 1,000-fold, or at least about 1,500-fold higher than the mRNA transcript levels in unmodified bacteria of the same subtype under the same conditions. In certain embodiments, the unmodified bacteria will not have detectable levels of arginine, intermediate byproduct, and/or transcription of the gene(s) in such operons. However, protein and/or transcription levels of arginine and/or intermediate byproduct will be detectable in the corresponding genetically engineered bacterium having the mutant arginine regulon. Transcription levels may be detected by directly measuring mRNA levels of the genes. Methods of measuring arginine and/or intermediate byproduct levels, as well as the levels of transcript expressed from the arginine biosynthesis genes, are known in the art. Arginine and citrulline, for example, may be measured by mass spectrometry. 
     “Gut” refers to the organs, glands, tracts, and systems that are responsible for the transfer and digestion of food, absorption of nutrients, and excretion of waste. In humans, the gut comprises the gastrointestinal tract, which starts at the mouth and ends at the anus, and additionally comprises the esophagus, stomach, small intestine, and large intestine. The gut also comprises accessory organs and glands, such as the spleen, liver, gallbladder, and pancreas. The upper gastrointestinal tract comprises the esophagus, stomach, and duodenum of the small intestine. The lower gastrointestinal tract comprises the remainder of the small intestine, i.e., the jejunum and ileum, and all of the large intestine, i.e., the cecum, colon, rectum, and anal canal. Bacteria can be found throughout the gut, e.g., in the gastrointestinal tract, and particularly in the intestines. 
     As used herein, the term “gene sequence” is meant to refer to a genetic sequence, e.g., a nucleic acid sequence. The gene sequence or genetic sequence is meant to include a complete gene sequence or a partial gene sequence. The gene sequence or genetic sequence is meant to include sequence that encodes a protein or polypeptide and is also meant to include genetic sequence that does not encode a protein or polypeptide, e.g., a regulatory sequence, leader sequence, signal sequence, or other non-protein coding sequence. 
     “Microorganism” refers to an organism or microbe of microscopic, submicroscopic, or ultramicroscopic size that typically consists of a single cell. Examples of microorganisms include bacteria, viruses, parasites, fungi, certain algae, and protozoa. In some aspects, the microorganism is engineered (“engineered microorganism”) to produce one or more therapeutic molecules. In certain aspects, the microorganism is engineered to import and/or catabolize certain toxic metabolites, substrates, or other compounds from its environment, e.g., the gut. In certain aspects, the microorganism is engineered to synthesize certain beneficial metabolites, molecules, or other compounds (synthetic or naturally occurring) and release them into its environment. In certain embodiments, the engineered microorganism is an engineered bacterium. In certain embodiments, the engineered microorganism is an engineered virus. 
     “Non-pathogenic bacteria” refer to bacteria that are not capable of causing disease or harmful responses in a host. In some embodiments, non-pathogenic bacteria are commensal bacteria. Examples of non-pathogenic bacteria include, but are not limited to  Bacillus, Bacteroides, Bifidobacterium, Brevibacteria, Clostridium, Enterococcus, Escherichia coli, Lactobacillus, Lactococcus, Saccharomyces , and  Staphylococcus , e.g.,  Bacillus coagulans, Bacillus subtilis, Bacteroides fragilis, Bacteroides subtilis, Bacteroides thetaiotaomicron, Bifidobacterium bifidum, Bifidobacterium infantis, Bifidobacterium lactis, Bifidobacterium longum, Clostridium butyricum, Enterococcus faecium, Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus casei, Lactobacillus johnsonii, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus rhamnosus, Lactococcus lactis , and  Saccharomyces boulardii  (Sonnenborn et al., 2009; Dinleyici et al., 2014; U.S. Pat. Nos. 6,835,376; 6,203,797; 5,589,168; 7,731,976). Naturally pathogenic bacteria may be genetically engineered to provide reduce or eliminate pathogenicity. 
     As used herein, “payload” refers to one or more polynucleotides and/or polypeptides of interest to be produced by a genetically engineered microorganism, such as a bacteria or a virus. In some embodiments, the payload is encoded by a gene or multiple genes or an operon. In some embodiments, the one or more genes and/or operon(s) comprising the payload are endogenous to the microorganism. In some embodiments, the one or more elements of the payload is derived from a different microorganism and/or organism. In some embodiments, the payload is a therapeutic payload. In some embodiments, the payload is encoded by genes for the biosynthesis of a molecule. In some embodiments, the payload is encoded by genes for the metabolism, catabolism, or degradation of a molecule. In some embodiments, the payload is encoded by genes for the importation of a molecule. In some embodiments, the payload is encoded by genes for the exportation of a molecule. In some embodiments, the payload is a regulatory molecule(s), e.g., a transcriptional regulator such as FNR. In some embodiments, the payload comprises a regulatory element, such as a promoter or a repressor. In some embodiments, the payload comprises an inducible promoter, such as from FNRS. In some embodiments the payload comprises a repressor element, such as a kill switch. In alternate embodiments, the payload is produced by a biosynthetic or biochemical pathway, wherein the biosynthetic or biochemical pathway may optionally be endogenous to the microorganism. In some embodiments, the genetically engineered microorganism comprises two or more payloads. Non-limiting examples of payload(s) include one or more of the following: (1) ArgAfbr, (2) mutated Arg Boxes, (3) mutated ArgR, (4) mutated ArgG, (5) butyrate biosynthetic cassette, (6) proprionate biosynthetic cassette, (7) acetate biosynthetic cassette; (8) GABA-metabolizing cassette, (9) GABA-transporter, (10) Mn-transporter. Other exemplary payloads include GLP-2, IL-10, IL-27, TGF-β1, TGF-β2, elafin (also known as peptidase inhibitor 3 or SKALP), trefoil factor, melatonin, PGD 2 , kynurenic acid, and kynurenine. Other exemplary payloads include mutated sequence(s) that result in an auxotrophy, e.g., thyA auxotrophy, kill switch circuit, antibiotic resistance circuits, transporter sequence for importing biological molecules or substrates, secretion circuit. 
     “Probiotic” is used to refer to live, non-pathogenic microorganisms, e.g., bacteria, which can confer health benefits to a host organism that contains an appropriate amount of the microorganism. In some embodiments, the host organism is a mammal. In some embodiments, the host organism is a human. Some species, strains, and/or subtypes of non-pathogenic bacteria are currently recognized as probiotic bacteria. Examples of probiotic bacteria include, but are not limited to, Bifidobacteria,  Escherichia coli, Lactobacillus , and  Saccharomyces , e.g.,  Bifidobacterium bifidum, Enterococcus faecium, Escherichia coli  strain Nissle,  Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus paracasei, Lactobacillus plantarum , and  Saccharomyces boulardii  (Dinleyici et al., 2014; U.S. Pat. Nos. 5,589,168; 6,203,797; 6,835,376). The probiotic may be a variant or a mutant strain of bacterium (Arthur et al., 2012; Cuevas-Ramos et al., 2010; Olier et al., 2012; Nougayrede et al., 2006). Non-pathogenic bacteria may be genetically engineered to enhance or improve desired biological properties, e.g., survivability. Non-pathogenic bacteria may be genetically engineered to provide probiotic properties. Probiotic bacteria may be genetically engineered to enhance or improve probiotic properties. 
     As used herein, “stably maintained” or “stable” bacterium is used to refer to a bacterial host cell carrying non-native genetic material, e.g., a feedback resistant argA gene, mutant arginine repressor, and/or other mutant arginine regulon that is incorporated into the host genome or propagated on a self-replicating extra-chromosomal plasmid, such that the non-native genetic material is retained, expressed, and propagated. The stable bacterium is capable of survival and/or growth in vitro, e.g., in medium, and/or in vivo, e.g., in the gut. For example, the stable bacterium may be a genetically engineered bacterium comprising an argA fbr  gene, in which the plasmid or chromosome carrying the argA fbr  gene is stably maintained in the bacterium, such that argA fbr  can be expressed in the bacterium, and the bacterium is capable of survival and/or growth in vitro and/or in vivo. 
     As used herein, the terms “modulate” and “treat” and their cognates refer to an amelioration of a disease, disorder, and/or condition, or at least one discernible symptom thereof. In another embodiment, “modulate” and “treat” refer to an amelioration of at least one measurable physical parameter, not necessarily discernible by the patient. In another embodiment, “modulate” and “treat” refer to inhibiting the progression of a disease, disorder, and/or condition, either physically (e.g., stabilization of a discernible symptom), physiologically (e.g., stabilization of a physical parameter), or both. In another embodiment, “modulate” and “treat” refer to slowing the progression or reversing the progression of a disease, disorder, and/or condition. As used herein, “prevent” and its cognates refer to delaying the onset or reducing the risk of acquiring a given disease, disorder and/or condition or a symptom associated with such disease, disorder, and/or condition. 
     Those in need of treatment may include individuals already having a particular medical disorder, as well as those at risk of having, or who may ultimately acquire the disorder. The need for treatment is assessed, for example, by the presence of one or more risk factors associated with the development of a disorder, the presence or progression of a disorder, or likely receptiveness to treatment of a subject having the disorder. Primary hyperammonemia is caused by UCDs, which are autosomal recessive or X-linked inborn errors of metabolism for which there are no known cures. Hyperammonemia can also be secondary to other disruptions of the urea cycle, e.g., toxic metabolites, infections, and/or substrate deficiencies. Hyperammonemia can also contribute to other pathologies. For example, Huntington&#39;s disease is an autosomal dominant disorder for which there are no known cures. Urea cycle abnormalities characterized by hyperammonemia, high blood citrulline, and suppression of urea cycle enzymes may contribute to the pathology of Huntington&#39;s disease, an autosomal dominant disorder for which there are no known cures. Treating hyperammonemia may encompass reducing or eliminating excess ammonia and/or associated symptoms, and does not necessarily encompass the elimination of the underlying hyperammonemia-associated disorder. 
     As used herein a “pharmaceutical composition” refers to a preparation of genetically engineered bacteria of the invention with other components such as a physiologically suitable carrier and/or excipient. 
     The phrases “physiologically acceptable carrier” and “pharmaceutically acceptable carrier” which may be used interchangeably refer to a carrier or a diluent that does not cause significant irritation to an organism and does not abrogate the biological activity and properties of the administered bacterial compound. An adjuvant is included under these phrases. 
     The term “excipient” refers to an inert substance added to a pharmaceutical composition to further facilitate administration of an active ingredient. Examples include, but are not limited to, calcium bicarbonate, calcium phosphate, various sugars and types of starch, cellulose derivatives, gelatin, vegetable oils, polyethylene glycols, and surfactants, including, for example, polysorbate 20. 
     The terms “therapeutically effective dose” and “therapeutically effective amount” are used to refer to an amount of a compound that results in prevention, delay of onset of symptoms, or amelioration of symptoms of a condition, e.g., hyperammonemia. A therapeutically effective amount may, for example, be sufficient to treat, prevent, reduce the severity, delay the onset, and/or reduce the risk of occurrence of one or more symptoms of a disorder associated with elevated ammonia concentrations. A therapeutically effective amount, as well as a therapeutically effective frequency of administration, can be determined by methods known in the art and discussed below. 
     As used herein, the term “polypeptide” includes “polypeptide” as well as “polypeptides,” and refers to a molecule composed of amino acid monomers linearly linked by amide bonds (i.e., peptide bonds). The term “polypeptide” refers to any chain or chains of two or more amino acids, and does not refer to a specific length of the product. Thus, “peptides,” “dipeptides,” “tripeptides, “oligopeptides,” “protein,” “amino acid chain,” or any other term used to refer to a chain or chains of two or more amino acids, are included within the definition of “polypeptide,” and the term “polypeptide” may be used instead of, or interchangeably with any of these terms. The term “polypeptide” is also intended to refer to the products of post-expression modifications of the polypeptide, including but not limited to glycosylation, acetylation, phosphorylation, amidation, derivatization, proteolytic cleavage, or modification by non-naturally occurring amino acids. A polypeptide may be derived from a natural biological source or produced by recombinant technology. In other embodiments, the polypeptide is produced by the genetically engineered bacteria or virus of the current invention. A polypeptide of the invention may be of a size of about 3 or more, 5 or more, 10 or more, 20 or more, 25 or more, 50 or more, 75 or more, 100 or more, 200 or more, 500 or more, 1,000 or more, or 2,000 or more amino acids. Polypeptides may have a defined three-dimensional structure, although they do not necessarily have such structure. Polypeptides with a defined three-dimensional structure are referred to as folded, and polypeptides, which do not possess a defined three-dimensional structure, but rather can adopt a large number of different conformations, are referred to as unfolded. The term “peptide” or “polypeptide” may refer to an amino acid sequence that corresponds to a protein or a portion of a protein or may refer to an amino acid sequence that corresponds with non-protein sequence, e.g., a sequence selected from a regulatory peptide sequence, leader peptide sequence, signal peptide sequence, linker peptide sequence, and other peptide sequence. 
     An “isolated” polypeptide or a fragment, variant, or derivative thereof refers to a polypeptide that is not in its natural milieu. No particular level of purification is required. Recombinantly produced polypeptides and proteins expressed in host cells, including but not limited to bacterial or mammalian cells, are considered isolated for purposed of the invention, as are native or recombinant polypeptides which have been separated, fractionated, or partially or substantially purified by any suitable technique. Recombinant peptides, polypeptides or proteins refer to peptides, polypeptides or proteins produced by recombinant DNA techniques, i.e. produced from cells, microbial or mammalian, transformed by an exogenous recombinant DNA expression construct encoding the polypeptide. Proteins or peptides expressed in most bacterial cultures will typically be free of glycan. Fragments, derivatives, analogs or variants of the foregoing polypeptides, and any combination thereof are also included as polypeptides. The terms “fragment,” “variant,” “derivative” and “analog” include polypeptides having an amino acid sequence sufficiently similar to the amino acid sequence of the original peptide and include any polypeptides, which retain at least one or more properties of the corresponding original polypeptide. Fragments of polypeptides of the present invention include proteolytic fragments, as well as deletion fragments. Fragments also include specific antibody or bioactive fragments or immunologically active fragments derived from any polypeptides described herein. Variants may occur naturally or be non-naturally occurring. Non-naturally occurring variants may be produced using mutagenesis methods known in the art. Variant polypeptides may comprise conservative or non-conservative amino acid substitutions, deletions or additions. 
     Polypeptides also include fusion proteins. As used herein, the term “variant” includes a fusion protein, which comprises a sequence of the original peptide or sufficiently similar to the original peptide. As used herein, the term “fusion protein” refers to a chimeric protein comprising amino acid sequences of two or more different proteins. Typically, fusion proteins result from well known in vitro recombination techniques. Fusion proteins may have a similar structural function (but not necessarily to the same extent), and/or similar regulatory function (but not necessarily to the same extent), and/or similar biochemical function (but not necessarily to the same extent) and/or immunological activity (but not necessarily to the same extent) as the individual original proteins which are the components of the fusion proteins. “Derivatives” include but are not limited to peptides, which contain one or more naturally occurring amino acid derivatives of the twenty standard amino acids. “Similarity” between two peptides is determined by comparing the amino acid sequence of one peptide to the sequence of a second peptide. An amino acid of one peptide is similar to the corresponding amino acid of a second peptide if it is identical or a conservative amino acid substitution. Conservative substitutions include those described in Dayhoff, M. O., ed., The Atlas of Protein Sequence and Structure 5, National Biomedical Research Foundation, Washington, D.C. (1978), and in Argos, EMBO J. 8 (1989), 779-785. For example, amino acids belonging to one of the following groups represent conservative changes or substitutions: -Ala, Pro, Gly, Gln, Asn, Ser, Thr; -Cys, Ser, Tyr, Thr; -Val, Ile, Leu, Met, Ala, Phe; -Lys, Arg, His; -Phe, Tyr, Trp, His; and -Asp, Glu. 
     As used herein, the term “sufficiently similar” means a first amino acid sequence that contains a sufficient or minimum number of identical or equivalent amino acid residues relative to a second amino acid sequence such that the first and second amino acid sequences have a common structural domain and/or common functional activity. For example, amino acid sequences that comprise a common structural domain that is at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 100%, identical are defined herein as sufficiently similar. Preferably, variants will be sufficiently similar to the amino acid sequence of the peptides of the invention. Such variants generally retain the functional activity of the peptides of the present invention. Variants include peptides that differ in amino acid sequence from the native and wt peptide, respectively, by way of one or more amino acid deletion(s), addition(s), and/or substitution(s). These may be naturally occurring variants as well as artificially designed ones. 
     As used herein the term “linker”, “linker peptide” or “peptide linkers” or “linker” refers to synthetic or non-native or non-naturally-occurring amino acid sequences that connect or link two polypeptide sequences, e.g., that link two polypeptide domains. As used herein the term “synthetic” refers to amino acid sequences that are not naturally occurring. Exemplary linkers are described herein. Additional exemplary linkers are provided in US 20140079701, the contents of which are herein incorporated by reference in its entirety. 
     As used herein the term “codon-optimized sequence” refers to a sequence, which was modified from an existing coding sequence, or designed, for example, to improve translation in an expression host cell or organism of a transcript RNA molecule transcribed from the coding sequence, or to improve transcription of a coding sequence. Codon optimization includes, but is not limited to, processes including selecting codons for the coding sequence to suit the codon preference of the expression host organism. 
     Many organisms display a bias or preference for use of particular codons to code for insertion of a particular amino acid in a growing polypeptide chain. Codon preference or codon bias, differences in codon usage between organisms, is allowed by the degeneracy of the genetic code, and is well documented among many organisms. Codon bias often correlates with the efficiency of translation of messenger RNA (mRNA), which is in turn believed to be dependent on, inter alia, the properties of the codons being translated and the availability of particular transfer RNA (tRNA) molecules. The predominance of selected tRNAs in a cell is generally a reflection of the codons used most frequently in peptide synthesis. Accordingly, genes can be tailored for optimal gene expression in a given organism based on codon optimization. 
     As used herein, the terms “secretion system” or “secretion protein” refers to a native or non-native secretion mechanism capable of secreting or exporting the protein of interest or therapeutic protein from the microbial, e.g., bacterial cytoplasm. The secretion system may comprise a single protein or may comprise two or more proteins assembled in a complex e.g. HlyBD. Non-limiting examples of secretion systems for gram negative bacteria include the modified type III flagellar, type I (e.g., hemolysin secretion system), type II, type IV, type V, type VI, and type VII secretion systems, resistance-nodulation-division (RND) multi-drug efflux pumps, various single membrane secretion systems. Non-liming examples of secretion systems for gram positive bacteria include Sec and TAT secretion systems. In some embodiments, the the protein(s) of interest or therapeutic protein(s) include a “secretion tag” of either RNA or peptide origin to direct the the protein(s) of interest or therapeutic protein(s) to specific secretion systems. In some embodiments, the secretion system is able to remove this tag before secreting the the protein(s) of interest or therapeutic protein(s) from the engineered bacteria. For example, in Type V auto-secretion-mediated secretion the N-terminal peptide secretion tag is removed upon translocation of the “passenger” peptide from the cytoplasm into the periplasmic compartment by the native Sec system. Further, once the auto-secretor is translocated across the outer membrane the C-terminal secretion tag can be removed by either an autocatalytic or protease-catalyzed e.g., OmpT cleavage thereby releasing the the protein(s) of interest or therapeutic protein(s) into the extracellular milieu. 
     As used herein, the term “transporter” is meant to refer to a mechanism, e.g., protein or proteins, for importing a molecule, e.g., amino acid, toxin, metabolite, substrate, etc. into the microorganism from the extracellular milieu. 
     The articles “a” and “an,” as used herein, should be understood to mean “at least one,” unless clearly indicated to the contrary. 
     The phrase “and/or,” when used between elements in a list, is intended to mean either (1) that only a single listed element is present, or (2) that more than one element of the list is present. For example, “A, B, and/or C” indicates that the selection may be A alone; B alone; C alone; A and B; A and C; B and C; or A, B, and C. The phrase “and/or” may be used interchangeably with “at least one of” or “one or more of” the elements in a list. 
     Bacteria 
     The genetically engineered bacteria disclosed herein are capable of reducing excess ammonia and converting ammonia and/or nitrogen into alternate byproducts. In some embodiments, the genetically engineered bacteria are naturally non-pathogenic bacteria. In some embodiments, the genetically engineered bacteria are commensal bacteria. In some embodiments, the genetically engineered bacteria are probiotic bacteria. In some embodiments, the genetically engineered bacteria are naturally pathogenic bacteria that are modified or mutated to reduce or eliminate pathogenicity. Exemplary bacteria include, but are not limited to  Bacillus, Bacteroides, Bifidobacterium, Brevibacteria, Clostridium, Enterococcus, Escherichia coli, Lactobacillus, Lactococcus, Saccharomyces , and  Staphylococcus , e.g.,  Bacillus coagulans, Bacillus subtilis, Bacteroides fragilis, Bacteroides subtilis, Bacteroides thetaiotaomicron, Bifidobacterium bifidum, Bifidobacterium infantis, Bifidobacterium lactis, Bifidobacterium longum, Clostridium butyricum, Enterococcus faecium, Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus casei, Lactobacillus johnsonii, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus rhamnosus, Lactococcus lactis , and  Saccharomyces boulardii . In certain embodiments, the genetically engineered bacteria are selected from the group consisting of  Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides subtilis, Bifidobacterium bifidum, Bifidobacterium infantis, Bifidobacterium lactis, Clostridium butyricum, Escherichia coli  Nissle,  Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus reuteri , and  Lactococcus lactis.    
     In some embodiments, the genetically engineered bacteria are  Escherichia coli  strain Nissle 1917 ( E. coli  Nissle), a Gram-negative bacterium of the Enterobacteriaceae family that has evolved into one of the best characterized probiotics (Ukena et al., 2007). The strain is characterized by its complete harmlessness (Schultz, 2008), and has GRAS (generally recognized as safe) status (Reister et al., 2014, emphasis added). Genomic sequencing confirmed that  E. coli  Nissle lacks prominent virulence factors (e.g.,  E. coli  α-hemolysin, P-fimbrial adhesins) (Schultz, 2008). In addition, it has been shown that  E. coli  Nissle does not carry pathogenic adhesion factors, does not produce any enterotoxins or cytotoxins, is not invasive, and not uropathogenic (Sonnenborn et al., 2009). As early as in 1917,  E. coli  Nissle was packaged into medicinal capsules, called Mutaflor, for therapeutic use.  E. coli  Nissle has since been used to treat ulcerative colitis in humans in vivo (Rembacken et al., 1999), to treat inflammatory bowel disease, Crohn&#39;s disease, and pouchitis in humans in vivo (Schultz, 2008), and to inhibit enteroinvasive  Salmonella, Legionella, Yersinia , and  Shigella  in vitro (Altenhoefer et al., 2004). It is commonly accepted that  E. coli  Nissle&#39;s therapeutic efficacy and safety have convincingly been proven (Ukena et al., 2007). 
     One of ordinary skill in the art would appreciate that the genetic modifications disclosed herein may be modified and adapted for other species, strains, and subtypes of bacteria. It is known, for example, that arginine-mediated regulation is remarkably well conserved in very divergent bacteria, i.e., Gram-negative bacteria, such as  E. coli, Salmonella enterica  serovar  Typhimurium, Thermotoga , and  Moritella profunda , and Gram-positive bacteria, such as  B. subtilis, Geobacillus stearothermophilus , and  Streptomyces clavuligerus , as well as other bacteria (Nicoloff et al., 2004). Furthermore, the arginine repressor is universally conserved in bacterial genomes and that its recognition signal (the ARG box), a weak palindrome, is also conserved between genomes (Makarova et al., 2001). 
     Unmodified  E. coli  Nissle and the genetically engineered bacteria of the invention may be destroyed, e.g., by defense factors in the gut or blood serum (Sonnenborn et al., 2009). The residence time of bacteria in vivo can be determined using the methods described herein. In some embodiments, the residence time is calculated for a human subject. A non-limiting example using a streptomycin-resistant  E. coli  Nissle comprising a wild-type ArgR and a wild-type arginine regulon is provided herein. In some embodiments, residence time in vivo is calculated for the genetically engineered bacteria of the invention. 
     Reduction of Excess Ammonia 
     Arginine Biosynthesis Pathway 
     In bacteria such as  Escherichia coli  ( E. coli ), the arginine biosynthesis pathway is capable of converting glutamate to arginine in an eight-step enzymatic process involving the enzymes N-acetylglutamate synthetase, N-acetylglutamate kinase, N-acetylglutamate phosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, carbamoylphosphate synthase, ornithine transcarbamylase, argininosuccinate synthase, and argininosuccinate lyase (Cunin et al., 1986). The first five steps involve N-acetylation to generate an ornithine precursor. In the sixth step, ornithine transcarbamylase (also known as ornithine carbamoyltransferase) catalyzes the formation of citrulline. The final two steps involve carbamoylphosphate utilization to generate arginine from citrulline. 
     In some bacteria, e.g.,  Bacillus stearothermophilus  and  Neisseria gonorrhoeae , the first and fifth steps in arginine biosynthesis may be catalyzed by the bifunctional enzyme ornithine acetyltransferase. This bifunctionality was initially identified when ornithine acetyltransferase (argJ) was shown to complement both N-acetylglutamate synthetase (argA) and N-acetylornithinase (argE) auxotrophic gene mutations in  E. coli  (Mountain et al., 1984; Crabeel et al., 1997). 
     ArgA encodes N-acetylglutamate synthetase, argB encodes N-acetylglutamate kinase, argC encodes N-acetylglutamylphosphate reductase, argD encodes acetylornithine aminotransferase, argE encodes N-acetylornithinase, argF encodes ornithine transcarbamylase, argI also encodes ornithine transcarbamylase, argG encodes argininosuccinate synthase, argH encodes argininosuccinate lyase, and argJ encodes ornithine acetyltransferase. CarA encodes the small A subunit of carbamoylphosphate synthase having glutaminase activity, and carB encodes the large B subunit of carbamoylphosphate synthase that catalyzes carbamoylphosphate synthesis from ammonia. Different combinations of one or more of these arginine biosynthesis genes (i.e., argA, argB, argC, argD, argE, argF, argG, argH, argI, argJ, carA, and care) may be organized, naturally or synthetically, into one or more operons, and such organization may vary between bacterial species, strains, and subtypes (see, e.g., Table 2). The regulatory region of each operon contains at least one ARG box, and the number of ARG boxes per regulatory region may vary between operons and bacteria. 
     All of the genes encoding these enzymes are subject to repression by arginine via its interaction with ArgR to form a complex that binds to the regulatory region of each gene and inhibits transcription. N-acetylglutamate synthetase is also subject to allosteric feedback inhibition at the protein level by arginine alone (Tuchman et al., 1997; Caldara et al., 2006; Caldara et al., 2008; Caldovic et al., 2010). 
     The genes that regulate arginine biosynthesis in bacteria are scattered across the chromosome and organized into multiple operons that are controlled by a single repressor, which Maas and Clark (1964) termed a “regulon.” Each operon is regulated by a regulatory region comprising at least one 18-nucleotide imperfect palindromic sequence, called an ARG box, that overlaps with the promoter and to which the repressor protein binds (Tian et al., 1992; Tian et al., 1994). The argR gene encodes the repressor protein, which binds to one or more ARG boxes (Lim et al., 1987). Arginine functions as a corepressor that activates the arginine repressor. The ARG boxes that regulate each operon may be non-identical, and the consensus ARG box sequence is A/T nTGAAT A/T A/T T/A T/A ATTCAn T/A (SEQ ID NO: 120)_(Maas, 1994). In addition, the regulatory region of argR contains two promoters, one of which overlaps with two ARG boxes and is autoregulated. 
     In some embodiments, the genetically engineered bacteria comprise a mutant arginine regulon and produce more arginine and/or an intermediate byproduct, e.g., citrulline, than unmodified bacteria of the same subtype under the same conditions. The mutant arginine regulon comprises one or more nucleic acid mutations that reduce or prevent arginine-mediated repression—via ArgR binding to ARG boxes and/or arginine binding to N-acetylglutamate synthetase—of one or more of the operons that encode the enzymes responsible for converting glutamate to arginine in the arginine biosynthesis pathway, thereby enhancing arginine and/or intermediate byproduct biosynthesis. 
     In alternate embodiments, the bacteria are genetically engineered to consume excess ammonia via another metabolic pathway, e.g., a histidine biosynthesis pathway, a methionine biosynthesis pathway, a lysine biosynthesis pathway, an asparagine biosynthesis pathway, a glutamine biosynthesis pathway, and a tryptophan biosynthesis pathway. As used herein, “an ammonia conversion circuit” refers to a metabolic pathway by which excess ammonia may be consumed and/or reduced. 
     Histidine Biosynthesis Pathway 
     Histidine biosynthesis, for example, is carried out by eight genes located within a single operon in  E. coli . Three of the eight genes of the operon (hisD, hisB, and hisI) encode bifunctional enzymes, and two (hisH and hisF) encode polypeptide chains which together form one enzyme to catalyze a single step, for a total of 10 enzymatic reactions (Alifano et al., 1996). The product of the hisG gene, ATP phosphoribosyltransferase, is inhibited at the protein level by histidine. In some embodiments, the genetically engineered bacteria of the invention comprise a feedback-resistant hisG. Bacteria may be mutagenized and/or screened for feedback-resistant hisG mutants using techniques known in the art. Bacteria engineered to comprise a feedback-resistant hisG would have elevated levels of histidine production, thus increasing ammonia consumption and reducing hyperammonemia. Alternatively, one or more genes required for histidine biosynthesis could be placed under the control of an inducible promoter, such as a FNR-inducible promoter, and allow for increased production of rate-limiting enzymes. Any other suitable modification(s) to the histidine biosynthesis pathway may be used to increase ammonia consumption. 
     Methionine Biosynthesis Pathway 
     The bacterial methionine regulon controls the three-step synthesis of methionine from homoserine (i.e., acylation, sulfurylation, and methylation). The metJ gene encodes a regulatory protein that, when combined with methionine or a derivative thereof, causes repression of genes within the methionine regulon at the transcriptional level (Saint-Girons et al., 1984; Shoeman et al., 1985). In some embodiments, the genetically engineered bacteria of the invention comprise deleted, disrupted, or mutated metJ. Bacteria engineered to delete, disrupt, or mutate metJ would have elevated levels of methionine production, thus increasing ammonia consumption and reducing hyperammonemia. Any other suitable modification(s) to the methionine biosynthesis pathway may be used to increase ammonia consumption. 
     Lysine Biosynthesis Pathway 
     Microorganisms synthesize lysine by one of two pathways. The diaminopimelate (DAP) pathway is used to synthesize lysine from aspartate and pyruvate (Dogovski et al., 2012), and the aminoadipic acid pathway is used to synthesize lysine from alpha-ketoglutarate and acetyl coenzyme A. The dihydrodipicolinate synthase (DHDPS) enzyme catalyzes the first step of the DAP pathway, and is subject to feedback inhibition by lysine (Liu et al., 2010; Reboul et al., 2012). In some embodiments, the genetically engineered bacteria of the invention comprise a feedback-resistant DHDPS. Bacteria engineered to comprise a feedback-resistant DHDPS would have elevated levels of histidine production, thus increasing ammonia consumption and reducing hyperammonemia. Alternatively, lysine production could be optimized by placing one or more genes required for lysine biosynthesis under the control of an inducible promoter, such as a FNR-inducible promoter. Any other suitable modification(s) to the lysine biosynthesis pathway may be used to increase ammonia consumption. 
     Asparagine Biosynthesis Pathway 
     Asparagine is synthesized directly from oxaloacetate and aspartic acid via the oxaloacetate transaminase and asparagine synthetase enzymes, respectively. In the second step of this pathway, either L-glutamine or ammonia serves as the amino group donor. In some embodiments, the genetically engineered bacteria of the invention overproduce asparagine as compared to unmodified bacteria of the same subtype under the same conditions, thereby consuming excess ammonia and reducing hyperammonemia. Alternatively, asparagine synthesis may be optimized by placing one or both of these genes under the control of an inducible promoter, such as a FNR-inducible promoter. Any other suitable modification(s) to the asparagine biosynthesis pathway may be used to increase ammonia consumption. 
     Glutamine Biosynthesis Pathway 
     The synthesis of glutamine and glutamate from ammonia and oxoglutarate is tightly regulated by three enzymes. Glutamate dehydrogenase catalyzes the reductive amination of oxoglutarate to yield glutamate in a single step. Glutamine synthetase catalyzes the ATP-dependent condensation of glutamate and ammonia to form glutamine (Lodeiro et al., 2008). Glutamine synthetase also acts with glutamine-oxoglutarate amino transferase (also known as glutamate synthase) in a cyclic reaction to produce glutamate from glutamine and oxoglutarate. In some embodiments, the genetically engineered bacteria of the invention express glutamine synthetase at elevated levels as compared to unmodified bacteria of the same subtype under the same conditions. Bacteria engineered to have increased expression of glutamine synthetase would have elevated levels of glutamine production, thus increasing ammonia consumption and reducing hyperammonemia. Alternatively, expression of glutamate dehydrogenase and/or glutamine-oxoglutarate amino transferase could be modified to favor the consumption of ammonia. Since the production of glutamine synthetase is regulated at the transcriptional level by nitrogen (Feng et al., 1992; van Heeswijk et al., 2013), placing the glutamine synthetase gene under the control of different inducible promoter, such as a FNR-inducible promoter, may also be used to improve glutamine production. Any other suitable modification(s) to the glutamine and glutamate biosynthesis pathway may be used to increase ammonia consumption. 
     Tryptophan Biosynthesis Pathway 
     In most bacteria, the genes required for the synthesis of tryptophan from a chorismate precursor are organized as a single transcriptional unit, the trp operon. The trp operon is under the control of a single promoter that is inhibited by the tryptophan repressor (TrpR) when high levels of tryptophan are present. Transcription of the trp operon may also be terminated in the presence of high levels of charged tryptophan tRNA. In some embodiments, the genetically engineered bacteria of the invention comprise a deleted, disrupted, or mutated trpR gene. The deletion, disruption, or mutation of the trpR gene, and consequent inactivation of TrpR function, would result in elevated levels of both tryptophan production and ammonia consumption. Alternatively, one or more enzymes required for tryptophan biosynthesis could be placed under the control of an inducible promoter, such as a FNR-inducible promoter. Any other suitable modification(s) to the tryptophan biosynthesis pathway may be used to increase ammonia consumption. 
     Engineered Bacteria Comprising a Mutant Arginine Regulon 
     In some embodiments, the genetically engineered bacteria comprise an arginine biosynthesis pathway and are capable of reducing excess ammonia. In a more specific aspect, the genetically engineered bacteria comprise a mutant arginine regulon in which one or more operons encoding arginine biosynthesis enzyme(s) is derepressed to produce more arginine or an intermediate byproduct, e.g., citrulline, than unmodified bacteria of the same subtype under the same conditions. In some embodiments, the genetically engineered bacteria overproduce arginine. In some embodiments, the genetically engineered bacteria overproduce citrulline; this may be additionally beneficial, because citrulline is currently used as a therapeutic for particular urea cycle disorders (National Urea Cycle Disorders Foundation). In some embodiments, the genetically engineered bacteria overproduce an alternate intermediate byproduct in the arginine biosynthesis pathway, such as any of the intermediates described herein. In some embodiments, the genetically engineered bacterium consumes excess ammonia by producing more arginine, citrulline, and/or other intermediate byproduct than an unmodified bacterium of the same bacterial subtype under the same conditions. Enhancement of arginine and/or intermediate byproduct biosynthesis may be used to incorporate excess nitrogen in the body into non-toxic molecules in order to treat conditions associated with hyperammonemia, including urea cycle disorders and hepatic encephalopathy. 
     One of skill in the art would appreciate that the organization of arginine biosynthesis genes within an operon varies across species, strains, and subtypes of bacteria, e.g., bipolar argECBH in  E. coli  K12, argCAEBD-carAB-argF in  B. subtilis , and bipolar carAB-argCJBDF in  L. plantarum . Non-limiting examples of operon organization from different bacteria are shown in Table 2 (in some instances, the genes are putative and/or identified by sequence homology to known sequences in  Escherichia coli ; in some instances, not all of the genes in the arginine regulon are known and/or shown below). In certain instances, the arginine biosynthesis enzymes vary across species, strains, and subtypes of bacteria. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Examples of arg operon organization 
               
            
           
           
               
               
            
               
                 Bacteria 
                 Operon organization 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 
                   Escherichia coli 
                 
                 argA 
                 bipolar 
                 argD 
                 argI 
                 argG 
                 carAB 
               
               
                 
                   Nissle 
                 
                   
                 argECBH 
                   
                   
                   
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 
                   Bacteroides 
                 
                 argRGCD 
                 argF 
                 argB 
                 argE 
                 carAB 
               
            
           
           
               
               
               
               
            
               
                 
                   Clostridium 
                 
                 argR 
                 argGH 
                 argI 
               
            
           
           
               
               
               
            
               
                 
                   Bacillus subtilis 
                 
                 argGH 
                 argCAEBD-carAB-argF 
               
               
                 
                   Bacillus subtilis 
                 
                 argGH 
                 argCJBD-carAB-argF 
               
               
                 
                   Lactobacillus 
                 
                 argGH 
                 bipolar carAB-argCJBDF 
               
            
           
           
               
               
               
               
               
            
               
                 
                   plantarum 
                 
                   
                   
                   
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 
                   Lactococcus 
                 
                 argE 
                 carA 
                 carB 
                 argGH 
                 argFBDJC 
               
               
                   
               
            
           
         
       
     
     Each operon is regulated by a regulatory region comprising at least one promoter and at least one ARG box, which control repression and expression of the arginine biosynthesis genes in said operon. 
     In some embodiments, the genetically engineered bacteria of the invention comprise an arginine regulon comprising one or more nucleic acid mutations that reduce or eliminate arginine-mediated repression of one or more of the operons that encode the enzymes responsible for converting glutamate to arginine and/or an intermediate byproduct in the arginine biosynthesis pathway. Reducing or eliminating arginine-mediated repression may be achieved by reducing or eliminating ArgR repressor binding (e.g., by mutating or deleting the arginine repressor or by mutating at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes) and/or arginine binding to N-acetylglutamate synthetase (e.g., by mutating the N-acetylglutamate synthetase to produce an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr ). 
     ARG Box 
     In some embodiments, the genetically engineered bacteria comprise a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for one or more of the operons that encode the arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, and carbamoylphosphate synthase, thereby derepressing the regulon and enhancing arginine and/or intermediate byproduct biosynthesis. In some embodiments, the genetically engineered bacteria comprise a mutant arginine repressor comprising one or more nucleic acid mutations such that arginine repressor function is decreased or inactive, or the genetically engineered bacteria do not have an arginine repressor (e.g., the arginine repressor gene has been deleted), resulting in derepression of the regulon and enhancement of arginine and/or intermediate byproduct biosynthesis. In either of these embodiments, the genetically engineered bacteria may further comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr . Thus, in some embodiments, the genetically engineered bacteria comprise a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for one or more of the operons that encode the arginine biosynthesis enzymes and an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr . In some embodiments, the genetically engineered bacteria comprise a mutant or deleted arginine repressor and an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr . In some embodiments, the genetically engineered bacteria comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr , a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes, and/or a mutant or deleted arginine repressor. 
     In some embodiments, the genetically engineered bacteria encode an arginine feedback resistant N-acetylglutamate synthase and further comprise a mutant arginine regulon comprising one or more nucleic acid mutations in each ARG box for one or more of the operons that encode N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, carbamoylphosphate synthase, and wild-type N-acetylglutamate synthetase, such that ArgR binding is reduced or eliminated, thereby derepressing the regulon and enhancing arginine and/or intermediate byproduct biosynthesis. 
     In some embodiments, the ARG boxes for the operon encoding argininosuccinate synthase (argG) maintain the ability to bind to ArgR, thereby driving citrulline biosynthesis. For example, the regulatory region of the operon encoding argininosuccinate synthase (argG) may be a constitutive, thereby driving arginine biosynthesis. In alternate embodiments, the regulatory region of one or more alternate operons may be constitutive. In certain bacteria, however, genes encoding multiple enzymes may be organized in bipolar operons or under the control of a shared regulatory region; in these instances, the regulatory regions may need to be deconvoluted in order to engineer constitutively active regulatory regions. For example, in  E. coli  K12 and Nissle, argE and argCBH are organized in two bipolar operons, argECBH, and those regulatory regions may be deconvoluted in order to generate constitutive versions of argE and/or argCBH. 
     In some embodiments, all ARG boxes in one or more operons that comprise an arginine biosynthesis gene are mutated to reduce or eliminate ArgR binding. In some embodiments, all ARG boxes in one or more operons that encode an arginine biosynthesis enzyme are mutated to reduce or eliminate ArgR binding. In some embodiments, all ARG boxes in each operon that comprises an arginine biosynthesis gene are mutated to reduce or eliminate ArgR binding. In some embodiments, all ARG boxes in each operon that encodes an arginine biosynthesis enzyme are mutated to reduce or eliminate ArgR binding. 
     In some embodiments, the genetically engineered bacteria encode an arginine feedback resistant N-acetylglutamate synthase, argininosuccinate synthase driven by a ArgR-repressible regulatory region, and further comprise a mutant arginine regulon comprising one or more nucleic acid mutations in each ARG box for each of the operons that encode N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine am inotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, carbamoylphosphate synthase, and optionally, wild-type N-acetylglutamate synthetase, such that ArgR binding is reduced or eliminated, thereby derepressing the regulon and enhancing citrulline biosynthesis. In some embodiments, the genetically engineered bacteria capable of producing citrulline is particularly advantageous, because citrulline further serves as a therapeutically effective supplement for the treatment of certain urea cycle disorders (National Urea Cycle Disorders Foundation). 
     In some embodiments, the genetically engineered bacteria encode an arginine feedback resistant N-acetylglutamate synthase, argininosuccinate synthase driven by a constitutive promoter, and further comprise a mutant arginine regulon comprising one or more nucleic acid mutations in each ARG box for each of the operons that encode N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine am inotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate lyase, carbamoylphosphate synthase, and optionally, wild-type N-acetylglutamate synthetase, such that ArgR binding is reduced or eliminated, thereby derepressing the regulon and enhancing arginine biosynthesis. 
     In some embodiments, the genetically engineered bacteria comprise a mutant arginine regulon and a feedback resistant ArgA, and when the arginine feedback resistant ArgA is expressed, are capable of producing more arginine and/or an intermediate byproduct than unmodified bacteria of the same subtype under the same conditions. In any of these embodiments, the mutant arginine regulon and/or a feedback resistant ArgA may be integrated into the bacterial chromosome at one or more integration sites or may be present on one or more plasmids. 
     Arginine Repressor Binding Sites (ARG Boxes) 
     In some embodiments, the genetically engineered bacteria additionally comprise a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for one or more of the operons that encode the arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine am inotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, and carbamoylphosphate synthase, such that the arginine regulon is derepressed and biosynthesis of arginine and/or an intermediate byproduct, e.g., citrulline, is enhanced. 
     In some embodiments, the mutant arginine regulon comprises an operon encoding ornithine acetyltransferase and one or more nucleic acid mutations in at least one ARG box for said operon. The one or more nucleic acid mutations results in the disruption of the palindromic ARG box sequence, such that ArgR binding to that ARG box and to the regulatory region of the operon is reduced or eliminated, as compared to ArgR binding to an unmodified ARG box and regulatory region in bacteria of the same subtype under the same conditions. In some embodiments, nucleic acids that are protected from DNA methylation and hydroxyl radical attack during ArgR binding are the primary targets for mutations to disrupt ArgR binding. In some embodiments, the mutant arginine regulon comprises at least three nucleic acid mutations in one or more ARG boxes for each of the operons that encode the arginine biosynthesis enzymes described above. The ARG box overlaps with the promoter, and in the mutant arginine regulon, the G/C:A/T ratio of the mutant promoter region differs by no more than 10% from the G/C:A/T ratio of the wild-type promoter region (Table 3). The promoter retains sufficiently high homology to the non-mutant promoter such that RNA polymerase binds with sufficient affinity to promote transcription. 
     The wild-type genomic sequences comprising ARG boxes and mutants thereof for each arginine biosynthesis operon in  E. coli  Nissle are shown in Table 3. For exemplary wild-type sequences, the ARG boxes are indicated in italics, and the start codon of each gene is  . The RNA polymerase binding sites are underlined (Cunin, 1983; Maas, 1994). In some embodiments, the underlined sequences are not altered. Bases that are protected from DNA methylation during ArgR binding are highlighted, and bases that are protected from hydroxyl radical attack during ArgR binding are bolded (Charlier et al., 1992). The highlighted and bolded bases are the primary targets for mutations to disrupt ArgR binding. 
     
       
         
           
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Regulatory 
                   
               
               
                 region 
                 Sequence 
               
               
                   
               
             
            
               
                 argA WT (SEQ ID NO: 1) 
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 argA mutant 
                 gcaaaaaaacactttaaaaacttaataatt 
               
               
                 (SEQ ID NO: 2) 
                 tcctttaatcacttaaagaggtgtaccgtg 
               
               
                   
               
               
                 argI WT (SEQ ID NO: 3) 
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 argI mutant 
                 agacttgcaaacttatacttatccatatag 
               
               
                 (SEQ ID NO: 4) 
                 attttgttttaatttgttaaggcgttagcc 
               
               
                   
                 acaggagggatctatg 
               
               
                   
               
               
                 argCBH WT 
                 TCAT TGTTGACA CACCTCTGGTCATGA TAG   
               
               
                 (SEQ ID NO: 5) 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 CACCAGCCGTAAGGTGAATGTTTTACGTTT 
               
               
                   
                 AACCTGGCAACCAGACATAAGAAGGTGAAT 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 argCBH mutant 
                 tcattgttgacacacctctggtcatgatag 
               
               
                 (SEQ ID NO: 6) 
                 tatcaaacttcatgggatatttatctttaa 
               
               
                   
                 aaatacttgaacgttgagcgtaataaaacc 
               
               
                   
                 caccagccgtaaggtgaatgttttacgttt 
               
               
                   
                 aacctggcaaccagacataagaaggtgaat 
               
               
                   
                 agccccgatg 
               
               
                 argE WT 
                 CATCGGGGCTATTCACCTTCTTATGTCTGG 
               
               
                 (SEQ ID NO: 7) 
                 TTGCCAGGTTAAACGTAAAACATTCACCTT 
               
               
                   
                 ACGGCTGGTG GGTTTTAT TACGCTCAACGT 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                   A   ATA   TTGATA CTATCATGACCAGAGGTGTG 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 argE mutant 
                 catcggggctattcaccttcttatgtctgg 
               
               
                 (SEQ ID NO: 8) 
                 ttgccaggttaaacgtaaaacattcacctt 
               
               
                   
                 acggctggtgggttttattacgctcaacgt 
               
               
                   
                 tcaagtatttttaaagataaatatcccatg 
               
               
                   
                 aagtttgatactatcatgaccagaggtgtg 
               
               
                   
                 tcaacaatga 
               
               
                   
               
               
                 carAB WT 
                 AGCAGATTTGCA TTGATT TACGTCATCATT 
               
               
                 (SEQ ID NO: 9) 
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 carAB mutant 
                 agcagatttgcattgatttacgtcatcatt 
               
               
                 (SEQ ID NO: 10) 
                 gtcttttaatatcttaataactggagtgac 
               
               
                   
                 gtttctctggagggtgttttg 
               
               
                   
               
               
                 argD WT (SEQ ID NO: 11) 
                 
                   
                     
                     
                         
                         
                     
                   
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 TTATGCGTAACAGGGTGATCATGAGATG 
               
               
                   
               
               
                 argD mutant 
                 tttctgattgccattcagtctttttttact 
               
               
                 (SEQ ID NO: 12) 
                 tatattttgtctttataatcttatatttat 
               
               
                   
                 ttatgcgtaacagggtgatcatgagatg 
               
               
                   
               
               
                 argG WT (SEQ ID NO: 13) 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 TTCATTTGTTGAATACTTTTACCTTCTCCT 
               
               
                   
                 GCTTTCCCTTAAGCGCATTATTTTACAAAA 
               
               
                   
                 AACACACTAAACTCTTCCTGTCTCCGATAA 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 GGCTCATCATCAGTTAATTAAGCAGGGTGT 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 argG mutant 
                 ctaatcaccttaatgaatcttcagttcact 
               
               
                 (SEQ ID NO: 14) 
                 ttcatttgttgaatacttttaccttctcct 
               
               
                   
                 gctttcccttaagcgcattattttacaaaa 
               
               
                   
                 aacacactaaactcttcctgtctccgataa 
               
               
                   
                 aagatgatcttatgaaaacctttttatttc 
               
               
                   
                 ttataaaaatcttgtgaaagcagaaatcca 
               
               
                   
                 ggctcatcatcagttaattaagcagggtgt 
               
               
                   
                 tattttatg 
               
               
                   
               
               
                 argG mutant 
                 cctgaaacgtggcaaattctactcgttttg 
               
               
                 (SEQ ID NO: 15) 
                 ggtaaaaaatgcaaatactgctgggatttg 
               
               
                   
                 gtgtaccgagacgggacgtaaaatctgcag 
               
               
                   
                 gcattatagtgatccacgccacattttgtc 
               
               
                   
                 aacgtttattgctaatcattgacggctagc 
               
               
                   
                 tcagtcctaggtacagtgctagcACCCGTT 
               
               
                   
                 TTTTTGGGCTAGAAATAATTTTGTTTAACT 
               
               
                   
                 TTAAGAAGGAGATATACATACCC 
               
               
                   
               
            
           
         
       
     
     In some embodiments, more than one ARG box may be present in a single operon. In one aspect of these embodiments, at least one of the ARG boxes in an operon is mutated to produce the requisite reduced ArgR binding to the regulatory region of the operon. In an alternate aspect of these embodiments, each of the ARG boxes in an operon is mutated to produce the requisite reduced ArgR binding to the regulatory region of the operon. One of skill in the art would appreciate that the number of ARG boxes per regulatory region may vary across bacteria, and the nucleotide sequences of the ARG boxes may vary for each operon. For example, the carAB operon in  E. coli  Nissle comprises two ARG boxes, and one or both ARG box sequences may be mutated. The argG operon in  E. coli  Nissle comprises three ARG boxes, and one, two, or three ARG box sequences may be mutated, disrupted, or deleted. In some embodiments, all three ARG box sequences are mutated, disrupted, or deleted, and a constitutive promoter, e.g., BBa_J23100, is inserted in the regulatory region of the argG operon. One of skill in the art would appreciate that the number of ARG boxes per regulatory region may vary across bacteria, and the nucleotide sequences of the ARG boxes may vary for each operon. 
     An exemplary embodiment of a constitutively expressed argG construct in  E. coli  Nissle is depicted in Table 4. Table 4 depicts the wild-type genomic sequence of the regulatory region and 5′ portion of the argG gene in  E. coli  Nissle, and a constitutive mutant thereof. The promoter region of each sequence is underlined, and a 5′ portion of the argG gene is  . In the wild-type sequence, ArgR binding sites are in uppercase and underlined. In the mutant sequence, the 5′ untranslated region is in uppercase and underlined. Bacteria expressing argG under the control of the constitutive promoter are capable of producing arginine. Bacteria expressing argG under the control of the wild-type, ArgR-repressible promoter are capable of producing citrulline. A map of the wild-type argG operon  E. coli  Nissle and a constitutively expressing mutant thereof is shown in  FIG. 12 . 
     
       
         
           
               
               
             
               
                 TABLE 4 
               
               
                   
               
             
            
               
                 Wild-type 
                 
                   gtgatccacgccacattttgtcaacgtttattgctaatcaCGTG 
                 
               
               
                 argG 
                 
                   AATGAATATCCAGTtcactttcatttgttgaatacttttacctt 
                 
               
               
                 (SEQ ID NO: 
                 
                   ctcctgctttcccttaagcgcattattttacaaaaaacacacta 
                 
               
               
                 16) 
                 
                   aactcttcctgtctccgataaaagatgATTAAATGAAAACTCAT 
                 
               
               
                   
                 
                   TtatTTTGCATAAAAATTCAGTgaaagcagaaatccaggctcat 
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 Constitutive 
                 
                   ttgacggctagctcagtcctaggtacagtgctagcACCCGTTTT 
                 
               
               
                 argG 
                 
                   TTTGGGCTAGAAATAATTTTGTTTAACTTTAAGAAGGAGATATA 
                 
               
               
                 (SEQ ID NO: 17) 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the ArgR binding affinity to a mutant ARG box or regulatory region of an operon is at least about 50% lower, at least about 60% lower, at least about 70% lower, at least about 80% lower, at least about 90% lower, or at least about 95% lower than the ArgR binding affinity to an unmodified ARG box and regulatory region in bacteria of the same subtype under the same conditions. In some embodiments, the reduced ArgR binding to a mutant ARG box and regulatory region increases mRNA expression of the gene(s) in the associated operon by at least about 1.5-fold, at least about 2-fold, at least about 10-fold, at least about 15-fold, at least about 20-fold, at least about 30-fold, at least about 50-fold, at least about 100-fold, at least about 200-fold, at least about 300-fold, at least about 400-fold, at least about 500-fold, at least about 600-fold, at least about 700-fold, at least about 800-fold, at least about 900-fold, at least about 1,000-fold, or at least about 1,500-fold. 
     In some embodiments, quantitative PCR (qPCR) is used to amplify, detect, and/or quantify mRNA expression levels of the arginine biosynthesis genes. Primers specific for arginine biosynthesis genes, e.g., argA, argB, argC, argD, argE, argF, argG, argH, argI, argJ, carA, and care, may be designed and used to detect mRNA in a sample according to methods known in the art (Fraga et al., 2008). In some embodiments, a fluorophore is added to a sample reaction mixture that may contain arg mRNA, and a thermal cycler is used to illuminate the sample reaction mixture with a specific wavelength of light and detect the subsequent emission by the fluorophore. The reaction mixture is heated and cooled to predetermined temperatures for predetermined time periods. In certain embodiments, the heating and cooling is repeated for a predetermined number of cycles. In some embodiments, the reaction mixture is heated and cooled to 90-100° C., 60-70° C., and 30-50° C. for a predetermined number of cycles. In a certain embodiment, the reaction mixture is heated and cooled to 93-97° C., 55-65° C., and 35-45° C. for a predetermined number of cycles. In some embodiments, the accumulating amplicon is quantified after each cycle of the qPCR. The number of cycles at which fluorescence exceeds the threshold is the threshold cycle (C T ). At least one C T  result for each sample is generated, and the C T  result(s) may be used to determine mRNA expression levels of the arginine biosynthesis genes. 
     In some embodiments, the genetically engineered bacteria comprising one or more nucleic acid mutations in at least one ARG box for one or more of the operons that encode the arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, and carbamoylphosphate synthase additionally comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr . 
     In some embodiments, the genetically engineered bacteria comprise a feedback resistant form of ArgA, as well as one or more nucleic acid mutations in each ARG box of one or more of the operons that encode the arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, ornithine acetyltransferase, and carbamoylphosphate synthase. 
     In some embodiments, the genetically engineered bacteria comprise a feedback resistant form of ArgA, argininosuccinate synthase driven by a ArgR-repressible regulatory region, as well as one or more nucleic acid mutations in each ARG box of each of the operons that encode the arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate lyase, ornithine acetyltransferase, and carbamoylphosphate synthase. In these embodiments, the bacteria are capable of producing citrulline. 
     In some embodiments, the genetically engineered bacteria comprise a feedback resistant form of ArgA, argininosuccinate synthase expressed from a constitutive promoter, as well as one or more nucleic acid mutations in each ARG box of each of the operons that encode the arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, ornithine acetyltransferase, and carbamoylphosphate synthase. In these embodiments, the bacteria are capable of producing arginine. 
     Table 3 shows examples of mutant constructs in which one or more nucleic acid mutations reduce or eliminate arginine-mediated repression of each of the arginine operons. The mutant constructs comprise feedback resistant form of ArgA driven by an oxygen level-dependent promoter, e.g., a FNR promoter. Each mutant arginine regulon comprises one or more nucleic acid mutations in at least one ARG box for one or more of the operons that encode N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, carbamoylphosphate synthase, and wild-type N-acetylglutamate synthetase, such that ArgR binding is reduced or eliminated, thereby enhancing arginine and/or intermediate byproduct biosynthesis. Non-limiting examples of mutant arginine regulon constructs are shown in Table 5. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Examples of ARG Box mutant constructs 
               
            
           
           
               
               
            
               
                   
                 Exemplary constructs (* indicates constitutive): 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Mutant construct comprises: 
                 Construct 1 
                 Construct 2 
                 Construct 3 
                 Construct 4 
                 Construct 5 
                 Construct 6 
               
               
                   
               
               
                 Arginine feedback resistant 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                 N-acetylglutamate synthetase 
                   
                   
                   
                   
                   
                   
               
               
                 driven by an oxygen level- 
                   
                   
                   
                   
                   
                   
               
               
                 dependent promoter 
                   
                   
                   
                   
                   
                   
               
               
                 Wild-type N-acetylglutamate 
                 ✓ 
                 ✓ 
                   
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                 synthetase 
                   
                   
                   
                   
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Mutation(s)  
                 Wild-type N- 
                 ✓ 
                   
                 ✓ 
                 ✓ 
                   
                 ✓ 
               
               
                 in at least one  
                 acetylglutamate 
                   
                   
                   
                   
                   
                   
               
               
                 ARG box 
                 synthetase 
                   
                   
                   
                   
                   
                   
               
               
                 for the  
                 N-acetylglutamate 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                 operon 
                 kinase 
                   
                   
                   
                   
                   
                   
               
               
                 encoding: 
                 N-acetylglutamylphosphate 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                   
                 reductase 
                   
                   
                   
                   
                   
                   
               
               
                   
                 acetylornithine 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                   
                 aminotransferase 
                   
                   
                   
                   
                   
                   
               
               
                   
                 N-acetylornithinase 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                   
                 ornithine 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                   
                 transcarbamylase 
                   
                   
                   
                   
                   
                   
               
               
                   
                 argininosuccinate 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓* 
                 ✓* 
                 ✓* 
               
               
                   
                 synthase 
                   
                   
                   
                   
                   
                   
               
               
                   
                 argininosuccinate 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                   
                 lyase 
                   
                   
                   
                   
                   
                   
               
               
                   
                 ornithine 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                   
                 acetyltransferase 
                   
                   
                   
                   
                   
                   
               
               
                   
                 carbamoylphosphate 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
                 ✓ 
               
               
                   
                 synthase 
               
               
                   
               
            
           
         
       
     
     The mutations may be present on a plasmid or chromosome. In some embodiments, the arginine regulon is regulated by a single repressor protein. In particular species, strains, and/or subtypes of bacteria, it has been proposed that the arginine regulon may be regulated by two putative repressors (Nicoloff et al., 2004). Thus, in certain embodiments, the arginine regulon of the invention is regulated by more than one repressor protein. 
     In certain embodiments, the mutant arginine regulon is expressed in one species, strain, or subtype of genetically engineered bacteria. In alternate embodiments, the mutant arginine regulon is expressed in two or more species, strains, and/or subtypes of genetically engineered bacteria. 
     Arginine Repressor (ArgR) 
     The genetically engineered bacteria of the invention comprise an arginine regulon comprising one or more nucleic acid mutations that reduce or eliminate arginine-mediated repression of one or more of the operons that encode the enzymes responsible for converting glutamate to arginine and/or an intermediate byproduct in the arginine biosynthesis pathway. In some embodiments, the reduction or elimination of arginine-mediated repression may be achieved by reducing or eliminating ArgR repressor binding, e.g., by mutating at least one ARG box for one or more of the operons that encode the arginine biosynthesis enzymes (as discussed above) or by mutating or deleting the arginine repressor (discussed here) and/or by reducing or eliminating arginine binding to N-acetylglutamate synthetase (e.g., by mutating the N-acetylglutamate synthetase to produce an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr ). 
     Thus, in some embodiments, the genetically engineered bacteria lack a functional ArgR repressor and therefore ArgR repressor-mediated transcriptional repression of each of the arginine biosynthesis operons is reduced or eliminated. In some embodiments, the engineered bacteria comprise a mutant arginine repressor comprising one or more nucleic acid mutations such that arginine repressor function is decreased or inactive. In some embodiments, the genetically engineered bacteria do not have an arginine repressor (e.g., the arginine repressor gene has been deleted), resulting in derepression of the regulon and enhancement of arginine and/or intermediate byproduct biosynthesis. In some embodiments, each copy of a functional argR gene normally present in a corresponding wild-type bacterium is independently deleted or rendered inactive by one or more nucleotide deletions, insertions, or substitutions. In some embodiments, each copy of the functional argR gene normally present in a corresponding wild-type bacterium is deleted. 
     In some embodiments, the arginine regulon is regulated by a single repressor protein. In particular species, strains, and/or subtypes of bacteria, it has been proposed that the arginine regulon may be regulated by two distinct putative repressors (Nicoloff et al., 2004). Thus, in certain embodiments, two distinct ArgR proteins each comprising a different amino acid sequence are mutated or deleted in the genetically engineered bacteria. 
     In some embodiments, the genetically modified bacteria comprising a mutant or deleted arginine repressor additionally comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr . In some embodiments, the genetically engineered bacteria comprise a feedback resistant form of ArgA, lack any functional arginine repressor, and are capable of producing arginine. In certain embodiments, the genetically engineered bacteria further lack functional ArgG and are capable of producing citrulline. In some embodiments, the argR gene is deleted in the genetically engineered bacteria. In some embodiments, the argR gene is mutated to inactivate ArgR function. In some embodiments, the argG gene is deleted in the genetically engineered bacteria. In some embodiments, the argG gene is mutated to inactivate ArgR function. In some embodiments, the genetically engineered bacteria comprise argA fbr  and deleted ArgR. In some embodiments, the genetically engineered bacteria comprise argA fbr , deleted ArgR, and deleted argG. In some embodiments, the deleted ArgR and/or the deleted argG is deleted from the bacterial genome and the argA fbr  is present in a plasmid. In some embodiments, the deleted ArgR and/or the deleted argG is deleted from the bacterial genome and the argA fbr  is chromosomally integrated. In one specific embodiment, the genetically modified bacteria comprise chromosomally integrated argA fbr , deleted genomic ArgR, and deleted genomic argG. In another specific embodiment, the genetically modified bacteria comprise argA fbr  present on a plasmid, deleted genomic ArgR, and deleted genomic argG. In any of the embodiments in which argG is deleted, citrulline rather than arginine is produced 
     In some embodiments, under conditions where a feedback resistant form of ArgA is expressed, the genetically engineered bacteria of the invention produce at least about 1.5-fold, at least about 2-fold, at least about 10-fold, at least about 15-fold, at least about 20-fold, at least about 30-fold, at least about 50-fold, at least about 100-fold, at least about 200-fold, at least about 300-fold, at least about 400-fold, at least about 500-fold, at least about 600-fold, at least about 700-fold, at least about 800-fold, at least about 900-fold, at least about 1,000-fold, or at least about 1,500-fold more arginine, citrulline, other intermediate byproduct, and/or transcript of the gene(s) in the operon as compared to unmodified bacteria of the same subtype under the same conditions. 
     In some embodiments, quantitative PCR (qPCR) is used to amplify, detect, and/or quantify mRNA expression levels of the arginine biosynthesis genes. Primers specific for arginine biosynthesis genes, e.g., argA, argB, argC, argD, argE, argF, argG, argH, argI, argJ, carA, and care, may be designed and used to detect mRNA in a sample according to methods known in the art (Fraga et al., 2008). In some embodiments, a fluorophore is added to a sample reaction mixture that may contain arg mRNA, and a thermal cycler is used to illuminate the sample reaction mixture with a specific wavelength of light and detect the subsequent emission by the fluorophore. The reaction mixture is heated and cooled to predetermined temperatures for predetermined time periods. In certain embodiments, the heating and cooling is repeated for a predetermined number of cycles. In some embodiments, the reaction mixture is heated and cooled to 90-100° C., 60-70° C., and 30-50° C. for a predetermined number of cycles. In a certain embodiment, the reaction mixture is heated and cooled to 93-97° C., 55-65° C., and 35-45° C. for a predetermined number of cycles. In some embodiments, the accumulating amplicon is quantified after each cycle of the qPCR. The number of cycles at which fluorescence exceeds the threshold is the threshold cycle (C T ). At least one C T  result for each sample is generated, and the C T  result(s) may be used to determine mRNA expression levels of the arginine biosynthesis genes. 
     In any of these embodiments in which the ArgR is mutated, the mutant ArgR and/or a feedback resistant ArgA may be integrated into the bacterial chromosome at one or more integration sites or may be present on one or more plasmids. 
     Feedback Resistant N-Acetylglutamate Synthetase 
     In some embodiments, the genetically engineered bacteria comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr . In some embodiments, the genetically engineered bacteria comprise a mutant arginine regulon comprising an arginine feedback resistant ArgA, and when the arginine feedback resistant ArgA is expressed, are capable of producing more arginine and/or an intermediate byproduct than unmodified bacteria of the same subtype under the same conditions. The arginine feedback resistant N-acetylglutamate synthetase protein (argA fbr ) is significantly less sensitive to L-arginine than the enzyme from the feedback sensitive parent strain (see, e.g., Eckhardt et al., 1975; Rajagopal et al., 1998). The feedback resistant argA gene can be present on a plasmid or chromosome. In some embodiments, expression from the plasmid may be useful for increasing argA fbr  expression. In some embodiments, expression from the chromosome may be useful for increasing stability of argA fbr  expression. 
     In some embodiments, any of the described mutant sequences involved in the arginine biosynthetic pathway (e.g., ArgR, argA fbr , Arg Box sequence) are integrated into the bacterial chromosome at one or more integration sites. For example, one or more copies of the sequence encoding the arginine feedback resistant N-acetylglutamate synthase may be integrated into the bacterial chromosome. Having multiple copies of the arginine feedback resistant N-acetylglutamate synthase integrated into the chromosome allows for greater production of the N-acetylglutamate synthase and also permits fine-tuning of the level of expression. Alternatively, different circuits described herein, such as any of the transporter or kill-switch circuits, in addition to the arginine feedback resistant N-acetylglutamate synthase could be integrated into the bacterial chromosome at one or more different integration sites to perform multiple different functions. Multiple distinct feedback resistant N-acetylglutamate synthetase proteins are known in the art and may be combined in the genetically engineered bacteria. In some embodiments, the argA fbr  gene is expressed under the control of a constitutive promoter. In some embodiments, the argA fbr  gene is expressed under the control of a promoter that is induced by exogenous environmental conditions. In some embodiments, the exogenous environmental conditions are specific to the gut of a mammal. In some embodiments, exogenous environmental conditions are molecules or metabolites that are specific to the mammalian gut in a healthy or disease state, e.g., propionate. In some embodiments, the exogenous environmental conditions are low-oxygen or anaerobic conditions, such as the environment of the mammalian gut. 
     Bacteria have evolved transcription factors that are capable of sensing oxygen levels. Different signaling pathways may be triggered by different oxygen levels and occur with different kinetics. An oxygen level-dependent promoter is a nucleic acid sequence to which one or more oxygen level-sensing transcription factors is capable of binding, wherein the binding and/or activation of the corresponding transcription factor activates downstream gene expression. In one embodiment, the argA fbr  gene is under control of an oxygen level-dependent promoter. In a more specific aspect, the argA fbr  gene is under control of an oxygen level-dependent promoter that is activated under low-oxygen or anaerobic environments, such as the environment of the mammalian gut. 
     In certain embodiments, the genetically engineered bacteria comprise argA fbr  expressed under the control of the fumarate and nitrate reductase regulator (FNR) promoter. In  E. coli , FNR is a major transcriptional activator that controls the switch from aerobic to anaerobic metabolism (Unden et al., 1997). In the anaerobic state, FNR dimerizes into an active DNA binding protein that activates hundreds of genes responsible for adapting to anaerobic growth. In the aerobic state, FNR is prevented from dimerizing by oxygen and is inactive. In alternate embodiments, the genetically engineered bacteria comprise argA fbr  expressed under the control of an alternate oxygen level-dependent promoter, e.g., an anaerobic regulation of arginine deiminiase and nitrate reduction ANR promoter (Ray et al., 1997), a dissimilatory nitrate respiration regulator DNR promoter (Trunk et al., 2010). In these embodiments, the arginine biosynthesis pathway is particularly activated in a low-oxygen or anaerobic environment, such as in the gut. 
     In  P. aeruginosa , the anaerobic regulation of arginine deiminiase and nitrate reduction (ANR) transcriptional regulator is “required for the expression of physiological functions which are inducible under oxygen-limiting or anaerobic conditions” (Winteler et al., 1996; Sawers 1991).  P. aeruginosa  ANR is homologous with  E. coli  FNR, and “the consensus FNR site (TTGAT----ATCAA) (SEQ ID NO: 121) was recognized efficiently by ANR and FNR” (Winteler et al., 1996). Like FNR, in the anaerobic state, ANR activates numerous genes responsible for adapting to anaerobic growth. In the aerobic state, ANR is inactive.  Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas syringae , and  Pseudomonas mendocina  all have functional analogs of ANR (Zimmermann et al., 1991). Promoters that are regulated by ANR are known in the art, e.g., the promoter of the arcDABC operon (see, e.g., Hasegawa et al., 1998). 
     The FNR family also includes the dissimilatory nitrate respiration regulator (DNR) (Arai et al., 1995), a transcriptional regulator that is required in conjunction with ANR for “anaerobic nitrate respiration of  Pseudomonas aeruginosa ” (Hasegawa et al., 1998). For certain genes, the FNR-binding motifs “are probably recognized only by DNR” (Hasegawa et al., 1998). Any suitable transcriptional regulator that is controlled by exogenous environmental conditions and corresponding regulatory region may be used. Non-limiting examples include ArcA/B, ResD/E, NreA/B/C, and AirSR, and others are known in the art. 
     FNR promoter sequences are known in the art, and any suitable FNR promoter sequence(s) may be used in the genetically engineered bacteria of the invention. Any suitable FNR promoter(s) may be combined with any suitable argA fbr  (e.g., the exemplary argA fbr  sequence shown in Table 7). Non-limiting FNR promoter sequences are provided in Table 6. Table 6 depicts the nucleic acid sequences of exemplary regulatory region sequences comprising a FNR-responsive promoter sequence. Underlined sequences are predicted ribosome binding sites, and bolded sequences are restriction sites used for cloning. In some embodiments, the genetically engineered bacteria of the invention comprise one or more of: SEQ ID NO: 18, SEQ ID NO: 19, nirB1 promoter (SEQ ID NO: 20), nirB2 promoter (SEQ ID NO: 21), nirB3 promoter (SEQ ID NO: 22), ydfZ promoter (SEQ ID NO: 23), nirB promoter fused to a strong ribosome binding site (SEQ ID NO: 24), ydfZ promoter fused to a strong ribosome binding site (SEQ ID NO: 25), fnrS, an anaerobically induced small RNA gene (fnrS1 promoter SEQ ID NO: 26 or fnrS2 promoter SEQ ID NO: 27), nirB promoter fused to a crp binding site (SEQ ID NO: 28), and fnrS fused to a crp binding site (SEQ ID NO: 29). 
     In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, or a functional fragment thereof. 
     
       
         
           
               
               
             
               
                 TABLE 6 
               
               
                   
               
               
                 FNR-responsive 
                   
               
               
                 regulatory 
                   
               
               
                 region 
                 12345678901234567890123456789012345678901234567890 
               
               
                   
               
             
            
               
                 SEQ ID NO: 
                 ATCCCCATCACTCTTGATGGAGATCAATTCCCCAAGCTGCTAGAGCGTTA 
               
               
                 18 
                 CCTTGCCCTTAAACATTAGCAATGTCGATTTATCAGAGGGCCGACAGGCT 
               
               
                   
                 CCCACAGGAGAAAACCG 
               
               
                   
               
               
                 SEQ ID NO: 
                 CTCTTGATCGTTATCAATTCCCACGCTGTTTCAGAGCGTTACCTTGCCCT 
               
               
                 19 
                 TAAACATTAGCAATGTCGATTTATCAGAGGGCCGACAGGCTCCCACAGGA 
               
               
                   
                 GAAAACCG 
               
               
                   
               
               
                 nirB1 
                 GTCAGCATAACACCCTGACCTCTCATTAATTGTTCATGCCGGGCGGCACT 
               
               
                 SEQ ID NO: 
                 ATCGTCGTCCGGCCTTTTCCTCTCTTACTCTGCTACGTACATCTATTTCT 
               
               
                 20 
                 ATAAATCCGTTCAATTTGTCTGTTTTTTGCACAAACATGAAATATCAGAC 
               
               
                   
                 AATTCCGTGACTTAAGAAAATTTATACAAATCAGCAATATACCCCTTAAG 
               
               
                   
                 GAGTATATAAAGGTGAATTTGATTTACATCAATAAGCGGGGTTGCTGAAT 
               
               
                   
                 CGTTAAGGTAGGCGGTAATAG AAAAGAAATCGAGGCAAAA   
               
               
                   
               
               
                 nirB2 
                 CGGCCCGATCGTTGAACATAGCGGTCCGCAGGCGGCACTGCTTACAGCAA 
               
               
                 SEQ ID NO: 
                 ACGGTCTGTACGCTGTCGTCTTTGTGATGTGCTTCCTGTTAGGTTTCGTC 
               
               
                 21 
                 AGCCGTCACCGTCAGCATAACACCCTGACCTCTCATTAATTGCTCATGCC 
               
               
                   
                 GGACGGCACTATCGTCGTCCGGCCTTTTCCTCTCTTCCCCCGCTACGTGC 
               
               
                   
                 ATCTATTTCTATAAACCCGCTCATTTTGTCTATTTTTTGCACAAACATGA 
               
               
                   
                 AATATCAGACAATTCCGTGACTTAAGAAAATTTATACAAATCAGCAATAT 
               
               
                   
                 ACCCATTAAGGAGTATATAAAGGTGAATTTGATTTACATCAATAAGCGGG 
               
               
                   
                 GTTGCTGAATCGTTAAGGTAGGCGGTAATAGAAAAGAAATCGAGGCAAAA 
               
               
                   
                 atgtttgtttaactttaagaaggagatatacat 
               
               
                   
               
               
                 nirB3 
                 GTCAGCATAACACCCTGACCTCTCATTAATTGCTCATGCCGGACGGCACT 
               
               
                 SEQ ID NO: 
                 ATCGTCGTCCGGCCTTTTCCTCTCTTCCCCCGCTACGTGCATCTATTTCT 
               
               
                 22 
                 ATAAACCCGCTCATTTTGTCTATTTTTTGCACAAACATGAAATATCAGAC 
               
               
                   
                 AATTCCGTGACTTAAGAAAATTTATACAAATCAGCAATATACCCATTAAG 
               
               
                   
                 GAGTATATAAAGGTGAATTTGATTTACATCAATAAGCGGGGTTGCTGAAT 
               
               
                   
                 CGTTAAGGTAGGCGGTAATAGAAAAGAAATCGAGGCAAAA 
               
               
                   
               
               
                 ydfZ 
                 ATTTCCTCTCATCCCATCCGGGGTGAGAGTCTTTTCCCCCGACTTATGGC 
               
               
                 SEQ ID NO: 
                 TCATGCATGCATCAAAAAAGATGTGAGCTTGATCAAAAACAAAAAATATT 
               
               
                 23 
                 TCACTCGACAGGAGTATTTATATTGCGCCCGTTACGTGGGCTTCGACTGT 
               
               
                   
                 AAATC AGAAAGGAGAAAACACCT   
               
               
                   
               
               
                 nirB + RBS 
                 GTCAGCATAACACCCTGACCTCTCATTAATTGTTCATGCCGGGCGGCACT 
               
               
                 SEQ ID NO: 
                 ATCGTCGTCCGGCCTTTTCCTCTCTTACTCTGCTACGTACATCTATTTCT 
               
               
                 24 
                 ATAAATCCGTTCAATTTGTCTGTTTTTTGCACAAACATGAAATATCAGAC 
               
               
                   
                 AATTCCGTGACTTAAGAAAATTTATACAAATCAGCAATATACCCCTTAAG 
               
               
                   
                 GAGTATATAAAGGTGAATTTGATTTACATCAATAAGCGGGGTTGCTGAAT 
               
               
                   
                 CGTTAA GGATCC   CTCTAGAAATAATTTTGTTTAACTTTAAGAAGGAGATA   
               
               
                   
                 
                   TACAT 
                 
               
               
                   
               
               
                 ydfZ + RBS 
                 CATTTCCTCTCATCCCATCCGGGGTGAGAGTCTTTTCCCCCGACTTATGG 
               
               
                 SEQ ID NO: 
                 CTCATGCATGCATCAAAAAAGATGTGAGCTTGATCAAAAACAAAAAATAT 
               
               
                 25 
                 TTCACTCGACAGGAGTATTTATATTGCGCCC GGATCC   CTCTAGAAATAAT   
               
               
                   
                 
                   TTTGTTTAACTTTAAGAAGGAGATATACAT 
                 
               
               
                   
               
               
                 fnrS1 
                 AGTTGTTCTTATTGGTGGTGTTGCTTTATGGTTGCATCGTAGTAAATGGT 
               
               
                 SEQ ID NO: 
                 TGTAACAAAAGCAATTTTTCCGGCTGTCTGTATACAAAAACGCCGTAAAG 
               
               
                 26 
                 TTTGAGCGAAGTCAATAAACTCTCTACCCATTCAGGGCAATATCTCTCTT 
               
               
                   
                 
                   GGATCC 
                   CTCTAGAAATAATTTTGTTTAACTTTAAGAAGGAGATATACAT 
                 
               
               
                   
               
               
                 fnrS2 
                 AGTTGTTCTTATTGGTGGTGTTGCTTTATGGTTGCATCGTAGTAAATGGT 
               
               
                 SEQ ID NO: 
                 TGTAACAAAAGCAATTTTTCCGGCTGTCTGTATACAAAAACGCCGCAAAG 
               
               
                 27 
                 TTTGAGCGAAGTCAATAAACTCTCTACCCATTCAGGGCAATATCTCTCTT 
               
               
                   
                 
                   GGATCCAAAGTGAACTCTAGAAATAATTTTGTTTAACTTTAAGAAGGAGA 
                 
               
               
                   
                 
                   TATACAT 
                 
               
               
                   
               
               
                 nirB + crp 
                 TCGTCTTTGTGATGTGCTTCCTGTTAGGTTTCGTCAGCCGTCACCGTCAG 
               
               
                 SEQ ID NO: 
                 CATAACACCCTGACCTCTCATTAATTGCTCATGCCGGACGGCACTATCGT 
               
               
                 28 
                 CGTCCGGCCTTTTCCTCTCTTCCCCCGCTACGTGCATCTATTTCTATAAA 
               
               
                   
                 CCCGCTCATTTTGTCTATTTTTTGCACAAACATGAAATATCAGACAATTC 
               
               
                   
                 CGTGACTTAAGAAAATTTATACAAATCAGCAATATACCCATTAAGGAGTA 
               
               
                   
                 TATAAAGGTGAATTTGATTTACATCAATAAGCGGGGTTGCTGAATCGTTA 
               
               
                   
                 AGGTAGaaatgtgatctagttcacatttGCGGTAATAGAAAAGAAATCGA 
               
               
                   
                 GGCAAAA atgtttgtttaactttaagaaggagatatacat   
               
               
                   
               
               
                 fnrS + crp 
                 AGTTGTTCTTATTGGTGGTGTTGCTTTATGGTTGCATCGTAGTAAATGGT 
               
               
                 SEQ ID NO: 
                 TGTAACAAAAGCAATTTTTCCGGCTGTCTGTATACAAAAACGCCGCAAAG 
               
               
                 29 
                 TTTGAGCGAAGTCAATAAACTCTCTACCCATTCAGGGCAATATCTCTCaa 
               
               
                   
                 atgtgatctagttcacattt tttgtttaactttaagaaggagatatacat   
               
               
                   
               
            
           
         
       
     
     In other embodiments, argA fbr  is expressed under the control of an oxygen level-dependent promoter fused to a binding site for a transcriptional activator, e.g., CRP. CRP (cyclic AMP receptor protein or catabolite activator protein or CAP) plays a major regulatory role in bacteria by repressing genes responsible for the uptake, metabolism and assimilation of less favorable carbon sources when rapidly metabolizable carbohydrates, such as glucose, are present (Wu et al., 2015). This preference for glucose has been termed glucose repression, as well as carbon catabolite repression (Deutscher, 2008; Görke and Stülke, 2008). In some embodiments, argA fbr  expression is controlled by an oxygen level-dependent promoter fused to a CRP binding site. In some embodiments, argA fbr  expression is controlled by a FNR promoter fused to a CRP binding site. In these embodiments, cyclic AMP binds to CRP when no glucose is present in the environment. This binding causes a conformational change in CRP, and allows CRP to bind tightly to its binding site. CRP binding then activates transcription of the argA fbr  gene by recruiting RNA polymerase to the FNR promoter via direct protein-protein interactions. In the presence of glucose, cyclic AMP does not bind to CRP and argA fbr  gene transcription is repressed. In some embodiments, an oxygen level-dependent promoter (e.g., a FNR promoter) fused to a binding site for a transcriptional activator is used to ensure that argA fbr  is not expressed under anaerobic conditions when sufficient amounts of glucose are present, e.g., by adding glucose to growth media in vitro. 
     In some embodiments, argA fbr  is expressed under the control of an inducible promoter that is responsive to specific molecules or metabolites in the environment, e.g., the mammalian gut. For example, the short-chain fatty acid propionate is a major microbial fermentation metabolite localized to the gut (Hosseini et al., 2011). In one embodiment, argA fbr  gene expression is under the control of a propionate-inducible promoter. In a more specific embodiment, argA fbr  gene expression is under the control of a propionate-inducible promoter that is activated by the presence of propionate in the mammalian gut. Any molecule or metabolite found in the mammalian gut, in a healthy and/or disease state, may be used to induce argA fbr  expression. Non-limiting examples include propionate, bilirubin, aspartate aminotransferase, alanine aminotransferase, blood coagulation factors II, VII, IX, and X, alkaline phosphatase, gamma glutamyl transferase, hepatitis antigens and antibodies, alpha fetoprotein, anti-mitochondrial, smooth muscle, and anti-nuclear antibodies, iron, transferrin, ferritin, copper, ceruloplasmin, ammonia, and manganese. In alternate embodiments, argA fbr  gene expression is under the control of a P araBAD  promoter, which is activated in the presence of the sugar arabinose (see, e.g.,  FIG. 13 ). 
     Subjects with hepatic encephalopathy (HE) and other liver disease or disorders have chronic liver damage that results in high ammonia levels in their blood and intestines. In addition to ammonia, these patients also have elevated levels of bilirubin, aspartate aminotransferase, alanine aminotransferase, blood coagulation factors II, VII, IX, and X, alkaline phosphatase, gamma glutamyl transferase, hepatitis antigens and antibodies, alpha fetoprotein, anti-mitochondrial, smooth muscle, and anti-nuclear antibodies, iron, transferrin, ferritin, copper, ceruloplasmin, ammonia, and manganese in their blood and intestines. Promoters that respond to one of these HE-related molecules or their metabolites may be used in the genetically engineered bacteria to induce expression of argA fbr  in the gut. These promoters would not be expected to be induced in non-HE patients. 
     In some embodiments, the argA fbr  gene is expressed under the control of a promoter that is induced by exposure to tetracycline. In some embodiments, the argA fbr  gene is expressed under the control of a promoter that is induced by exposure to inflammation or an inflammatory response (e.g., RNS or ROS promoters). In some embodiments, the argA fbr  gene is expressed under the control of a promoter that is induced by exposure to a metabolite such as arabinose (e.g., AraBAD promoter). 
     In some embodiments, gene expression is further optimized by methods known in the art, e.g., by optimizing ribosomal binding sites, manipulating transcriptional regulators, and/or increasing mRNA stability. The nucleic acid sequence of an exemplary argA fbr  sequence is shown in Table 7. The polypeptide sequence of an exemplary argA fbr  sequence is shown in Table 8. 
     
       
         
           
               
             
               
                 TABLE 7 
               
               
                   
               
               
                 Nucleotide sequence of exemplary argA fbr  sequence 
               
               
                 (SEQ ID NO: 30) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 ATGGTAAAGGAACGTAAAACCGAGTTGGTCGAGGGATTCCGCCATTCGGT 
               
               
                 TCCCTGTATCAATACCCACCGGGGAAAAACGTTTGTCATCATGCTCGGCG 
               
               
                 GTGAAGCCATTGAGCATGAGAATTTCTCCAGTATCGTTAATGATATCGGG 
               
               
                 TTGTTGCACAGCCTCGGCATCCGTCTGGTGGTGGTCTATGGCGCACGTCC 
               
               
                 GCAGATCGACGCAAATCTGGCTGCGCATCACCACGAACCGCTGTATCACA 
               
               
                 AGAATATACGTGTGACCGACGCCAAAACACTGGAACTGGTGAAGCAGGCT 
               
               
                 GCGGGAACATTGCAACTGGATATTACTGCTCGCCTGTCGATGAGTCTCAA 
               
               
                 TAACACGCCGCTGCAGGGCGCGCATATCAACGTCGTCAGTGGCAATTTTA 
               
               
                 TTATTGCCCAGCCGCTGGGCGTCGATGACGGCGTGGATTACTGCCATAGC 
               
               
                 GGGCGTATCCGGCGGATTGATGAAGACGCGATCCATCGTCAACTGGACAG 
               
               
                 CGGTGCAATAGTGCTAATGGGGCCGGTCGCTGTTTCAGTCACTGGCGAGA 
               
               
                 GCTTTAACCTGACCTCGGAAGAGATTGCCACTCAACTGGCCATCAAACTG 
               
               
                 AAAGCTGAAAAGATGATTGGTTTTTGCTCTTCCCAGGGCGTCACTAATGA 
               
               
                 CGACGGTGATATTGTCTCCGAACTTTTCCCTAACGAAGCGCAAGCGCGGG 
               
               
                 TAGAAGCCCAGGAAGAGAAAGGCGATTACAACTCCGGTACGGTGCGCTTT 
               
               
                 TTGCGTGGCGCAGTGAAAGCCTGCCGCAGCGGCGTGCGTCGCTGTCATTT 
               
               
                 AATCAGTTATCAGGAAGATGGCGCGCTGTTGCAAGAGTTGTTCTCACGCG 
               
               
                 ACGGTATCGGTACGCAGATTGTGATGGAAAGCGCCGAGCAGATTCGTCGC 
               
               
                 GCAACAATCAACGATATTGGCGGTATTCTGGAGTTGATTCGCCCACTGGA 
               
               
                 GCAGCAAGGTATTCTGGTACGCCGTTCTCGCGAGCAGCTGGAGATGGAAA 
               
               
                 TCGACAAATTCACCATTATTCAGCGCGATAACACGACTATTGCCTGCGCC 
               
               
                 GCGCTCTATCCGTTCCCGGAAGAGAAGATTGGGGAAATGGCCTGTGTGGC 
               
               
                 AGTTCACCCGGATTACCGCAGTTCATCAAGGGGTGAAGTTCTGCTGGAAC 
               
               
                 GCATTGCCGCTCAGGCTAAGCAGAGCGGCTTAAGCAAATTGTTTGTGCTG 
               
               
                 ACCACGCGCAGTATTCACTGGTTCCAGGAACGTGGATTTACCCCAGTGGA 
               
               
                 TATTGATTTACTGCCCGAGAGCAAAAAGCAGTTGTACAACTACCAGCGTA 
               
               
                 AATCCAAAGTGTTGATGGCGGATTTAGGGTAA 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 8 
               
               
                   
               
               
                 Polypeptide sequence of exemplary argA fbr  sequence 
               
               
                 (SEQ ID NO: 31) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 MVKERKTELVEGFRHSVP   C   INTHRGKTFVIMLGGEAIEHENFSSIVNDIG 
               
               
                 LLHSLGIRLVVVYGARPQIDANLAAHHHEPLYHKNIRVTDAKTLELVKQA 
               
               
                 AGTLQLDITARLSMSLNNTPLQGAHINVVSGNFIIAQPLGVDDGVDYCHS 
               
               
                 GRIRRIDEDAIHRQLDSGAIVLMGPVAVSVTGESFNLTSEEIATQLAIKL 
               
               
                 KAEKMIGFCSSQGVTNDDGDIVSELFPNEAQARVEAQEEKGDYNSGTVRF 
               
               
                 LRGAVKACRSGVRRCHLISYQEDGALLQELFSRDGIGTQIVMESAEQIRR 
               
               
                 ATINDIGGILELIRPLEQQGILVRRSREQLEMEIDKFTIIQRDNTTIACA 
               
               
                 ALYPFPEEKIGEMACVAVHPDYRSSSRGEVLLERIAAQAKQSGLSKLFVL 
               
               
                 TTRSIHWFQERGFTPVDIDLLPESKKQLYNYQRKSKVLMADLG 
               
               
                   
               
               
                 Bold underline: mutated amino acid resulting feedback resistance. (mutation is Y19C) 
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 30 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 30 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 30 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 30 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria encode a polypeptide sequence of SEQ ID NO: 31 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria encode a polypeptide sequence encodes a polypeptide, which contains one or more conservative amino acid substitutions relative to SEQ ID NO: 31 or a functional fragment thereof. In some embodiments, genetically engineered bacteria encode a polypeptide sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 31 or a functional fragment thereof. 
     In some embodiments, arginine feedback inhibition of N-acetylglutamate synthetase is reduced by at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or at least about 95% in the genetically engineered bacteria when the arginine feedback resistant N-acetylglutamate synthetase is active, as compared to a wild-type N-acetylglutamate synthetase from bacteria of the same subtype under the same conditions. 
     In some embodiments, the genetically engineered bacteria comprise a stably maintained plasmid or chromosome carrying the argA fbr  gene, such that argA fbr  can be expressed in the host cell, and the host cell is capable of survival and/or growth in vitro, e.g., in medium, and/or in vivo, e.g., in the gut. In some embodiments, a bacterium may comprise multiple copies of the feedback resistant argA gene. In some embodiments, the feedback resistant argA gene is expressed on a low-copy plasmid. In some embodiments, the low-copy plasmid may be useful for increasing stability of expression. In some embodiments, the low-copy plasmid may be useful for decreasing leaky expression under non-inducing conditions. In some embodiments, the feedback resistant argA gene is expressed on a high-copy plasmid. In some embodiments, the high-copy plasmid may be useful for increasing argA fbr  expression. In some embodiments, the feedback resistant argA gene is expressed on a chromosome. 
     In some embodiments, the bacteria are genetically engineered to include multiple mechanisms of action (MOAs), e.g., circuits producing multiple copies of the same product or circuits performing multiple different functions. Examples of insertion sites include, but are not limited to, malE/K, insB/I, araC/BAD, lacZ, dapA, cea, and other shown in  FIG. 18 . For example, the genetically engineered bacteria may include four copies of argA fbr  inserted at four different insertion sites, e.g., malE/K, insB/I, araC/BAD, and lacZ. Alternatively, the genetically engineered bacteria may include three copies of argA fbr  inserted at three different insertion sites, e.g., malE/K, insB/I, and lacZ, and three mutant arginine regulons, e.g., two producing citrulline and one producing arginine, inserted at three different insertion sites dapA, cea, and araC/BAD. 
     In some embodiments, the plasmid or chromosome also comprises wild-type ArgR binding sites, e.g., ARG boxes. In some instances, the presence and/or build-up of functional ArgR may result in off-target binding at sites other than the ARG boxes, which may cause off-target changes in gene expression. A plasmid or chromosome that further comprises functional ARG boxes may be used to reduce or eliminate off-target ArgR binding, i.e., by acting as an ArgR sink. In some embodiments, the plasmid or chromosome does not comprise functional ArgR binding sites, e.g., the plasmid or chromosome comprises modified ARG boxes or does not comprise ARG boxes. 
     In some embodiments, the feedback resistant argA gene is present on a plasmid and operably linked to a promoter that is induced under low-oxygen or anaerobic conditions. In some embodiments, the feedback resistant argA gene is present in the chromosome and operably linked to a promoter that is induced under low-oxygen or anaerobic conditions. In some embodiments, the feedback resistant argA gene is present on a plasmid and operably linked to a promoter that is induced by molecules or metabolites that are specific to the mammalian gut. In some embodiments, the feedback resistant argA gene is present on a chromosome and operably linked to a promoter that is induced by molecules or metabolites that are specific to the mammalian gut. In some embodiments, the feedback resistant argA gene is present on a chromosome and operably linked to a promoter that is induced by exposure to tetracycline. In some embodiments, the feedback resistant argA gene is present on a plasmid and operably linked to a promoter that is induced by exposure to tetracycline. 
     In some embodiments, the genetically engineered bacteria comprise a variant or mutated oxygen level-dependent transcriptional regulator, e.g., FNR, ANR, or DNR, in addition to the corresponding oxygen level-dependent promoter. The variant or mutated oxygen level-dependent transcriptional regulator increases the transcription of operably linked genes in a low-oxygen or anaerobic environment. In some embodiments, the corresponding wild-type transcriptional regulator retains wild-type activity. In alternate embodiments, the corresponding wild-type transcriptional regulator is deleted or mutated to reduce or eliminate wild-type activity. In certain embodiments, the mutant oxygen level-dependent transcriptional regulator is a FNR protein comprising amino acid substitutions that enhance dimerization and FNR activity (see, e.g., Moore et al., 2006). 
     In some embodiments, the genetically engineered bacteria comprise an oxygen level-dependent transcriptional regulator from a different bacterial species that reduces and/or consumes ammonia in low-oxygen or anaerobic environments. In certain embodiments, the mutant oxygen level-dependent transcriptional regulator is a FNR protein from  N. gonorrhoeae  (see, e.g., Isabella et al., 2011). In some embodiments, the corresponding wild-type transcriptional regulator is left intact and retains wild-type activity. In alternate embodiments, the corresponding wild-type transcriptional regulator is deleted or mutated to reduce or eliminate wild-type activity. 
     In some embodiments, the genetically engineered bacteria comprise argA fbr  expressed under the control of an oxygen level-dependent promoter, e.g., a FNR promoter, as well as wild-type argA expressed under the control of a mutant regulatory region comprising one or more ARG box mutations as discussed above. In certain embodiments, the genetically engineered bacteria comprise argA fbr  expressed under the control of an oxygen level-dependent promoter, e.g., a FNR promoter and do not comprise wild-type argA. In still other embodiments, the mutant arginine regulon comprises argA fbr  expressed under the control of an oxygen level-dependent promoter, e.g., a FNR promoter, and further comprises wild-type argA without any ARG box mutations. 
     In some embodiments, the genetically engineered bacteria express argA fbr  from a plasmid and/or chromosome. In some embodiments, the argA fbr  gene is expressed under the control of a constitutive promoter. In some embodiments, the argA fbr  gene is expressed under the control of an inducible promoter. In one embodiment, argA fbr  is expressed under the control of an oxygen level-dependent promoter that is activated under low-oxygen or anaerobic environments, e.g., a FNR promoter. The nucleic acid sequence of an exemplary FNR promoter-driven argA fbr  fbr sequence is shown in Table 9. The FNR promoter sequence is bolded and the argA sequence is  . The nucleic acid sequence of a FNR promoter-driven argA fbr  plasmid is shown in Table 10, with the FNR promoter sequence bolded and argA fbr  sequence  . Table 11 shows the nucleic acid sequence of an exemplary pSC101 plasmid. Any suitable FNR promoter(s) may be combined with any suitable feedback-resistant ArgA. Non-limiting FNR promoter sequences are provided in Table 6. In some embodiments, the genetically engineered bacteria of the invention comprise one or more of: SEQ ID NO: 16, SEQ ID NO: 17, nirB1 promoter (SEQ ID NO: 18), nirB2 promoter (SEQ ID NO: 19), nirB3 promoter (SEQ ID NO: 20), ydfZ promoter (SEQ ID NO: 21), nirB promoter fused to a strong ribosome binding site (SEQ ID NO: 22), ydfZ promoter fused to a strong ribosome binding site (SEQ ID NO: 23), fnrS, an anaerobically induced small RNA gene (fnrS1 promoter SEQ ID NO: 24 or fnrS2 promoter SEQ ID NO: 25), nirB promoter fused to a crp binding site (SEQ ID NO: 26), and fnrS fused to a crp binding site (SEQ ID NO: 27). Table 12 depicts the nucleic acid sequence of an exemplary fnrS promoter-driven argA fbr  sequence. The FNR promoter sequence is bolded, the ribosome binding site is highlighted, and the argA fbr  sequence is  . 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 32 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 32. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 32, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 32. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 33 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 33. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 33, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 33. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 35 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 35. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 35, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 35. 
     
       
         
           
               
             
               
                 TABLE 9 
               
               
                   
               
               
                 Exemplary FNR promoter-driven argA fbr  sequence 
               
               
                 (SEQ ID NO: 32) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 
                   AGTTGTTCTTATTGGTGGTGTTGCTTTATGGTTGCATCGTAGTAAATGGTTGTAACAA 
                 
               
               
                   
               
               
                 
                   AAGCAATTTTTCCGGCTGTCTGTATACAAAAACGCCGCAAAGTTTGAGCGAAGTCAAT 
                 
               
               
                   
               
               
                   AAACTCTCTACCCATTCAGGGCAATATCTCTCTT ggatccaaagtgaactctagaaat 
               
               
                   
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 10 
               
               
                   
               
               
                 Exemplary sequence of FNR promoter-driven argA fbr  plasmid 
               
               
                 (SEQ ID NO: 33) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 GTAAAACGACGGCCAGTGAATTCGAGCTCGGTACC ATCCCCATCACTCTTGATGGAGATCAA   
               
               
                   
               
               
                 
                   TTCCCCAAGCTGCTAGAGCGTTACCTTGCCCTTAAACATTAGCAATGTCGATTTATCAGAGG 
                 
               
               
                   
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 AATAAAAATACAATAATTTCGAATAATCATGCAAAGCTTGGCGTAATCATGGTCATAGCTGT 
               
               
                   
               
               
                 TTCCTGTGTGAAATTGTTATCCGCTCACAATTCCACACAACATACGAGCCGGAAGCATGTAC 
               
               
                   
               
               
                 GGGTTTTGCTGCCCGCAAACGGGCTGTTCTGGTGTTGCTAGTTTGTTATCAGAATCGCAGAT 
               
               
                   
               
               
                 CCGGCTTCAGGTTTGCCGGCTGAAAGCGCTATTTCTTCCAGAATTGCCATGATTTTTTCCCC 
               
               
                   
               
               
                 ACGGGAGGCGTCACTGGCTCCCGTGTTGTCGGCAGCTTTGATTCGATAAGCAGCATCGCCTG 
               
               
                   
               
               
                 TTTCAGGCTGTCTATGTGTGACTGTTGAGCTGTAACAAGTTGTCTCAGGTGTTCAATTTCAT 
               
               
                   
               
               
                 GTTCTAGTTGCTTTGTTTTACTGGTTTCACCTGTTCTATTAGGTGTTACATGCTGTTCATCT 
               
               
                   
               
               
                 GTTACATTGTCGATCTGTTCATGGTGAACAGCTTTAAATGCACCAAAAACTCGTAAAAGCTC 
               
               
                   
               
               
                 TGATGTATCTATCTTTTTTACACCGTTTTCATCTGTGCATATGGACAGTTTTCCCTTTGATA 
               
               
                   
               
               
                 TCTAACGGTGAACAGTTGTTCTACTTTTGTTTGTTAGTCTTGATGCTTCACTGATAGATACA 
               
               
                   
               
               
                 AGAGCCATAAGAACCTCAGATCCTTCCGTATTTAGCCAGTATGTTCTCTAGTGTGGTTCGTT 
               
               
                   
               
               
                 GTTTTTGCGTGAGCCATGAGAACGAACCATTGAGATCATGCTTACTTTGCATGTCACTCAAA 
               
               
                   
               
               
                 AATTTTGCCTCAAAACTGGTGAGCTGAATTTTTGCAGTTAAAGCATCGTGTAGTGTTTTTCT 
               
               
                   
               
               
                 TAGTCCGTTACGTAGGTAGGAATCTGATGTAATGGTTGTTGGTATTTTGTCACCATTCATTT 
               
               
                   
               
               
                 TTATCTGGTTGTTCTCAAGTTCGGTTACGAGATCCATTTGTCTATCTAGTTCAACTTGGAAA 
               
               
                   
               
               
                 ATCAACGTATCAGTCGGGCGGCCTCGCTTATCAACCACCAATTTCATATTGCTGTAAGTGTT 
               
               
                   
               
               
                 TAAATCTTTACTTATTGGTTTCAAAACCCATTGGTTAAGCCTTTTAAACTCATGGTAGTTAT 
               
               
                   
               
               
                 TTTCAAGCATTAACATGAACTTAAATTCATCAAGGCTAATCTCTATATTTGCCTTGTGAGTT 
               
               
                   
               
               
                 TTCTTTTGTGTTAGTTCTTTTAATAACCACTCATAAATCCTCATAGAGTATTTGTTTTCAAA 
               
               
                   
               
               
                 AGACTTAACATGTTCCAGATTATATTTTATGAATTTTTTTAACTGGAAAAGATAAGGCAATA 
               
               
                   
               
               
                 TCTCTTCACTAAAAACTAATTCTAATTTTTCGCTTGAGAACTTGGCATAGTTTGTCCACTGG 
               
               
                   
               
               
                 AAAATCTCAAAGCCTTTAACCAAAGGATTCCTGATTTCCACAGTTCTCGTCATCAGCTCTCT 
               
               
                   
               
               
                 GGTTGCTTTAGCTAATACACCATAAGCATTTTCCCTACTGATGTTCATCATCTGAGCGTATT 
               
               
                   
               
               
                 GGTTATAAGTGAACGATACCGTCCGTTCTTTCCTTGTAGGGTTTTCAATCGTGGGGTTGAGT 
               
               
                   
               
               
                 AGTGCCACACAGCATAAAATTAGCTIGGITICATGCTCCGTTAAGICATAGCGACTAATCGC 
               
               
                   
               
               
                 TAGTTCATTTGCTTTGAAAACAACTAATTCAGACATACATCTCAATTGGTCTAGGTGATTTT 
               
               
                   
               
               
                 AATCACTATACCAATTGAGATGGGCTAGTCAATGATAATTACTAGTCCTTTTCCTTTGAGTT 
               
               
                   
               
               
                 GTGGGTATCTGTAAATTCTGCTAGACCTTTGCTGGAAAACTTGTAAATTCTGCTAGACCCTC 
               
               
                   
               
               
                 TGTAAATTCCGCTAGACCTTTGTGTGTTTTTTTTGTTTATATTCAAGTGGTTATAATTTATA 
               
               
                   
               
               
                 GAATAAAGAAAGAATAAAAAAAGATAAAAAGAATAGATCCCAGCCCTGTGTATAACTCACTA 
               
               
                   
               
               
                 CTTTAGTCAGTTCCGCAGTATTACAAAAGGATGTCGCAAACGCTGTTTGCTCCTCTACAAAA 
               
               
                   
               
               
                 CAGACCTTAAAACCCTAAAGGCTTAAGTAGCACCCTCGCAAGCTCGGGCAAATCGCTGAATA 
               
               
                   
               
               
                 TTCCTTTTGTCTCCGACCATCAGGCACCTGAGTCGCTGTCTTTTTCGTGACATTCAGTTCGC 
               
               
                   
               
               
                 TGCGCTCACGGCTCTGGCAGTGAATGGGGGTAAATGGCACTACAGGCGCCTTTTATGGATTC 
               
               
                   
               
               
                 ATGCAAGGAAACTACCCATAATACAAGAAAAGCCCGTCACGGGCTTCTCAGGGCGTTTTATG 
               
               
                   
               
               
                 GCGGGTCTGCTATGTGGTGCTATCTGACTTTTTGCTGTTCAGCAGTTCCTGCCCTCTGATTT 
               
               
                   
               
               
                 TCCAGTCTGACCACTTCGGATTATCCCGTGACAGGTCATTCAGACTGGCTAATGCACCCAGT 
               
               
                   
               
               
                 AAGGCAGCGGTATCATCAACAGGCTTACCCGTCTTACTGTCTTTTCTACGGGGTCTGACGCT 
               
               
                   
               
               
                 CAGTGGAACGAAAACTCACGTTAAGGGATTTTGGTCATGAGATTATCAAAAAGGATCTTCAC 
               
               
                   
               
               
                 CTAGATCCTTTTAAATTAAAAATGAAGTTTTAAATCAATCTAAAGTATATATGAGTAAACTT 
               
               
                   
               
               
                 GGTCTGACAGTTACCAATGCTTAATCAGTGAGGCACCTATCTCAGCGATCTGTCTATTTCGT 
               
               
                   
               
               
                 TCATCCATAGTTGCCTGACTCCCCGTCGTGTAGATAACTACGATACGGGAGGGCTTACCATC 
               
               
                   
               
               
                 TGGCCCCAGTGCTGCAATGATACCGCGAGACCCACGCTCACCGGCTCCAGATTTATCAGCAA 
               
               
                   
               
               
                 TAAACCAGCCAGCCGGAAGGGCCGAGCGCAGAAGTGGTCCTGCAACTTTATCCGCCTCCATC 
               
               
                   
               
               
                 CAGTCTATTAATTGTTGCCGGGAAGCTAGAGTAAGTAGTTCGCCAGTTAATAGTTTGCGCAA 
               
               
                   
               
               
                 CGTTGTTGCCATTGCTACAGGCATCGTGGTGTCACGCTCGTCGTTTGGTATGGCTTCATTCA 
               
               
                   
               
               
                 GCTCCGGTTCCCAACGATCAAGGCGAGTTACATGATCCCCCATGTTGTGCAAAAAAGCGGTT 
               
               
                   
               
               
                 AGCTCCTTCGGTCCTCCGATCGTTGTCAGAAGTAAGTTGGCCGCAGTGTTATCACTCATGGT 
               
               
                   
               
               
                 TATGGCAGCACTGCATAATTCTCTTACTGTCATGCCATCCGTAAGATGCTTTTCTGTGACTG 
               
               
                   
               
               
                 GTGAGTACTCAACCAAGTCATTCTGAGAATAGTGTATGCGGCGACCGAGTTGCTCTTGCCCG 
               
               
                   
               
               
                 GCGTCAATACGGGATAATACCGCGCCACATAGCAGAACTTTAAAAGTGCTCATCATTGGAAA 
               
               
                   
               
               
                 ACGTTCTTCGGGGCGAAAACTCTCAAGGATCTTACCGCTGTTGAGATCCAGTTCGATGTAAC 
               
               
                   
               
               
                 CCACTCGTGCACCCAACTGATCTTCAGCATCTTTTACTTTCACCAGCGTTTCTGGGTGAGCA 
               
               
                   
               
               
                 AAAACAGGAAGGCAAAATGCCGCAAAAAAGGGAATAAGGGCGACACGGAAATGTTGAATACT 
               
               
                   
               
               
                 CATACTCTTCCTTTTTCAATATTATTGAAGCATTTATCAGGGTTATTGTCTCATGAGCGGAT 
               
               
                   
               
               
                 ACATATTTGAATGTATTTAGAAAAATAAACAAATAGGGGTTCCGCGCACATTTCCCCGAAAA 
               
               
                   
               
               
                 GTGCCACCTGACGTCTAAGAAACCATTATTATCATGACATTAACCTATAAAAATAGGCGTAT 
               
               
                   
               
               
                 CACGAGGCCCTTTCGTCTCGCGCGTTTCGGTGATGACGGTGAAAACCTCTGACACATGCAGC 
               
               
                   
               
               
                 TCCCGGAGACGGTCACAGCTTGTCTGTAAGCGGATGCCGGGAGCAGACAAGCCCGTCAGGGC 
               
               
                   
               
               
                 GCGTCAGCGGGTGTTGGCGGGTGTCGGGGCTGGCTTAACTATGCGGCATCAGAGCAGATTGT 
               
               
                   
               
               
                 ACTGAGAGTGCACCATATGCGGTGTGAAATACCGCACAGATGCGTAAGGAGAAAATACCGCA 
               
               
                   
               
               
                 TCAGGCGCCATTCGCCATTCAGGCTGCGCAACTGTTGGGAAGGGCGATCGGTGCGGGCCTCT 
               
               
                   
               
               
                 TCGCTATTACGCCAGCTGGCGAAAGGGGGATGTGCTGCAAGGCGATTAAGTTGGGTAACGCC 
               
               
                   
               
               
                 AGGGTTTTCCCAGTCACGACGTT 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 11 
               
               
                   
               
               
                 Nucleic acid sequence of pSC101 plasmid 
               
               
                 (SEQ ID NO: 34) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 ATTAAGTTGGGTAACGCCAGGGTTTTCCCAGTCACGACGTTATTGCGTTG 
               
               
                 CGCTCACTGCCCGCTTTCCAGTCGGGAAACCTGTCGTGCCAGCTGCATTA 
               
               
                 ATGAATCGGCCAACGCGCGGGGAGAGGCGGTTTGCGTATTGGGCGCTCTT 
               
               
                 CCGCTTCCTCGCTCACTGACTCGCTGCGCTCGGTCGTTCGGCTGCGGCGA 
               
               
                 GCGGTATCAGCTCACTCAAAGGCGGTAGTACGGGTTTTGCTGCCCGCAAA 
               
               
                 CGGGCTGTTCTGGTGTTGCTAGTTTGTTATCAGAATCGCAGATCCGGCTT 
               
               
                 CAGGTTTGCCGGCTGAAAGCGCTATTTCTTCCAGAATTGCCATGATTTTT 
               
               
                 TCCCCACGGGAGGCGTCACTGGCTCCCGTGTTGTCGGCAGCTTTGATTCG 
               
               
                 ATAAGCAGCATCGCCTGTTTCAGGCTGTCTATGTGTGACTGTTGAGCTGT 
               
               
                 AACAAGTTGTCTCAGGTGTTCAATTTCATGTTCTAGTTGCTTTGTTTTAC 
               
               
                 TGGTTTCACCTGTTCTATTAGGTGTTACATGCTGTTCATCTGTTACATTG 
               
               
                 TCGATCTGTTCATGGTGAACAGCTTTAAATGCACCAAAAACTCGTAAAAG 
               
               
                 CTCTGATGTATCTATCTTTTTTACACCGTTTTCATCTGTGCATATGGACA 
               
               
                 GTTTTCCCTTTGATATCTAACGGTGAACAGTTGTTCTACTTTTGTTTGTT 
               
               
                 AGTCTTGATGCTTCACTGATAGATACAAGAGCCATAAGAACCTCAGATCC 
               
               
                 TTCCGTATTTAGCCAGTATGTTCTCTAGTGTGGTTCGTTGTTTTTGCGTG 
               
               
                 AGCCATGAGAACGAACCATTGAGATCATGCTTACTTTGCATGTCACTCAA 
               
               
                 AAATTTTGCCTCAAAACTGGTGAGCTGAATTTTTGCAGTTAAAGCATCGT 
               
               
                 GTAGTGTTTTTCTTAGTCCGTTACGTAGGTAGGAATCTGATGTAATGGTT 
               
               
                 GTTGGTATTTTGTCACCATTCATTTTTATCTGGTTGTTCTCAAGTTCGGT 
               
               
                 TACGAGATCCATTTGTCTATCTAGTTCAACTTGGAAAATCAACGTATCAG 
               
               
                 TCGGGCGGCCTCGCTTATCAACCACCAATTTCATATTGCTGTAAGTGTTT 
               
               
                 AAATCTTTACTTATTGGTTTCAAAACCCATTGGTTAAGCCTTTTAAACTC 
               
               
                 ATGGTAGTTATTTTCAAGCATTAACATGAACTTAAATTCATCAAGGCTAA 
               
               
                 TCTCTATATTTGCCTTGTGAGTTTTCTTTTGTGTTAGTTCTTTTAATAAC 
               
               
                 CACTCATAAATCCTCATAGAGTATTTGTTTTCAAAAGACTTAACATGTTC 
               
               
                 CAGATTATATTTTATGAATTTTTTTAACTGGAAAAGATAAGGCAATATCT 
               
               
                 CTTCACTAAAAACTAATTCTAATTTTTCGCTTGAGAACTTGGCATAGTTT 
               
               
                 GTCCACTGGAAAATCTCAAAGCCTTTAACCAAAGGATTCCTGATTTCCAC 
               
               
                 AGTTCTCGTCATCAGCTCTCTGGTTGCTTTAGCTAATACACCATAAGCAT 
               
               
                 TTTCCCTACTGATGTTCATCATCTGAGCGTATTGGTTATAAGTGAACGAT 
               
               
                 ACCGTCCGTTCTTTCCTTGTAGGGTTTTCAATCGTGGGGTTGAGTAGTGC 
               
               
                 CACACAGCATAAAATTAGCTTGGTTTCATGCTCCGTTAAGTCATAGCGAC 
               
               
                 TAATCGCTAGTTCATTTGCTTTGAAAACAACTAATTCAGACATACATCTC 
               
               
                 AATTGGTCTAGGTGATTTTAATCACTATACCAATTGAGATGGGCTAGTCA 
               
               
                 ATGATAATTACTAGTCCTTTTCCTTTGAGTTGTGGGTATCTGTAAATTCT 
               
               
                 GCTAGACCTTTGCTGGAAAACTTGTAAATTCTGCTAGACCCTCTGTAAAT 
               
               
                 TCCGCTAGACCTTTGTGTGTTTTTTTTGTTTATATTCAAGTGGTTATAAT 
               
               
                 TTATAGAATAAAGAAAGAATAAAAAAAGATAAAAAGAATAGATCCCAGCC 
               
               
                 CTGTGTATAACTCACTACTTTAGTCAGTTCCGCAGTATTACAAAAGGATG 
               
               
                 TCGCAAACGCTGTTTGCTCCTCTACAAAACAGACCTTAAAACCCTAAAGG 
               
               
                 CTTAAGTAGCACCCTCGCAAGCTCGGGCAAATCGCTGAATATTCCTTTTG 
               
               
                 TCTCCGACCATCAGGCACCTGAGTCGCTGTCTTTTTCGTGACATTCAGTT 
               
               
                 CGCTGCGCTCACGGCTCTGGCAGTGAATGGGGGTAAATGGCACTACAGGC 
               
               
                 GCCTTTTATGGATTCATGCAAGGAAACTACCCATAATACAAGAAAAGCCC 
               
               
                 GTCACGGGCTTCTCAGGGCGTTTTATGGCGGGTCTGCTATGTGGTGCTAT 
               
               
                 CTGACTTTTTGCTGTTCAGCAGTTCCTGCCCTCTGATTTTCCAGTCTGAC 
               
               
                 CACTTCGGATTATCCCGTGACAGGTCATTCAGACTGGCTAATGCACCCAG 
               
               
                 TAAGGCAGCGGTATCATCAACAGGCTTACCCGTCTTACTGTCTTTTCTAC 
               
               
                 GGGGTCTGACGCTCAGTGGAACGAAAACTCACGTTAAGGGATTTTGGTCA 
               
               
                 TGAGATTATCAAAAAGGATCTTCACCTAGATCCTTTTAAATTAAAAATGA 
               
               
                 AGTTTTAAATCAATCTAAAGTATATATGAGTAAACTTGGTCTGACAGTTA 
               
               
                 CCAATGCTTAATCAGTGAGGCACCTATCTCAGCGATCTGTCTATTTCGTT 
               
               
                 CATCCATAGTTGCCTGACTCCCCGTCGTGTAGATAACTACGATACGGGAG 
               
               
                 GGCTTACCATCTGGCCCCAGTGCTGCAATGATACCGCGAGACCCACGCTC 
               
               
                 ACCGGCTCCAGATTTATCAGCAATAAACCAGCCAGCCGGAAGGGCCGAGC 
               
               
                 GCAGAAGTGGTCCTGCAACTTTATCCGCCTCCATCCAGTCTATTAATTGT 
               
               
                 TGCCGGGAAGCTAGAGTAAGTAGTTCGCCAGTTAATAGTTTGCGCAACGT 
               
               
                 TGTTGCCATTGCTACAGGCATCGTGGTGTCACGCTCGTCGTTTGGTATGG 
               
               
                 CTTCATTCAGCTCCGGTTCCCAACGATCAAGGCGAGTTACATGATCCCCC 
               
               
                 ATGTTGTGCAAAAAAGCGGTTAGCTCCTTCGGTCCTCCGATCGTTGTCAG 
               
               
                 AAGTAAGTTGGCCGCAGTGTTATCACTCATGGTTATGGCAGCACTGCATA 
               
               
                 ATTCTCTTACTGTCATGCCATCCGTAAGATGCTTTTCTGTGACTGGTGAG 
               
               
                 TACTCAACCAAGTCATTCTGAGAATAGTGTATGCGGCGACCGAGTTGCTC 
               
               
                 TTGCCCGGCGTCAATACGGGATAATACCGCGCCACATAGCAGAACTTTAA 
               
               
                 AAGTGCTCATCATTGGAAAACGTTCTTCGGGGCGAAAACTCTCAAGGATC 
               
               
                 TTACCGCTGTTGAGATCCAGTTCGATGTAACCCACTCGTGCACCCAACTG 
               
               
                 ATCTTCAGCATCTTTTACTTTCACCAGCGTTTCTGGGTGAGCAAAAACAG 
               
               
                 GAAGGCAAAATGCCGCAAAAAAGGGAATAAGGGCGACACGGAAATGTTGA 
               
               
                 ATACTCATACTCTTCCTTTTTCAATATTATTGAAGCATTTATCAGGGTTA 
               
               
                 TTGTCTCATGAGCGGATACATATTTGAATGTATTTAGAAAAATAAACAAA 
               
               
                 TAGGGGTTCCGCGCACATTTCCCCGAAAAGTGCCACCTGACGTCTAAGAA 
               
               
                 ACCATTATTATCATGACATTAACCTATAAAAATAGGCGTATCACGAGGCC 
               
               
                 CTTTCGTCTCGCGCGTTTCGGTGATGACGGTGAAAACCTCTGACACATGC 
               
               
                 AGCTCCCGGAGACGGTCACAGCTTGTCTGTAAGCGGATGCCGGGAGCAGA 
               
               
                 CAAGCCCGTCAGGGCGCGTCAGCGGGTGTTGGCGGGTGTCGGGGCTGGCT 
               
               
                 TAACTATGCGGCATCAGAGCAGATTGTACTGAGAGTGCACCATATGCGGT 
               
               
                 GTGAAATACCGCACAGATGCGTAAGGAGAAAATACCGCATCAGGCGCCAT 
               
               
                 TCGCCATTCAGGCTGCGCAACTGTTGGGAAGGGCGATCGGTGCGGGCCTC 
               
               
                 TTCGCTATTACGCCAGCTGGCGAAAGGGGGATGTGCTGCAAGGCG 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 12 
               
               
                   
               
               
                 Nucleotide sequence of exemplary fnrS promoter-driven 
               
               
                 argA fbr  pSC101 plasmid (SEQ ID NO: 35) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 GTTTCCTGTGTGAAATTGTTATCCGCTCACAATTCCACACAACATACGAGCCGGAAGCATAAAG 
               
               
                   
               
               
                 TGTAAAGCCTGGGGTGCCTAATGAGTGAGCTAACTCACATTAATTGCGTTGCGCTCACTGCCCG 
               
               
                   
               
               
                 CTTTCCAGTCGGGAAACCTGTCGTGCCAGCTGCATTAATGAATCGGCCAACGCGCGGGGAGAGG 
               
               
                   
               
               
                 CGGTTTGCGTATTGGGCGCTCTTCCGCTTCCTCGCTCACTGACTCGCTGCGCTCGGTCGTTCGG 
               
               
                   
               
               
                 CTGCGGCGAGCGGTATCAGCTCACTCAAAGGCGGTAGTACGGGTTTTGCTGCCCGCAAACGGGC 
               
               
                   
               
               
                 TGTTCTGGTGTTGCTAGTTTGTTATCAGAATCGCAGATCCGGCTTCAGGTTTGCCGGCTGAAAG 
               
               
                   
               
               
                 CGCTATTTCTTCCAGAATTGCCATGATTTTTTCCCCACGGGAGGCGTCACTGGCTCCCGTGTTG 
               
               
                   
               
               
                 TCGGCAGCTTTGATTCGATAAGCAGCATCGCCTGTTTCAGGCTGTCTATGTGTGACTGTTGAGC 
               
               
                   
               
               
                 TGTAACAAGTTGTCTCAGGTGTTCAATTTCATGTTCTAGTTGCTTTGTTTTACTGGTTTCACCT 
               
               
                   
               
               
                 GTTCTATTAGGTGTTACATGCTGTTCATCTGTTACATTGTCGATCTGTTCATGGTGAACAGCTT 
               
               
                   
               
               
                 TAAATGCACCAAAAACTCGTAAAAGCTCTGATGTATCTATCTTTTTTACACCGTTTTCATCTGT 
               
               
                   
               
               
                 GCATATGGACAGTTTTCCCTTTGATATCTAACGGTGAACAGTTGTTCTACTTTTGTTTGTTAGT 
               
               
                   
               
               
                 CTTGATGCTTCACTGATAGATACAAGAGCCATAAGAACCTCAGATCCTTCCGTATTTAGCCAGT 
               
               
                   
               
               
                 ATGTTCTCTAGTGTGGTTCGTTGTTTTTGCGTGAGCCATGAGAACGAACCATTGAGATCATGCT 
               
               
                   
               
               
                 TACTTTGCATGTCACTCAAAAATTTTGCCTCAAAACTGGTGAGCTGAATTTTTGCAGTTAAAGC 
               
               
                   
               
               
                 ATCGTGTAGTGTTTTTCTTAGTCCGTTACGTAGGTAGGAATCTGATGTAATGGTTGTTGGTATT 
               
               
                   
               
               
                 TTGTCACCATTCATTTTTATCTGGTTGTTCTCAAGTTCGGTTACGAGATCCATTTGTCTATCTA 
               
               
                   
               
               
                 GTTCAACTTGGAAAATCAACGTATCAGTCGGGCGGCCTCGCTTATCAACCACCAATTTCATATT 
               
               
                   
               
               
                 GCTGTAAGTGTTTAAATCTTTACTTATTGGTTTCAAAACCCATTGGTTAAGCCTTTTAAACTCA 
               
               
                   
               
               
                 TGGTAGTTATTTTCAAGCATTAACATGAACTTAAATTCATCAAGGCTAATCTCTATATTTGCCT 
               
               
                   
               
               
                 TGTGAGTTTTCTTTTGTGTTAGTTCTTTTAATAACCACTCATAAATCCTCATAGAGTATTTGTT 
               
               
                   
               
               
                 TTCAAAAGACTTAACATGTTCCAGATTATATTTTATGAATTTTTTTAACTGGAAAAGATAAGGC 
               
               
                   
               
               
                 AATATCTCTTCACTAAAAACTAATTCTAATTTTTCGCTTGAGAACTTGGCATAGTTTGTCCACT 
               
               
                   
               
               
                 GGAAAATCTCAAAGCCTTTAACCAAAGGATTCCTGATTTCCACAGTTCTCGTCATCAGCTCTCT 
               
               
                   
               
               
                 GGTTGCTTTAGCTAATACACCATAAGCATTTTCCCTACTGATGTTCATCATCTGAGCGTATTGG 
               
               
                   
               
               
                 TTATAAGTGAACGATACCGTCCGTTCTTTCCTTGTAGGGTTTTCAATCGTGGGGTTGAGTAGTG 
               
               
                   
               
               
                 CCACACAGCATAAAATTAGCTTGGTTTCATGCTCCGTTAAGTCATAGCGACTAATCGCTAGTTC 
               
               
                   
               
               
                 ATTTGCTTTGAAAACAACTAATTCAGACATACATCTCAATTGGTCTAGGTGATTTTAATCACTA 
               
               
                   
               
               
                 TACCAATTGAGATGGGCTAGTCAATGATAATTACTAGTCCTTTTCCTTTGAGTTGTGGGTATCT 
               
               
                   
               
               
                 GTAAATTCTGCTAGACCTTTGCTGGAAAACTTGTAAATTCTGCTAGACCCTCTGTAAATTCCGC 
               
               
                   
               
               
                 TAGACCTTTGTGTGTTTTTTTTGTTTATATTCAAGTGGTTATAATTTATAGAATAAAGAAAGAA 
               
               
                   
               
               
                 TAAAAAAAGATAAAAAGAATAGATCCCAGCCCTGTGTATAACTCACTACTTTAGTCAGTTCCGC 
               
               
                   
               
               
                 AGTATTACAAAAGGATGTCGCAAACGCTGTTTGCTCCTCTACAAAACAGACCTTAAAACCCTAA 
               
               
                   
               
               
                 AGGCTTAAGTAGCACCCTCGCAAGCTCGGGCAAATCGCTGAATATTCCTTTTGTCTCCGACCAT 
               
               
                   
               
               
                 CAGGCACCTGAGTCGCTGTCTTTTTCGTGACATTCAGTTCGCTGCGCTCACGGCTCTGGCAGTG 
               
               
                   
               
               
                 AATGGGGGTAAATGGCACTACAGGCGCCTTTTATGGATTCATGCAAGGAAACTACCCATAATAC 
               
               
                   
               
               
                 AAGAAAAGCCCGTCACGGGCTTCTCAGGGCGTTTTATGGCGGGTCTGCTATGTGGTGCTATCTG 
               
               
                   
               
               
                 ACTTTTTGCTGTTCAGCAGTTCCTGCCCTCTGATTTTCCAGTCTGACCACTTCGGATTATCCCG 
               
               
                   
               
               
                 TGACAGGTCATTCAGACTGGCTAATGCACCCAGTAAGGCAGCGGTATCATCAACAGGCTTACCC 
               
               
                   
               
               
                 GTCTTACTGTCTTTTCTACGGGGTCTGACGCTCAGTGGAACGAAAACTCACGTTAAGGGATTTT 
               
               
                   
               
               
                 GGTCATGAGATTATCAAAAAGGATCTTCACCTAGATCCTTTTAAATTAAAAATGAAGTTTTAAA 
               
               
                   
               
               
                 TCAATCTAAAGTATATATGAGTAAACTTGGTCTGACAGTTACCAATGCTTAATCAGTGAGGCAC 
               
               
                   
               
               
                 CTATCTCAGCGATCTGTCTATTTCGTTCATCCATAGTTGCCTGACTCCCCGTCGTGTAGATAAC 
               
               
                   
               
               
                 TACGATACGGGAGGGCTTACCATCTGGCCCCAGTGCTGCAATGATACCGCGAGACCCACGCTCA 
               
               
                   
               
               
                 CCGGCTCCAGATTTATCAGCAATAAACCAGCCAGCCGGAAGGGCCGAGCGCAGAAGTGGTCCTG 
               
               
                   
               
               
                 CAACTTTATCCGCCTCCATCCAGTCTATTAATTGTTGCCGGGAAGCTAGAGTAAGTAGTTCGCC 
               
               
                   
               
               
                 AGTTAATAGTTTGCGCAACGTTGTTGCCATTGCTACAGGCATCGTGGTGTCACGCTCGTCGTTT 
               
               
                   
               
               
                 GGTATGGCTTCATTCAGCTCCGGTTCCCAACGATCAAGGCGAGTTACATGATCCCCCATGTTGT 
               
               
                   
               
               
                 GCAAAAAAGCGGTTAGCTCCTTCGGTCCTCCGATCGTTGTCAGAAGTAAGTTGGCCGCAGTGTT 
               
               
                   
               
               
                 ATCACTCATGGTTATGGCAGCACTGCATAATTCTCTTACTGTCATGCCATCCGTAAGATGCTTT 
               
               
                   
               
               
                 TCTGTGACTGGTGAGTACTCAACCAAGTCATTCTGAGAATAGTGTATGCGGCGACCGAGTTGCT 
               
               
                   
               
               
                 CTTGCCCGGCGTCAATACGGGATAATACCGCGCCACATAGCAGAACTTTAAAAGTGCTCATCAT 
               
               
                   
               
               
                 TGGAAAACGTTCTTCGGGGCGAAAACTCTCAAGGATCTTACCGCTGTTGAGATCCAGTTCGATG 
               
               
                   
               
               
                 TAACCCACTCGTGCACCCAACTGATCTTCAGCATCTTTTACTTTCACCAGCGTTTCTGGGTGAG 
               
               
                   
               
               
                 CAAAAACAGGAAGGCAAAATGCCGCAAAAAAGGGAATAAGGGCGACACGGAAATGTTGAATACT 
               
               
                   
               
               
                 CATACTCTTCCTTTTTCAATATTATTGAAGCATTTATCAGGGTTATTGTCTCATGAGCGGATAC 
               
               
                   
               
               
                 ATATTTGAATGTATTTAGAAAAATAAACAAATAGGGGTTCCGCGCACATTTCCCCGAAAAGTGC 
               
               
                   
               
               
                 CACCTGACGTCTAAGAAACCATTATTATCATGACATTAACCTATAAAAATAGGCGTATCACGAG 
               
               
                   
               
               
                 GCCCTTTCGTCTCGCGCGTTTCGGTGATGACGGTGAAAACCTCTGACACATGCAGCTCCCGGAG 
               
               
                   
               
               
                 ACGGTCACAGCTTGTCTGTAAGCGGATGCCGGGAGCAGACAAGCCCGTCAGGGCGCGTCAGCGG 
               
               
                   
               
               
                 GTGTTGGCGGGTGTCGGGGCTGGCTTAACTATGCGGCATCAGAGCAGATTGTACTGAGAGTGCA 
               
               
                   
               
               
                 CCATATGCGGTGTGAAATACCGCACAGATGCGTAAGGAGAAAATACCGCATCAGGCGCCATTCG 
               
               
                   
               
               
                 CCATTCAGGCTGCGCAACTGTTGGGAAGGGCGATCGGTGCGGGCCTCTTCGCTATTACGCCAGC 
               
               
                   
               
               
                 TGGCGAAAGGGGGATGTGCTGCAAGGCG 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria comprise argA fbr  integrated into the chromosome. In some embodiments, the integrated fbrArgA is under the control of the fnrS promoter. In some embodiments, an antibiotic resistance cassette is also present at the same site. In some embodiments, no antibiotic resistance cassette is present. In some embodiments, the antibiotic resistance is chloramphenicol. In some embodiments, the antibiotic resistance is kanamycin. In some embodiments, the genetically engineered bacteria comprising argA fbr  integrated into the chromosome is a thyA auxotroph. In some embodiments, the genetically engineered bacteria comprise argA fbr  integrated into the chromosome and also comprise an ArgR mutation or have ArgR deleted. In one specific embodiment, the genetically engineered bacteria comprise argA fbr  under the control of the fnrS promoter and integrated into the chromosome, comprise an ArgR mutation or have ArgR deleted, and comprise a thyA auxotrophy. In another specific embodiment, the genetically engineered bacteria comprise argA fbr  under the control of the fnrS promoter and integrated into the chromosome, comprise an ArgR mutation or have ArgR deleted, comprise a thyA auxotrophy, and comprise an antibiotic resistance cassette. In another specific embodiment, the genetically engineered bacteria comprise argAfbr under the control of the fnrS promoter and integrated into the chromosome, comprise an ArgR mutation or have ArgR deleted, comprise a thyA auxotrophy, and comprise a kanamycin resistance cassette. In one specific embodiment, the genetically engineered bacteria is SYN-UCD305. In another specific embodiment, the genetically engineered bacteria is SYN_UCD303. 
     Table 13 shows non-limiting examples of FNRS-fbrArgA constructs which are integrated into the chromosome. 
     SEQ ID NO: 36 comprises FNRS-fbrArgA and chloramphenicol resistance, e.g., as comprised in SYN-UCD301, SYN-UCD302. SEQ ID NO: 37 comprises FNRS-fbrArgA and kanamycin resistance, e.g., as comprised in SYN-UCD303, SYN-UCD306, SYN-UCD307, and SYN-UCD309. SEQ ID NO: 38 FNRS-fbrArgA and no antibiotic resistance, e.g., as comprised in SYN-UCD305 SYN-UCD304, SYN-UCD308, SYNUCD310. 
     
       
         
           
               
             
               
                 TABLE 13 
               
             
            
               
                   
               
               
                 of Integrated argA fbr  sequences 
               
            
           
           
               
               
               
            
               
                   
                   
                 SEQ ID 
               
               
                 Description 
                 Sequence 
                 NO 
               
               
                   
               
               
                 FNRS-fbrArgA 
                 ctacgccccatcgttgctttgtgtgatctctgttacaga 
                 SEQ ID 
               
               
                 and 
                 attggcggtaatgtggagatgcgcacataaaatcgccat 
                 NO: 36 
               
               
                 chloram- 
                 gatttttgcaagcaacatcacgaaattccttacatgacc 
                   
               
               
                 phenicol 
                 tcggtttagttcacaggacgtcccatggctcgagCATGC 
                   
               
               
                 resistance, 
                 GAGAGTAGGGAACTGCCAGGCAT   CAAATAAAAtGAAAGG     
                   
               
               
                 e.g., SYN- 
                 
                   
                     CTCAGTCGAAAGACTGGGCCTTTCGTTTTATCTGTTGTT 
                   
                 
                   
               
               
                 UCD301, SYN- 
                     TGTCGGTGAACGCTCTCCTGAGTAGGACAAAT   CCGCCGG 
                   
               
               
                 UCD302; a 
                 GAGCGGATTTGAACGTTGCGAAGCAACGGCCCGGAGGGT 
                   
               
               
                 schematic of 
                 GGCGGGCAGGACGCCCGCCATAAACTGCCAGGCATCAAA 
                   
               
               
                 the 
                 TTAAGC   AGAAGGCCATCCTGACGGATGGCCTTTT   TGCGT 
                   
               
               
                 construct is 
                 GGCCAGTGCCAAGCTTGCATGCAGATTGCAGCATTACAC 
                   
               
               
                 depicted in 
                 GTCTTGAGCGATTGTGTAGGCTGGAGCTGCTTC   
                   
               
               
                 FIG. 20; 
                 
                   
                   
                 
                   
               
               
                 UPPERCASE 
                    ATTTAAATGGCGCGCCTTACGCCCCGCCCTGCCAC T   
                   
               
               
                 underlined: 
                 
                   CATCGCAGTACTGTTGTATTCATTAAGCATCTGCCGACA 
                 
                   
               
               
                 CmR gene; 
                 
                   TGGAAGCCATCACAAACGGCATGATGAACCTGAATCGCC 
                 
                   
               
               
                 UPPERCASE 
                 
                   AGCGGCATCAGCACCTTGTCGCCTTGCGTATAATATTTG 
                 
                   
               
               
                 italics: CmR 
                 
                   CCCATGGTGAAAACGGGGGCGAAGAAGTTGTCCATATTG 
                 
                   
               
               
                 promoter; 
                 
                   GCCACGTTTAAATCAAAACTGGTGAAACTCACCCAGGGA 
                 
                   
               
               
                 UPPERCASE 
                 
                   TTGGCTGAGACGAAAAACATATTCTCAATAAACCCTTTA 
                 
                   
               
               
                 italic and 
                 
                   GGGAAATAGGCCAGGTTTTCACCGTAACACGCCACATCT 
                 
                   
               
               
                 underlined: 
                 
                   TGCGAATATATGTGTAGAAACTGCCGGAAATCGTCGTGG 
                 
                   
               
               
                 fnrS 
                 
                   TATTCACTCCAGAGCGATGAAAACGTTTCAGTTTGCTCA 
                 
                   
               
               
                 promoter; 
                 
                   TGGAAAACGGTGTAACAAGGGTGAACACTATCCCATATC 
                 
                   
               
               
                 UPPERCASE 
                 
                   ACCAGCTCACCGTCTTTCATTGCCATACGTAATTCCGGA 
                 
                   
               
               
                 bold: 
                 
                   TGAGCATTCATCAGGCGGGCAAGAATGTGAATAAAGGCC 
                 
                   
               
               
                 ArgAfbr; 
                 
                   GGATAAAACTTGTGCTTATTTTTCTTTACGGTCTTTAAA 
                 
                   
               
               
                 UPPERCASE 
                 
                   AAGGCCGTAATATCCAGCTGAACGGTCTGGTTATAGGTA 
                 
                   
               
               
                 bold 
                 
                   CATTGAGCAACTGACTGAAATGCCTCAAAATGTTCTTTA 
                 
                   
               
               
                 underline: 
                 
                   CGATGCCATTGGGATATATCAACGGTGGTATATCCAGTG 
                 
                   
               
               
                 terminator 
                 
                   ATTTTTTTCTCCAT 
                   TTTAGCTTCCTTAGCTCCTGAAAAT 
                 
                   
               
               
                 sequence; 
                 
                   CTCGACAACTCAAAAAATACGCCCGGTAGTGATCTTATT 
                 
                   
               
               
                 UPPERCASE 
                 
                   TCATTATGGTGAAAGTTGGAACCTCTTACGTGCCGATCA 
                 
                   
               
               
                 italic bold: 
                 ACGTCTCATTTTCGCCAAAAGTTGGCCCAGGGCTTCCCG 
                   
               
               
                 frt sites 
                 GTATCAACAGGGACACCAGGATTTATTTATTCTGCGAAG 
                   
               
               
                   
                 TGATCTTCCGTCACAGGTAGGCGCGCC   
                   
               
               
                   
                      AGGA 
                   
               
               
                   
                 GGATATTCATATGGACCATGGCTAATTCCCAG   GTACCAG     
                   
               
               
                   
                 
                   
                     TTGTTCTTATTGGTGGTGTTGCTTTATGGTTGCATCGTA 
                   
                 
                   
               
               
                   
                 
                   
                     GTAAATGGTTGTAACAAAAGCAATTTTTCCGGCTGTCTG 
                   
                 
                   
               
               
                   
                 
                   
                     TATACAAAAACGCCGTAAAGTTTGAGCGAAGTCAATAAA 
                   
                 
                   
               
               
                   
                     CTCTCTACCCATTCAGGGCAATATCTCTCTTGGATCC   aa 
                   
               
               
                   
                 agtgaactctagaaataattttgtttaactttaagaagg 
                   
               
               
                   
                 agatatacat ATGGTAAAGGAACGTAAAACCGAGTTGGT   
                   
               
               
                   
                 
                   CGAGGGATTCCGCCATTCGGTTCCCTGTATCAATACCCA 
                 
                   
               
               
                   
                 
                   CCGGGGAAAAACGTTTGTCATCATGCTCGGCGGTGAAGC 
                 
                   
               
               
                   
                 
                   CATTGAGCATGAGAATTTCTCCAGTATCGTTAATGATAT 
                 
                   
               
               
                   
                 
                   CGGGTTGTTGCACAGCCTCGGCATCCGTCTGGTGGTGGT 
                 
                   
               
               
                   
                 
                   CTATGGCGCACGTCCGCAGATCGACGCAAATCTGGCTGC 
                 
                   
               
               
                   
                 
                   GCATCACCACGAACCGCTGTATCACAAGAATATACGTGT 
                 
                   
               
               
                   
                 
                   GACCGACGCCAAAACACTGGAACTGGTGAAGCAGGCTGC 
                 
                   
               
               
                   
                 
                   GGGAACATTGCAACTGGATATTACTGCTCGCCTGTCGAT 
                 
                   
               
               
                   
                 
                   GAGTCTCAATAACACGCCGCTGCAGGGCGCGCATATCAA 
                 
                   
               
               
                   
                 
                   CGTCGTCAGTGGCAATTTTATTATTGCCCAGCCGCTGGG 
                 
                   
               
               
                   
                 
                   CGTCGATGACGGCGTGGATTACTGCCATAGCGGGCGTAT 
                 
                   
               
               
                   
                 
                   CCGGCGGATTGATGAAGACGCGATCCATCGTCAACTGGA 
                 
                   
               
               
                   
                 
                   CAGCGGTGCAATAGTGCTAATGGGGCCGGTCGCTGTTTC 
                 
                   
               
               
                   
                 
                   AGTCACTGGCGAGAGCTTTAACCTGACCTCGGAAGAGAT 
                 
                   
               
               
                   
                 
                   TGCCACTCAACTGGCCATCAAACTGAAAGCTGAAAAGAT 
                 
                   
               
               
                   
                 
                   GATTGGTTTTTGCTCTTCCCAGGGCGTCACTAATGACGA 
                 
                   
               
               
                   
                 
                   CGGTGATATTGTCTCCGAACTTTTCCCTAACGAAGCGCA 
                 
                   
               
               
                   
                 
                   AGCGCGGGTAGAAGCCCAGGAAGAGAAAGGCGATTACAA 
                 
                   
               
               
                   
                 
                   CTCCGGTACGGTGCGCTTTTTGCGTGGCGCAGTGAAAGC 
                 
                   
               
               
                   
                 
                   CTGCCGCAGCGGCGTGCGTCGCTGTCATTTAATCAGTTA 
                 
                   
               
               
                   
                 
                   TCAGGAAGATGGCGCGCTGTTGCAAGAGTTGTTCTCACG 
                 
                   
               
               
                   
                 
                   CGACGGTATCGGTACGCAGATTGTGATGGAAAGCGCCGA 
                 
                   
               
               
                   
                 
                   GCAGATTCGTCGCGCAACAATCAACGATATTGGCGGTAT 
                 
                   
               
               
                   
                 
                   TCTGGAGTTGATTCGCCCACTGGAGCAGCAAGGTATTCT 
                 
                   
               
               
                   
                 
                   GGTACGCCGTTCTCGCGAGCAGCTGGAGATGGAAATCGA 
                 
                   
               
               
                   
                 
                   CAAATTCACCATTATTCAGCGCGATAACACGACTATTGC 
                 
                   
               
               
                   
                 
                   CTGCGCCGCGCTCTATCCGTTCCCGGAAGAGAAGATTGG 
                 
                   
               
               
                   
                 
                   GGAAATGGCCTGTGTGGCAGTTCACCCGGATTACCGCAG 
                 
                   
               
               
                   
                 
                   TTCATCAAGGGGTGAAGTTCTGCTGGAACGCATTGCCGC 
                 
                   
               
               
                   
                 
                   TCAGGCTAAGCAGAGCGGCTTAAGCAAATTGTTTGTGCT 
                 
                   
               
               
                   
                 
                   GACCACGCGCAGTATTCACTGGTTCCAGGAACGTGGATT 
                 
                   
               
               
                   
                 
                   TACCCCAGTGGATATTGATTTACTGCCCGAGAGCAAAAA 
                 
                   
               
               
                   
                 
                   GCAGTTGTACAACTACCAGCGTAAATCCAAAGTGTTGAT 
                 
                   
               
               
                   
                   GGCGGATTTAGGGTAA gtcgacgcatgcatcgataagcc 
                   
               
               
                   
                 gcgttctcatcctcccgcctcctcccccataaaaaagcc 
                   
               
               
                   
                 agggggtggaggatttaagccatctcctgatgac 
                   
               
               
                   
               
               
                 FNRS-fbrArgA 
                 ctacgccccatcgttgctttgtgtgatctctgttacaga 
                 SEQ ID 
               
               
                 and 
                 attggcggtaatgtggagatgcgcacataaaatcgccat 
                 NO: 37 
               
               
                 kanamycin 
                 gatttttgcaagcaacatcacgaaattccttacatgacc 
                   
               
               
                 resistance, 
                 tcggtttagttcacaggacgtcccatggctcgagCATGC 
                   
               
               
                 e.g., SYN- 
                 GAGAGTAGGGAACTGCCAGGCAT   CAAATAAAATGAAAGG     
                   
               
               
                 UCD303, SYN- 
                 
                   
                     CTCAGTCGAAAGACTGGGCCTTTCGTTTTATCTGTTGTT 
                   
                 
                   
               
               
                 UCD306, SYN- 
                     TGTCGGTGAACGCTCTCCTGAGTAGGACAAAT   CCGCCGG 
                   
               
               
                 UCD307, and 
                 GAGCGGATTTGAACGTTGCGAAGCAACGGCCCGGAGGGT 
                   
               
               
                 SYN-UCD309; 
                 GGCGGGCAGGACGCCCGCCATAAACTGCCAGGCATCAAA 
                   
               
               
                 a schematic 
                 TTAAGC   AGAAGGCCATCCTGACGGATGGCCTTTT   TGCGT 
                   
               
               
                 of the 
                 GGCCAGTGCCAAGCTTGCATGCAGATTGCAGCATTACAC 
                   
               
               
                 construct is 
                 GTCTTGAGCGATTGTGTAGGCTGGAGCTGCTTC   
                   
               
               
                 depicted in 
                 
                   
                   
                 
                   
               
               
                 FIG. 21 
                    aagatcccctcacgctgccgcaagcactcagggcgc 
                   
               
               
                 Lowercase 
                 aagggctgctaaaggaagcggaacacgtagaaagccagt 
                   
               
               
                 underlined: 
                 ccgcagaaacggtgctgaccccggatgaatgtcagctac 
                   
               
               
                 KanR 
                 tgggctatctggacaagggaaaacgcaagcgcaaagaga 
                   
               
               
                 promoter; 
                 aagcaggtagcttgcagtgggcttacatggcgatagcta 
                   
               
               
                 lowercase 
                 gactgggcggttttatggacagcaagcgaaccggaattg 
                   
               
               
                 italic: KanR 
                 ccagctggggcgccctctggtaa ggttgggaagccctgc   
                   
               
               
                 gene; 
                 
                   aaagtaaactggatggctttcttgccgccaaggatctga 
                 
                   
               
               
                 UPPERCASE 
                 
                   tggcgcaggggatcaagatctgatcaagagacaggatga 
                 
                   
               
               
                 underlined: 
                 
                   ggatcgtttcgc 
                   atgattgaacaagatggattgcacgca 
                 
                   
               
               
                 fnrS 
                 
                   ggttctccggccgcttgggtggagaggctattcggctat 
                 
                   
               
               
                 promoter; 
                 
                   gactgggcacaacagacaatcggctgctctgatgccgcc 
                 
                   
               
               
                 UPPERCASE 
                 
                   gtgttccggctgtcagcgcaggggcgcccggttcttttt 
                 
                   
               
               
                 bold: 
                 
                   gtcaagaccgacctgtccggtgccctgaatgaactgcag 
                 
                   
               
               
                 ArgAfbr 
                 
                   gacgaggcagcgcggctatcgtggctggccacgacgggc 
                 
                   
               
               
                 UPPERCASE 
                 
                   gttccttgcgcagctgtgctcgacgttgtcactgaagcg 
                 
                   
               
               
                 bold 
                 
                   ggaagggactggctgctattgggcgaagtgccggggcag 
                 
                   
               
               
                 underline: 
                 
                   gatctcctgtcatctcaccttgctcctgccgagaaagta 
                 
                   
               
               
                 terminator 
                 
                   tccatcatggctgatgcaatgcggcggctgcatacgctt 
                 
                   
               
               
                 sequence; 
                 
                   gatccggctacctgcccattcgaccaccaagcgaaacat 
                 
                   
               
               
                 UPPERCASE 
                 
                   cgcatcgagcgagcacgtactcggatggaagccggtctt 
                 
                   
               
               
                 italic bold: 
                 
                   gtcgatcaggatgatctggacgaagagcatcaggggctc 
                 
                   
               
               
                 frt sites 
                 
                   gcgccagccgaactgttcgccaggctcaaggcgcgcatg 
                 
                   
               
               
                   
                 
                   cccgacggcgaggatctcgtcgtgacccatggcgatgcc 
                 
                   
               
               
                   
                 
                   tgcttgccgaatatcatggtggaaaatggccgcttttct 
                 
                   
               
               
                   
                 
                   ggattcatcgactgtggccggctgggtgtggcggaccgc 
                 
                   
               
               
                   
                 
                   tatcaggacatagcgttggctacccgtgatattgctgaa 
                 
                   
               
               
                   
                 
                   gagcttggcggcgaatgggctgaccgcttcctcgtgctt 
                 
                   
               
               
                   
                 
                   tacggtatcgccgctcccgattcgcagcgcatcgccttc 
                 
                   
               
               
                   
                   tatcgccttcttgacgagttcttctga gcgggactctgg 
                   
               
               
                   
                 ggttcgaaatgaccgaccaagcgacgcccaacctgccat 
                   
               
               
                   
                 cacgagatttcgattccaccgccgccttctatgaaaggt 
                   
               
               
                   
                 tgggcttcggaatcgttttccgggacgccggctggatga 
                   
               
               
                   
                 tcctccagcgcggggatctcatgctggagttcttcgccc 
                   
               
               
                   
                 accccagcttcaaaagcgctct   
                   
               
               
                   
                      AGGAGGATA 
                   
               
               
                   
                 TTCATATGGACCATGGCTAATTCCCAGATATG GTACCAG   
                   
               
               
                   
                 
                   TTGTTCTTATTGGTGGTGTTGCTTTATGGTTGCATCGTA 
                 
                   
               
               
                   
                 
                   GTAAATGGTTGTAACAAAAGCAATTTTTCCGGCTGTCTG 
                 
                   
               
               
                   
                 
                   TATACAAAAACGCCGTAAAGTTTGAGCGAAGTCAATAAA 
                 
                   
               
               
                   
                   CTCTCTACCCATTCAGGGCAATATCTCTCTTGGATCC aa 
                   
               
               
                   
                 agtgaactctagaaataattttgtttaactttaagaagg 
                   
               
               
                   
                 agatatacat ATGGTAAAGGAACGTAAAACCGAGTTGGT   
                   
               
               
                   
                 
                   CGAGGGATTCCGCCATTCGGTTCCCTGTATCAATACCCA 
                 
                   
               
               
                   
                 
                   CCGGGGAAAAACGTTTGTCATCATGCTCGGCGGTGAAGC 
                 
                   
               
               
                   
                 
                   CATTGAGCATGAGAATTTCTCCAGTATCGTTAATGATAT 
                 
                   
               
               
                   
                 
                   CGGGTTGTTGCACAGCCTCGGCATCCGTCTGGTGGTGGT 
                 
                   
               
               
                   
                 
                   CTATGGCGCACGTCCGCAGATCGACGCAAATCTGGCTGC 
                 
                   
               
               
                   
                 
                   GCATCACCACGAACCGCTGTATCACAAGAATATACGTGT 
                 
                   
               
               
                   
                 
                   GACCGACGCCAAAACACTGGAACTGGTGAAGCAGGCTGC 
                 
                   
               
               
                   
                 
                   GGGAACATTGCAACTGGATATTACTGCTCGCCTGTCGAT 
                 
                   
               
               
                   
                 
                   GAGTCTCAATAACACGCCGCTGCAGGGCGCGCATATCAA 
                 
                   
               
               
                   
                 
                   CGTCGTCAGTGGCAATTTTATTATTGCCCAGCCGCTGGG 
                 
                   
               
               
                   
                 
                   CGTCGATGACGGCGTGGATTACTGCCATAGCGGGCGTAT 
                 
                   
               
               
                   
                 
                   CCGGCGGATTGATGAAGACGCGATCCATCGTCAACTGGA 
                 
                   
               
               
                   
                 
                   CAGCGGTGCAATAGTGCTAATGGGGCCGGTCGCTGTTTC 
                 
                   
               
               
                   
                 
                   AGTCACTGGCGAGAGCTTTAACCTGACCTCGGAAGAGAT 
                 
                   
               
               
                   
                 
                   TGCCACTCAACTGGCCATCAAACTGAAAGCTGAAAAGAT 
                 
                   
               
               
                   
                 
                   GATTGGTTTTTGCTCTTCCCAGGGCGTCACTAATGACGA 
                 
                   
               
               
                   
                 
                   CGGTGATATTGTCTCCGAACTTTTCCCTAACGAAGCGCA 
                 
                   
               
               
                   
                 
                   AGCGCGGGTAGAAGCCCAGGAAGAGAAAGGCGATTACAA 
                 
                   
               
               
                   
                 
                   CTCCGGTACGGTGCGCTTTTTGCGTGGCGCAGTGAAAGC 
                 
                   
               
               
                   
                 
                   CTGCCGCAGCGGCGTGCGTCGCTGTCATTTAATCAGTTA 
                 
                   
               
               
                   
                 
                   TCAGGAAGATGGCGCGCTGTTGCAAGAGTTGTTCTCACG 
                 
                   
               
               
                   
                 
                   CGACGGTATCGGTACGCAGATTGTGATGGAAAGCGCCGA 
                 
                   
               
               
                   
                 
                   GCAGATTCGTCGCGCAACAATCAACGATATTGGCGGTAT 
                 
                   
               
               
                   
                 
                   TCTGGAGTTGATTCGCCCACTGGAGCAGCAAGGTATTCT 
                 
                   
               
               
                   
                 
                   GGTACGCCGTTCTCGCGAGCAGCTGGAGATGGAAATCGA 
                 
                   
               
               
                   
                 
                   CAAATTCACCATTATTCAGCGCGATAACACGACTATTGC 
                 
                   
               
               
                   
                 
                   CTGCGCCGCGCTCTATCCGTTCCCGGAAGAGAAGATTGG 
                 
                   
               
               
                   
                 
                   GGAAATGGCCTGTGTGGCAGTTCACCCGGATTACCGCAG 
                 
                   
               
               
                   
                 
                   TTCATCAAGGGGTGAAGTTCTGCTGGAACGCATTGCCGC 
                 
                   
               
               
                   
                 
                   TCAGGCTAAGCAGAGCGGCTTAAGCAAATTGTTTGTGCT 
                 
                   
               
               
                   
                 
                   GACCACGCGCAGTATTCACTGGTTCCAGGAACGTGGATT 
                 
                   
               
               
                   
                 
                   TACCCCAGTGGATATTGATTTACTGCCCGAGAGCAAAAA 
                 
                   
               
               
                   
                 
                   GCAGTTGTACAACTACCAGCGTAAATCCAAAGTGTTGAT 
                 
                   
               
               
                   
                   GGCGGATTTAGGGTAA gtcgacgcatgcatcgataagcc 
                   
               
               
                   
                 gcgttctcatcctcccgcctcctcccccataaaaaagcc 
                   
               
               
                   
                 agggggtggaggatttaagccatctcctgatgac 
                   
               
               
                   
               
               
                 FNRS-fbrArgA 
                 ctacgccccatcgttgctttgtgtgatctctgttacaga 
                 SEQ ID 
               
               
                 and no 
                 attggcggtaatgtggagatgcgcacataaaatcgccat 
                 NO: 38 
               
               
                 antibiotic 
                 gatttttgcaagcaacatcacgaaattccttacatgacc 
                   
               
               
                 resistance, 
                 tcggtttagttcacaggacgtcccatggctcgagCATGC 
                   
               
               
                 e.g., SYN- 
                 GAGAGTAGGGAACTGCCAGGCAT   CAAATAAAATGAAAGG     
                   
               
               
                 UCD305 SYN- 
                 
                   
                     CTCAGTCGAAAGACTGGGCCTTTCGTTTTATCT 
                   
                 
                   
               
               
                 UCD304, SYN- 
                     GTTGTTTGTCGGTGAACGCTCTCCTGAGTAGGACAAAT   C 
                   
               
               
                 UCD308, 
                 CGCCGGGAGCGGATTTGAACGTTGCGAAGCAACGGCCCG 
                   
               
               
                 SYNUCD310; a 
                 GAGGGTGGCGGGCAGGACGCCCGCCATAAACTGCCAGGC 
                   
               
               
                 schematic of 
                 ATCAAATTAAGC   AGAAGGCCATCCTGACGGATGGCCTTT     
                   
               
               
                 the 
                     T   TGCGTGGCCAGTGCCAAGCTTGCATGCAGATTGCAGCA 
                   
               
               
                 construct is 
                 TTACACGTCTTGAGCGATTGTGTAGGCTGGAGCTGCTTC 
                   
               
               
                 depicted in 
                 
                   
                   
                 
                   
               
               
                 FIG. 22; 
                    AGGAGGATATTCATATGGACCATGGCTAATT 
                   
               
               
                 UPPERCASE 
                 CCCAG GTACCAGTTGTTCTTATTGGTGGTGTTGCTTTAT   
                   
               
               
                 underline: 
                 
                   GGTTGCATCGTAGTAAATGGTTGTAACAAAAGCAATTTT 
                 
                   
               
               
                 fnrS 
                 
                   TCCGGCTGTCTGTATACAAAAACGCCGTAAAGTTTGAGC 
                 
                   
               
               
                 promoter; 
                 
                   GAAGTCAATAAACTCTCTACCCATTCAGGGCAATATCTC 
                 
                   
               
               
                 UPPERCASE 
                   TCTTGGATCC aaagtgaactctagaaataattttgttta 
                   
               
               
                 bold: 
                 actttaagaaggagatatacat ATGGTAAAGGAACGTAA   
                   
               
               
                 ArgAfbr; 
                 
                   AACCGAGTTGGTCGAGGGATTCCGCCATTCGGTTCCCTG 
                 
                   
               
               
                 UPPERCASE 
                 
                   TATCAATACCCACCGGGGAAAAACGTTTGTCATCATGCT 
                 
                   
               
               
                 bold 
                 
                   CGGCGGTGAAGCCATTGAGCATGAGAATTTCTCCAGTAT 
                 
                   
               
               
                 underline: 
                 
                   CGTTAATGATATCGGGTTGTTGCACAGCCTCGGCATCCG 
                 
                   
               
               
                 terminator 
                 
                   TCTGGTGGTGGTCTATGGCGCACGTCCGCAGATCGACGC 
                 
                   
               
               
                 sequence; 
                 
                   AAATCTGGCTGCGCATCACCACGAACCGCTGTATCACAA 
                 
                   
               
               
                 UPPERCASE 
                 
                   GAATATACGTGTGACCGACGCCAAAACACTGGAACTGGT 
                 
                   
               
               
                 italic bold: 
                 
                   GAAGCAGGCTGCGGGAACATTGCAACTGGATATTACTGC 
                 
                   
               
               
                 frt sites 
                 
                   TCGCCTGTCGATGAGTCTCAATAACACGCCGCTGCAGGG 
                 
                   
               
               
                   
                 
                   CGCGCATATCAACGTCGTCAGTGGCAATTTTATTATTGC 
                 
                   
               
               
                   
                 
                   CCAGCCGCTGGGCGTCGATGACGGCGTGGATTACTGCCA 
                 
                   
               
               
                   
                 
                   TAGCGGGCGTATCCGGCGGATTGATGAAGACGCGATCCA 
                 
                   
               
               
                   
                 
                   TCGTCAACTGGACAGCGGTGCAATAGTGCTAATGGGGCC 
                 
                   
               
               
                   
                 
                   GGTCGCTGTTTCAGTCACTGGCGAGAGCTTTAACCTGAC 
                 
                   
               
               
                   
                 
                   CTCGGAAGAGATTGCCACTCAACTGGCCATCAAACTGAA 
                 
                   
               
               
                   
                 
                   AGCTGAAAAGATGATTGGTTTTTGCTCTTCCCAGGGCGT 
                 
                   
               
               
                   
                 
                   CACTAATGACGACGGTGATATTGTCTCCGAACTTTTCCC 
                 
                   
               
               
                   
                 
                   TAACGAAGCGCAAGCGCGGGTAGAAGCCCAGGAAGAGAA 
                 
                   
               
               
                   
                 
                   AGGCGATTACAACTCCGGTACGGTGCGCTTTTTGCGTGG 
                 
                   
               
               
                   
                 
                   CGCAGTGAAAGCCTGCCGCAGCGGCGTGCGTCGCTGTCA 
                 
                   
               
               
                   
                 
                   TTTAATCAGTTATCAGGAAGATGGCGCGCTGTTGCAAGA 
                 
                   
               
               
                   
                 
                   GTTGTTCTCACGCGACGGTATCGGTACGCAGATTGTGAT 
                 
                   
               
               
                   
                 
                   GGAAAGCGCCGAGCAGATTCGTCGCGCAACAATCAACGA 
                 
                   
               
               
                   
                 
                   TATTGGCGGTATTCTGGAGTTGATTCGCCCACTGGAGCA 
                 
                   
               
               
                   
                 
                   GCAAGGTATTCTGGTACGCCGTTCTCGCGAGCAGCTGGA 
                 
                   
               
               
                   
                 
                   GATGGAAATCGACAAATTCACCATTATTCAGCGCGATAA 
                 
                   
               
               
                   
                 
                   CACGACTATTGCCTGCGCCGCGCTCTATCCGTTCCCGGA 
                 
                   
               
               
                   
                 
                   AGAGAAGATTGGGGAAATGGCCTGTGTGGCAGTTCACCC 
                 
                   
               
               
                   
                 
                   GGATTACCGCAGTTCATCAAGGGGTGAAGTTCTGCTGGA 
                 
                   
               
               
                   
                 
                   ACGCATTGCCGCTCAGGCTAAGCAGAGCGGCTTAAGCAA 
                 
                   
               
               
                   
                 
                   ATTGTTTGTGCTGACCACGCGCAGTATTCACTGGTTCCA 
                 
                   
               
               
                   
                 
                   GGAACGTGGATTTACCCCAGTGGATATTGATTTACTGCC 
                 
                   
               
               
                   
                 
                   CGAGAGCAAAAAGCAGTTGTACAACTACCAGCGTAAATC 
                 
                   
               
               
                   
                   CAAAGTGTTGATGGCGGATTTAGGGTAA gtcgacgcatg 
                   
               
               
                   
                 catcgataagccgcgttctcatcctcccgcctcctcccc 
                   
               
               
                   
                 cataaaaaagccagggggtggaggatttaagccatctcc 
                   
               
               
                   
                 tgatgac 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 36 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 36 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 36 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 37 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 37 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 37 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 37 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 37 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 38 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 38 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 38 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 38 or a functional fragment thereof. 
     Arginine Catabolism 
     An important consideration in practicing the invention is to ensure that ammonia is not overproduced as a byproduct of arginine and/or citrulline catabolism. In the final enzymatic step of the urea cycle, arginase catalyzes the hydrolytic cleavage of arginine into ornithine and urea (Cunin et al., 1986). Urease, which may be produced by gut bacteria, catalyzes the cleavage of urea into carbon dioxide and ammonia (Summerskill, 1966; Aoyagi et al., 1966; Cunin et al., 1986). Thus, urease activity may generate ammonia that can be toxic for human tissue (Konieczna et al., 2012). In some bacteria, including  E. coli  Nissle, the gene arcD encodes an arginine/ornithine antiporter, which may also liberate ammonia (Vander Wauven et al., 1984; Gamper et al., 1991; Meng et al., 1992). 
     AstA is an enzyme involved in the conversion of arginine to succinate, which liberates ammonia. SpeA is an enzyme involved in the conversion of arginine to agmatine, which can be further catabolized to produce ammonia. Thus, in some instances, it may be advantageous to prevent the breakdown of arginine. In some embodiments, the genetically engineered bacteria comprising a mutant arginine regulon additionally includes mutations that reduce or eliminate arginine catabolism, thereby reducing or eliminating further ammonia production. In some embodiments, the genetically engineered bacteria also comprise mutations that reduce or eliminate ArcD activity. In certain embodiments, ArcD is deleted. In some embodiments, the genetically engineered bacteria also comprise mutations that reduce or eliminate AstA activity. In certain embodiments, AstA is deleted. In some embodiments, the genetically engineered bacteria also comprise mutations that reduce or eliminate SpeA activity. In certain embodiments, SpeA is deleted. In some embodiments, the genetically engineered bacteria also comprise mutations that reduce or eliminate arginase activity. In certain embodiments, arginase is deleted. In some embodiments, the genetically engineered bacteria also comprise mutations that reduce or eliminate urease activity. In certain embodiments, urease is deleted. In some embodiments, one or more other genes involved in arginine catabolism are mutated or deleted. 
     Other Hyperammonemia Disorders 
     Hepatic encephalopathy (HE) is characterized by neurocognitive changes in patients and biochemical derangements have been implicated in pathogenesis. Specifically, elevated ammonia levels are suspected to partly contribute to disease pathophysiology. In addition to hyperammonemia, elevated levels of cerebral GABA and manganese levels have been noted and suspected to contribute to clinical presentation. 
     In some embodiments, the disclosure provides genetically engineered microorganisms, e.g., bacteria and virus, pharmaceutical compositions thereof, and methods of modulating or treating diseases or disorders associated with hyperammonemia, e.g., hepatic encephalopathy and Huntington&#39;s disease. The genetically engineered bacteria are capable of reducing excess ammonia in a mammal. In some embodiments, the genetically engineered bacteria reduce excess ammonia by incorporating excess nitrogen in the body into non-toxic molecules, e.g., arginine, citrulline, methionine, histidine, lysine, asparagine, glutamine, or tryptophan. In some embodiments, the genetically engineered bacteria further comprise one or more circuits (genetic sequence) to reduce the levels of other toxic or deleterious molecule(s), e.g., GABA, manganese. In some embodiments, the genetically engineered bacteria further comprise one or more circuits to produce a gut barrier enhancer molecule, e.g., a short chain fatty acid such as butyrate, propionate, and acetate. This disclosure also provides compositions and therapeutic methods for reducing excess ammonia and other deleterious molecules, e.g., GABA and manganese. In certain aspects, the disclosure provides genetically engineered bacteria that are capable of reducing excess ammonia and other deleterious molecules. In certain embodiments, the disclosure provides genetically engineered bacteria that are capable of reducing excess ammonia and other deleterious molecules and further producing one or more therapeutic molecules, such as a gut barrier function enhancer molecule, e.g., butyrate. In some embodiments, the disclosure provides genetically engineered bacteria comprising one or more circuits for reducing excess ammonia in which the circuits are under the control of an inducible promoter. In some embodiments, the disclosure provides genetically engineered bacteria comprising one or more circuits for reducing excess ammonia and one or more circuits for reducing other deleterious molecules in which one or more of the circuits are under the control of an inducible promoter. In some embodiments, the disclosure provides genetically engineered bacteria comprising one or more circuits for reducing excess ammonia and one or more circuits for reducing other deleterious molecules and further producing one or more therapeutic molecules, such as a gut barrier function enhancer molecule, e.g., butyrate in which one or more of the circuits and/or therapeutic molecule(s) are under the control of an inducible promoter. In certain aspects, the compositions and methods disclosed herein may be used for treating a disease or disorder associated with excess ammonia, for example, hepatic encephalopathy or Huntington&#39;s disease, and/or one or more symptoms associated with disease or disorder associated with excess ammonia, such as hepatic encephalopathy or Huntington&#39;s disease. 
     GABA Transport and Metabolism 
     γ-Aminobutyric acid (GABA) is the predominant inhibitory neurotransmitter in the mammalian central nervous system. In humans, GABA activates the post-synaptic GABA A  receptor, which is part of a ligand-gated chloride-specific ion channel complex. Activation of this complex on a post-synaptic neuron allows chloride ions to enter the neuron and exert an inhibitory effect. Alterations of such GABAergic neurotransmission have been implicated in the pathophysiology of several neurological disorders, including epilepsy (Jones-Davis and MacDonald, 2003), Huntington&#39;s disease (Krogsgaard-Larsen, 1992), and hepatic encephalopathy (Jones and Basile, 1997). 
     Neurons in the brain that are modulated by GABA are said to be under inhibitory GABAergic tone. This inhibitory tone prevents neuronal firing until a sufficiently potent stimulatory stimulus is received, or until the inhibitory tone is otherwise released. Increased GABAergic tone in hepatic encephalopathy was initially described in the early 1980s, based on a report of similar visual response patterns in rabbits with galactosamine-induced liver failure and rabbits treated with allosteric modulators of the GABA A  receptor (e.g., pentobarbital, diazepam) (Jones and Basile, 1997). Clinical improvements in HE patients treated with a highly selective benzodiazapene antagonist at the GABA A  receptor, flumazenil, further confirmed these observations (Banksy et al., 1985; Scollo-Lavizzari and Steinmann, 1985). Increased GABAergic tone in HE has since been proposed as a consequence of one or more of the following: (1) increased GABA concentrations in the brain, (2) altered integrity of the GABA A  receptor, and/or (3) increased concentrations of endogenous modulators of the GABA A  receptor (Ahboucha and Butterworth, 2004). 
     GABA uptake in  E. coli  is driven by membrane potential and facilitated by the membrane transport protein, GabP (Li et al., 2001). GabP is a member of the amino acid/polymaine/organocation (APC) transporter superfamily, one of the two largest families of secondary active transporters (Jack et al., 2000). GabP protein, encoded by the gabP gene, consists of 466 amino acids and 12 transmembrane alpha-helices, wherein both N- and C-termini face the cytosol (Hu and King, 1998a). The GabP residue sequence also includes a consensus amphipathic region (CAR), which is conserved between members of the APC family from bacteria to mammals (Hu and King, 1998b). Upon entry into the cell, GABA is converted to succinyl semialdehyde (SSA) by GABA α-ketoglutarate transaminase (GSST). Succinate-semialdehyde dehydrogenase (SSDH) then catalyzes the second and only other specific step in GABA catabolism, the oxidation of succinyl semialdehyde to succinate (Dover and Halpern, 1972). Ultimately, succinate becomes a substrate for the citric acid (TCA) cycle. 
     In some embodiments, the bacteria are genetically engineered to consume excess ammonia via a metabolic pathway, e.g., an arginine biosynthesis pathway, a histidine biosynthesis pathway, a methionine biosynthesis pathway, a lysine biosynthesis pathway, an asparagine biosynthesis pathway, a glutamine biosynthesis pathway, or a tryptophan biosynthesis pathway as described herein (an “ammonia conversion circuit”). In some embodiments, the genetically engineered bacteria comprise an arginine biosynthesis pathway and are capable of reducing excess ammonia. In some embodiments, the ammonia conversion circuit is under the control of an inducible promoter. In some embodiments, the ammonia conversion circuit is under the control of an an oxygen level-dependent promoter, e.g., an FNR-inducible promoter. In some embodiments, the ammonia conversion circuit is under the control of a promoter induced by a molecule or metabolite associated with hepatic encephalopathy, e.g., bilirubin, aspartate aminotransferase, alanine aminotransferase, transferase, hepatitis antigens and antibodies, alpha fetoprotein, anti-mitochondrial, smooth muscle, and anti-nuclear antibodies, iron, transferrin, ferritin, copper, ceruloplasmin, ammonia, or manganese 
     In some embodiments, the genetically engineered bacteria comprising an ammonia conversion circuit further comprise one or more circuits for producing one or more GABA membrane transport protein(s), e.g., GabP, and are capable of transporting GABA into the cell (a “GABA transport circuit”) ( FIG. 41 ). 
     In some embodiments, the genetically engineered bacteria comprising an ammonia conversion circuit further comprise one or more circuits for producing one or more GABA catabolism enzyme(s), e.g., GSST, SSDH, and/or COT (a “GABA metabolic circuit”) ( FIG. 49 ). In some embodiments, the genetically engineered bacteria comprising an ammonia conversion circuit further comprise one or more circuits for producing one or more GABA membrane transport protein(s), e.g., GabP, and one or more circuits for producing one or more GABA catabolism enzyme(s), e.g., GSST, SSDH, and/or COT (a “GABA metabolic circuit”) ( FIG. 41 ). 
     In a more specific aspect, the genetically engineered bacteria comprise an ammonia conversion circuit, a GABA transport circuit, and a GABA metabolic circuit. In some embodiments, the ammonia conversion circuit, GABA transport circuit, and GABA metabolic circuit are under the control of the same promoter. In alternate embodiments, the ammonia conversion circuit, GABA transport circuit, and GABA metabolic circuit are under the control of different promoters. Exemplary promoters include any of the promoters disclosed herein. For example, in some embodiments, the genetically engineered bacteria of the invention comprise an oxygen level-dependent promoter induced by low-oxygen, microaerobic, or anaerobic conditions. In some embodiments, the genetically engineered bacteria comprise a promoter induced by a molecule or metabolite, for example, a tissue-specific molecule or metabolite or a molecule or metabolite indicative of liver damage. Non-limiting examples of molecules or metabolites include, e.g., bilirubin, aspartate aminotransferase, alanine aminotransferase, blood coagulation factors II, VII, IX, and X, alkaline phosphatase, gamma glutamyl transferase, hepatitis antigens and antibodies, alpha fetoprotein, anti-mitochondrial, smooth muscle, and anti-nuclear antibodies, iron, transferrin, ferritin, copper, ceruloplasmin, ammonia, and manganese in their blood and intestines. In some embodiments, the genetically engineered bacteria comprise a promoter induced by inflammation or an inflammatory response, e.g., RNS or ROS promoter. In some embodiments, the genetically engineered bacteria comprise a promoter induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose and tetracycline. 
     The amino acid sequence of an exemplary GabP transporter is shown in Table 42. In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 105 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 105 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 105 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 105 or a functional fragment thereof. 
     A non-limiting example of a polynucleotide sequence is shown in Table 43 (SEQ ID NO: 106). 
     Manganese Transport 
     Manganese is a biologically important trace metal and is required for the survival of most living organisms. In mammals, manganese is excreted in the bile, but its disposal is affected by the impaired flow of bile from the liver to the duodenum (i.e., cholestasis) that accompanies liver failure. Similar to ammonia, elevated concentrations of manganese play a role in the development of hepatic encephalopathy (Rivera-Mancia et al., 2012). Astrocytes in the brain which detoxify ammonia in a reaction catalyzed by glutamine synthetase, require manganese as a cofactor and thus have a tendency to accumulate this metal (Aschner et al., 1999). In vitro studies have demonstrated that manganese can result in the inhibition of glutamate transport (Hazell and Norenberg, 1996), abnormalities in astrocyte morphology (Hazell et al., 2006), and increased cell volume (Rama Rao et al., 2007). Manganese and ammonia have also been shown to act synergistically in the pathogenesis of hepatic encephalopathy (Jayakumar et al., 2004). 
     Metal ion homeostasis in prokaryotic cells, which lack internal compartmentalization, is maintained by the tight regulation of metal ion flux across in cytoplasmic membrane (Jensen and Jensen, 2014). Manganese uptake in bacteria predominantly involves two major types of transporters: proton-dependent Nramp-related transporters, and/or ATP-dependent ABC transporters. The Nramp (Natural resistance-associated macrophage protein) transporter family was first described in plants, animals, and yeasts (Cellier et al., 1996), but MntH has since been characterized in several bacterial species (Porcheron et al., 2013). Selectivity of the Nrampl transporter for manganese has been shown in metal accumulation studies, wherein overexpression of  Staphylococcus aureus  mntH resulted in increased levels of cell-associated manganese, but no accumulation of calcium, copper, iron, magnesium, or zinc (Horsburgh et al., 2002). Additionally,  Bacillus subtilis  strains comprising a mutation in the mntH gene exhibited impaired growth in metal-free medium that was rescued by the addition of manganese (Que and Helmann, 2000). The amino acid sequence of an exemplary MntH transporter is shown in Table 44. In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 107 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 36 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 107 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 107 or a functional fragment thereof. A non-limiting example of a polynucleotide sequence is shown in Table 45 (SEQ ID NO: 108). 
     High-affinity manganese uptake may also be mediated by ABC (ATP-binding cassette) transporters. Members of this transporter superfamily utilize the hydrolysis of ATP to fuel the import or export of diverse substrates, ranging from ions to macromolecules, and are well characterized for their role in multi-drug resistance in both prokaryotic and eukaryotic cells. Non-limiting examples of bacterial ABC transporters involved in manganese import include MntABCD ( Bacillus subtilis, Staphylococcus aureus ), SitABCD ( Salmonella typhimurium, Shigella flexneri ), PsaABCD ( Streptococcus pneumoniae ), and YfeABCD ( Yersinia pestis ) (Bearden and Perry, 1999; Kehres et al., 2002; McAllister et al., 2004; Zhou et al., 1999). The MntABCD transporter complex consists of three subunits, wherein MntC and MntD are integral membrane proteins that comprise the permease subunit mediate cation transport, MntB is the ATPase, and MntA binds and delivers manganese to the permease submit. Other ABC transporter operons, such as sitABCD, psaABCD, and yfeABCD, exhibit similar subunit organization and function (Higgins, 1992; Rees et al., 2009). 
     In some embodiments, the genetically engineered bacteria comprising an ammonia conversion circuit further comprise one or more circuits for producing a manganese membrane transport protein, e.g., MntH, and are capable of transporting manganese ions into the cell (a “manganese transport circuit”) ( FIG. 42 ). 
     In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a manganese transport circuit, and a GABA metabolic circuit. In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a manganese transport circuit, and a GABA transport circuit. In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a manganese transport circuit, a GABA transport circuit, and a GABA metabolic circuit. In some embodiments, the circuits are under the control of the same promoter. In alternate embodiments, the circuits are under the control of different promoters. In some embodiments, the genetically engineered bacteria of the invention comprise an oxygen level-dependent promoter induced by low-oxygen, microaerobic, or anaerobic conditions. In some embodiments, the genetically engineered bacteria comprise a promoter induced by a molecule or metabolite, for example, a tissue-specific molecule or metabolite or a molecule or metabolite indicative of liver damage. Non-limiting examples of molecules or metabolites include, e.g., bilirubin, aspartate aminotransferase, alanine aminotransferase, blood coagulation factors II, VII, IX, and X, alkaline phosphatase, gamma glutamyl transferase, hepatitis antigens and antibodies, alpha fetoprotein, anti-mitochondrial, smooth muscle, and anti-nuclear antibodies, iron, transferrin, ferritin, copper, ceruloplasmin, ammonia, and manganese in their blood and intestines. In some embodiments, the genetically engineered bacteria comprise a promoter induced by inflammation or an inflammatory response, e.g., RNS or ROS promoter. In some embodiments, the genetically engineered bacteria comprise a promoter induced by a metabolite that may or may not be naturally present (e.g., can be exogenously added) in the gut, e.g., arabinose and tetracycline. 
     Production of Butyrate and Other Gut Barrier Function Enhancer Molecules 
     In some embodiments, the genetically engineered bacteria of the invention further comprise a gene encoding a gut barrier function enhancer molecule, or a gene cassette encoding a biosynthetic pathway capable of producing a gut barrier function enhancer molecule. In some embodiments, the molecule is selected from the group consisting of a short-chain fatty acid, butyrate, propionate, acetate, GLP-2, IL-10, IL-27, TGF-β1, TGF-β2, elafin (also known as peptidase inhibitor 3 or SKALP), trefoil factor, melatonin, PGD 2 , kynurenic acid, and kynurenine. 
     In some embodiments, the genetically engineered bacteria of the invention express a gut barrier function enhancer molecule that is encoded by a single gene, e.g., the molecule is elafin and encoded by the PI3 gene. In alternate embodiments, the genetically engineered bacteria of the invention encode a gut barrier function enhancer molecule, e.g., butyrate or propionate, that is synthesized by a biosynthetic pathway requiring multiple genes. 
     The gene or gene cassette may be expressed on a high-copy plasmid, a low-copy plasmid, or a chromosome. In some embodiments, expression from the plasmid may be useful for increasing expression of the gut barrier function enhancer molecule. In some embodiments, expression from the chromosome may be useful for increasing stability of expression of the gut barrier function enhancer molecule. In some embodiments, the gene or gene cassette for producing the gut barrier function enhancer molecule is integrated into the bacterial chromosome at one or more integration sites in the genetically engineered bacteria. For example, one or more copies of the butyrate biosynthesis gene cassette may be integrated into the bacterial chromosome. In some embodiments, the gene or gene cassette for producing the gut barrier function enhancer molecule is expressed from a plasmid in the genetically engineered bacteria. In some embodiments, the gene or gene cassette for producing the gut barrier function enhancer molecule is inserted into the bacterial genome at one or more of the following insertion sites in  E. coli  Nissle: malE/K, araC/BAD, lacZ, thyA, malP/T. Any suitable insertion site may be used (see, e.g.,  FIG. 18 ). The insertion site may be anywhere in the genome, e.g., in a gene required for survival and/or growth, such as thyA (to create an auxotroph); in an active area of the genome, such as near the site of genome replication; and/or in between divergent promoters in order to reduce the risk of unintended transcription, such as between AraB and AraC of the arabinose operon. 
     In some embodiments, the genetically engineered bacteria of the invention comprise a butyrogenic gene cassette and are capable of producing butyrate. The genetically engineered bacteria may include any suitable set of butyrogenic genes (see, e.g., Table 14). Unmodified bacteria comprising butyrate biosynthesis genes are known and include, but are not limited to,  Peptoclostridium, Clostridium, Fusobacterium, Butyrivibrio, Eubacterium , and  Treponema , and these endogenous butyrate biosynthesis pathways may be a source of genes for the genetically engineered bacteria of the invention. In some embodiments, the genetically engineered bacteria of the invention comprise butyrate biosynthesis genes from a different species, strain, or substrain of bacteria. In some embodiments, the genetically engineered bacteria comprise the eight genes of the butyrate biosynthesis pathway from  Peptoclostridium difficile , e.g.,  Peptoclostridium difficile  strain 630: bcd2, etfB3, etfA3, thiA1, hbd, crt2, pbt, and buk (Aboulnaga et al., 2013), and are capable of producing butyrate in low-oxygen conditions, in the presence of HE-specific molecules or metabolites, in the presence of molecules or metabolites associated with liver damage, inflammation or an inflammatory response, or in the presence of some other metabolite such as arabinose.  Peptoclostridium difficile  strain 630 and strain 1296 are both capable of producing butyrate, but comprise different nucleic acid sequences for etfA3, thiA1, hbd, crt2, pbt, and buk. In some embodiments, the genetically engineered bacteria comprise a combination of butyrogenic genes from different species, strains, and/or substrains of bacteria, and are capable of producing butyrate in low-oxygen conditions or in the presence of HE-specific molecules or metabolites. For example, in some embodiments, the genetically engineered bacteria comprise bcd2, etfB3, etfA3, and thiA1 from  Peptoclostridium difficile  strain 630, and hbd, crt2, pbt, and buk from  Peptoclostridium difficile  strain 1296. In some embodiments, the genetically engineered bacteria are capable of expressing the butyrate biosynthesis cassette and producing butyrate in low-oxygen conditions or in the presence of HE-specific molecules or metabolites. The genes may be codon-optimized, and translational and transcriptional elements may be added. Table 14 depicts the nucleic acid sequences of exemplary genes in butyrate biosynthesis gene cassettes. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 39, 40, 41, 42, 43, 44, 45, 46, 47, or 48 a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 39, 40, 41, 42, 43, 44, 45, 46, 47, or 48, or a functional fragment thereof. 
     
       
         
           
               
               
             
               
                 TABLE 14 
               
               
                   
               
               
                 Description 
                 Sequence 
               
               
                   
               
             
            
               
                 bcd2 
                 ATGGATTTAAATTCTAAAAAATATCAGATGCTTAAAGAGCTATATGTAAG 
               
               
                 (SEQ ID 
                 CTTCGCTGAAAATGAAGTTAAACCTTTAGCAACAGAACTTGATGAAGAAG 
               
               
                 NO: 39) 
                 AAAGATTTCCTTATGAAACAGTGGAAAAAATGGCAAAAGCAGGAATGATG 
               
               
                   
                 GGTATACCATATCCAAAAGAATATGGTGGAGAAGGTGGAGACACTGTAGG 
               
               
                   
                 ATATATAATGGCAGTTGAAGAATTGTCTAGAGTTTGTGGTACTACAGGAG 
               
               
                   
                 TTATATTATCAGCTCATACATCTCTTGGCTCATGGCCTATATATCAATAT 
               
               
                   
                 GGTAATGAAGAACAAAAACAAAAATTCTTAAGACCACTAGCAAGTGGAGA 
               
               
                   
                 AAAATTAGGAGCATTTGGTCTTACTGAGCCTAATGCTGGTACAGATGCGT 
               
               
                   
                 CTGGCCAACAAACAACTGCTGTTTTAGACGGGGATGAATACATACTTAAT 
               
               
                   
                 GGCTCAAAAATATTTATAACAAACGCAATAGCTGGTGACATATATGTAGT 
               
               
                   
                 AATGGCAATGACTGATAAATCTAAGGGGAACAAAGGAATATCAGCATTTA 
               
               
                   
                 TAGTTGAAAAAGGAACTCCTGGGTTTAGCTTTGGAGTTAAAGAAAAGAAA 
               
               
                   
                 ATGGGTATAAGAGGTTCAGCTACGAGTGAATTAATATTTGAGGATTGCAG 
               
               
                   
                 AATACCTAAAGAAAATTTACTTGGAAAAGAAGGTCAAGGATTTAAGATAG 
               
               
                   
                 CAATGTCTACTCTTGATGGTGGTAGAATTGGTATAGCTGCACAAGCTTTA 
               
               
                   
                 GGTTTAGCACAAGGTGCTCTTGATGAAACTGTTAAATATGTAAAAGAAAG 
               
               
                   
                 AGTACAATTTGGTAGACCATTATCAAAATTCCAAAATACACAATTCCAAT 
               
               
                   
                 TAGCTGATATGGAAGTTAAGGTACAAGCGGCTAGACACCTTGTATATCAA 
               
               
                   
                 GCAGCTATAAATAAAGACTTAGGAAAACCTTATGGAGTAGAAGCAGCAAT 
               
               
                   
                 GGCAAAATTATTTGCAGCTGAAACAGCTATGGAAGTTACTACAAAAGCTG 
               
               
                   
                 TACAACTTCATGGAGGATATGGATACACTCGTGACTATCCAGTAGAAAGA 
               
               
                   
                 ATGATGAGAGATGCTAAGATAACTGAAATATATGAAGGAACTAGTGAAGT 
               
               
                   
                 TCAAAGAATGGTTATTTCAGGAAAACTATTAAAATAG 
               
               
                   
               
               
                 etfB3 
                 ATGAATATAGTCGTTTGTATAAAACAAGTTCCAGATACAACAGAAGTTAA 
               
               
                 (SEQ ID 
                 ACTAGATCCTAATACAGGTACTTTAATTAGAGATGGAGTACCAAGTATAA 
               
               
                 NO: 40) 
                 TAAACCCTGATGATAAAGCAGGTTTAGAAGAAGCTATAAAATTAAAAGAA 
               
               
                   
                 GAAATGGGTGCTCATGTAACTGTTATAACAATGGGACCTCCTCAAGCAGA 
               
               
                   
                 TATGGCTTTAAAAGAAGCTTTAGCAATGGGTGCAGATAGAGGTATATTAT 
               
               
                   
                 TAACAGATAGAGCATTTGCGGGTGCTGATACTTGGGCAACTTCATCAGCA 
               
               
                   
                 TTAGCAGGAGCATTAAAAAATATAGATTTTGATATTATAATAGCTGGAAG 
               
               
                   
                 ACAGGCGATAGATGGAGATACTGCACAAGTTGGACCTCAAATAGCTGAAC 
               
               
                   
                 ATTTAAATCTTCCATCAATAACATATGCTGAAGAAATAAAAACTGAAGGT 
               
               
                   
                 GAATATGTATTAGTAAAAAGACAATTTGAAGATTGTTGCCATGACTTAAA 
               
               
                   
                 AGTTAAAATGCCATGCCTTATAACAACTCTTAAAGATATGAACACACCAA 
               
               
                   
                 GATACATGAAAGTTGGAAGAATATATGATGCTTTCGAAAATGATGTAGTA 
               
               
                   
                 GAAACATGGACTGTAAAAGATATAGAAGTTGACCCTTCTAATTTAGGTCT 
               
               
                   
                 TAAAGGTTCTCCAACTAGTGTATTTAAATCATTTACAAAATCAGTTAAAC 
               
               
                   
                 CAGCTGGTACAATATACAATGAAGATGCGAAAACATCAGCTGGAATTATC 
               
               
                   
                 ATAGATAAATTAAAAGAGAAGTATATCATATAA 
               
               
                   
               
               
                 etfA3 
                 ATGGGTAACGTTTTAGTAGTAATAGAACAAAGAGAAAATGTAATTCAAAC 
               
               
                 (SEQ ID 
                 TGTTTCTTTAGAATTACTAGGAAAGGCTACAGAAATAGCAAAAGATTATG 
               
               
                 NO: 41) 
                 ATACAAAAGTTTCTGCATTACTTTTAGGTAGTAAGGTAGAAGGTTTAATA 
               
               
                   
                 GATACATTAGCACACTATGGTGCAGATGAGGTAATAGTAGTAGATGATGA 
               
               
                   
                 AGCTTTAGCAGTGTATACAACTGAACCATATACAAAAGCAGCTTATGAAG 
               
               
                   
                 CAATAAAAGCAGCTGACCCTATAGTTGTATTATTTGGTGCAACTTCAATA 
               
               
                   
                 GGTAGAGATTTAGCGCCTAGAGTTTCTGCTAGAATACATACAGGTCTTAC 
               
               
                   
                 TGCTGACTGTACAGGTCTTGCAGTAGCTGAAGATACAAAATTATTATTAA 
               
               
                   
                 TGACAAGACCTGCCTTTGGTGGAAATATAATGGCAACAATAGTTTGTAAA 
               
               
                   
                 GATTTCAGACCTCAAATGTCTACAGTTAGACCAGGGGTTATGAAGAAAAA 
               
               
                   
                 TGAACCTGATGAAACTAAAGAAGCTGTAATTAACCGTTTCAAGGTAGAAT 
               
               
                   
                 TTAATGATGCTGATAAATTAGTTCAAGTTGTACAAGTAATAAAAGAAGCT 
               
               
                   
                 AAAAAACAAGTTAAAATAGAAGATGCTAAGATATTAGTTTCTGCTGGACG 
               
               
                   
                 TGGAATGGGTGGAAAAGAAAACTTAGACATACTTTATGAATTAGCTGAAA 
               
               
                   
                 TTATAGGTGGAGAAGTTTCTGGTTCTCGTGCCACTATAGATGCAGGTTGG 
               
               
                   
                 TTAGATAAAGCAAGACAAGTTGGTCAAACTGGTAAAACTGTAAGACCAGA 
               
               
                   
                 CCTTTATATAGCATGTGGTATATCTGGAGCAATACAACATATAGCTGGTA 
               
               
                   
                 TGGAAGATGCTGAGTTTATAGTTGCTATAAATAAAAATCCAGAAGCTCCA 
               
               
                   
                 ATATTTAAATATGCTGATGTTGGTATAGTTGGAGATGTTCATAAAGTGCT 
               
               
                   
                 TCCAGAACTTATCAGTCAGTTAAGTGTTGCAAAAGAAAAAGGTGAAGTTT 
               
               
                   
                 TAGCTAACTAA 
               
               
                   
               
               
                 thiA 1 
                 ATGAGAGAAGTAGTAATTGCCAGTGCAGCTAGAACAGCAGTAGGAAGTTT 
               
               
                 (SEQ ID 
                 TGGAGGAGCATTTAAATCAGTTTCAGCGGTAGAGTTAGGGGTAACAGCAG 
               
               
                 NO: 42) 
                 CTAAAGAAGCTATAAAAAGAGCTAACATAACTCCAGATATGATAGATGAA 
               
               
                   
                 TCTCTTTTAGGGGGAGTACTTACAGCAGGTCTTGGACAAAATATAGCAAG 
               
               
                   
                 ACAAATAGCATTAGGAGCAGGAATACCAGTAGAAAAACCAGCTATGACTA 
               
               
                   
                 TAAATATAGTTTGTGGTTCTGGATTAAGATCTGTTTCAATGGCATCTCAA 
               
               
                   
                 CTTATAGCATTAGGTGATGCTGATATAATGTTAGTTGGTGGAGCTGAAAA 
               
               
                   
                 CATGAGTATGTCTCCTTATTTAGTACCAAGTGCGAGATATGGTGCAAGAA 
               
               
                   
                 TGGGTGATGCTGCTTTTGTTGATTCAATGATAAAAGATGGATTATCAGAC 
               
               
                   
                 ATATTTAATAACTATCACATGGGTATTACTGCTGAAAACATAGCAGAGCA 
               
               
                   
                 ATGGAATATAACTAGAGAAGAACAAGATGAATTAGCTCTTGCAAGTCAAA 
               
               
                   
                 ATAAAGCTGAAAAAGCTCAAGCTGAAGGAAAATTTGATGAAGAAATAGTT 
               
               
                   
                 CCTGTTGTTATAAAAGGAAGAAAAGGTGACACTGTAGTAGATAAAGATGA 
               
               
                   
                 ATATATTAAGCCTGGCACTACAATGGAGAAACTTGCTAAGTTAAGACCTG 
               
               
                   
                 CATTTAAAAAAGATGGAACAGTTACTGCTGGTAATGCATCAGGAATAAAT 
               
               
                   
                 GATGGTGCTGCTATGTTAGTAGTAATGGCTAAAGAAAAAGCTGAAGAACT 
               
               
                   
                 AGGAATAGAGCCTCTTGCAACTATAGTTTCTTATGGAACAGCTGGTGTTG 
               
               
                   
                 ACCCTAAAATAATGGGATATGGACCAGTTCCAGCAACTAAAAAAGCTTTA 
               
               
                   
                 GAAGCTGCTAATATGACTATTGAAGATATAGATTTAGTTGAAGCTAATGA 
               
               
                   
                 GGCATTTGCTGCCCAATCTGTAGCTGTAATAAGAGACTTAAATATAGATA 
               
               
                   
                 TGAATAAAGTTAATGTTAATGGTGGAGCAATAGCTATAGGACATCCAATA 
               
               
                   
                 GGATGCTCAGGAGCAAGAATACTTACTACACTTTTATATGAAATGAAGAG 
               
               
                   
                 AAGAGATGCTAAAACTGGTCTTGCTACACTTTGTATAGGCGGTGGAATGG 
               
               
                   
                 GAACTACTTTAATAGTTAAGAGATAG 
               
               
                   
               
               
                 hbd 
                 ATGAAATTAGCTGTAATAGGTAGTGGAACTATGGGAAGTGGTATTGTACA 
               
               
                 (SEQ ID 
                 AACTTTTGCAAGTTGTGGACATGATGTATGTTTAAAGAGTAGAACTCAAG 
               
               
                 NO: 43) 
                 GTGCTATAGATAAATGTTTAGCTTTATTAGATAAAAATTTAACTAAGTTA 
               
               
                   
                 GTTACTAAGGGAAAAATGGATGAAGCTACAAAAGCAGAAATATTAAGTCA 
               
               
                   
                 TGTTAGTTCAACTACTAATTATGAAGATTTAAAAGATATGGATTTAATAA 
               
               
                   
                 TAGAAGCATCTGTAGAAGACATGAATATAAAGAAAGATGTTTTCAAGTTA 
               
               
                   
                 CTAGATGAATTATGTAAAGAAGATACTATCTTGGCAACAAATACTTCATC 
               
               
                   
                 ATTATCTATAACAGAAATAGCTTCTTCTACTAAGCGCCCAGATAAAGTTA 
               
               
                   
                 TAGGAATGCATTTCTTTAATCCAGTTCCTATGATGAAATTAGTTGAAGTT 
               
               
                   
                 ATAAGTGGTCAGTTAACATCAAAAGTTACTTTTGATACAGTATTTGAATT 
               
               
                   
                 ATCTAAGAGTATCAATAAAGTACCAGTAGATGTATCTGAATCTCCTGGAT 
               
               
                   
                 TTGTAGTAAATAGAATACTTATACCTATGATAAATGAAGCTGTTGGTATA 
               
               
                   
                 TATGCAGATGGTGTTGCAAGTAAAGAAGAAATAGATGAAGCTATGAAATT 
               
               
                   
                 AGGAGCAAACCATCCAATGGGACCACTAGCATTAGGTGATTTAATCGGAT 
               
               
                   
                 TAGATGTTGTTTTAGCTATAATGAACGTTTTATATACTGAATTTGGAGAT 
               
               
                   
                 ACTAAATATAGACCTCATCCACTTTTAGCTAAAATGGTTAGAGCTAATCA 
               
               
                   
                 ATTAGGAAGAAAAACTAAGATAGGATTCTATGATTATAATAAATAA 
               
               
                   
               
               
                 crt2 
                 ATGAGTACAAGTGATGTTAAAGTTTATGAGAATGTAGCTGTTGAAGTAGA 
               
               
                 (SEQ ID 
                 TGGAAATATATGTACAGTGAAAATGAATAGACCTAAAGCCCTTAATGCAA 
               
               
                 NO: 44) 
                 TAAATTCAAAGACTTTAGAAGAACTTTATGAAGTATTTGTAGATATTAAT 
               
               
                   
                 AATGATGAAACTATTGATGTTGTAATATTGACAGGGGAAGGAAAGGCATT 
               
               
                   
                 TGTAGCTGGAGCAGATATTGCATACATGAAAGATTTAGATGCTGTAGCTG 
               
               
                   
                 CTAAAGATTTTAGTATCTTAGGAGCAAAAGCTTTTGGAGAAATAGAAAAT 
               
               
                   
                 AGTAAAAAAGTAGTGATAGCTGCTGTAAACGGATTTGCTTTAGGTGGAGG 
               
               
                   
                 ATGTGAACTTGCAATGGCATGTGATATAAGAATTGCATCTGCTAAAGCTA 
               
               
                   
                 AATTTGGTCAGCCAGAAGTAACTCTTGGAATAACTCCAGGATATGGAGGA 
               
               
                   
                 ACTCAAAGGCTTACAAGATTGGTTGGAATGGCAAAAGCAAAAGAATTAAT 
               
               
                   
                 CTTTACAGGTCAAGTTATAAAAGCTGATGAAGCTGAAAAAATAGGGCTAG 
               
               
                   
                 TAAATAGAGTCGTTGAGCCAGACATTTTAATAGAAGAAGTTGAGAAATTA 
               
               
                   
                 GCTAAGATAATAGCTAAAAATGCTCAGCTTGCAGTTAGATACTCTAAAGA 
               
               
                   
                 AGCAATACAACTTGGTGCTCAAACTGATATAAATACTGGAATAGATATAG 
               
               
                   
                 AATCTAATTTATTTGGTCTTTGTTTTTCAACTAAAGACCAAAAAGAAGGA 
               
               
                   
                 ATGTCAGCTTTCGTTGAAAAGAGAGAAGCTAACTTTATAAAAGGGTAA 
               
               
                   
               
               
                 pbt 
                 ATGAGAAGTTTTGAAGAAGTAATTAAGTTTGCAAAAGAAAGAGGACCTAA 
               
               
                 (SEQ ID 
                 AACTATATCAGTAGCATGTTGCCAAGATAAAGAAGTTTTAATGGCAGTTG 
               
               
                 NO: 45) 
                 AAATGGCTAGAAAAGAAAAAATAGCAAATGCCATTTTAGTAGGAGATATA 
               
               
                   
                 GAAAAGACTAAAGAAATTGCAAAAAGCATAGACATGGATATCGAAAATTA 
               
               
                   
                 TGAACTGATAGATATAAAAGATTTAGCAGAAGCATCTCTAAAATCTGTTG 
               
               
                   
                 AATTAGTTTCACAAGGAAAAGCCGACATGGTAATGAAAGGCTTAGTAGAC 
               
               
                   
                 ACATCAATAATACTAAAAGCAGTTTTAAATAAAGAAGTAGGTCTTAGAAC 
               
               
                   
                 TGGAAATGTATTAAGTCACGTAGCAGTATTTGATGTAGAGGGATATGATA 
               
               
                   
                 GATTATTTTTCGTAACTGACGCAGCTATGAACTTAGCTCCTGATACAAAT 
               
               
                   
                 ACTAAAAAGCAAATCATAGAAAATGCTTGCACAGTAGCACATTCATTAGA 
               
               
                   
                 TATAAGTGAACCAAAAGTTGCTGCAATATGCGCAAAAGAAAAAGTAAATC 
               
               
                   
                 CAAAAATGAAAGATACAGTTGAAGCTAAAGAACTAGAAGAAATGTATGAA 
               
               
                   
                 AGAGGAGAAATCAAAGGTTGTATGGTTGGTGGGCCTTTTGCAATTGATAA 
               
               
                   
                 TGCAGTATCTTTAGAAGCAGCTAAACATAAAGGTATAAATCATCCTGTAG 
               
               
                   
                 CAGGACGAGCTGATATATTATTAGCCCCAGATATTGAAGGTGGTAACATA 
               
               
                   
                 TTATATAAAGCTTTGGTATTCTTCTCAAAATCAAAAAATGCAGGAGTTAT 
               
               
                   
                 AGTTGGGGCTAAAGCACCAATAATATTAACTTCTAGAGCAGACAGTGAAG 
               
               
                   
                 AAACTAAACTAAACTCAATAGCTTTAGGTGTTTTAATGGCAGCAAAGGCA 
               
               
                   
                 TAA 
               
               
                   
               
               
                 buk 
                 ATGAGCAAAATATTTAAAATCTTAACAATAAATCCTGGTTCGACATCAAC 
               
               
                 (SEQ ID 
                 TAAAATAGCTGTATTTGATAATGAGGATTTAGTATTTGAAAAAACTTTAA 
               
               
                 NO: 46) 
                 GACATTCTTCAGAAGAAATAGGAAAATATGAGAAGGTGTCTGACCAATTT 
               
               
                   
                 GAATTTCGTAAACAAGTAATAGAAGAAGCTCTAAAAGAAGGTGGAGTAAA 
               
               
                   
                 AACATCTGAATTAGATGCTGTAGTAGGTAGAGGAGGACTTCTTAAACCTA 
               
               
                   
                 TAAAAGGTGGTACTTATTCAGTAAGTGCTGCTATGATTGAAGATTTAAAA 
               
               
                   
                 GTGGGAGTTTTAGGAGAACACGCTTCAAACCTAGGTGGAATAATAGCAAA 
               
               
                   
                 ACAAATAGGTGAAGAAGTAAATGTTCCTTCATACATAGTAGACCCTGTTG 
               
               
                   
                 TTGTAGATGAATTAGAAGATGTTGCTAGAATTTCTGGTATGCCTGAAATA 
               
               
                   
                 AGTAGAGCAAGTGTAGTACATGCTTTAAATCAAAAGGCAATAGCAAGAAG 
               
               
                   
                 ATATGCTAGAGAAATAAACAAGAAATATGAAGATATAAATCTTATAGTTG 
               
               
                   
                 CACACATGGGTGGAGGAGTTTCTGTTGGAGCTCATAAAAATGGTAAAATA 
               
               
                   
                 GTAGATGTTGCAAACGCATTAGATGGAGAAGGACCTTTCTCTCCAGAAAG 
               
               
                   
                 AAGTGGTGGACTACCAGTAGGTGCATTAGTAAAAATGTGCTTTAGTGGAA 
               
               
                   
                 AATATACTCAAGATGAAATTAAAAAGAAAATAAAAGGTAATGGCGGACTA 
               
               
                   
                 GTTGCATACTTAAACACTAATGATGCTAGAGAAGTTGAAGAAAGAATTGA 
               
               
                   
                 AGCTGGTGATGAAAAAGCTAAATTAGTATATGAAGCTATGGCATATCAAA 
               
               
                   
                 TCTCTAAAGAAATAGGAGCTAGTGCTGCAGTTCTTAAGGGAGATGTAAAA 
               
               
                   
                 GCAATATTATTAACTGGTGGAATCGCATATTCAAAAATGTTTACAGAAAT 
               
               
                   
                 GATTGCAGATAGAGTTAAATTTATAGCAGATGTAAAAGTTTATCCAGGTG 
               
               
                   
                 AAGATGAAATGATTGCATTAGCTCAAGGTGGACTTAGAGTTTTAACTGGT 
               
               
                   
                 GAAGAAGAGGCTCAAGTTTATGATAACTAA 
               
               
                   
               
               
                 ter 
                 ATGATCGTAAAACCTATGGTACGCAACAATATCTGCCTGAACGCCCATCC 
               
               
                 (SEQ ID 
                 TCAGGGCTGCAAGAAGGGAGTGGAAGATCAGATTGAATATACCAAGAAAC 
               
               
                 NO: 47) 
                 GCATTACCGCAGAAGTCAAAGCTGGCGCAAAAGCTCCAAAAAACGTTCTG 
               
               
                   
                 GTGCTTGGCTGCTCAAATGGTTACGGCCTGGCGAGCCGCATTACTGCTGC 
               
               
                   
                 GTTCGGATACGGGGCTGCGACCATCGGCGTGTCCTTTGAAAAAGCGGGTT 
               
               
                   
                 CAGAAACCAAATATGGTACACCGGGATGGTACAATAATTTGGCATTTGAT 
               
               
                   
                 GAAGCGGCAAAACGCGAGGGTCTTTATAGCGTGACGATCGACGGCGATGC 
               
               
                   
                 GTTTTCAGACGAGATCAAGGCCCAGGTAATTGAGGAAGCCAAAAAAAAAG 
               
               
                   
                 GTATCAAATTTGATCTGATCGTATACAGCTTGGCCAGCCCAGTACGTACT 
               
               
                   
                 GATCCTGATACAGGTATCATGCACAAAAGCGTTTTGAAACCCTTTGGAAA 
               
               
                   
                 AACGTTCACAGGCAAAACAGTAGATCCGTTTACTGGCGAGCTGAAGGAAA 
               
               
                   
                 TCTCCGCGGAACCAGCAAATGACGAGGAAGCAGCCGCCACTGTTAAAGTT 
               
               
                   
                 ATGGGGGGTGAAGATTGGGAACGTTGGATTAAGCAGCTGTCGAAGGAAGG 
               
               
                   
                 CCTCTTAGAAGAAGGCTGTATTACCTTGGCCTATAGTTATATTGGCCCTG 
               
               
                   
                 AAGCTACCCAAGCTTTGTACCGTAAAGGCACAATCGGCAAGGCCAAAGAA 
               
               
                   
                 CACCTGGAGGCCACAGCACACCGTCTCAACAAAGAGAACCCGTCAATCCG 
               
               
                   
                 TGCCTTCGTGAGCGTGAATAAAGGCCTGGTAACCCGCGCAAGCGCCGTAA 
               
               
                   
                 TCCCGGTAATCCCTCTGTATCTCGCCAGCTTGTTCAAAGTAATGAAAGAG 
               
               
                   
                 AAGGGCAATCATGAAGGTTGTATTGAACAGATCACGCGTCTGTACGCCGA 
               
               
                   
                 GCGCCTGTACCGTAAAGATGGTACAATTCCAGTTGATGAGGAAAATCGCA 
               
               
                   
                 TTCGCATTGATGATTGGGAGTTAGAAGAAGACGTCCAGAAAGCGGTATCC 
               
               
                   
                 GCGTTGATGGAGAAAGTCACGGGTGAAAACGCAGAATCTCTCACTGACTT 
               
               
                   
                 AGCGGGGTACCGCCATGATTTCTTAGCTAGTAACGGCTTTGATGTAGAAG 
               
               
                   
                 GTATTAATTATGAAGCGGAAGTTGAACGCTTCGACCGTATCTGA 
               
               
                   
               
               
                 tesB 
                 ATGAGTCAGGCGCTAAAAAATTTACTGACATTGTTAAATCTGGAAAAAAT 
               
               
                 SEQ ID 
                 TGAGGAAGGACTCTTTCGCGGCCAGAGTGAAGATTTAGGTTTACGCCAGG 
               
               
                 NO: 48 
                 TGTTTGGCGGCCAGGTCGTGGGTCAGGCCTTGTATGCTGCAAAAGAGACC 
               
               
                   
                 GTCCCTGAAGAGCGGCTGGTACATTCGTTTCACAGCTACTTTCTTCGCCC 
               
               
                   
                 TGGCGATAGTAAGAAGCCGATTATTTATGATGTCGAAACGCTGCGTGACG 
               
               
                   
                 GTAACAGCTTCAGCGCCCGCCGGGTTGCTGCTATTCAAAACGGCAAACCG 
               
               
                   
                 ATTTTTTATATGACTGCCTCTTTCCAGGCACCAGAAGCGGGTTTCGAACA 
               
               
                   
                 TCAAAAAACAATGCCGTCCGCGCCAGCGCCTGATGGCCTCCCTTCGGAAA 
               
               
                   
                 CGCAAATCGCCCAATCGCTGGCGCACCTGCTGCCGCCAGTGCTGAAAGAT 
               
               
                   
                 AAATTCATCTGCGATCGTCCGCTGGAAGTCCGTCCGGTGGAGTTTCATAA 
               
               
                   
                 CCCACTGAAAGGTCACGTCGCAGAACCACATCGTCAGGTGTGGATCCGCG 
               
               
                   
                 CAAATGGTAGCGTGCCGGATGACCTGCGCGTTCATCAGTATCTGCTCGGT 
               
               
                   
                 TACGCTTCTGATCTTAACTTCCTGCCGGTAGCTCTACAGCCGCACGGCAT 
               
               
                   
                 CGGTTTTCTCGAACCGGGGATTCAGATTGCCACCATTGACCATTCCATGT 
               
               
                   
                 GGTTCCATCGCCCGTTTAATTTGAATGAATGGCTGCTGTATAGCGTGGAG 
               
               
                   
                 AGCACCTCGGCGTCCAGCGCACGTGGCTTTGTGCGCGGTGAGTTTTATAC 
               
               
                   
                 CCAAGACGGCGTACTGGTTGCCTCGACCGTTCAGGAAGGGGTGATGCGTA 
               
               
                   
                 ATCACAATTAA 
               
               
                   
               
            
           
         
       
     
     The gene products of the bcd2, etfA3, and etfB3 genes in  Clostridium difficile  form a complex that converts crotonyl-CoA to butyryl-CoA, which may function as an oxygen-dependent co-oxidant. In some embodiments, because the genetically engineered bacteria of the invention are designed to produce butyrate in a microaerobic or oxygen-limited environment, e.g., the mammalian gut, oxygen-dependence could have a negative effect on butyrate production in the gut. It has been shown that a single gene from  Treponema denticola  (ter, encoding trans-2-enoynl-CoA reductase) can functionally replace this three-gene complex in an oxygen-independent manner. In some embodiments, the genetically engineered bacteria comprise a ter gene, e.g., from  Treponema denticola , which can functionally replace all three of the bcd2, etfB3, and etfA3 genes, e.g., from  Peptoclostridium difficile . In this embodiment, the genetically engineered bacteria comprise thiA1, hbd, crt2, pbt, and buk, e.g., from  Peptoclostridium difficile , and ter, e.g., from  Treponema denticola , and produce butyrate in low-oxygen conditions, in the presence of HE-specific molecules or metabolites, in the presence of molecules or metabolites associated with liver damage, inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. In some embodiments, the genetically engineered bacteria comprise genes for aerobic butyrate biosynthesis and/or genes for anaerobic or microaerobic butyrate biosynthesis. In some embodiments, the genetically engineered bacteria of the invention comprise thiA1, hbd, crt2, pbt, and buk, e.g., from  Peptoclostridium difficile ; ter, e.g., from  Treponema denticola ; one or more of bcd2, etfB3, and etfA3, e.g., from  Peptoclostridium difficile ; and produce butyrate in low-oxygen conditions or in the presence of HE-specific molecules or metabolites. In some embodiments, one or more of the butyrate biosynthesis genes is functionally replaced, modified, and/or mutated in order to enhance stability and/or increase butyrate production in low-oxygen conditions or in the presence of HE-specific molecules or metabolites, or molecules or metabolites associated with liver damage, or other condition(s) such as inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. In some embodiments, the local production of butyrate induces the differentiation of regulatory T cells in the gut and/or promotes the barrier function of colonic epithelial cells. 
     The gene products of pbt and buk convert butyrylCoA to Butyrate. In some embodiments, the pbt and buk genes can be replaced by a tesB gene. tesB can be used to cleave off the CoA from butyryl-coA. In one embodiment, the genetically engineered bacteria comprise bcd2, etfB3, etfA3, thiA1, hbd, and crt2, e.g., from  Peptoclostridium difficile , and tesB from  E. coli  and produce butyrate in low-oxygen conditions, in the presence of HE-specific molecules or metabolites, in the presence of molecules or metabolites associated with liver damage, inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. In one embodiment, the genetically engineered bacteria comprise ter gene (encoding trans-2-enoynl-CoA reductase) e.g., from  Treponema denticola , thiA1, hbd, crt2, pbt, and buk, e.g., from  Peptoclostridium difficile , and tesB from  E. coli , and produce butyrate in low-oxygen conditions, in the presence of HE-specific molecules or metabolites, in the presence of molecules or metabolites associated with liver damage, inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. In some embodiments, one or more of the butyrate biosynthesis genes is functionally replaced, modified, and/or mutated in order to enhance stability and/or increase butyrate production in low-oxygen conditions or in the presence of HE-specific molecules or metabolites, or molecules or metabolites associated with liver damage, or other condition(s) such as inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. In some embodiments, the local production of butyrate induces the differentiation of regulatory T cells in the gut and/or promotes the barrier function of colonic epithelial cells. 
     In some embodiments, the genetically engineered bacteria of the invention comprise a propionate gene cassette and are capable of producing propionate in low-oxygen conditions or in the presence of HE-specific molecules or metabolites. The genetically engineered bacteria may express any suitable set of propionate biosynthesis genes (see, e.g., Table 15). Unmodified bacteria that are capable of producing propionate via an endogenous propionate biosynthesis pathway include, but are not limited to,  Clostridium propionicum, Megasphaera elsdenii , and  Prevotella ruminicola , and these endogenous propionate biosynthesis pathways may be a source of genes for the genetically engineered bacteria of the invention. In some embodiments, the genetically engineered bacteria of the invention comprise propionate biosynthesis genes from a different species, strain, or substrain of bacteria. In some embodiments, the genetically engineered bacteria comprise the genes pct, lcd, and acr from  Clostridium propionicum . In some embodiments, the genetically engineered bacteria comprise acrylate pathway genes for propionate biosynthesis, e.g., pct, lcdA, lcdB, lcdC, etfA, acre, and acrC. In alternate embodiments, the genetically engineered bacteria comprise pyruvate pathway genes for propionate biosynthesis, e.g., thrA fbr , thrB, thrC, ilvA fbr , aceE, aceF, and lpd, and optionally further comprise tesB. The genes may be codon-optimized, and translational and transcriptional elements may be added. Table 15 depicts the nucleic acid sequences of exemplary genes in the propionate biosynthesis gene cassette. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61 or 62 a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61 or 62, or a functional fragment thereof. 
     
       
         
           
               
               
             
               
                 TABLE 15 
               
               
                   
               
               
                 Description 
                 Sequence 
               
               
                   
               
             
            
               
                 pct 
                 ATGCGCAAAGTGCCGATTATCACGGCTGACGAGGCCGCAAAACTGATCAA 
               
               
                 SEQ ID 
                 GGACGGCGACACCGTGACAACTAGCGGCTTTGTGGGTAACGCGATCCCTG 
               
               
                 NO: 49 
                 AGGCCCTTGACCGTGCAGTCGAAAAGCGTTTCCTGGAAACGGGCGAACCG 
               
               
                   
                 AAGAACATTACTTATGTATATTGCGGCAGTCAGGGCAATCGCGACGGTCG 
               
               
                   
                 TGGCGCAGAACATTTCGCGCATGAAGGCCTGCTGAAACGTTATATCGCTG 
               
               
                   
                 GCCATTGGGCGACCGTCCCGGCGTTAGGGAAAATGGCCATGGAGAATAAA 
               
               
                   
                 ATGGAGGCCTACAATGTCTCTCAGGGCGCCTTGTGTCATCTCTTTCGCGA 
               
               
                   
                 TATTGCGAGCCATAAACCGGGTGTGTTCACGAAAGTAGGAATCGGCACCT 
               
               
                   
                 TCATTGATCCACGTAACGGTGGTGGGAAGGTCAACGATATTACCAAGGAA 
               
               
                   
                 GATATCGTAGAACTGGTGGAAATTAAAGGGCAGGAATACCTGTTTTATCC 
               
               
                   
                 GGCGTTCCCGATCCATGTCGCGCTGATTCGTGGCACCTATGCGGACGAGA 
               
               
                   
                 GTGGTAACATCACCTTTGAAAAAGAGGTAGCGCCTTTGGAAGGGACTTCT 
               
               
                   
                 GTCTGTCAAGCGGTGAAGAACTCGGGTGGCATTGTCGTGGTTCAGGTTGA 
               
               
                   
                 GCGTGTCGTCAAAGCAGGCACGCTGGATCCGCGCCATGTGAAAGTTCCGG 
               
               
                   
                 GTATCTATGTAGATTACGTAGTCGTCGCGGATCCGGAGGACCATCAACAG 
               
               
                   
                 TCCCTTGACTGCGAATATGATCCTGCCCTTAGTGGAGAGCACCGTCGTCC 
               
               
                   
                 GGAGGTGGTGGGTGAACCACTGCCTTTATCCGCGAAGAAAGTCATCGGCC 
               
               
                   
                 GCCGTGGCGCGATTGAGCTCGAGAAAGACGTTGCAGTGAACCTTGGGGTA 
               
               
                   
                 GGTGCACCTGAGTATGTGGCCTCCGTGGCCGATGAAGAAGGCATTGTGGA 
               
               
                   
                 TTTTATGACTCTCACAGCGGAGTCCGGCGCTATCGGTGGCGTTCCAGCCG 
               
               
                   
                 GCGGTGTTCGCTTTGGGGCGAGCTACAATGCTGACGCCTTGATCGACCAG 
               
               
                   
                 GGCTACCAATTTGATTATTACGACGGTGGGGGTCTGGATCTTTGTTACCT 
               
               
                   
                 GGGTTTAGCTGAATGCGACGAAAAGGGTAATATCAATGTTAGCCGCTTCG 
               
               
                   
                 GTCCTCGTATCGCTGGGTGCGGCGGATTCATTAACATTACCCAAAACACG 
               
               
                   
                 CCGAAAGTCTTCTTTTGTGGGACCTTTACAGCCGGGGGGCTGAAAGTGAA 
               
               
                   
                 AATTGAAGATGGTAAGGTGATTATCGTTCAGGAAGGGAAACAGAAGAAAT 
               
               
                   
                 TCCTTAAGGCAGTGGAGCAAATCACCTTTAATGGAGACGTGGCCTTAGCG 
               
               
                   
                 AACAAGCAACAAGTTACCTACATCACGGAGCGTTGCGTCTTCCTCCTCAA 
               
               
                   
                 AGAAGACGGTTTACACCTTTCGGAAATCGCGCCAGGCATCGATCTGCAGA 
               
               
                   
                 CCCAGATTTTGGATGTTATGGACTTTGCCCCGATCATTGATCGTGACGCA 
               
               
                   
                 AACGGGCAGATTAAACTGATGGACGCGGCGTTATTCGCAGAAGGGCTGAT 
               
               
                   
                 GGGCTTGAAAGAAATGAAGTCTTAA 
               
               
                   
               
               
                 lcdA 
                 ATGAGCTTAACCCAAGGCATGAAAGCTAAACAACTGTTAGCATACTTTCA 
               
               
                 SEQ ID 
                 GGGTAAAGCCGATCAGGATGCACGTGAAGCGAAAGCCCGCGGTGAGCTGG 
               
               
                 NO: 50 
                 TCTGCTGGTCGGCGTCAGTCGCGCCGCCGGAATTTTGCGTAACAATGGGC 
               
               
                   
                 ATTGCCATGATCTACCCGGAGACTCATGCAGCGGGCATCGGTGCCCGCAA 
               
               
                   
                 AGGTGCGATGGACATGCTGGAAGTTGCGGACCGCAAAGGCTACAACGTGG 
               
               
                   
                 ATTGTTGTTCCTACGGCCGTGTAAATATGGGTTACATGGAATGTTTAAAA 
               
               
                   
                 GAAGCCGCCATCACGGGCGTCAAGCCGGAAGTTTTGGTTAATTCCCCTGC 
               
               
                   
                 TGCTGACGTTCCGCTTCCCGATTTGGTGATTACGTGTAATAATATCTGTA 
               
               
                   
                 ACACGCTGCTGAAATGGTACGAAAACTTAGCAGCAGAACTCGATATTCCT 
               
               
                   
                 TGCATCGTGATCGACGTACCGTTTAATCATACCATGCCGATTCCGGAATA 
               
               
                   
                 TGCCAAGGCCTACATCGCGGACCAGTTCCGCAATGCAATTTCTCAGCTGG 
               
               
                   
                 AAGTTATTTGTGGCCGTCCGTTCGATTGGAAGAAATTTAAGGAGGTCAAA 
               
               
                   
                 GATCAGACCCAGCGTAGCGTATACCACTGGAACCGCATTGCCGAGATGGC 
               
               
                   
                 GAAATACAAGCCTAGCCCGCTGAACGGCTTCGATCTGTTCAATTACATGG 
               
               
                   
                 CGTTAATCGTGGCGTGCCGCAGCCTGGATTATGCAGAAATTACCTTTAAA 
               
               
                   
                 GCGTTCGCGGACGAATTAGAAGAGAATTTGAAGGCGGGTATCTACGCCTT 
               
               
                   
                 TAAAGGTGCGGAAAAAACGCGCTTTCAATGGGAAGGTATCGCGGTGTGGC 
               
               
                   
                 CACATTTAGGTCACACGTTTAAATCTATGAAGAATCTGAATTCGATTATG 
               
               
                   
                 ACCGGTACGGCATACCCCGCCCTTTGGGACCTGCACTATGACGCTAACGA 
               
               
                   
                 CGAATCTATGCACTCTATGGCTGAAGCGTACACCCGTATTTATATTAATA 
               
               
                   
                 CTTGTCTGCAGAACAAAGTAGAGGTCCTGCTTGGGATCATGGAAAAAGGC 
               
               
                   
                 CAGGTGGATGGTACCGTATATCATCTGAATCGCAGCTGCAAACTGATGAG 
               
               
                   
                 TTTCCTGAACGTGGAAACGGCTGAAATTATTAAAGAGAAGAACGGTCTTC 
               
               
                   
                 CTTACGTCTCCATTGATGGCGATCAGACCGATCCTCGCGTTTTTTCTCCG 
               
               
                   
                 GCCCAGTTTGATACCCGTGTTCAGGCCCTGGTTGAGATGATGGAGGCCAA 
               
               
                   
                 TATGGCGGCAGCGGAATAA 
               
               
                   
               
               
                 lcdB 
                 ATGTCACGCGTGGAGGCAATCCTGTCGCAGCTGAAAGATGTCGCCGCGAA 
               
               
                 SEQ ID 
                 TCCGAAAAAAGCCATGGATGACTATAAAGCTGAAACAGGTAAGGGCGCGG 
               
               
                 NO: 51 
                 TTGGTATCATGCCGATCTACAGCCCCGAAGAAATGGTACACGCCGCTGGC 
               
               
                   
                 TATTTGCCGATGGGAATCTGGGGCGCCCAGGGCAAAACGATTAGTAAAGC 
               
               
                   
                 GCGCACCTATCTGCCTGCTTTTGCCTGCAGCGTAATGCAGCAGGTTATGG 
               
               
                   
                 AATTACAGTGCGAGGGCGCGTATGATGACCTGTCCGCAGTTATTTTTAGC 
               
               
                   
                 GTACCGTGCGACACTCTCAAATGTCTTAGCCAGAAATGGAAAGGTACGTC 
               
               
                   
                 CCCAGTGATTGTATTTACGCATCCGCAGAACCGCGGATTAGAAGCGGCGA 
               
               
                   
                 ACCAATTCTTGGTTACCGAGTATGAACTGGTAAAAGCACAACTGGAATCA 
               
               
                   
                 GTTCTGGGTGTGAAAATTTCAAACGCCGCCCTGGAAAATTCGATTGCAAT 
               
               
                   
                 TTATAACGAGAATCGTGCCGTGATGCGTGAGTTCGTGAAAGTGGCAGCGG 
               
               
                   
                 ACTATCCTCAAGTCATTGACGCAGTGAGCCGCCACGCGGTTTTTAAAGCG 
               
               
                   
                 CGCCAGTTTATGCTTAAGGAAAAACATACCGCACTTGTGAAAGAACTGAT 
               
               
                   
                 CGCTGAGATTAAAGCAACGCCAGTCCAGCCGTGGGACGGAAAAAAGGTTG 
               
               
                   
                 TAGTGACGGGCATTCTGTTGGAACCGAATGAGTTATTAGATATCTTTAAT 
               
               
                   
                 GAGTTTAAGATCGCGATTGTTGATGATGATTTAGCGCAGGAAAGCCGTCA 
               
               
                   
                 GATCCGTGTTGACGTTCTGGACGGAGAAGGCGGACCGCTCTACCGTATGG 
               
               
                   
                 CTAAAGCGTGGCAGCAAATGTATGGCTGCTCGCTGGCAACCGACACCAAG 
               
               
                   
                 AAGGGTCGCGGCCGTATGTTAATTAACAAAACGATTCAGACCGGTGCGGA 
               
               
                   
                 CGCTATCGTAGTTGCAATGATGAAGTTTTGCGACCCAGAAGAATGGGATT 
               
               
                   
                 ATCCGGTAATGTACCGTGAATTTGAAGAAAAAGGGGTCAAATCACTTATG 
               
               
                   
                 ATTGAGGTGGATCAGGAAGTATCGTCTTTCGAACAGATTAAAACCCGTCT 
               
               
                   
                 GCAGTCATTCGTCGAAATGCTTTAA 
               
               
                   
               
               
                 lcdC 
                 ATGTATACCTTGGGGATTGATGTCGGTTCTGCCTCTAGTAAAGCGGTGAT 
               
               
                 SEQ ID 
                 TCTGAAAGATGGAAAAGATATTGTCGCTGCCGAGGTTGTCCAAGTCGGTA 
               
               
                 NO: 52 
                 CCGGCTCCTCGGGTCCCCAACGCGCACTGGACAAAGCCTTTGAAGTCTCT 
               
               
                   
                 GGCTTAAAAAAGGAAGACATCAGCTACACAGTAGCTACGGGCTATGGGCG 
               
               
                   
                 CTTCAATTTTAGCGACGCGGATAAACAGATTTCGGAAATTAGCTGTCATG 
               
               
                   
                 CCAAAGGCATTTATTTCTTAGTACCAACTGCGCGCACTATTATTGACATT 
               
               
                   
                 GGCGGCCAAGATGCGAAAGCCATCCGCCTGGACGACAAGGGGGGTATTAA 
               
               
                   
                 GCAATTCTTCATGAATGATAAATGCGCGGCGGGCACGGGGCGTTTCCTGG 
               
               
                   
                 AAGTCATGGCTCGCGTACTTGAAACCACCCTGGATGAAATGGCTGAACTG 
               
               
                   
                 GATGAACAGGCGACTGACACCGCTCCCATTTCAAGCACCTGCACGGTTTT 
               
               
                   
                 CGCCGAAAGCGAAGTAATTAGCCAATTGAGCAATGGTGTCTCACGCAACA 
               
               
                   
                 ACATCATTAAAGGTGTCCATCTGAGCGTTGCGTCACGTGCGTGTGGTCTG 
               
               
                   
                 GCGTATCGCGGCGGTTTGGAGAAAGATGTTGTTATGACAGGTGGCGTGGC 
               
               
                   
                 AAAAAATGCAGGGGTGGTGCGCGCGGTGGCGGGCGTTCTGAAGACCGATG 
               
               
                   
                 TTATCGTTGCTCCGAATCCTCAGACGACCGGTGCACTGGGGGCAGCGCTG 
               
               
                   
                 TATGCTTATGAGGCCGCCCAGAAGAAGTA 
               
               
                   
               
               
                 etfA 
                 ATGGCCTTCAATAGCGCAGATATTAATTCTTTCCGCGATATTTGGGTGTT 
               
               
                 SEQ ID 
                 TTGTGAACAGCGTGAGGGCAAACTGATTAACACCGATTTCGAATTAATTA 
               
               
                 NO: 53 
                 GCGAAGGTCGTAAACTGGCTGACGAACGCGGAAGCAAACTGGTTGGAATT 
               
               
                   
                 TTGCTGGGGCACGAAGTTGAAGAAATCGCAAAAGAATTAGGCGGCTATGG 
               
               
                   
                 TGCGGACAAGGTAATTGTGTGCGATCATCCGGAACTTAAATTTTACACTA 
               
               
                   
                 CGGATGCTTATGCCAAAGTTTTATGTGACGTCGTGATGGAAGAGAAACCG 
               
               
                   
                 GAGGTAATTTTGATCGGTGCCACCAACATTGGCCGTGATCTCGGACCGCG 
               
               
                   
                 TTGTGCTGCACGCTTGCACACGGGGCTGACGGCTGATTGCACGCACCTGG 
               
               
                   
                 ATATTGATATGAATAAATATGTGGACTTTCTTAGCACCAGTAGCACCTTG 
               
               
                   
                 GATATCTCGTCGATGACTTTCCCTATGGAAGATACAAACCTTAAAATGAC 
               
               
                   
                 GCGCCCTGCATTTGGCGGACATCTGATGGCAACGATCATTTGTCCACGCT 
               
               
                   
                 TCCGTCCCTGTATGAGCACAGTGCGCCCCGGAGTGATGAAGAAAGCGGAG 
               
               
                   
                 TTCTCGCAGGAGATGGCGCAAGCATGTCAAGTAGTGACCCGTCACGTAAA 
               
               
                   
                 TTTGTCGGATGAAGACCTTAAAACTAAAGTAATTAATATCGTGAAGGAAA 
               
               
                   
                 CGAAAAAGATTGTGGATCTGATCGGCGCAGAAATTATTGTGTCAGTTGGT 
               
               
                   
                 CGTGGTATCTCGAAAGATGTCCAAGGTGGAATTGCACTGGCTGAAAAACT 
               
               
                   
                 TGCGGACGCATTTGGTAACGGTGTCGTGGGCGGCTCGCGCGCAGTGATTG 
               
               
                   
                 ATTCCGGCTGGTTACCTGCGGATCATCAGGTTGGACAAACCGGTAAGACC 
               
               
                   
                 GTGCACCCGAAAGTCTACGTGGCGCTGGGTATTAGTGGGGCTATCCAGCA 
               
               
                   
                 TAAGGCTGGGATGCAAGACTCTGAACTGATCATTGCCGTCAACAAAGACG 
               
               
                   
                 AAACGGCGCCTATCTTCGACTGCGCCGATTATGGCATCACCGGTGATTTA 
               
               
                   
                 TTTAAAATCGTACCGATGATGATCGACGCGATCAAAGAGGGTAAAAACGC 
               
               
                   
                 ATGA 
               
               
                   
               
               
                 acrB 
                 ATGCGCATCTATGTGTGTGTGAAACAAGTCCCAGATACGAGCGGCAAGGT 
               
               
                 SEQ ID 
                 GGCCGTTAACCCTGATGGGACCCTTAACCGTGCCTCAATGGCAGCGATTA 
               
               
                 NO: 54 
                 TTAACCCGGACGATATGTCCGCGATCGAACAGGCATTAAAACTGAAAGAT 
               
               
                   
                 GAAACCGGATGCCAGGTTACGGCGCTTACGATGGGTCCTCCTCCTGCCGA 
               
               
                   
                 GGGCATGTTGCGCGAAATTATTGCAATGGGGGCCGACGATGGTGTGCTGA 
               
               
                   
                 TTTCGGCCCGTGAATTTGGGGGGTCCGATACCTTCGCAACCAGTCAAATT 
               
               
                   
                 ATTAGCGCGGCAATCCATAAATTAGGCTTAAGCAATGAAGACATGATCTT 
               
               
                   
                 TTGCGGTCGTCAGGCCATTGACGGTGATACGGCCCAAGTCGGCCCTCAAA 
               
               
                   
                 TTGCCGAAAAACTGAGCATCCCACAGGTAACCTATGGCGCAGGAATCAAA 
               
               
                   
                 AAATCTGGTGATTTAGTGCTGGTGAAGCGTATGTTGGAGGATGGTTATAT 
               
               
                   
                 GATGATCGAAGTCGAAACTCCATGTCTGATTACCTGCATTCAGGATAAAG 
               
               
                   
                 CGGTAAAACCACGTTACATGACTCTCAACGGTATTATGGAATGCTACTCC 
               
               
                   
                 AAGCCGCTCCTCGTTCTCGATTACGAAGCACTGAAAGATGAACCGCTGAT 
               
               
                   
                 CGAACTTGATACCATTGGGCTTAAAGGCTCCCCGACGAATATCTTTAAAT 
               
               
                   
                 CGTTTACGCCGCCTCAGAAAGGCGTTGGTGTCATGCTCCAAGGCACCGAT 
               
               
                   
                 AAGGAAAAAGTCGAGGATCTGGTGGATAAGCTGATGCAGAAACATGTCAT 
               
               
                   
                 CTAA 
               
               
                   
               
               
                 acrC 
                 ATGTTCTTACTGAAGATTAAAAAAGAACGTATGAAACGCATGGACTTTAG 
               
               
                 SEQ ID 
                 TTTAACGCGTGAACAGGAGATGTTAAAAAAACTGGCGCGTCAGTTTGCTG 
               
               
                 NO: 55 
                 AGATCGAGCTGGAACCGGTGGCCGAAGAGATTGATCGTGAGCACGTTTTT 
               
               
                   
                 CCTGCAGAAAACTTTAAGAAGATGGCGGAAATTGGCTTAACCGGCATTGG 
               
               
                   
                 TATCCCGAAAGAATTTGGTGGCTCCGGTGGAGGCACCCTGGAGAAGGTCA 
               
               
                   
                 TTGCCGTGTCAGAATTCGGCAAAAAGTGTATGGCCTCAGCTTCCATTTTA 
               
               
                   
                 AGCATTCATCTTATCGCGCCGCAGGCAATCTACAAATATGGGACCAAAGA 
               
               
                   
                 ACAGAAAGAGACGTACCTGCCGCGTCTTACCAAAGGTGGTGAACTGGGCG 
               
               
                   
                 CCTTTGCGCTGACAGAACCAAACGCCGGAAGCGATGCCGGCGCGGTAAAA 
               
               
                   
                 ACGACCGCGATTCTGGACAGCCAGACAAACGAGTACGTGCTGAATGGCAC 
               
               
                   
                 CAAATGCTTTATCAGCGGGGGCGGGCGCGCGGGTGTTCTTGTAATTTTTG 
               
               
                   
                 CGCTTACTGAACCGAAAAAAGGTCTGAAAGGGATGAGCGCGATTATCGTG 
               
               
                   
                 GAGAAAGGGACCCCGGGCTTCAGCATCGGCAAGGTGGAGAGCAAGATGGG 
               
               
                   
                 GATCGCAGGTTCGGAAACCGCGGAACTTATCTTCGAAGATTGTCGCGTTC 
               
               
                   
                 CGGCTGCCAACCTTTTAGGTAAAGAAGGCAAAGGCTTTAAAATTGCTATG 
               
               
                   
                 GAAGCCCTGGATGGCGCCCGTATTGGCGTGGGCGCTCAAGCAATCGGAAT 
               
               
                   
                 TGCCGAGGGGGCGATCGACCTGAGTGTGAAGTACGTTCACGAGCGCATTC 
               
               
                   
                 AATTTGGTAAACCGATCGCGAATCTGCAGGGAATTCAATGGTATATCGCG 
               
               
                   
                 GATATGGCGACCAAAACCGCCGCGGCACGCGCACTTGTTGAGTTTGCAGC 
               
               
                   
                 GTATCTTGAAGACGCGGGTAAACCGTTCACAAAGGAATCTGCTATGTGCA 
               
               
                   
                 AGCTGAACGCCTCCGAAAACGCGCGTTTTGTGACAAATTTAGCTCTGCAG 
               
               
                   
                 ATTCACGGGGGTTACGGTTATATGAAAGATTATCCGTTAGAGCGTATGTA 
               
               
                   
                 TCGCGATGCTAAGATTACGGAAATTTACGAGGGGACATCAGAAATCCATA 
               
               
                   
                 AGGTGGTGATTGCGCGTGAAGTAATGAAACGCTAA 
               
               
                   
               
               
                 thrA fbr   
                 ATGCGAGTGTTGAAGTTCGGCGGTACATCAGTGGCAAATGCAGAACGTTT 
               
               
                 SEQ ID 
                 TCTGCGTGTTGCCGATATTCTGGAAAGCAATGCCAGGCAGGGGCAGGTGG 
               
               
                 NO: 56 
                 CCACCGTCCTCTCTGCCCCCGCCAAAATCACCAACCACCTGGTGGCGATG 
               
               
                   
                 ATTGAAAAAACCATTAGCGGCCAGGATGCTTTACCCAATATCAGCGATGC 
               
               
                   
                 CGAACGTATTTTTGCCGAACTTTTGACGGGACTCGCCGCCGCCCAGCCGG 
               
               
                   
                 GGTTCCCGCTGGCGCAATTGAAAACTTTCGTCGATCAGGAATTTGCCCAA 
               
               
                   
                 ATAAAACATGTCCTGCATGGCATTAGTTTGTTGGGGCAGTGCCCGGATAG 
               
               
                   
                 CATCAACGCTGCGCTGATTTGCCGTGGCGAGAAAATGTCGATCGCCATTA 
               
               
                   
                 TGGCCGGCGTATTAGAAGCGCGCGGTCACAACGTTACTGTTATCGATCCG 
               
               
                   
                 GTCGAAAAACTGCTGGCAGTGGGGCATTACCTCGAATCTACCGTCGATAT 
               
               
                   
                 TGCTGAGTCCACCCGCCGTATTGCGGCAAGCCGCATTCCGGCTGATCACA 
               
               
                   
                 TGGTGCTGATGGCAGGTTTCACCGCCGGTAATGAAAAAGGCGAACTGGTG 
               
               
                   
                 GTGCTTGGACGCAACGGTTCCGACTACTCTGCTGCGGTGCTGGCTGCCTG 
               
               
                   
                 TTTACGCGCCGATTGTTGCGAGATTTGGACGGACGTTGACGGGGTCTATA 
               
               
                   
                 CCTGCGACCCGCGTCAGGTGCCCGATGCGAGGTTGTTGAAGTCGATGTCC 
               
               
                   
                 TACCAGGAAGCGATGGAGCTTTCCTACTTCGGCGCTAAAGTTCTTCACCC 
               
               
                   
                 CCGCACCATTACCCCCATCGCCCAGTTCCAGATCCCTTGCCTGATTAAAA 
               
               
                   
                 ATACCGGAAATCCTCAAGCACCAGGTACGCTCATTGGTGCCAGCCGTGAT 
               
               
                   
                 GAAGACGAATTACCGGTCAAGGGCATTTCCAATCTGAATAACATGGCAAT 
               
               
                   
                 GTTCAGCGTTTCTGGTCCGGGGATGAAAGGGATGGTCGGCATGGCGGCGC 
               
               
                   
                 GCGTCTTTGCAGCGATGTCACGCGCCCGTATTTCCGTGGTGCTGATTACG 
               
               
                   
                 CAATCATCTTCCGAATACAGCATCAGTTTCTGCGTTCCACAAAGCGACTG 
               
               
                   
                 TGTGCGAGCTGAACGGGCAATGCAGGAAGAGTTCTACCTGGAACTGAAAG 
               
               
                   
                 AAGGCTTACTGGAGCCGCTGGCAGTGACGGAACGGCTGGCCATTATCTCG 
               
               
                   
                 GTGGTAGGTGATGGTATGCGCACCTTGCGTGGGATCTCGGCGAAATTCTT 
               
               
                   
                 TGCCGCACTGGCCCGCGCCAATATCAACATTGTCGCCATTGCTCAGAGAT 
               
               
                   
                 CTTCTGAACGCTCAATCTCTGTCGTGGTAAATAACGATGATGCGACCACT 
               
               
                   
                 GGCGTGCGCGTTACTCATCAGATGCTGTTCAATACCGATCAGGTTATCGA 
               
               
                   
                 AGTGTTTGTGATTGGCGTCGGTGGCGTTGGCGGTGCGCTGCTGGAGCAAC 
               
               
                   
                 TGAAGCGTCAGCAAAGCTGGCTGAAGAATAAACATATCGACTTACGTGTC 
               
               
                   
                 TGCGGTGTTGCCAACTCGAAGGCTCTGCTCACCAATGTACATGGCCTTAA 
               
               
                   
                 TCTGGAAAACTGGCAGGAAGAACTGGCGCAAGCCAAAGAGCCGTTTAATC 
               
               
                   
                 TCGGGCGCTTAATTCGCCTCGTGAAAGAATATCATCTGCTGAACCCGGTC 
               
               
                   
                 ATTGTTGACTGCACTTCCAGCCAGGCAGTGGCGGATCAATATGCCGACTT 
               
               
                   
                 CCTGCGCGAAGGTTTCCACGTTGTCACGCCGAACAAAAAGGCCAACACCT 
               
               
                   
                 CGTCGATGGATTACTACCATCAGTTGCGTTATGCGGCGGAAAAATCGCGG 
               
               
                   
                 CGTAAATTCCTCTATGACACCAACGTTGGGGCTGGATTACCGGTTATTGA 
               
               
                   
                 GAACCTGCAAAATCTGCTCAATGCAGGTGATGAATTGATGAAGTTCTCCG 
               
               
                   
                 GCATTCTTTCTGGTTCGCTTTCTTATATCTTCGGCAAGTTAGACGAAGGC 
               
               
                   
                 ATGAGTTTCTCCGAGGCGACCACGCTGGCGCGGGAAATGGGTTATACCGA 
               
               
                   
                 ACCGGACCCGCGAGATGATCTTTCTGGTATGGATGTGGCGCGTAAACTAT 
               
               
                   
                 TGATTCTCGCTCGTGAAACGGGACGTGAACTGGAGCTGGCGGATATTGAA 
               
               
                   
                 ATTGAACCTGTGCTGCCCGCAGAGTTTAACGCCGAGGGTGATGTTGCCGC 
               
               
                   
                 TTTTATGGCGAATCTGTCACAACTCGACGATCTCTTTGCCGCGCGCGTGG 
               
               
                   
                 CGAAGGCCCGTGATGAAGGAAAAGTTTTGCGCTATGTTGGCAATATTGAT 
               
               
                   
                 GAAGATGGCGTCTGCCGCGTGAAGATTGCCGAAGTGGATGGTAATGATCC 
               
               
                   
                 GCTGTTCAAAGTGAAAAATGGCGAAAACGCCCTGGCCTTCTATAGCCACT 
               
               
                   
                 ATTATCAGCCGCTGCCGTTGGTACTGCGCGGATATGGTGCGGGCAATGAC 
               
               
                   
                 GTTACAGCTGCCGGTGTCTTTGCTGATCTGCTACGTACCCTCTCATGGAA 
               
               
                   
                 GTTAGGAGTCTGA 
               
               
                   
               
               
                 thrB 
                 ATGGTTAAAGTTTATGCCCCGGCTTCCAGTGCCAATATGAGCGTCGGGTT 
               
               
                 SEQ ID 
                 TGATGTGCTCGGGGCGGCGGTGACACCTGTTGATGGTGCATTGCTCGGAG 
               
               
                 NO: 57 
                 ATGTAGTCACGGTTGAGGCGGCAGAGACATTCAGTCTCAACAACCTCGGA 
               
               
                   
                 CGCTTTGCCGATAAGCTGCCGTCAGAACCACGGGAAAATATCGTTTATCA 
               
               
                   
                 GTGCTGGGAGCGTTTTTGCCAGGAACTGGGTAAGCAAATTCCAGTGGCGA 
               
               
                   
                 TGACCCTGGAAAAGAATATGCCGATCGGTTCGGGCTTAGGCTCCAGTGCC 
               
               
                   
                 TGTTCGGTGGTCGCGGCGCTGATGGCGATGAATGAACACTGCGGCAAGCC 
               
               
                   
                 GCTTAATGACACTCGTTTGCTGGCTTTGATGGGCGAGCTGGAAGGCCGTA 
               
               
                   
                 TCTCCGGCAGCATTCATTACGACAACGTGGCACCGTGTTTTCTCGGTGGT 
               
               
                   
                 ATGCAGTTGATGATCGAAGAAAACGACATCATCAGCCAGCAAGTGCCAGG 
               
               
                   
                 GTTTGATGAGTGGCTGTGGGTGCTGGCGTATCCGGGGATTAAAGTCTCGA 
               
               
                   
                 CGGCAGAAGCCAGGGCTATTTTACCGGCGCAGTATCGCCGCCAGGATTGC 
               
               
                   
                 ATTGCGCACGGGCGACATCTGGCAGGCTTCATTCACGCCTGCTATTCCCG 
               
               
                   
                 TCAGCCTGAGCTTGCCGCGAAGCTGATGAAAGATGTTATCGCTGAACCCT 
               
               
                   
                 ACCGTGAACGGTTACTGCCAGGCTTCCGGCAGGCGCGGCAGGCGGTCGCG 
               
               
                   
                 GAAATCGGCGCGGTAGCGAGCGGTATCTCCGGCTCCGGCCCGACCTTGTT 
               
               
                   
                 CGCTCTGTGTGACAAGCCGGAAACCGCCCAGCGCGTTGCCGACTGGTTGG 
               
               
                   
                 GTAAGAACTACCTGCAAAATCAGGAAGGTTTTGTTCATATTTGCCGGCTG 
               
               
                   
                 GATACGGCGGGCGCACGAGTACTGGAAAACTAA 
               
               
                   
               
               
                 thrC 
                 ATGAAACTCTACAATCTGAAAGATCACAACGAGCAGGTCAGCTTTGCGCA 
               
               
                 SEQ ID 
                 AGCCGTAACCCAGGGGTTGGGCAAAAATCAGGGGCTGTTTTTTCCGCACG 
               
               
                 NO: 58 
                 ACCTGCCGGAATTCAGCCTGACTGAAATTGATGAGATGCTGAAGCTGGAT 
               
               
                   
                 TTTGTCACCCGCAGTGCGAAGATCCTCTCGGCGTTTATTGGTGATGAAAT 
               
               
                   
                 CCCACAGGAAATCCTGGAAGAGCGCGTGCGCGCGGCGTTTGCCTTCCCGG 
               
               
                   
                 CTCCGGTCGCCAATGTTGAAAGCGATGTCGGTTGTCTGGAATTGTTCCAC 
               
               
                   
                 GGGCCAACGCTGGCATTTAAAGATTTCGGCGGTCGCTTTATGGCACAAAT 
               
               
                   
                 GCTGACCCATATTGCGGGTGATAAGCCAGTGACCATTCTGACCGCGACCT 
               
               
                   
                 CCGGTGATACCGGAGCGGCAGTGGCTCATGCTTTCTACGGTTTACCGAAT 
               
               
                   
                 GTGAAAGTGGTTATCCTCTATCCACGAGGCAAAATCAGTCCACTGCAAGA 
               
               
                   
                 AAAACTGTTCTGTACATTGGGCGGCAATATCGAAACTGTTGCCATCGACG 
               
               
                   
                 GCGATTTCGATGCCTGTCAGGCGCTGGTGAAGCAGGCGTTTGATGATGAA 
               
               
                   
                 GAACTGAAAGTGGCGCTAGGGTTAAACTCGGCTAACTCGATTAACATCAG 
               
               
                   
                 CCGTTTGCTGGCGCAGATTTGCTACTACTTTGAAGCTGTTGCGCAGCTGC 
               
               
                   
                 CGCAGGAGACGCGCAACCAGCTGGTTGTCTCGGTGCCAAGCGGAAACTTC 
               
               
                   
                 GGCGATTTGACGGCGGGTCTGCTGGCGAAGTCACTCGGTCTGCCGGTGAA 
               
               
                   
                 ACGTTTTATTGCTGCGACCAACGTGAACGATACCGTGCCACGTTTCCTGC 
               
               
                   
                 ACGACGGTCAGTGGTCACCCAAAGCGACTCAGGCGACGTTATCCAACGCG 
               
               
                   
                 ATGGACGTGAGTCAGCCGAACAACTGGCCGCGTGTGGAAGAGTTGTTCCG 
               
               
                   
                 CCGCAAAATCTGGCAACTGAAAGAGCTGGGTTATGCAGCCGTGGATGATG 
               
               
                   
                 AAACCACGCAACAGACAATGCGTGAGTTAAAAGAACTGGGCTACACTTCG 
               
               
                   
                 GAGCCGCACGCTGCCGTAGCTTATCGTGCGCTGCGTGATCAGTTGAATCC 
               
               
                   
                 AGGCGAATATGGCTTGTTCCTCGGCACCGCGCATCCGGCGAAATTTAAAG 
               
               
                   
                 AGAGCGTGGAAGCGATTCTCGGTGAAACGTTGGATCTGCCAAAAGAGCTG 
               
               
                   
                 GCAGAACGTGCTGATTTACCCTTGCTTTCACATAATCTGCCCGCCGATTT 
               
               
                   
                 TGCTGCGTTGCGTAAATTGATGATGAATCATCAGTAA 
               
               
                   
               
               
                 iIvAfbr 
                 ATGAGTGAAACATACGTGTCTGAGAAAAGTCCAGGAGTGATGGCTAGCGG 
               
               
                 SEQ ID 
                 AGCGGAGCTGATTCGTGCCGCCGACATTCAAACGGCGCAGGCACGAATTT 
               
               
                 NO: 59 
                 CCTCCGTCATTGCACCAACTCCATTGCAGTATTGCCCTCGTCTTTCTGAG 
               
               
                   
                 GAAACCGGAGCGGAAATCTACCTTAAGCGTGAGGATCTGCAGGATGTTCG 
               
               
                   
                 TTCCTACAAGATCCGCGGTGCGCTGAACTCTGGAGCGCAGCTCACCCAAG 
               
               
                   
                 AGCAGCGCGATGCAGGTATCGTTGCCGCATCTGCAGGTAACCATGCCCAG 
               
               
                   
                 GGCGTGGCCTATGTGTGCAAGTCCTTGGGCGTTCAGGGACGCATCTATGT 
               
               
                   
                 TCCTGTGCAGACTCCAAAGCAAAAGCGTGACCGCATCATGGTTCACGGCG 
               
               
                   
                 GAGAGTTTGTCTCCTTGGTGGTCACTGGCAATAACTTCGACGAAGCATCG 
               
               
                   
                 GCTGCAGCGCATGAAGATGCAGAGCGCACCGGCGCAACGCTGATCGAGCC 
               
               
                   
                 TTTCGATGCTCGCAACACCGTCATCGGTCAGGGCACCGTGGCTGCTGAGA 
               
               
                   
                 TCTTGTCGCAGCTGACTTCCATGGGCAAGAGTGCAGATCACGTGATGGTT 
               
               
                   
                 CCAGTCGGCGGTGGCGGACTTCTTGCAGGTGTGGTCAGCTACATGGCTGA 
               
               
                   
                 TATGGCACCTCGCACTGCGATCGTTGGTATCGAACCAGCGGGAGCAGCAT 
               
               
                   
                 CCATGCAGGCTGCATTGCACAATGGTGGACCAATCACTTTGGAGACTGTT 
               
               
                   
                 GATCCCTTTGTGGACGGCGCAGCAGTCAAACGTGTCGGAGATCTCAACTA 
               
               
                   
                 CACCATCGTGGAGAAGAACCAGGGTCGCGTGCACATGATGAGCGCGACCG 
               
               
                   
                 AGGGCGCTGTGTGTACTGAGATGCTCGATCTTTACCAAAACGAAGGCATC 
               
               
                   
                 ATCGCGGAGCCTGCTGGCGCGCTGTCTATCGCTGGGTTGAAGGAAATGTC 
               
               
                   
                 CTTTGCACCTGGTTCTGCAGTGGTGTGCATCATCTCTGGTGGCAACAACG 
               
               
                   
                 ATGTGCTGCGTTATGCGGAAATCGCTGAGCGCTCCTTGGTGCACCGCGGT 
               
               
                   
                 TTGAAGCACTACTTCTTGGTGAACTTCCCGCAAAAGCCTGGTCAGTTGCG 
               
               
                   
                 TCACTTCCTGGAAGATATCCTGGGACCGGATGATGACATCACGCTGTTTG 
               
               
                   
                 AGTACCTCAAGCGCAACAACCGTGAGACCGGTACTGCGTTGGTGGGTATT 
               
               
                   
                 CACTTGAGTGAAGCATCAGGATTGGATTCTTTGCTGGAACGTATGGAGGA 
               
               
                   
                 ATCGGCAATTGATTCCCGTCGCCTCGAGCCGGGCACCCCTGAGTACGAAT 
               
               
                   
                 ACTTGACCTAA 
               
               
                   
               
               
                 aceE 
                 ATGTCAGAACGTTTCCCAAATGACGTGGATCCGATCGAAACTCGCGACTG 
               
               
                 SEQ ID 
                 GCTCCAGGCGATCGAATCGGTCATCCGTGAAGAAGGTGTTGAGCGTGCTC 
               
               
                 NO: 60 
                 AGTATCTGATCGACCAACTGCTTGCTGAAGCCCGCAAAGGCGGTGTAAAC 
               
               
                   
                 GTAGCCGCAGGCACAGGTATCAGCAACTACATCAACACCATCCCCGTTGA 
               
               
                   
                 AGAACAACCGGAGTATCCGGGTAATCTGGAACTGGAACGCCGTATTCGTT 
               
               
                   
                 CAGCTATCCGCTGGAACGCCATCATGACGGTGCTGCGTGCGTCGAAAAAA 
               
               
                   
                 GACCTCGAACTGGGCGGCCATATGGCGTCCTTCCAGTCTTCCGCAACCAT 
               
               
                   
                 TTATGATGTGTGCTTTAACCACTTCTTCCGTGCACGCAACGAGCAGGATG 
               
               
                   
                 GCGGCGACCTGGTTTACTTCCAGGGCCACATCTCCCCGGGCGTGTACGCT 
               
               
                   
                 CGTGCTTTCCTGGAAGGTCGTCTGACTCAGGAGCAGCTGGATAACTTCCG 
               
               
                   
                 TCAGGAAGTTCACGGCAATGGCCTCTCTTCCTATCCGCACCCGAAACTGA 
               
               
                   
                 TGCCGGAATTCTGGCAGTTCCCGACCGTATCTATGGGTCTGGGTCCGATT 
               
               
                   
                 GGTGCTATTTACCAGGCTAAATTCCTGAAATATCTGGAACACCGTGGCCT 
               
               
                   
                 GAAAGATACCTCTAAACAAACCGTTTACGCGTTCCTCGGTGACGGTGAAA 
               
               
                   
                 TGGACGAACCGGAATCCAAAGGTGCGATCACCATCGCTACCCGTGAAAAA 
               
               
                   
                 CTGGATAACCTGGTCTTCGTTATCAACTGTAACCTGCAGCGTCTTGACGG 
               
               
                   
                 CCCGGTCACCGGTAACGGCAAGATCATCAACGAACTGGAAGGCATCTTCG 
               
               
                   
                 AAGGTGCTGGCTGGAACGTGATCAAAGTGATGTGGGGTAGCCGTTGGGAT 
               
               
                   
                 GAACTGCTGCGTAAGGATACCAGCGGTAAACTGATCCAGCTGATGAACGA 
               
               
                   
                 AACCGTTGACGGCGACTACCAGACCTTCAAATCGAAAGATGGTGCGTACG 
               
               
                   
                 TTCGTGAACACTTCTTCGGTAAATATCCTGAAACCGCAGCACTGGTTGCA 
               
               
                   
                 GACTGGACTGACGAGCAGATCTGGGCACTGAACCGTGGTGGTCACGATCC 
               
               
                   
                 GAAGAAAATCTACGCTGCATTCAAGAAAGCGCAGGAAACCAAAGGCAAAG 
               
               
                   
                 CGACAGTAATCCTTGCTCATACCATTAAAGGTTACGGCATGGGCGACGCG 
               
               
                   
                 GCTGAAGGTAAAAACATCGCGCACCAGGTTAAGAAAATGAACATGGACGG 
               
               
                   
                 TGTGCGTCATATCCGCGACCGTTTCAATGTGCCGGTGTCTGATGCAGATA 
               
               
                   
                 TCGAAAAACTGCCGTACATCACCTTCCCGGAAGGTTCTGAAGAGCATACC 
               
               
                   
                 TATCTGCACGCTCAGCGTCAGAAACTGCACGGTTATCTGCCAAGCCGTCA 
               
               
                   
                 GCCGAACTTCACCGAGAAGCTTGAGCTGCCGAGCCTGCAAGACTTCGGCG 
               
               
                   
                 CGCTGTTGGAAGAGCAGAGCAAAGAGATCTCTACCACTATCGCTTTCGTT 
               
               
                   
                 CGTGCTCTGAACGTGATGCTGAAGAACAAGTCGATCAAAGATCGTCTGGT 
               
               
                   
                 ACCGATCATCGCCGACGAAGCGCGTACTTTCGGTATGGAAGGTCTGTTCC 
               
               
                   
                 GTCAGATTGGTATTTACAGCCCGAACGGTCAGCAGTACACCCCGCAGGAC 
               
               
                   
                 CGCGAGCAGGTTGCTTACTATAAAGAAGACGAGAAAGGTCAGATTCTGCA 
               
               
                   
                 GGAAGGGATCAACGAGCTGGGCGCAGGTTGTTCCTGGCTGGCAGCGGCGA 
               
               
                   
                 CCTCTTACAGCACCAACAATCTGCCGATGATCCCGTTCTACATCTATTAC 
               
               
                   
                 TCGATGTTCGGCTTCCAGCGTATTGGCGATCTGTGCTGGGCGGCTGGCGA 
               
               
                   
                 CCAGCAAGCGCGTGGCTTCCTGATCGGCGGTACTTCCGGTCGTACCACCC 
               
               
                   
                 TGAACGGCGAAGGTCTGCAGCACGAAGATGGTCACAGCCACATTCAGTCG 
               
               
                   
                 CTGACTATCCCGAACTGTATCTCTTACGACCCGGCTTACGCTTACGAAGT 
               
               
                   
                 TGCTGTCATCATGCATGACGGTCTGGAGCGTATGTACGGTGAAAAACAAG 
               
               
                   
                 AGAACGTTTACTACTACATCACTACGCTGAACGAAAACTACCACATGCCG 
               
               
                   
                 GCAATGCCGGAAGGTGCTGAGGAAGGTATCCGTAAAGGTATCTACAAACT 
               
               
                   
                 CGAAACTATTGAAGGTAGCAAAGGTAAAGTTCAGCTGCTCGGCTCCGGTT 
               
               
                   
                 CTATCCTGCGTCACGTCCGTGAAGCAGCTGAGATCCTGGCGAAAGATTAC 
               
               
                   
                 GGCGTAGGTTCTGACGTTTATAGCGTGACCTCCTTCACCGAGCTGGCGCG 
               
               
                   
                 TGATGGTCAGGATTGTGAACGCTGGAACATGCTGCACCCGCTGGAAACTC 
               
               
                   
                 CGCGCGTTCCGTATATCGCTCAGGTGATGAACGACGCTCCGGCAGTGGCA 
               
               
                   
                 TCTACCGACTATATGAAACTGTTCGCTGAGCAGGTCCGTACTTACGTACC 
               
               
                   
                 GGCTGACGACTACCGCGTACTGGGTACTGATGGCTTCGGTCGTTCCGACA 
               
               
                   
                 GCCGTGAGAACCTGCGTCACCACTTCGAAGTTGATGCTTCTTATGTCGTG 
               
               
                   
                 GTTGCGGCGCTGGGCGAACTGGCTAAACGTGGCGAAATCGATAAGAAAGT 
               
               
                   
                 GGTTGCTGACGCAATCGCCAAATTCAACATCGATGCAGATAAAGTTAACC 
               
               
                   
                 CGCGTCTGGCGTAA 
               
               
                   
               
               
                 aceF 
                 ATGGCTATCGAAATCAAAGTACCGGACATCGGGGCTGATGAAGTTGAAAT 
               
               
                 SEQ ID 
                 CACCGAGATCCTGGTCAAAGTGGGCGACAAAGTTGAAGCCGAACAGTCGC 
               
               
                 NO: 61 
                 TGATCACCGTAGAAGGCGACAAAGCCTCTATGGAAGTTCCGTCTCCGCAG 
               
               
                   
                 GCGGGTATCGTTAAAGAGATCAAAGTCTCTGTTGGCGATAAAACCCAGAC 
               
               
                   
                 CGGCGCACTGATTATGATTTTCGATTCCGCCGACGGTGCAGCAGACGCTG 
               
               
                   
                 CACCTGCTCAGGCAGAAGAGAAGAAAGAAGCAGCTCCGGCAGCAGCACCA 
               
               
                   
                 GCGGCTGCGGCGGCAAAAGACGTTAACGTTCCGGATATCGGCAGCGACGA 
               
               
                   
                 AGTTGAAGTGACCGAAATCCTGGTGAAAGTTGGCGATAAAGTTGAAGCTG 
               
               
                   
                 AACAGTCGCTGATCACCGTAGAAGGCGACAAGGCTTCTATGGAAGTTCCG 
               
               
                   
                 GCTCCGTTTGCTGGCACCGTGAAAGAGATCAAAGTGAACGTGGGTGACAA 
               
               
                   
                 AGTGTCTACCGGCTCGCTGATTATGGTCTTCGAAGTCGCGGGTGAAGCAG 
               
               
                   
                 GCGCGGCAGCTCCGGCCGCTAAACAGGAAGCAGCTCCGGCAGCGGCCCCT 
               
               
                   
                 GCACCAGCGGCTGGCGTGAAAGAAGTTAACGTTCCGGATATCGGCGGTGA 
               
               
                   
                 CGAAGTTGAAGTGACTGAAGTGATGGTGAAAGTGGGCGACAAAGTTGCCG 
               
               
                   
                 CTGAACAGTCACTGATCACCGTAGAAGGCGACAAAGCTTCTATGGAAGTT 
               
               
                   
                 CCGGCGCCGTTTGCAGGCGTCGTGAAGGAACTGAAAGTCAACGTTGGCGA 
               
               
                   
                 TAAAGTGAAAACTGGCTCGCTGATTATGATCTTCGAAGTTGAAGGCGCAG 
               
               
                   
                 CGCCTGCGGCAGCTCCTGCGAAACAGGAAGCGGCAGCGCCGGCACCGGCA 
               
               
                   
                 GCAAAAGCTGAAGCCCCGGCAGCAGCACCAGCTGCGAAAGCGGAAGGCAA 
               
               
                   
                 ATCTGAATTTGCTGAAAACGACGCTTATGTTCACGCGACTCCGCTGATCC 
               
               
                   
                 GCCGTCTGGCACGCGAGTTTGGTGTTAACCTTGCGAAAGTGAAGGGCACT 
               
               
                   
                 GGCCGTAAAGGTCGTATCCTGCGCGAAGACGTTCAGGCTTACGTGAAAGA 
               
               
                   
                 AGCTATCAAACGTGCAGAAGCAGCTCCGGCAGCGACTGGCGGTGGTATCC 
               
               
                   
                 CTGGCATGCTGCCGTGGCCGAAGGTGGACTTCAGCAAGTTTGGTGAAATC 
               
               
                   
                 GAAGAAGTGGAACTGGGCCGCATCCAGAAAATCTCTGGTGCGAACCTGAG 
               
               
                   
                 CCGTAACTGGGTAATGATCCCGCATGTTACTCACTTCGACAAAACCGATA 
               
               
                   
                 TCACCGAGTTGGAAGCGTTCCGTAAACAGCAGAACGAAGAAGCGGCGAAA 
               
               
                   
                 CGTAAGCTGGATGTGAAGATCACCCCGGTTGTCTTCATCATGAAAGCCGT 
               
               
                   
                 TGCTGCAGCTCTTGAGCAGATGCCTCGCTTCAATAGTTCGCTGTCGGAAG 
               
               
                   
                 ACGGTCAGCGTCTGACCCTGAAGAAATACATCAACATCGGTGTGGCGGTG 
               
               
                   
                 GATACCCCGAACGGTCTGGTTGTTCCGGTATTCAAAGACGTCAACAAGAA 
               
               
                   
                 AGGCATCATCGAGCTGTCTCGCGAGCTGATGACTATTTCTAAGAAAGCGC 
               
               
                   
                 GTGACGGTAAGCTGACTGCGGGCGAAATGCAGGGCGGTTGCTTCACCATC 
               
               
                   
                 TCCAGCATCGGCGGCCTGGGTACTACCCACTTCGCGCCGATTGTGAACGC 
               
               
                   
                 GCCGGAAGTGGCTATCCTCGGCGTTTCCAAGTCCGCGATGGAGCCGGTGT 
               
               
                   
                 GGAATGGTAAAGAGTTCGTGCCGCGTCTGATGCTGCCGATTTCTCTCTCC 
               
               
                   
                 TTCGACCACCGCGTGATCGACGGTGCTGATGGTGCCCGTTTCATTACCAT 
               
               
                   
                 CATTAACAACACGCTGTCTGACATTCGCCGTCTGGTGATGTAA 
               
               
                   
               
               
                 Ipd 
                 ATGAGTACTGAAATCAAAACTCAGGTCGTGGTACTTGGGGCAGGCCCCGC 
               
               
                 SEQ ID 
                 AGGTTACTCCGCTGCCTTCCGTTGCGCTGATTTAGGTCTGGAAACCGTAA 
               
               
                 NO: 62 
                 TCGTAGAACGTTACAACACCCTTGGCGGTGTTTGCCTGAACGTCGGCTGT 
               
               
                   
                 ATCCCTTCTAAAGCACTGCTGCACGTAGCAAAAGTTATCGAAGAAGCCAA 
               
               
                   
                 AGCGCTGGCTGAACACGGTATCGTCTTCGGCGAACCGAAAACCGATATCG 
               
               
                   
                 ACAAGATTCGTACCTGGAAAGAGAAAGTGATCAATCAGCTGACCGGTGGT 
               
               
                   
                 CTGGCTGGTATGGCGAAAGGCCGCAAAGTCAAAGTGGTCAACGGTCTGGG 
               
               
                   
                 TAAATTCACCGGGGCTAACACCCTGGAAGTTGAAGGTGAGAACGGCAAAA 
               
               
                   
                 CCGTGATCAACTTCGACAACGCGATCATTGCAGCGGGTTCTCGCCCGATC 
               
               
                   
                 CAACTGCCGTTTATTCCGCATGAAGATCCGCGTATCTGGGACTCCACTGA 
               
               
                   
                 CGCGCTGGAACTGAAAGAAGTACCAGAACGCCTGCTGGTAATGGGTGGCG 
               
               
                   
                 GTATCATCGGTCTGGAAATGGGCACCGTTTACCACGCGCTGGGTTCACAG 
               
               
                   
                 ATTGACGTGGTTGAAATGTTCGACCAGGTTATCCCGGCAGCTGACAAAGA 
               
               
                   
                 CATCGTTAAAGTCTTCACCAAGCGTATCAGCAAGAAATTCAACCTGATGC 
               
               
                   
                 TGGAAACCAAAGTTACCGCCGTTGAAGCGAAAGAAGACGGCATTTATGTG 
               
               
                   
                 ACGATGGAAGGCAAAAAAGCACCCGCTGAACCGCAGCGTTACGACGCCGT 
               
               
                   
                 GCTGGTAGCGATTGGTCGTGTGCCGAACGGTAAAAACCTCGACGCAGGCA 
               
               
                   
                 AAGCAGGCGTGGAAGTTGACGACCGTGGTTTCATCCGCGTTGACAAACAG 
               
               
                   
                 CTGCGTACCAACGTACCGCACATCTTTGCTATCGGCGATATCGTCGGTCA 
               
               
                   
                 ACCGATGCTGGCACACAAAGGTGTTCACGAAGGTCACGTTGCCGCTGAAG 
               
               
                   
                 TTATCGCCGGTAAGAAACACTACTTCGATCCGAAAGTTATCCCGTCCATC 
               
               
                   
                 GCCTATACCAAACCAGAAGTTGCATGGGTGGGTCTGACTGAGAAAGAAGC 
               
               
                   
                 GAAAGAGAAAGGCATCAGCTATGAAACCGCCACCTTCCCGTGGGCTGCTT 
               
               
                   
                 CTGGTCGTGCTATCGCTTCCGACTGCGCAGACGGTATGACCAAGCTGATT 
               
               
                   
                 TTCGACAAAGAATCTCACCGTGTGATCGGTGGTGCGATTGTCGGTACTAA 
               
               
                   
                 CGGCGGCGAGCTGCTGGGTGAAATCGGCCTGGCAATCGAAATGGGTTGTG 
               
               
                   
                 ATGCTGAAGACATCGCACTGACCATCCACGCGCACCCGACTCTGCACGAG 
               
               
                   
                 TCTGTGGGCCTGGCGGCAGAAGTGTTCGAAGGTAGCATTACCGACCTGCC 
               
               
                   
                 GAACCCGAAAGCGAAGAAGAAGTAA 
               
               
                   
               
               
                 tesB 
                 ATGAGTCAGGCGCTAAAAAATTTACTGACATTGTTAAATCTGGAAAAAAT 
               
               
                 SEQ ID 
                 TGAGGAAGGACTCTTTCGCGGCCAGAGTGAAGATTTAGGTTTACGCCAGG 
               
               
                 NO: 48 
                 TGTTTGGCGGCCAGGTCGTGGGTCAGGCCTTGTATGCTGCAAAAGAGACC 
               
               
                   
                 GTCCCTGAAGAGCGGCTGGTACATTCGTTTCACAGCTACTTTCTTCGCCC 
               
               
                   
                 TGGCGATAGTAAGAAGCCGATTATTTATGATGTCGAAACGCTGCGTGACG 
               
               
                   
                 GTAACAGCTTCAGCGCCCGCCGGGTTGCTGCTATTCAAAACGGCAAACCG 
               
               
                   
                 ATTTTTTATATGACTGCCTCTTTCCAGGCACCAGAAGCGGGTTTCGAACA 
               
               
                   
                 TCAAAAAACAATGCCGTCCGCGCCAGCGCCTGATGGCCTCCCTTCGGAAA 
               
               
                   
                 CGCAAATCGCCCAATCGCTGGCGCACCTGCTGCCGCCAGTGCTGAAAGAT 
               
               
                   
                 AAATTCATCTGCGATCGTCCGCTGGAAGTCCGTCCGGTGGAGTTTCATAA 
               
               
                   
                 CCCACTGAAAGGTCACGTCGCAGAACCACATCGTCAGGTGTGGATCCGCG 
               
               
                   
                 CAAATGGTAGCGTGCCGGATGACCTGCGCGTTCATCAGTATCTGCTCGGT 
               
               
                   
                 TACGCTTCTGATCTTAACTTCCTGCCGGTAGCTCTACAGCCGCACGGCAT 
               
               
                   
                 CGGTTTTCTCGAACCGGGGATTCAGATTGCCACCATTGACCATTCCATGT 
               
               
                   
                 GGTTCCATCGCCCGTTTAATTTGAATGAATGGCTGCTGTATAGCGTGGAG 
               
               
                   
                 AGCACCTCGGCGTCCAGCGCACGTGGCTTTGTGCGCGGTGAGTTTTATAC 
               
               
                   
                 CCAAGACGGCGTACTGGTTGCCTCGACCGTTCAGGAAGGGGTGATGCGTA 
               
               
                   
                 ATCACAATTAA 
               
               
                   
               
            
           
         
       
     
     In some embodiments, one or more of the propionate biosynthesis genes is a synthetic propionate biosynthesis gene. In some embodiments, one or more of the propionate biosynthesis genes is an  E. coli  propionate biosynthesis gene. In some embodiments, one or more of the propionate biosynthesis genes is a  C. glutamicum  propionate biosynthesis gene. In some embodiments, one or more of the propionate biosynthesis genes is a  C. propionicum  propionate biosynthesis gene. The propionate gene cassette may comprise genes for the aerobic biosynthesis of propionate and/or genes for the anaerobic or microaerobic biosynthesis of propionate. One or more of the propionate biosynthesis genes may be functionally replaced or modified, e.g., codon optimized. In some embodiments, the genetically engineered bacteria comprise a combination of propionate biosynthesis genes from different species, strains, and/or substrains of bacteria, and are capable of producing propionate in low-oxygen conditions, in the presence of HE-specific molecules or metabolites, in the presence of molecules or metabolites associated with liver damage, inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. In some embodiments, one or more of the propionate biosynthesis genes is functionally replaced, modified, and/or mutated in order to enhance stability and/or increase propionate production in low-oxygen conditions, in the presence of HE-specific molecules or metabolites, in the presence of molecules or metabolites associated with liver damage, inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. In some embodiments, the genetically engineered bacteria are capable of expressing the propionate biosynthesis cassette and producing propionate in low-oxygen conditions, in the presence of HE-specific molecules or metabolites, in the presence of molecules or metabolites associated with liver damage, inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. 
     In some embodiments, the genetically engineered bacteria of the invention comprise an acetate gene cassette and produce acetate. The genetically engineered bacteria may include any suitable set of acetate biosynthesis genes. Unmodified bacteria comprising endogenous acetate biosynthesis genes are known in the art and are capable of consuming various substrates to produce acetate under aerobic and/or anaerobic conditions (see, e.g., Ragsdale et al., 2008). These endogenous acetate biosynthesis genes may be a source of genes for the genetically engineered bacteria of the invention. In some embodiments, the genetically engineered bacteria of the invention comprise acetate biosynthesis genes from a different species, strain, or substrain of bacteria. In some embodiments, the native acetate biosynthesis genes in the genetically engineered bacteria are enhanced. In some embodiments, the genetically engineered bacteria comprise aerobic acetate biosynthesis genes, e.g., from  Escherichia coli . In some embodiments, the genetically engineered bacteria comprise anaerobic acetate biosynthesis genes, e.g., from  Acetitomaculum, Acetoanaerobium, Acetohalobium, Acetonema, Balutia, Butyribacterium, Clostridium, Moorella, Oxobacter, Sporomusa , and/or  Thermoacetogenium . The genetically engineered bacteria may comprise genes for aerobic acetate biosynthesis or genes for anaerobic or microaerobic acetate biosynthesis. In some embodiments, the genetically engineered bacteria comprise both aerobic and anaerobic or microaerobic acetate biosynthesis genes. In some embodiments, the genetically engineered bacteria comprise a combination of acetate biosynthesis genes from different species, strains, and/or substrains of bacteria, and are capable of producing acetate. In some embodiments, one or more of the acetate biosynthesis genes is functionally replaced, modified, and/or mutated in order to enhance stability and/or acetate production. In some embodiments, the genetically engineered bacteria are capable of expressing the acetate biosynthesis cassette and producing acetate in low-oxygen conditions or in the presence of HE-specific molecules or metabolites. In some embodiments, the genetically engineered bacteria are capable of producing an alternate short-chain fatty acid. 
     One of skill in the art would appreciate that additional genes and gene cassettes capable of producing gut barrier function enhancer molecules are known in the art and may be expressed by the genetically engineered bacteria of the invention. In some embodiments, the gene or gene cassette for producing a therapeutic molecule also comprises additional transcription and translation elements, e.g., a ribosome binding site, to enhance expression of the therapeutic molecule. 
     In some embodiments, the genetically engineered bacteria produce two or more gut barrier function enhancer molecules. In certain embodiments, the two or more molecules behave synergistically to enhance gut barrier function. In certain embodiments, the genetically engineered bacteria express butyrate and propionate. 
     In some embodiments, the genetically engineered bacteria comprising an ammonia conversion circuit further comprise one or more circuits for producing a gut barrier enhancer molecule, e.g., butyrate ( FIG. 43 ). 
     In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a GABA metabolic circuit, and one or more circuits for producing a gut barrier enhancer molecule, e.g., butyrate. In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a GABA transport circuit, and one or more circuits for producing a gut barrier enhancer molecule, e.g., butyrate. In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a GABA transport circuit, a GABA metabolic circuit, and one or more circuits for producing a gut barrier enhancer molecule, e.g., butyrate. In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a manganese transport circuit, a GABA metabolic circuit, and one or more circuits for producing a gut barrier enhancer molecule, e.g., butyrate. In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a manganese transport circuit, a GABA transport circuit, and one or more circuits for producing a gut barrier enhancer molecule, e.g., butyrate. In some embodiments, the genetically engineered bacteria comprise an ammonia conversion circuit, a manganese transport circuit, a GABA transport circuit, a GABA metabolic circuit, and one or more circuits for producing a gut barrier enhancer molecule, e.g., butyrate. In some embodiments, the circuits are under the control of the same promoter. In alternate embodiments, the circuits are under the control of different promoters. 
     In some embodiments, the genetically engineered bacteria are capable of expressing any one or more of the described circuits in low-oxygen conditions, in the presence of HE-specific molecules or metabolites, in the presence of molecules or metabolites associated with liver damage, inflammation or an inflammatory response, or in the presence of some other metabolite that may or may not be present in the gut, such as arabinose. In some embodiments, any one or more of the described circuits are present on one or more plasmids (e.g., high copy or low copy) or are integrated into one or more sites in the bacterial chromosome. Also, in some embodiments, the genetically engineered bacteria are further capable of expressing any one or more of the described circuits and further comprise one or more of the following: (1) one or more auxotrophies, such as any auxotrophies known in the art and provided herein, e.g., thyA auxotrophy, (2) one or more kill switch circuits, such as any of the kill-switches described herein or otherwise known in the art, (3) one or more antibiotic resistance circuits, (4) one or more transporters for importing biological molecules or substrates, such any of the transporters described herein or otherwise known in the art, (5) one or more secretion circuits, such as any of the secretion circuits described herein and otherwise known in the art, and (6) combinations of one or more of such additional circuits. 
     In any of the embodiments described herein, the genetically engineered bacteria may further comprise a resistance to rifaximin. Resistance to rifaximin is caused primarily by mutations in the rpoB gene. In some embodiments, the genetically engineered bacteria comprise a known rifaximin resistance mutation, e.g., in the rpoB gene. In other embodiments, a screen can be employed, exposing the genetically engineered bacteria to increasing amounts of rifaximin, to identify a useful mutation which confers rifaximin resistance. 
     Inducible Promoters 
     In some embodiments, the bacterial cell comprises a stably maintained plasmid or chromosome carrying the gene(s) encoding the payload (s), such that the payload(s) can be expressed in the host cell, and the host cell is capable of survival and/or growth in vitro, e.g., in medium, and/or in vivo, e.g., in the gut. In some embodiments, bacterial cell comprises two or more distinct payloads or operons, e.g., two or more payload genes. In some embodiments, bacterial cell comprises three or more distinct transporters or operons, e.g., three or more payload genes. In some embodiments, bacterial cell comprises 4, 5, 6, 7, 8, 9, 10, or more distinct payloads or operons, e.g., 4, 5, 6, 7, 8, 9, 10, or more payload genes. 
     In some embodiments, the genetically engineered bacteria comprise multiple copies of the same payload gene(s). In some embodiments, the gene encoding the payload is present on a plasmid and operably linked to a directly or indirectly inducible promoter. In some embodiments, the gene encoding the payload is present on a plasmid and operably linked to a promoter that is induced under low-oxygen or anaerobic conditions. In some embodiments, the gene encoding the payload is present on a chromosome and operably linked to a directly or indirectly inducible promoter. In some embodiments, the gene encoding the payload is present in the chromosome and operably linked to a promoter that is induced under low-oxygen or anaerobic conditions. In some embodiments, the gene encoding the payload is present on a plasmid and operably linked to a promoter that is induced by exposure to tetracycline or arabinose. 
     In some embodiments, the promoter that is operably linked to the gene encoding the payload is directly induced by exogenous environmental conditions. In some embodiments, the promoter that is operably linked to the gene encoding the payload is indirectly induced by exogenous environmental conditions. In some embodiments, the promoter is directly or indirectly induced by exogenous environmental conditions specific to the gut of a mammal. In some embodiments, the promoter is directly or indirectly induced by exogenous environmental conditions specific to the small intestine of a mammal. In some embodiments, the promoter is directly or indirectly induced by low-oxygen or anaerobic conditions such as the environment of the mammalian gut. In some embodiments, the promoter is directly or indirectly induced by molecules or metabolites that are specific to the gut of a mammal. In some embodiments, the promoter is directly or indirectly induced by a molecule that is co-administered with the bacterial cell. 
     In certain embodiments, the bacterial cell comprises a gene encoding a payload expressed under the control of a fumarate and nitrate reductase regulator (FNR) responsive promoter. In  E. coli , FNR is a major transcriptional activator that controls the switch from aerobic to anaerobic metabolism (Unden et al., 1997). In the anaerobic state, FNR dimerizes into an active DNA binding protein that activates hundreds of genes responsible for adapting to anaerobic growth. In the aerobic state, FNR is prevented from dimerizing by oxygen and is inactive. FNR responsive promoters include, but are not limited to, the FNR responsive promoters listed in the chart, below. Underlined sequences are predicted ribosome binding sites, and bolded sequences are restriction sites used for cloning. 
     FNR promoter sequences are known in the art, and any suitable FNR promoter sequence(s) may be used in the genetically engineered bacteria of the invention. Any suitable FNR promoter(s) may be combined with any suitable payload (e.g., the exemplary argA fbr  sequence shown in Table 7). Non-limiting FNR promoter sequences are provided in Table 6. Table 6 depicts the nucleic acid sequences of exemplary regulatory region sequences comprising a FNR-responsive promoter sequence. Underlined sequences are predicted ribosome binding sites, and bolded sequences are restriction sites used for cloning. In some embodiments, the genetically engineered bacteria of the invention comprise one or more of: SEQ ID NO: 18, SEQ ID NO: 19, nirB1 promoter (SEQ ID NO: 20), nirB2 promoter (SEQ ID NO: 21), nirB3 promoter (SEQ ID NO: 22), ydfZ promoter (SEQ ID NO: 23), nirB promoter fused to a strong ribosome binding site (SEQ ID NO: 24), ydfZ promoter fused to a strong ribosome binding site (SEQ ID NO: 25), fnrS, an anaerobically induced small RNA gene (fnrS1 promoter SEQ ID NO: 26 or fnrS2 promoter SEQ ID NO: 27), nirB promoter fused to a crp binding site (SEQ ID NO: 28), and fnrS fused to a crp binding site (SEQ ID NO: 29). 
     In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, or a functional fragment thereof. 
     In one embodiment, the FNR responsive promoter comprises SEQ ID NO:1. In another embodiment, the FNR responsive promoter comprises SEQ ID NO:2. In another embodiment, the FNR responsive promoter comprises SEQ ID NO:3. In another embodiment, the FNR responsive promoter comprises SEQ ID NO:4. In yet another embodiment, the FNR responsive promoter comprises SEQ ID NO:5. 
     In some embodiments, multiple distinct FNR nucleic acid sequences are inserted in the genetically engineered bacteria. In alternate embodiments, the genetically engineered bacteria comprise a gene encoding a payload expressed under the control of an alternate oxygen level-dependent promoter, e.g., DNR (Trunk et al., 2010) or ANR (Ray et al., 1997). In these embodiments, expression of the payload gene is particularly activated in a low-oxygen or anaerobic environment, such as in the gut. In some embodiments, gene expression is further optimized by methods known in the art, e.g., by optimizing ribosomal binding sites and/or increasing mRNA stability. In one embodiment, the mammalian gut is a human mammalian gut. 
     In some embodiments, the bacterial cell comprises an oxygen-level dependent transcriptional regulator, e.g., FNR, ANR, or DNR, and corresponding promoter from a different bacterial species. The heterologous oxygen-level dependent transcriptional regulator and promoter increase the transcription of genes operably linked to said promoter, e.g., the gene encoding the payload, in a low-oxygen or anaerobic environment, as compared to the native gene(s) and promoter in the bacteria under the same conditions. In certain embodiments, the non-native oxygen-level dependent transcriptional regulator is an FNR protein from  N. gonorrhoeae  (see, e.g., Isabella et al., 2011). In some embodiments, the corresponding wild-type transcriptional regulator is left intact and retains wild-type activity. In alternate embodiments, the corresponding wild-type transcriptional regulator is deleted or mutated to reduce or eliminate wild-type activity. 
     In some embodiments, the genetically engineered bacteria comprise a wild-type oxygen-level dependent transcriptional regulator, e.g., FNR, ANR, or DNR, and corresponding promoter that is mutated relative to the wild-type promoter from bacteria of the same subtype. The mutated promoter enhances binding to the wild-type transcriptional regulator and increases the transcription of genes operably linked to said promoter, e.g., the gene encoding the payload, in a low-oxygen or anaerobic environment, as compared to the wild-type promoter under the same conditions. In some embodiments, the genetically engineered bacteria comprise a wild-type oxygen-level dependent promoter, e.g., FNR, ANR, or DNR promoter, and corresponding transcriptional regulator that is mutated relative to the wild-type transcriptional regulator from bacteria of the same subtype. The mutated transcriptional regulator enhances binding to the wild-type promoter and increases the transcription of genes operably linked to said promoter, e.g., the gene encoding the payload, in a low-oxygen or anaerobic environment, as compared to the wild-type transcriptional regulator under the same conditions. In certain embodiments, the mutant oxygen-level dependent transcriptional regulator is an FNR protein comprising amino acid substitutions that enhance dimerization and FNR activity (see, e.g., Moore et al., (2006). 
     In some embodiments, the bacterial cells comprise multiple copies of the endogenous gene encoding the oxygen level-sensing transcriptional regulator, e.g., the FNR gene. In some embodiments, the gene encoding the oxygen level-sensing transcriptional regulator is present on a plasmid. In some embodiments, the gene encoding the oxygen level-sensing transcriptional regulator and the gene encoding the payload are present on different plasmids. In some embodiments, the gene encoding the oxygen level-sensing transcriptional regulator and the gene encoding the payload are present on the same plasmid. In some embodiments, the gene encoding the oxygen level-sensing transcriptional regulator is present on a chromosome. In some embodiments, the gene encoding the oxygen level-sensing transcriptional regulator and the gene encoding the payload are present on different chromosomes. In some embodiments, the gene encoding the oxygen level-sensing transcriptional regulator and the gene encoding the payload are present on the same chromosome. In some instances, it may be advantageous to express the oxygen level-sensing transcriptional regulator under the control of an inducible promoter in order to enhance expression stability. In some embodiments, expression of the transcriptional regulator is controlled by a different promoter than the promoter that controls expression of the gene encoding the payload. In some embodiments, expression of the transcriptional regulator is controlled by the same promoter that controls expression of the payload. In some embodiments, the transcriptional regulator and the payload are divergently transcribed from a promoter region. 
     RNS-Dependent Regulation 
     In some embodiments, the genetically engineered bacteria or genetically engineered virus comprise a gene encoding a payload that is expressed under the control of an inducible promoter. In some embodiments, the genetically engineered bacterium or genetically engineered virus that expresses a payload under the control of a promoter that is activated by inflammatory conditions. In one embodiment, the gene for producing the payload is expressed under the control of an inflammatory-dependent promoter that is activated in inflammatory environments, e.g., a reactive nitrogen species or RNS promoter. 
     As used herein, “reactive nitrogen species” and “RNS” are used interchangeably to refer to highly active molecules, ions, and/or radicals derived from molecular nitrogen. RNS can cause deleterious cellular effects such as nitrosative stress. RNS includes, but is not limited to, nitric oxide (NO.), peroxynitrite or peroxynitrite anion (ONOO−), nitrogen dioxide (.NO2), dinitrogen trioxide (N2O3), peroxynitrous acid (ONOOH), and nitroperoxycarbonate (ONOOCO2-) (unpaired electrons denoted by .). Bacteria have evolved transcription factors that are capable of sensing RNS levels. Different RNS signaling pathways are triggered by different RNS levels and occur with different kinetics. 
     As used herein, “RNS-inducible regulatory region” refers to a nucleic acid sequence to which one or more RNS-sensing transcription factors is capable of binding, wherein the binding and/or activation of the corresponding transcription factor activates downstream gene expression; in the presence of RNS, the transcription factor binds to and/or activates the regulatory region. In some embodiments, the RNS-inducible regulatory region comprises a promoter sequence. In some embodiments, the transcription factor senses RNS and subsequently binds to the RNS-inducible regulatory region, thereby activating downstream gene expression. In alternate embodiments, the transcription factor is bound to the RNS-inducible regulatory region in the absence of RNS; in the presence of RNS, the transcription factor undergoes a conformational change, thereby activating downstream gene expression. The RNS-inducible regulatory region may be operatively linked to a gene or genes, e.g., a payload gene sequence(s), e.g., any of the payloads described herein. For example, in the presence of RNS, a transcription factor senses RNS and activates a corresponding RNS-inducible regulatory region, thereby driving expression of an operatively linked gene sequence. Thus, RNS induces expression of the gene or gene sequences. 
     As used herein, “RNS-derepressible regulatory region” refers to a nucleic acid sequence to which one or more RNS-sensing transcription factors is capable of binding, wherein the binding of the corresponding transcription factor represses downstream gene expression; in the presence of RNS, the transcription factor does not bind to and does not repress the regulatory region. In some embodiments, the RNS-derepressible regulatory region comprises a promoter sequence. The RNS-derepressible regulatory region may be operatively linked to a gene or genes, e.g., a payload gene sequence(s). For example, in the presence of RNS, a transcription factor senses RNS and no longer binds to and/or represses the regulatory region, thereby derepressing an operatively linked gene sequence or gene cassette. Thus, RNS derepresses expression of the gene or genes. 
     As used herein, “RNS-repressible regulatory region” refers to a nucleic acid sequence to which one or more RNS-sensing transcription factors is capable of binding, wherein the binding of the corresponding transcription factor represses downstream gene expression; in the presence of RNS, the transcription factor binds to and represses the regulatory region. In some embodiments, the RNS-repressible regulatory region comprises a promoter sequence. In some embodiments, the transcription factor that senses RNS is capable of binding to a regulatory region that overlaps with part of the promoter sequence. In alternate embodiments, the transcription factor that senses RNS is capable of binding to a regulatory region that is upstream or downstream of the promoter sequence. The RNS-repressible regulatory region may be operatively linked to a gene sequence or gene cassette. For example, in the presence of RNS, a transcription factor senses RNS and binds to a corresponding RNS-repressible regulatory region, thereby blocking expression of an operatively linked gene sequence or gene sequences. Thus, RNS represses expression of the gene or gene sequences. 
     As used herein, a “RNS-responsive regulatory region” refers to a RNS-inducible regulatory region, a RNS-repressible regulatory region, and/or a RNS-derepressible regulatory region. In some embodiments, the RNS-responsive regulatory region comprises a promoter sequence. Each regulatory region is capable of binding at least one corresponding RNS-sensing transcription factor. Examples of transcription factors that sense RNS and their corresponding RNS-responsive genes, promoters, and/or regulatory regions include, but are not limited to, those shown in Table A. 
     
       
         
           
               
             
               
                 TABLE A 
               
             
            
               
                   
               
               
                 Examples of RNS-sensing transcription factors and 
               
               
                 RNS-responsive genes 
               
            
           
           
               
               
               
            
               
                 RNS-sensing 
                 Primarily  
                 Examples of responsive  
               
               
                 transcription  
                 capable  
                 genes, promoters,  
               
               
                 factor: 
                 of sensing: 
                 and/or regulatory regions: 
               
               
                   
               
               
                 NsrR 
                 NO 
                 norB, aniA, nsrR, hmpA, ytfE,  
               
               
                   
                   
                 ygbA, hcp, hcr, nrfA, aox 
               
               
                 NorR 
                 NO 
                 norVW, norR 
               
               
                 DNR 
                 NO 
                 norCB, nir, nor, nos 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria of the invention comprise a tunable regulatory region that is directly or indirectly controlled by a transcription factor that is capable of sensing at least one reactive nitrogen species. The tunable regulatory region is operatively linked to a gene or genes capable of directly or indirectly driving the expression of a payload, thus controlling expression of the payload relative to RNS levels. For example, the tunable regulatory region is a RNS-inducible regulatory region, and the payload is a payload, such as any of the payloads provided herein; when RNS is present, e.g., in an inflamed tissue, a RNS-sensing transcription factor binds to and/or activates the regulatory region and drives expression of the payload gene or genes. Subsequently, when inflammation is ameliorated, RNS levels are reduced, and production of the payload is decreased or eliminated. 
     In some embodiments, the tunable regulatory region is a RNS-inducible regulatory region; in the presence of RNS, a transcription factor senses RNS and activates the RNS-inducible regulatory region, thereby driving expression of an operatively linked gene or genes. In some embodiments, the transcription factor senses RNS and subsequently binds to the RNS-inducible regulatory region, thereby activating downstream gene expression. In alternate embodiments, the transcription factor is bound to the RNS-inducible regulatory region in the absence of RNS; when the transcription factor senses RNS, it undergoes a conformational change, thereby inducing downstream gene expression. 
     In some embodiments, the tunable regulatory region is a RNS-inducible regulatory region, and the transcription factor that senses RNS is NorR. NorR “is an NO-responsive transcriptional activator that regulates expression of the norVW genes encoding flavorubredoxin and an associated flavoprotein, which reduce NO to nitrous oxide” (Spiro 2006). The genetically engineered bacteria of the invention may comprise any suitable RNS-responsive regulatory region from a gene that is activated by NorR. Genes that are capable of being activated by NorR are known in the art (see, e.g., Spiro 2006; Vine et al., 2011; Karlinsey et al., 2012). In certain embodiments, the genetically engineered bacteria of the invention comprise a RNS-inducible regulatory region from norVW that is operatively linked to a gene or genes, e.g., one or more payload gene sequence(s). In the presence of RNS, a NorR transcription factor senses RNS and activates to the norVW regulatory region, thereby driving expression of the operatively linked gene(s) and producing the payload. 
     In some embodiments, the tunable regulatory region is a RNS-inducible regulatory region, and the transcription factor that senses RNS is DNR. DNR (dissimilatory nitrate respiration regulator) “promotes the expression of the nir, the nor and the nos genes” in the presence of nitric oxide (Castiglione et al., 2009). The genetically engineered bacteria of the invention may comprise any suitable RNS-responsive regulatory region from a gene that is activated by DNR. Genes that are capable of being activated by DNR are known in the art (see, e.g., Castiglione et al., 2009; Giardina et al., 2008). In certain embodiments, the genetically engineered bacteria of the invention comprise a RNS-inducible regulatory region from norCB that is operatively linked to a gene or gene cassette, e.g., a butyrogenic gene cassette. In the presence of RNS, a DNR transcription factor senses RNS and activates to the norCB regulatory region, thereby driving expression of the operatively linked gene or genes and producing one or more payloads. In some embodiments, the DNR is  Pseudomonas aeruginosa  DNR. 
     In some embodiments, the tunable regulatory region is a RNS-derepressible regulatory region, and binding of a corresponding transcription factor represses downstream gene expression; in the presence of RNS, the transcription factor no longer binds to the regulatory region, thereby derepressing the operatively linked gene or gene cassette. 
     In some embodiments, the tunable regulatory region is a RNS-derepressible regulatory region, and the transcription factor that senses RNS is NsrR. NsrR is “an Rrf2-type transcriptional repressor [that] can sense NO and control the expression of genes responsible for NO metabolism” (Isabella et al., 2009). The genetically engineered bacteria of the invention may comprise any suitable RNS-responsive regulatory region from a gene that is repressed by NsrR. In some embodiments, the NsrR is  Neisseria gonorrhoeae  NsrR. Genes that are capable of being repressed by NsrR are known in the art (see, e.g., Isabella et al., 2009; Dunn et al., 2010). In certain embodiments, the genetically engineered bacteria of the invention comprise a RNS-derepressible regulatory region from norB that is operatively linked to a gene or genes, e.g., a payload gene or genes. In the presence of RNS, an NsrR transcription factor senses RNS and no longer binds to the norB regulatory region, thereby derepressing the operatively linked a payload gene or genes and producing the encoding a payload(s). 
     In some embodiments, it is advantageous for the genetically engineered bacteria to express a RNS-sensing transcription factor that does not regulate the expression of a significant number of native genes in the bacteria. In some embodiments, the genetically engineered bacterium of the invention expresses a RNS-sensing transcription factor from a different species, strain, or substrain of bacteria, wherein the transcription factor does not bind to regulatory sequences in the genetically engineered bacterium of the invention. In some embodiments, the genetically engineered bacterium of the invention is  Escherichia coli , and the RNS-sensing transcription factor is NsrR, e.g., from is  Neisseria gonorrhoeae , wherein the  Escherichia coli  does not comprise binding sites for said NsrR. In some embodiments, the heterologous transcription factor minimizes or eliminates off-target effects on endogenous regulatory regions and genes in the genetically engineered bacteria. 
     In some embodiments, the tunable regulatory region is a RNS-repressible regulatory region, and binding of a corresponding transcription factor represses downstream gene expression; in the presence of RNS, the transcription factor senses RNS and binds to the RNS-repressible regulatory region, thereby repressing expression of the operatively linked gene or gene cassette. In some embodiments, the RNS-sensing transcription factor is capable of binding to a regulatory region that overlaps with part of the promoter sequence. In alternate embodiments, the RNS-sensing transcription factor is capable of binding to a regulatory region that is upstream or downstream of the promoter sequence. 
     In these embodiments, the genetically engineered bacteria may comprise a two repressor activation regulatory circuit, which is used to express a payload. The two repressor activation regulatory circuit comprises a first RNS-sensing repressor and a second repressor, which is operatively linked to a gene or gene cassette, e.g., encoding a payload. In one aspect of these embodiments, the RNS-sensing repressor inhibits transcription of the second repressor, which inhibits the transcription of the gene or gene cassette. Examples of second repressors useful in these embodiments include, but are not limited to, TetR, C1, and LexA. In the absence of binding by the first repressor (which occurs in the absence of RNS), the second repressor is transcribed, which represses expression of the gene or genes. In the presence of binding by the first repressor (which occurs in the presence of RNS), expression of the second repressor is repressed, and the gene or genes, e.g., a payload gene or genes is expressed. 
     A RNS-responsive transcription factor may induce, derepress, or repress gene expression depending upon the regulatory region sequence used in the genetically engineered bacteria. One or more types of RNS-sensing transcription factors and corresponding regulatory region sequences may be present in genetically engineered bacteria. In some embodiments, the genetically engineered bacteria comprise one type of RNS-sensing transcription factor, e.g., NsrR, and one corresponding regulatory region sequence, e.g., from norB. In some embodiments, the genetically engineered bacteria comprise one type of RNS-sensing transcription factor, e.g., NsrR, and two or more different corresponding regulatory region sequences, e.g., from norB and aniA. In some embodiments, the genetically engineered bacteria comprise two or more types of RNS-sensing transcription factors, e.g., NsrR and NorR, and two or more corresponding regulatory region sequences, e.g., from norB and norR, respectively. One RNS-responsive regulatory region may be capable of binding more than one transcription factor. In some embodiments, the genetically engineered bacteria comprise two or more types of RNS-sensing transcription factors and one corresponding regulatory region sequence. Nucleic acid sequences of several RNS-regulated regulatory regions are known in the art (see, e.g., Spiro 2006; Isabella et al., 2009; Dunn et al., 2010; Vine et al., 2011; Karlinsey et al., 2012). 
     In some embodiments, the genetically engineered bacteria of the invention comprise a gene encoding a RNS-sensing transcription factor, e.g., the nsrR gene, that is controlled by its native promoter, an inducible promoter, a promoter that is stronger than the native promoter, e.g., the GlnRS promoter or the P(Bla) promoter, or a constitutive promoter. In some instances, it may be advantageous to express the RNS-sensing transcription factor under the control of an inducible promoter in order to enhance expression stability. In some embodiments, expression of the RNS-sensing transcription factor is controlled by a different promoter than the promoter that controls expression of the therapeutic molecule. In some embodiments, expression of the RNS-sensing transcription factor is controlled by the same promoter that controls expression of the therapeutic molecule. In some embodiments, the RNS-sensing transcription factor and therapeutic molecule are divergently transcribed from a promoter region. 
     In some embodiments, the genetically engineered bacteria of the invention comprise a gene for a RNS-sensing transcription factor from a different species, strain, or substrain of bacteria. In some embodiments, the genetically engineered bacteria comprise a RNS-responsive regulatory region from a different species, strain, or substrain of bacteria. In some embodiments, the genetically engineered bacteria comprise a RNS-sensing transcription factor and corresponding RNS-responsive regulatory region from a different species, strain, or substrain of bacteria. The heterologous RNS-sensing transcription factor and regulatory region may increase the transcription of genes operatively linked to said regulatory region in the presence of RNS, as compared to the native transcription factor and regulatory region from bacteria of the same subtype under the same conditions. 
     In some embodiments, the genetically engineered bacteria comprise a RNS-sensing transcription factor, NsrR, and corresponding regulatory region, nsrR, from  Neisseria gonorrhoeae . In some embodiments, the native RNS-sensing transcription factor, e.g., NsrR, is left intact and retains wild-type activity. In alternate embodiments, the native RNS-sensing transcription factor, e.g., NsrR, is deleted or mutated to reduce or eliminate wild-type activity. 
     In some embodiments, the genetically engineered bacteria of the invention comprise multiple copies of the endogenous gene encoding the RNS-sensing transcription factor, e.g., the nsrR gene. In some embodiments, the gene encoding the RNS-sensing transcription factor is present on a plasmid. In some embodiments, the gene encoding the RNS-sensing transcription factor and the gene or gene cassette for producing the therapeutic molecule are present on different plasmids. In some embodiments, the gene encoding the RNS-sensing transcription factor and the gene or gene cassette for producing the therapeutic molecule are present on the same plasmid. In some embodiments, the gene encoding the RNS-sensing transcription factor is present on a chromosome. In some embodiments, the gene encoding the RNS-sensing transcription factor and the gene or gene cassette for producing the therapeutic molecule are present on different chromosomes. In some embodiments, the gene encoding the RNS-sensing transcription factor and the gene or gene cassette for producing the therapeutic molecule are present on the same chromosome. 
     In some embodiments, the genetically engineered bacteria comprise a wild-type gene encoding a RNS-sensing transcription factor, e.g., the NsrR gene, and a corresponding regulatory region, e.g., a norB regulatory region, that is mutated relative to the wild-type regulatory region from bacteria of the same subtype. The mutated regulatory region increases the expression of the payload in the presence of RNS, as compared to the wild-type regulatory region under the same conditions. In some embodiments, the genetically engineered bacteria comprise a wild-type RNS-responsive regulatory region, e.g., the norB regulatory region, and a corresponding transcription factor, e.g., NsrR, that is mutated relative to the wild-type transcription factor from bacteria of the same subtype. The mutant transcription factor increases the expression of the payload in the presence of RNS, as compared to the wild-type transcription factor under the same conditions. In some embodiments, both the RNS-sensing transcription factor and corresponding regulatory region are mutated relative to the wild-type sequences from bacteria of the same subtype in order to increase expression of the payload in the presence of RNS. 
     In some embodiments, the gene or gene cassette for producing the anti-inflammation and/or gut barrier function enhancer molecule is present on a plasmid and operably linked to a promoter that is induced by RNS. In some embodiments, expression is further optimized by methods known in the art, e.g., by optimizing ribosomal binding sites, manipulating transcriptional regulators, and/or increasing mRNA stability. 
     In some embodiments, any of the gene(s) of the present disclosure may be integrated into the bacterial chromosome at one or more integration sites. For example, one or more copies of one or more encoding a payload gene(s) may be integrated into the bacterial chromosome. Having multiple copies of the gene or gen(s) integrated into the chromosome allows for greater production of the payload(s) and also permits fine-tuning of the level of expression. Alternatively, different circuits described herein, such as any of the secretion or exporter circuits, in addition to the therapeutic gene(s) or gene cassette(s) could be integrated into the bacterial chromosome at one or more different integration sites to perform multiple different functions. 
     ROS-Dependent Regulation 
     In some embodiments, the genetically engineered bacteria or genetically engineered virus comprise a gene for producing a payload that is expressed under the control of an inducible promoter. In some embodiments, the genetically engineered bacterium or genetically engineered virus that expresses a payload under the control of a promoter that is activated by conditions of cellular damage. In one embodiment, the gene for producing the payload is expressed under the control of an cellular damaged-dependent promoter that is activated in environments in which there is cellular or tissue damage, e.g., a reactive oxygen species or ROS promoter. 
     As used herein, “reactive oxygen species” and “ROS” are used interchangeably to refer to highly active molecules, ions, and/or radicals derived from molecular oxygen. ROS can be produced as byproducts of aerobic respiration or metal-catalyzed oxidation and may cause deleterious cellular effects such as oxidative damage. ROS includes, but is not limited to, hydrogen peroxide (H2O2), organic peroxide (ROOH), hydroxyl ion (OH−), hydroxyl radical (.OH), superoxide or superoxide anion (.O2−), singlet oxygen (1O2), ozone (O3), carbonate radical, peroxide or peroxyl radical (.O2−2), hypochlorous acid (HOCl), hypochlorite ion (OCl−), sodium hypochlorite (NaOCl), nitric oxide (NO.), and peroxynitrite or peroxynitrite anion (ONOO−) (unpaired electrons denoted by .). Bacteria have evolved transcription factors that are capable of sensing ROS levels. Different ROS signaling pathways are triggered by different ROS levels and occur with different kinetics (Marinho et al., 2014). 
     As used herein, “ROS-inducible regulatory region” refers to a nucleic acid sequence to which one or more ROS-sensing transcription factors is capable of binding, wherein the binding and/or activation of the corresponding transcription factor activates downstream gene expression; in the presence of ROS, the transcription factor binds to and/or activates the regulatory region. In some embodiments, the ROS-inducible regulatory region comprises a promoter sequence. In some embodiments, the transcription factor senses ROS and subsequently binds to the ROS-inducible regulatory region, thereby activating downstream gene expression. In alternate embodiments, the transcription factor is bound to the ROS-inducible regulatory region in the absence of ROS; in the presence of ROS, the transcription factor undergoes a conformational change, thereby activating downstream gene expression. The ROS-inducible regulatory region may be operatively linked to a gene sequence or gene sequence, e.g., a sequence or sequences encoding one or more payload(s). For example, in the presence of ROS, a transcription factor, e.g., OxyR, senses ROS and activates a corresponding ROS-inducible regulatory region, thereby driving expression of an operatively linked gene sequence or gene sequences. Thus, ROS induces expression of the gene or genes. 
     As used herein, “ROS-derepressible regulatory region” refers to a nucleic acid sequence to which one or more ROS-sensing transcription factors is capable of binding, wherein the binding of the corresponding transcription factor represses downstream gene expression; in the presence of ROS, the transcription factor does not bind to and does not repress the regulatory region. In some embodiments, the ROS-derepressible regulatory region comprises a promoter sequence. The ROS-derepressible regulatory region may be operatively linked to a gene or genes, e.g., one or more genes encoding one or more payload(s). For example, in the presence of ROS, a transcription factor, e.g., OhrR, senses ROS and no longer binds to and/or represses the regulatory region, thereby derepressing an operatively linked gene sequence or gene cassette. Thus, ROS derepresses expression of the gene or gene cassette. 
     As used herein, “ROS-repressible regulatory region” refers to a nucleic acid sequence to which one or more ROS-sensing transcription factors is capable of binding, wherein the binding of the corresponding transcription factor represses downstream gene expression; in the presence of ROS, the transcription factor binds to and represses the regulatory region. In some embodiments, the ROS-repressible regulatory region comprises a promoter sequence. In some embodiments, the transcription factor that senses ROS is capable of binding to a regulatory region that overlaps with part of the promoter sequence. In alternate embodiments, the transcription factor that senses ROS is capable of binding to a regulatory region that is upstream or downstream of the promoter sequence. The ROS-repressible regulatory region may be operatively linked to a gene sequence or gene sequences. For example, in the presence of ROS, a transcription factor, e.g., PerR, senses ROS and binds to a corresponding ROS-repressible regulatory region, thereby blocking expression of an operatively linked gene sequence or gene sequences. Thus, ROS represses expression of the gene or genes. 
     As used herein, a “ROS-responsive regulatory region” refers to a ROS-inducible regulatory region, a ROS-repressible regulatory region, and/or a ROS-derepressible regulatory region. In some embodiments, the ROS-responsive regulatory region comprises a promoter sequence. Each regulatory region is capable of binding at least one corresponding ROS-sensing transcription factor. Examples of transcription factors that sense ROS and their corresponding ROS-responsive genes, promoters, and/or regulatory regions include, but are not limited to, those shown in Table B. 
     
       
         
           
               
             
               
                 TABLE B 
               
             
            
               
                   
               
               
                 Examples of ROS-sensing transcription factors and 
               
               
                 ROS-responsive genes 
               
            
           
           
               
               
               
            
               
                 ROS-sensing 
                 Primarily  
                   
               
               
                 transcription  
                 capable of 
                 Examples of responsive genes, 
               
               
                 factor: 
                 sensing: 
                 promoters, and/or regulatory regions: 
               
               
                   
               
               
                 OxyR 
                 H 2 O 2   
                 ahpC; ahpF; dps; dsbG; fhuF; flu; fur; 
               
               
                   
                   
                 gor; grxA; hemH; katG; oxyS; sufA; 
               
               
                   
                   
                 sufB; sufC; sufD; sufE; sufS; trxC; uxuA; 
               
               
                   
                   
                 yaaA; yaeH; yaiA; ybjM; ydcH; ydeN; 
               
               
                   
                   
                 ygaQ; yljA; ytfK 
               
               
                 PerR 
                 H 2 O 2   
                 katA; ahpCF; mrgA; zoaA; fur; 
               
               
                   
                   
                 hemAXCDBL; srfA 
               
               
                 OhrR 
                 Organic  
                 ohrA 
               
               
                   
                 peroxides 
                   
               
               
                   
                 NaOCl 
                   
               
               
                 SoxR 
                 •O 2   −   
                 soxS 
               
               
                   
                 NO• 
                   
               
               
                   
                 (also capable of 
                   
               
               
                   
                 sensing H 2 O 2 ) 
                   
               
               
                 RosR 
                 H 2 O 2   
                 rbtT; tnp16a; rluC1; tnp5a; mscL; 
               
               
                   
                   
                 tnp2d; phoD; tnp15b; pstA; tnp5b; xylC; 
               
               
                   
                   
                 gabD1; rluC2; cgtS9; azlC; narKGHJI; 
               
               
                   
                   
                 rosR 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria comprise a tunable regulatory region that is directly or indirectly controlled by a transcription factor that is capable of sensing at least one reactive oxygen species. The tunable regulatory region is operatively linked to a gene or gene cassette capable of directly or indirectly driving the expression of a payload, thus controlling expression of the payload relative to ROS levels. For example, the tunable regulatory region is a ROS-inducible regulatory region, and the molecule is a payload; when ROS is present, e.g., in an inflamed tissue, a ROS-sensing transcription factor binds to and/or activates the regulatory region and drives expression of the gene sequence for the payload, thereby producing the payload. Subsequently, when inflammation is ameliorated, ROS levels are reduced, and production of the payload is decreased or eliminated. 
     In some embodiments, the tunable regulatory region is a ROS-inducible regulatory region; in the presence of ROS, a transcription factor senses ROS and activates the ROS-inducible regulatory region, thereby driving expression of an operatively linked gene or gene cassette. In some embodiments, the transcription factor senses ROS and subsequently binds to the ROS-inducible regulatory region, thereby activating downstream gene expression. In alternate embodiments, the transcription factor is bound to the ROS-inducible regulatory region in the absence of ROS; when the transcription factor senses ROS, it undergoes a conformational change, thereby inducing downstream gene expression. 
     In some embodiments, the tunable regulatory region is a ROS-inducible regulatory region, and the transcription factor that senses ROS is OxyR. OxyR “functions primarily as a global regulator of the peroxide stress response” and is capable of regulating dozens of genes, e.g., “genes involved in H2O2 detoxification (katE, ahpCF), heme biosynthesis (hem H), reductant supply (grxA, gor, trxC), thiol-disulfide isomerization (dsbG), Fe—S center repair (sufA-E, sufS), iron binding (yaaA), repression of iron import systems (fur)” and “OxyS, a small regulatory RNA” (Dubbs et al., 2012). The genetically engineered bacteria may comprise any suitable ROS-responsive regulatory region from a gene that is activated by OxyR. Genes that are capable of being activated by OxyR are known in the art (see, e.g., Zheng et al., 2001; Dubbs et al., 2012). In certain embodiments, the genetically engineered bacteria of the invention comprise a ROS-inducible regulatory region from oxyS that is operatively linked to a gene, e.g., a payload gene. In the presence of ROS, e.g., H2O2, an OxyR transcription factor senses ROS and activates to the oxyS regulatory region, thereby driving expression of the operatively linked payload gene and producing the payload. In some embodiments, OxyR is encoded by an  E. coli  oxyR gene. In some embodiments, the oxyS regulatory region is an  E. coli  oxyS regulatory region. In some embodiments, the ROS-inducible regulatory region is selected from the regulatory region of katG, dps, and ahpC. 
     In alternate embodiments, the tunable regulatory region is a ROS-inducible regulatory region, and the corresponding transcription factor that senses ROS is SoxR. When SoxR is “activated by oxidation of its [2Fe-2S] cluster, it increases the synthesis of SoxS, which then activates its target gene expression” (Koo et al., 2003). “SoxR is known to respond primarily to superoxide and nitric oxide” (Koo et al., 2003), and is also capable of responding to H2O2. The genetically engineered bacteria of the invention may comprise any suitable ROS-responsive regulatory region from a gene that is activated by SoxR. Genes that are capable of being activated by SoxR are known in the art (see, e.g., Koo et al., 2003). In certain embodiments, the genetically engineered bacteria of the invention comprise a ROS-inducible regulatory region from soxS that is operatively linked to a gene, e.g., a payload. In the presence of ROS, the SoxR transcription factor senses ROS and activates the soxS regulatory region, thereby driving expression of the operatively linked a payload gene and producing the a payload. 
     In some embodiments, the tunable regulatory region is a ROS-derepressible regulatory region, and binding of a corresponding transcription factor represses downstream gene expression; in the presence of ROS, the transcription factor no longer binds to the regulatory region, thereby derepressing the operatively linked gene or gene cassette. 
     In some embodiments, the tunable regulatory region is a ROS-derepressible regulatory region, and the transcription factor that senses ROS is OhrR. OhrR “binds to a pair of inverted repeat DNA sequences overlapping the ohrA promoter site and thereby represses the transcription event,” but oxidized OhrR is “unable to bind its DNA target” (Duarte et al., 2010). OhrR is a “transcriptional repressor [that] . . . senses both organic peroxides and NaOCl” (Dubbs et al., 2012) and is “weakly activated by H2O2 but it shows much higher reactivity for organic hydroperoxides” (Duarte et al., 2010). The genetically engineered bacteria of the invention may comprise any suitable ROS-responsive regulatory region from a gene that is repressed by OhrR. Genes that are capable of being repressed by OhrR are known in the art (see, e.g., Dubbs et al., 2012). In certain embodiments, the genetically engineered bacteria of the invention comprise a ROS-derepressible regulatory region from ohrA that is operatively linked to a gene or gene cassette, e.g., a payload gene. In the presence of ROS, e.g., NaOCl, an OhrR transcription factor senses ROS and no longer binds to the ohrA regulatory region, thereby derepressing the operatively linked payload gene and producing the payload. 
     OhrR is a member of the MarR family of ROS-responsive regulators. “Most members of the MarR family are transcriptional repressors and often bind to the −10 or −35 region in the promoter causing a steric inhibition of RNA polymerase binding” (Bussmann et al., 2010). Other members of this family are known in the art and include, but are not limited to, OspR, MgrA, RosR, and SarZ. In some embodiments, the transcription factor that senses ROS is OspR, MgRA, RosR, and/or SarZ, and the genetically engineered bacteria of the invention comprises one or more corresponding regulatory region sequences from a gene that is repressed by OspR, MgRA, RosR, and/or SarZ. Genes that are capable of being repressed by OspR, MgRA, RosR, and/or SarZ are known in the art (see, e.g., Dubbs et al., 2012). 
     In some embodiments, the tunable regulatory region is a ROS-derepressible regulatory region, and the corresponding transcription factor that senses ROS is RosR. RosR is “a MarR-type transcriptional regulator” that binds to an “18-bp inverted repeat with the consensus sequence TTGTTGAYRYRTCAACWA” (SEQ ID NO: 122) and is “reversibly inhibited by the oxidant H2O2” (Bussmann et al., 2010). RosR is capable of repressing numerous genes and putative genes, including but not limited to “a putative polyisoprenoid-binding protein (cg1322, gene upstream of and divergent from rosR), a sensory histidine kinase (cgtS9), a putative transcriptional regulator of the Crp/FNR family (cg3291), a protein of the glutathione S-transferase family (cg1426), two putative FMN reductases (cg1150 and cg1850), and four putative monooxygenases (cg0823, cg1848, cg2329, and cg3084)” (Bussmann et al., 2010). The genetically engineered bacteria of the invention may comprise any suitable ROS-responsive regulatory region from a gene that is repressed by RosR. Genes that are capable of being repressed by RosR are known in the art (see, e.g., Bussmann et al., 2010). In certain embodiments, the genetically engineered bacteria of the invention comprise a ROS-derepressible regulatory region from cgtS9 that is operatively linked to a gene or gene cassette, e.g., a payload. In the presence of ROS, e.g., H2O2, a RosR transcription factor senses ROS and no longer binds to the cgtS9 regulatory region, thereby derepressing the operatively linked payload gene and producing the payload. 
     In some embodiments, it is advantageous for the genetically engineered bacteria to express a ROS-sensing transcription factor that does not regulate the expression of a significant number of native genes in the bacteria. In some embodiments, the genetically engineered bacterium of the invention expresses a ROS-sensing transcription factor from a different species, strain, or substrain of bacteria, wherein the transcription factor does not bind to regulatory sequences in the genetically engineered bacterium of the invention. In some embodiments, the genetically engineered bacterium of the invention is  Escherichia coli , and the ROS-sensing transcription factor is RosR, e.g., from  Corynebacterium glutamicum , wherein the  Escherichia coli  does not comprise binding sites for said RosR. In some embodiments, the heterologous transcription factor minimizes or eliminates off-target effects on endogenous regulatory regions and genes in the genetically engineered bacteria. 
     In some embodiments, the tunable regulatory region is a ROS-repressible regulatory region, and binding of a corresponding transcription factor represses downstream gene expression; in the presence of ROS, the transcription factor senses ROS and binds to the ROS-repressible regulatory region, thereby repressing expression of the operatively linked gene or gene cassette. In some embodiments, the ROS-sensing transcription factor is capable of binding to a regulatory region that overlaps with part of the promoter sequence. In alternate embodiments, the ROS-sensing transcription factor is capable of binding to a regulatory region that is upstream or downstream of the promoter sequence. 
     In some embodiments, the tunable regulatory region is a ROS-repressible regulatory region, and the transcription factor that senses ROS is PerR. In  Bacillus subtilis , PerR “when bound to DNA, represses the genes coding for proteins involved in the oxidative stress response (katA, ahpC, and mrgA), metal homeostasis (hemAXCDBL, fur, and zoaA) and its own synthesis (perR)” (Marinho et al., 2014). PerR is a “global regulator that responds primarily to H2O2” (Dubbs et al., 2012) and “interacts with DNA at the per box, a specific palindromic consensus sequence (TTATAATNATTATAA) (SEQ ID NO: 123) residing within and near the promoter sequences of PerR-controlled genes” (Marinho et al., 2014). PerR is capable of binding a regulatory region that “overlaps part of the promoter or is immediately downstream from it” (Dubbs et al., 2012). The genetically engineered bacteria of the invention may comprise any suitable ROS-responsive regulatory region from a gene that is repressed by PerR. Genes that are capable of being repressed by PerR are known in the art (see, e.g., Dubbs et al., 2012). 
     In these embodiments, the genetically engineered bacteria may comprise a two repressor activation regulatory circuit, which is used to express a payload. The two repressor activation regulatory circuit comprises a first ROS-sensing repressor, e.g., PerR, and a second repressor, e.g., TetR, which is operatively linked to a gene or gene cassette, e.g., a payload. In one aspect of these embodiments, the ROS-sensing repressor inhibits transcription of the second repressor, which inhibits the transcription of the gene or gene cassette. Examples of second repressors useful in these embodiments include, but are not limited to, TetR, C1, and LexA. In some embodiments, the ROS-sensing repressor is PerR. In some embodiments, the second repressor is TetR. In this embodiment, a PerR-repressible regulatory region drives expression of TetR, and a TetR-repressible regulatory region drives expression of the gene or gene cassette, e.g., a payload. In the absence of PerR binding (which occurs in the absence of ROS), tetR is transcribed, and TetR represses expression of the gene or gene cassette, e.g., a payload. In the presence of PerR binding (which occurs in the presence of ROS), tetR expression is repressed, and the gene or gene cassette, e.g., a payload, is expressed. 
     A ROS-responsive transcription factor may induce, derepress, or repress gene expression depending upon the regulatory region sequence used in the genetically engineered bacteria. For example, although “OxyR is primarily thought of as a transcriptional activator under oxidizing conditions . . . OxyR can function as either a repressor or activator under both oxidizing and reducing conditions” (Dubbs et al., 2012), and OxyR “has been shown to be a repressor of its own expression as well as that of fhuF (encoding a ferric ion reductase) and flu (encoding the antigen 43 outer membrane protein)” (Zheng et al., 2001). The genetically engineered bacteria of the invention may comprise any suitable ROS-responsive regulatory region from a gene that is repressed by OxyR. In some embodiments, OxyR is used in a two repressor activation regulatory circuit, as described above. Genes that are capable of being repressed by OxyR are known in the art (see, e.g., Zheng et al., 2001). Or, for example, although RosR is capable of repressing a number of genes, it is also capable of activating certain genes, e.g., the narKGHJI operon. In some embodiments, the genetically engineered bacteria comprise any suitable ROS-responsive regulatory region from a gene that is activated by RosR. In addition, “PerR-mediated positive regulation has also been observed . . . and appears to involve PerR binding to distant upstream sites” (Dubbs et al., 2012). In some embodiments, the genetically engineered bacteria comprise any suitable ROS-responsive regulatory region from a gene that is activated by PerR. 
     One or more types of ROS-sensing transcription factors and corresponding regulatory region sequences may be present in genetically engineered bacteria. For example, “OhrR is found in both Gram-positive and Gram-negative bacteria and can coreside with either OxyR or PerR or both” (Dubbs et al., 2012). In some embodiments, the genetically engineered bacteria comprise one type of ROS-sensing transcription factor, e.g., OxyR, and one corresponding regulatory region sequence, e.g., from oxyS. In some embodiments, the genetically engineered bacteria comprise one type of ROS-sensing transcription factor, e.g., OxyR, and two or more different corresponding regulatory region sequences, e.g., from oxyS and katG. In some embodiments, the genetically engineered bacteria comprise two or more types of ROS-sensing transcription factors, e.g., OxyR and PerR, and two or more corresponding regulatory region sequences, e.g., from oxyS and katA, respectively. One ROS-responsive regulatory region may be capable of binding more than one transcription factor. In some embodiments, the genetically engineered bacteria comprise two or more types of ROS-sensing transcription factors and one corresponding regulatory region sequence. 
     Nucleic acid sequences of several exemplary OxyR-regulated regulatory regions are shown in Table C. OxyR binding sites are underlined and bolded. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 63, 64, 65, or 66, or a functional fragment thereof. 
     
       
         
           
               
             
               
                 TABLE C 
               
             
            
               
                   
               
               
                 Nucleotide sequences of exemplary 
               
               
                 OxyR-regulated regulatory regions 
               
            
           
           
               
               
               
            
               
                   
                 Regulatory 
                   
               
               
                   
                 sequence 
                 Sequence 
               
               
                   
                   
               
               
                   
                 katG 
                 TGTGGCTTTTATGAAAATCACACAGTGATCACAAAT 
               
               
                   
                 (SEQ ID 
                 TTTAAACAGAGCACAAAATGCTGCCTCGAAATGAGG 
               
               
                   
                 NO: 63) 
                 GCGGGAAAATAAGGTTATCAGCCTTGTTTTCTCCCT 
               
               
                   
                   
                 CATTACTTGAAGGATATGAAGCTAAAACCCTTTTTT  
               
               
                   
                   
                 ATAAAGCATTTGTCCGAATTCGGACATAATCAAAAA 
               
               
                   
                   
                 AGCTTAATTAAGATCAATTTGATCTACATCTCTTTA 
               
               
                   
                   
                 ACCAACAATAT   GTAAGATCTCAACTATC   GCATC   CGT     
               
               
                   
                   
                     GGATTAATTCAATT   ATAACTTCTCTCTAACGCTGTG 
               
               
                   
                   
                 TATCGTAACGGTAACACTGTAGAGGGGAGCACATTG 
               
               
                   
                   
                 ATGCGAATTCATTAAAGAGGAGAAAGGTACC 
               
               
                   
                   
               
               
                   
                 dps 
                 TTCCGAAAATTCCTGGCGAGCAGATAAATAAGAATT 
               
               
                   
                 (SEQ ID 
                 GTTCTTATCAATATATCTAACTCATTGAATCTTTAT 
               
               
                   
                 NO: 64) 
                 TAGTTTTGTTTTTCA   CGCTTGTTACCACTATT   AGTG 
               
               
                   
                   
                 T   GATAGGAACAGCCAGAA   TAGCGGAACACATAGCCG 
               
               
                   
                   
                 GTGCTATACTTAATCTCGTTAATTACTGGGACATAA 
               
               
                   
                   
                 CATCAAGAGGATATGAAATTCGAATTCATTAAAGAG 
               
               
                   
                   
                 GAGAAAGGTACC 
               
               
                   
                   
               
               
                   
                 ahpC 
                 GCTTAGATCAGGTGATTGCCCTTTGTTTATGAGGGT 
               
               
                   
                 (SEQ ID 
                 GTTGTAATCCATGTCGTTGTTGCATTTGTAAGGGCA  
               
               
                   
                 NO: 65) 
                 ACACCTCAGCCTGCAGGCAGGCACTGAAGATACCAA  
               
               
                   
                   
                 AGGGTAGTTCAGATTACACGGTCACCTGGAAAGGGG  
               
               
                   
                   
                 GCCATTTTACTTTTTATCGCCGCTGGCGGTGCAAAG 
               
               
                   
                   
                 TTCACAAAGTTGTCTTACGAAGGTT   GTAAGGTAAAA     
               
               
                   
                   
                     CTTATC   GATTT   GATAATGGAAACGCATT   AGCCGAAT 
               
               
                   
                   
                 CGGCAAAAATTGGTTACCTTACATCTCATCGAAAAC 
               
               
                   
                   
                 ACGGAGGAAGTATAGATGCGAATTCATTAAAGAGGA 
               
               
                   
                   
                 GAAAGGTACC 
               
               
                   
                   
               
               
                   
                 oxyS 
                 CTCGAGTTCATTATCCATCCTCCATCGCCAC   GATAG     
               
               
                   
                 (SEQ ID 
                     TTCATGGCGATA   GGTAG   AATAGCAATGAACGATT   AT 
               
               
                   
                 NO: 66) 
                 CCCTATCAAGCATTCTGACTGATAATTGCTCACACG 
               
               
                   
                   
                 AATTCATTAAAGAGGAGAAAGGTACC 
               
               
                   
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria of the invention comprise a gene encoding a ROS-sensing transcription factor, e.g., the oxyR gene, that is controlled by its native promoter, an inducible promoter, a promoter that is stronger than the native promoter, e.g., the GlnRS promoter or the P(Bla) promoter, or a constitutive promoter. In some instances, it may be advantageous to express the ROS-sensing transcription factor under the control of an inducible promoter in order to enhance expression stability. In some embodiments, expression of the ROS-sensing transcription factor is controlled by a different promoter than the promoter that controls expression of the therapeutic molecule. In some embodiments, expression of the ROS-sensing transcription factor is controlled by the same promoter that controls expression of the therapeutic molecule. In some embodiments, the ROS-sensing transcription factor and therapeutic molecule are divergently transcribed from a promoter region. 
     In some embodiments, the genetically engineered bacteria of the invention comprise a gene for a ROS-sensing transcription factor from a different species, strain, or substrain of bacteria. In some embodiments, the genetically engineered bacteria comprise a ROS-responsive regulatory region from a different species, strain, or substrain of bacteria. In some embodiments, the genetically engineered bacteria comprise a ROS-sensing transcription factor and corresponding ROS-responsive regulatory region from a different species, strain, or substrain of bacteria. The heterologous ROS-sensing transcription factor and regulatory region may increase the transcription of genes operatively linked to said regulatory region in the presence of ROS, as compared to the native transcription factor and regulatory region from bacteria of the same subtype under the same conditions. 
     In some embodiments, the genetically engineered bacteria comprise a ROS-sensing transcription factor, OxyR, and corresponding regulatory region, oxyS, from  Escherichia coli . In some embodiments, the native ROS-sensing transcription factor, e.g., OxyR, is left intact and retains wild-type activity. In alternate embodiments, the native ROS-sensing transcription factor, e.g., OxyR, is deleted or mutated to reduce or eliminate wild-type activity. 
     In some embodiments, the genetically engineered bacteria of the invention comprise multiple copies of the endogenous gene encoding the ROS-sensing transcription factor, e.g., the oxyR gene. In some embodiments, the gene encoding the ROS-sensing transcription factor is present on a plasmid. In some embodiments, the gene encoding the ROS-sensing transcription factor and the gene or gene cassette for producing the therapeutic molecule are present on different plasmids. In some embodiments, the gene encoding the ROS-sensing transcription factor and the gene or gene cassette for producing the therapeutic molecule are present on the same. In some embodiments, the gene encoding the ROS-sensing transcription factor is present on a chromosome. In some embodiments, the gene encoding the ROS-sensing transcription factor and the gene or gene cassette for producing the therapeutic molecule are present on different chromosomes. In some embodiments, the gene encoding the ROS-sensing transcription factor and the gene or gene cassette for producing the therapeutic molecule are present on the same chromosome. 
     In some embodiments, the genetically engineered bacteria comprise a wild-type gene encoding a ROS-sensing transcription factor, e.g., the soxR gene, and a corresponding regulatory region, e.g., a soxS regulatory region, that is mutated relative to the wild-type regulatory region from bacteria of the same subtype. The mutated regulatory region increases the expression of the payload in the presence of ROS, as compared to the wild-type regulatory region under the same conditions. In some embodiments, the genetically engineered bacteria comprise a wild-type ROS-responsive regulatory region, e.g., the oxyS regulatory region, and a corresponding transcription factor, e.g., OxyR, that is mutated relative to the wild-type transcription factor from bacteria of the same subtype. The mutant transcription factor increases the expression of the payload in the presence of ROS, as compared to the wild-type transcription factor under the same conditions. In some embodiments, both the ROS-sensing transcription factor and corresponding regulatory region are mutated relative to the wild-type sequences from bacteria of the same subtype in order to increase expression of the payload in the presence of ROS. 
     In some embodiments, the gene or gene cassette for producing the payload is present on a plasmid and operably linked to a promoter that is induced by ROS. In some embodiments, the gene or gene cassette for producing the payload is present in the chromosome and operably linked to a promoter that is induced by ROS. In some embodiments, the gene or gene cassette for producing the payload is present on a chromosome and operably linked to a promoter that is induced by exposure to tetracycline. In some embodiments, the gene or gene cassette for producing the payload is present on a plasmid and operably linked to a promoter that is induced by exposure to tetracycline. In some embodiments, expression is further optimized by methods known in the art, e.g., by optimizing ribosomal binding sites, manipulating transcriptional regulators, and/or increasing mRNA stability. 
     In some embodiments, the genetically engineered bacteria may comprise multiple copies of the gene(s) capable of producing a payload(s). In some embodiments, the gene(s) capable of producing a payload(s) is present on a plasmid and operatively linked to a ROS-responsive regulatory region. In some embodiments, the gene(s) capable of producing a payload is present in a chromosome and operatively linked to a ROS-responsive regulatory region. 
     Thus, in some embodiments, the genetically engineered bacteria or genetically engineered virus produce one or more payloads under the control of an oxygen level-dependent promoter, a reactive oxygen species (ROS)-dependent promoter, or a reactive nitrogen species (RNS)-dependent promoter, and a corresponding transcription factor. 
     In some embodiments, the genetically engineered bacteria comprise a stably maintained plasmid or chromosome carrying a gene for producing a payload, such that the payload can be expressed in the host cell, and the host cell is capable of survival and/or growth in vitro, e.g., in medium, and/or in vivo. In some embodiments, a bacterium may comprise multiple copies of the gene encoding the payload. In some embodiments, the gene encoding the payload is expressed on a low-copy plasmid. In some embodiments, the low-copy plasmid may be useful for increasing stability of expression. In some embodiments, the low-copy plasmid may be useful for decreasing leaky expression under non-inducing conditions. In some embodiments, the gene encoding the payload is expressed on a high-copy plasmid. In some embodiments, the high-copy plasmid may be useful for increasing expression of the payload. In some embodiments, the gene encoding the payload is expressed on a chromosome. 
     In some embodiments, the bacteria are genetically engineered to include multiple mechanisms of action (MOAs), e.g., circuits producing multiple copies of the same product (e.g., to enhance copy number) or circuits performing multiple different functions. For example, the genetically engineered bacteria may include four copies of the gene encoding a particular payload inserted at four different insertion sites. Alternatively, the genetically engineered bacteria may include three copies of the gene encoding a particular payload inserted at three different insertion sites and three copies of the gene encoding a different payload inserted at three different insertion sites. 
     In some embodiments, under conditions where the payload is expressed, the genetically engineered bacteria of the disclosure produce at least about 1.5-fold, at least about 2-fold, at least about 10-fold, at least about 15-fold, at least about 20-fold, at least about 30-fold, at least about 50-fold, at least about 100-fold, at least about 200-fold, at least about 300-fold, at least about 400-fold, at least about 500-fold, at least about 600-fold, at least about 700-fold, at least about 800-fold, at least about 900-fold, at least about 1,000-fold, or at least about 1,500-fold more of the payload, and/or transcript of the gene(s) in the operon as compared to unmodified bacteria of the same subtype under the same conditions. 
     In some embodiments, quantitative PCR (qPCR) is used to amplify, detect, and/or quantify mRNA expression levels of the payload gene(s). Primers specific for payload the gene(s) may be designed and used to detect mRNA in a sample according to methods known in the art. In some embodiments, a fluorophore is added to a sample reaction mixture that may contain payload mRNA, and a thermal cycler is used to illuminate the sample reaction mixture with a specific wavelength of light and detect the subsequent emission by the fluorophore. The reaction mixture is heated and cooled to predetermined temperatures for predetermined time periods. In certain embodiments, the heating and cooling is repeated for a predetermined number of cycles. In some embodiments, the reaction mixture is heated and cooled to 90-100° C., 60-70° C., and 30-50° C. for a predetermined number of cycles. In a certain embodiment, the reaction mixture is heated and cooled to 93-97° C., 55-65° C., and 35-45° C. for a predetermined number of cycles. In some embodiments, the accumulating amplicon is quantified after each cycle of the qPCR. The number of cycles at which fluorescence exceeds the threshold is the threshold cycle (CT). At least one CT result for each sample is generated, and the CT result(s) may be used to determine mRNA expression levels of the payload gene(s). 
     In some embodiments, quantitative PCR (qPCR) is used to amplify, detect, and/or quantify mRNA expression levels of the payload gene(s). Primers specific for payload the gene(s) may be designed and used to detect mRNA in a sample according to methods known in the art. In some embodiments, a fluorophore is added to a sample reaction mixture that may contain payload mRNA, and a thermal cycler is used to illuminate the sample reaction mixture with a specific wavelength of light and detect the subsequent emission by the fluorophore. The reaction mixture is heated and cooled to predetermined temperatures for predetermined time periods. In certain embodiments, the heating and cooling is repeated for a predetermined number of cycles. In some embodiments, the reaction mixture is heated and cooled to 90-100° C., 60-70° C., and 30-50° C. for a predetermined number of cycles. In a certain embodiment, the reaction mixture is heated and cooled to 93-97° C., 55-65° C., and 35-45° C. for a predetermined number of cycles. In some embodiments, the accumulating amplicon is quantified after each cycle of the qPCR. The number of cycles at which fluorescence exceeds the threshold is the threshold cycle (CT). At least one CT result for each sample is generated, and the CT result(s) may be used to determine mRNA expression levels of the payload gene(s). 
     Multiple Mechanisms of Action 
     In some embodiments, the bacteria are genetically engineered to include multiple mechanisms of action (MoAs), e.g., circuits producing multiple copies of the same product or circuits performing multiple different functions. Examples of insertion sites include, but are not limited to, malE/K, insB/I, araC/BAD, lacZ, dapA, cea, and other shown in  FIG. 18 . For example, the genetically engineered bacteria may include four copies of argA fbr  inserted at four different insertion sites, e.g., malE/K, insB/I, araC/BAD, and lacZ. Alternatively, the genetically engineered bacteria may include three copies of argA fbr  inserted at three different insertion sites, e.g., malE/K, insB/I, and lacZ, and three mutant arginine regulons, e.g., two producing citrulline and one producing arginine, inserted at three different insertion sites dapA, cea, and araC/BAD. In some embodiments, the genetically engineered bacteria may include one or more ammonia conversion circuit(s) inserted at one or more different insertion sites and one or more additional circuits inserted at one or more other insertion sites. For example, the genetically engineered bacteria may include one or more copies of argA fbr  (and/or other ammonia conversion circuit(s)) inserted at one or more different insertion sites, and one or more gut barrier enhancing circuits, e.g., one or more butyrate production circuit(s) (or other gut barrier enhancing circuit(s)) at other insertion sites. In other exemplary embodiments, the genetically engineered bacteria may include one or more copies of argA fbr  and/or other ammonia conversion circuit(s)) inserted at one or more different insertion sites, and one or more GABA reducing circuits, e.g., GABA transport and/or GABA metabolic circuit(s), inserted at other insertion site(s). In other exemplary embodiments, the genetically engineered bacteria may include one or more copies of argA fbr  (and/or other ammonia conversion circuit(s)) inserted at one or more different insertion sites, and one or more manganese transport circuit(s) inserted at other insertion sites ( FIG. 47A ). In some embodiments, one or more ammonia conversion circuit(s) (e.g., argA fbr  and/or other ammonia conversion circuit(s)), one or more gut barrier enhancing circuit (e.g., butyrate, propionate, acetate biosynthetic circuit(s)), one or more GABA reducing circuit(s) (e.g., GABA transport and/or GABA metabolic circuit), and one or more manganese transport circuit(s) are inserted at four or more different chromosomal insertion sites (e.g.,  FIG. 45 ). In some embodiments, an ammonia conversion circuit, a gut barrier enhancing circuit, a GABA transport and/or GABA metabolic circuit are inserted at three different chromosomal insertion sites. In some embodiments, an ammonia conversion circuit, a GABA transport/metabolic circuit, and a manganese transport circuit are inserted at three different chromosomal insertion sites ( FIG. 46B ). In other embodiments, an ammonia conversion circuit, and a manganese transport circuit are inserted at two different chromosomal insertion sites ( FIG. 47A ). In still other embodiments, an ammonia conversion circuit, and a GABA transport and/or GABA metabolic circuit are inserted at two different chromosomal insertion sites. In still other embodiments, an ammonia conversion circuit, and a gut barrier enhancing circuit are inserted at two different chromosomal insertion sites. In still other embodiments, an ammonia conversion circuit, and a manganese reducing circuit are inserted at two different chromosomal insertion sites. 
     Table 14 lists non-limiting examples of embodiments of the disclosure. 
     
       
         
           
               
             
               
                 TABLE 14 
               
             
            
               
                   
               
               
                 Non-limiting examples of embodiments of the disclosure 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Code Name 
                 ARG box 
                 ArgR 
                 argA fb   
                 ThyA 
                 Antibiotic 
                 Other 
               
               
                   
               
            
           
           
               
            
               
                 Control Strains 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Strep 
                 none 
               
               
                 UCD103 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                   
               
               
                   
                   
                   
                   
                 ThyA 
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Kan 
                 none 
               
               
                 UCD107 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                   
               
               
                   
                   
                   
                   
                 ThyA 
                   
                   
               
            
           
           
               
            
               
                 ΔARG box 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 SYN- 
                 ΔARG box 
                 Wild type 
                 none 
                 Wild 
                 none 
                 none 
               
               
                 UCD101 
                   
                 ArgR 
                   
                 type 
                   
                   
               
               
                   
                   
                   
                   
                 ThyA 
                   
                   
               
               
                 SYN- 
                 ΔARG box 
                 Wild type 
                 tetracycline-  
                 Wild 
                 Amp 
                 none 
               
               
                 UCD102 
                   
                 ArgR 
                 inducible 
                 type 
                   
                   
               
               
                   
                   
                   
                 argA fbr  on a 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 low copy 
                   
                   
                   
               
               
                   
                   
                   
                 plasmid 
                   
                   
                   
               
               
                 SYN- 
                 ΔARG box 
                 Wild type 
                 tetracycline- 
                 Wild 
                 Amp, 
                 Inducible 
               
               
                 UCD104 
                   
                 ArgR 
                 inducible 
                 type 
                 Cam 
                 ArgG 
               
               
                   
                   
                   
                 arg fbr  on a 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 low copy 
                   
                   
                   
               
               
                   
                   
                   
                 plasmid 
                   
                   
                   
               
               
                   
                   
                   
                 (Amp) 
                   
                   
                   
               
               
                 SYN- 
                 ΔARG box 
                 Wild type 
                 tetracycline-  
                 Wild 
                 Amp 
                 constitutively 
               
               
                 UCD105 
                   
                 ArgR 
                 inducible 
                 type 
                   
                 expressed 
               
               
                   
                   
                   
                 arg fbr  on a 
                 ThyA 
                   
                 argG 
               
               
                   
                   
                   
                 low copy 
                   
                   
                 (BBa_J23100 
               
               
                   
                   
                   
                 plasmid 
                   
                   
                 constitutive 
               
               
                   
                   
                   
                 (Amp) 
                   
                   
                 promoter) 
               
            
           
           
               
            
               
                 ΔArgR 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 Cam 
                 none 
               
               
                 UCD106 
                 ARG Box 
                   
                   
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 none 
                 none 
               
               
                 UCD201/ 
                 ARG Box 
                   
                   
                 type 
                   
                   
               
               
                 SYN- 
                   
                   
                   
                 ThyA 
                   
                   
               
               
                 UCD312 
                   
                   
                   
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 tetracycline-  
                 Wild 
                 Amp 
                 none 
               
               
                 UCD202 
                 ARG Box 
                   
                 inducible 
                 type 
                   
                   
               
               
                   
                   
                   
                 argAfbr on a 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 high-copy 
                   
                   
                   
               
               
                   
                   
                   
                 plasmid 
                   
                   
                   
               
               
                   
                   
                   
                 (Amp) 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 tetracycline-  
                 Wild 
                 Amp 
                 none 
               
               
                 UCD203 
                 ARG Box 
                   
                 inducible 
                 type 
                   
                   
               
               
                   
                   
                   
                 argAfbr on a 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 low-copy 
                   
                   
                   
               
               
                   
                   
                   
                 plasmid 
                   
                   
                   
               
               
                   
                   
                   
                 (Amp) 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 tet-ArgAfbr 
                 Wild 
                 Amp 
                 none 
               
               
                 UCD204 
                 ARG Box 
                   
                 on a low- 
                 type 
                   
                   
               
               
                   
                   
                   
                 copy plasmid 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 (Amp) 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 Amp 
                 none 
               
               
                 UCD205 
                 ARG Box 
                   
                 ArgAfbr on a 
                 type 
                   
                   
               
               
                   
                   
                   
                 low-copy 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 plasmid 
                   
                   
                   
               
               
                   
                   
                   
                 (Amp) 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 Amp, 
                 none 
               
               
                 UCD206 
                 ARG Box 
                   
                 ArgAfbr on a 
                   
                 Cam 
                   
               
               
                   
                   
                   
                 low-copy 
                   
                   
                   
               
               
                   
                   
                   
                 plasmid 
                   
                   
                   
               
               
                   
                   
                   
                 (Amp) 
                   
                   
                   
               
            
           
           
               
            
               
                 Integrated FNRS-argAfbr 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 Cam 
                 none 
               
               
                 UCD301 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                   
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 Cam 
                 none 
               
               
                 UCD302 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                   
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 Kan 
                 none 
               
               
                 UCD303 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                   
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 None 
                 none 
               
               
                 UCD305 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                   
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 None 
                 none 
               
               
                 UCD304 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                   
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 Kan 
                 none 
               
               
                 UCD306 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                   
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 ΔThyA 
                 Kan 
                 none 
               
               
                 UCD307 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                   
                   
                   
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 ΔThyA 
                 none 
                 none 
               
               
                 UCD308 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                   
                   
                   
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 Wild 
                 Kan 
                 none 
               
               
                 UCD309 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                 type 
                   
                   
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 Wild 
                 none 
                 none 
               
               
                 UCD310 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                 type 
                   
                   
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 Kan 
                 none 
               
               
                 UCD311 
                 ARG Box 
                   
                   
                 type 
                   
                   
               
               
                   
                   
                   
                   
                 ThyA 
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 none 
                 none 
               
               
                 UCD312/ 
                 ARG Box 
                   
                   
                 type 
                   
                   
               
               
                 SYN- 
                   
                   
                   
                 ThyA 
                   
                   
               
               
                 UCD201 
                   
                   
                   
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 Kan 
                 none 
               
               
                 UCD313 
                 ARG Box 
                   
                   
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 none 
                 none 
               
               
                 UCD314 
                 ARG Box 
                   
                   
                   
                   
                   
               
            
           
           
               
            
               
                 Rifaximin resistance 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 Kan 
                 Rifaximin 
               
               
                 UCD403 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                 resistance 
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 None 
                 Rifaximin 
               
               
                 UCD405 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                 resistance 
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 None 
                 Rifaximin 
               
               
                 UCD404 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                 resistance 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 Kan 
                 Rifaximin 
               
               
                 UCD406 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                 resistance 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 ΔThyA 
                 Kan 
                 Rifaximin 
               
               
                 UCD407 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                   
                   
                 resistance 
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 ΔThyA 
                 none 
                 Rifaximin 
               
               
                 UCD408 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                   
                   
                 resistance 
               
               
                   
                   
                   
                 integrated 
                   
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 Wild 
                 Kan 
                 Rifaximin 
               
               
                 UCD409 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                 type 
                   
                 resistance 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 Wild 
                 none 
                 Rifaximin 
               
               
                 UCD410 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                 type 
                   
                 resistance 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                   
               
               
                   
                   
                   
                 into the 
                   
                   
                   
               
               
                   
                   
                   
                 chromosome 
                   
                   
                   
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                   
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 Kan 
                 Rifaximin 
               
               
                 UCD411 
                 ARG Box 
                   
                   
                 type 
                   
                 resistance 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 none 
                 Rifaximin 
               
               
                 UCD412 
                 ARG Box 
                   
                   
                 type 
                   
                 resistance 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 Kan 
                 Rifaximin 
               
               
                 UCD413 
                 ARG Box 
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 none 
                 Rifaximin 
               
               
                 UCD414 
                 ARG Box 
                   
                   
                   
                   
                 resistance 
               
            
           
           
               
            
               
                 Butyrate Circuits 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 SYN- 
                 Wild type 
                 Wild 
                 none 
                 Wild 
                 Amp 
                 Log ic156 
               
               
                 UCD500 
                 ARG Box 
                 type 
                   
                 type 
                   
                 (pSC101 
               
               
                   
                   
                 ArgR 
                   
                 ThyA 
                   
                 PydfZ-Bcd 
               
               
                   
                   
                   
                   
                   
                   
                 butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 plasmid; amp 
               
               
                   
                   
                   
                   
                   
                   
                 resistance) 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Amp 
                 Logic156 
               
               
                 UCD501 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 (pSC101 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 PydfZ-ter 
               
               
                   
                   
                   
                   
                   
                   
                 butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 plasmid; amp 
               
               
                   
                   
                   
                   
                   
                   
                 resistance) 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 None 
                 PydfZ-ter 
               
               
                 UCD502 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Amp 
                 pLogic031 
               
               
                 UCD503 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 (bdc2 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette under 
               
               
                   
                   
                   
                   
                   
                   
                 control of tet 
               
               
                   
                   
                   
                   
                   
                   
                 promoter on a 
               
               
                   
                   
                   
                   
                   
                   
                 plasmid) 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 None 
                 pLogic046 (ter 
               
               
                 UCD504 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette under 
               
               
                   
                   
                   
                   
                   
                   
                 control of tet 
               
               
                   
                   
                   
                   
                   
                   
                 promoter on a 
               
               
                   
                   
                   
                   
                   
                   
                 plasmid) 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Amp 
                 pLOGIC046- 
               
               
                 UCD505 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 delta.pbt- 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 buk/tesB+ 
               
               
                   
                   
                   
                   
                   
                   
                 (tesB butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 cassette under 
               
               
                   
                   
                   
                   
                   
                   
                 control of tet 
               
               
                   
                   
                   
                   
                   
                   
                 promoter on a 
               
               
                   
                   
                   
                   
                   
                   
                 plasmid) 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Amp 
                 Logic156 
               
               
                 UCD506 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 (pSC101 nirB- 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 Bcd butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 plasmid; amp 
               
               
                   
                   
                   
                   
                   
                   
                 resistance) 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Amp 
                 pLogic031- 
               
               
                 UCD507 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 nsrR-norB- 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 construct 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Amp 
                 pLogic046- 
               
               
                 UCD508 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 nsrR-norB- 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 construct 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 Amp 
                 tesB-butyrate 
               
               
                 UCD509 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control 
               
               
                   
                   
                   
                   
                   
                   
                 of FNR 
               
               
                   
                   
                   
                   
                   
                   
                 promoter 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 None 
                 pLogic031 
               
               
                 UCD510 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 (bdc2 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette under 
               
               
                   
                   
                   
                   
                   
                   
                 control of tet 
               
               
                   
                   
                   
                   
                   
                   
                 promoter on a 
               
               
                   
                   
                   
                   
                   
                   
                 plasmid); 
               
               
                   
                   
                   
                   
                   
                   
                 nuoB deletion 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 none 
                 Wild 
                 None 
                 pLogic046 (ter 
               
               
                 UCD511 
                 ARG Box 
                 ArgR 
                   
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette under 
               
               
                   
                   
                   
                   
                   
                   
                 control of tet 
               
               
                   
                   
                   
                   
                   
                   
                 promoter on a 
               
               
                   
                   
                   
                   
                   
                   
                 plasmid); 
               
               
                   
                   
                   
                   
                   
                   
                 nuoB deletion 
               
            
           
           
               
            
               
                 Butyrate and Ammonium Circuits 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 Amp 
                 Logic156 
               
               
                 UCD601 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                 (pSC101 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 PydfZ-ter 
               
               
                   
                   
                   
                 into the 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 plasmid; amp 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 resistance) 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD603 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 None 
                 PydfZ-ter 
               
               
                 UCD605 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 None 
                 PydfZ-ter 
               
               
                 UCD604 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD606 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 ΔThyA 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD607 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 ΔThyA 
                 none 
                 PydfZ-ter 
               
               
                 UCD608 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 Wild 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD609 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 Wild 
                 none 
                 PydfZ-ter 
               
               
                 UCD610 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 locus 
                   
                   
                   
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD611 
                 ARG Box 
                   
                   
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 none 
                 PydfZ-ter 
               
               
                 UCD612 
                 ARG Box 
                   
                   
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD613 
                 ARG Box 
                   
                   
                   
                   
                 butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 none 
                 PydfZ-ter 
               
               
                 UCD614 
                 ARG Box 
                   
                   
                   
                   
                 butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD703 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                 locus 
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 ΔThyA 
                 None 
                 PydfZ-ter 
               
               
                 UCD705 
                 ARG Box 
                   
                 ArgAfbr 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                 locus 
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 None 
                 PydfZ-ter 
               
               
                 UCD704 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                 locus 
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS- 
                 Wild 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD706 
                 ARG Box 
                   
                 ArgAfbr 
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                 locus 
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 ΔThyA 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD707 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                 locus 
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 ΔThyA 
                 none 
                 PydfZ-ter 
               
               
                 UCD708 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                   
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                 locus 
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 Wild 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD709 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                 locus 
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 Wild type 
                 PfnrS- 
                 Wild 
                 none 
                 PydfZ-ter 
               
               
                 UCD710 
                 ARG Box 
                 ArgR 
                 ArgAfbr 
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                 integrated 
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                 into the 
                   
                   
                 integrated on 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 the 
               
               
                   
                   
                   
                 at the malEK 
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                 locus 
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD711 
                 ARG Box 
                   
                   
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 none 
                 PydfZ-ter 
               
               
                 UCD712 
                 ARG Box 
                   
                   
                 type 
                   
                 butyrate 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 Kan 
                 PydfZ-ter 
               
               
                 UCD713 
                 ARG Box 
                   
                   
                   
                   
                 butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 none 
                 PydfZ-ter 
               
               
                 UCD714 
                 ARG Box 
                   
                   
                   
                   
                 butyrate 
               
               
                   
                   
                   
                   
                   
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated on 
               
               
                   
                   
                   
                   
                   
                   
                 the 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS-ArgAfbr  
                 ΔThyA 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD715 
                 ARG Box 
                   
                 integrated into 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 the 
                   
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS-ArgAfbr  
                 ΔThyA 
                 None 
                 tesB-butyrate 
               
               
                 UCD716 
                 ARG Box 
                   
                 integrated into 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 the 
                   
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS-ArgAfbr  
                 Wild 
                 None 
                 tesB-butyrate 
               
               
                 UCD717 
                 ARG Box 
                   
                 integrated into 
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                 the 
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS-ArgAfbr  
                 Wild 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD718 
                 ARG Box 
                   
                 integrated into 
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                 the 
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 Wild 
                 PfnrS-ArgAfbr 
                 ΔThyA 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD719 
                 ARG Box 
                 type 
                 integrated into  
                   
                   
                 cassette 
               
               
                   
                   
                 ArgR 
                 the 
                   
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 Wild 
                 PfnrS-ArgAfbr 
                 ΔThyA 
                 none 
                 tesB-butyrate 
               
               
                 UCD720 
                 ARG Box 
                 type 
                 integrated into  
                   
                   
                 cassette 
               
               
                   
                   
                 ArgR 
                 the 
                   
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 Wild 
                 PfnrS-ArgAfbr 
                 Wild 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD721 
                 ARG Box 
                 type 
                 integrated into  
                 type 
                   
                 cassette 
               
               
                   
                   
                 ArgR 
                 the 
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 Wild 
                 PfnrS-ArgAfbr 
                 Wild 
                 none 
                 tesB-butyrate 
               
               
                 UCD722 
                 ARG Box 
                 type 
                 integrated into  
                 type 
                   
                 cassette 
               
               
                   
                   
                 ArgR 
                 the 
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD723 
                 ARG Box 
                   
                   
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control of 
               
               
                   
                   
                   
                   
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 none 
                 tesB-butyrate 
               
               
                 UCD724 
                 ARG Box 
                   
                   
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control of 
               
               
                   
                   
                   
                   
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD725 
                 ARG Box 
                   
                   
                   
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control of 
               
               
                   
                   
                   
                   
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 none 
                 tesB-butyrate 
               
               
                 UCD726 
                 ARG Box 
                   
                   
                   
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control of 
               
               
                   
                   
                   
                   
                   
                   
                 FNR promoter 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS-ArgAfbr 
                 ΔThyA 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD727 
                 ARG Box 
                   
                 integrated into  
                   
                   
                 cassette 
               
               
                   
                   
                   
                 the 
                   
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS-ArgAfbr 
                 ΔThyA 
                 None 
                 tesB-butyrate 
               
               
                 UCD728 
                 ARG Box 
                   
                 integrated into 
                   
                   
                 cassette 
               
               
                   
                   
                   
                 the 
                   
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS-ArgAfbr 
                 Wild 
                 None 
                 tesB-butyrate 
               
               
                 UCD729 
                 ARG Box 
                   
                 integrated into 
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                 the 
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 PfnrS-ArgAfbr 
                 Wild 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD730 
                 ARG Box 
                   
                 integrated into 
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                 the 
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 Wild 
                 PfnrS-ArgAfbr 
                 ΔThyA 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD731 
                 ARG Box 
                 type 
                 integrated into  
                   
                   
                 cassette 
               
               
                   
                   
                 ArgR 
                 the 
                   
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 Wild 
                 PfnrS-ArgAfbr 
                 ΔThyA 
                 none 
                 tesB-butyrate 
               
               
                 UCD732 
                 ARG Box 
                 type 
                 integrated into  
                   
                   
                 cassette 
               
               
                   
                   
                 ArgR 
                 the 
                   
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 Wild 
                 PfnrS-ArgAfbr 
                 Wild 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD733 
                 ARG Box 
                 type 
                 integrated into  
                 type 
                   
                 cassette 
               
               
                   
                   
                 ArgR 
                 the 
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 Wild 
                 PfnrS-ArgAfbr 
                 Wild 
                 none 
                 tesB-butyrate 
               
               
                 UCD734 
                 ARG Box 
                 type 
                 integrated into 
                 type 
                   
                 cassette 
               
               
                   
                   
                 ArgR 
                 the 
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                 chromosome 
                   
                   
                 chromosome 
               
               
                   
                   
                   
                 at malEK 
                   
                   
                 under control of 
               
               
                   
                   
                   
                 locus 
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD735 
                 ARG Box 
                   
                   
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control of 
               
               
                   
                   
                   
                   
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 Wild 
                 none 
                 tesB-butyrate 
               
               
                 UCD736 
                 ARG Box 
                   
                   
                 type 
                   
                 cassette 
               
               
                   
                   
                   
                   
                 ThyA 
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control of 
               
               
                   
                   
                   
                   
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN- 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 Kan 
                 tesB-butyrate 
               
               
                 UCD737 
                 ARG Box 
                   
                   
                   
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control of 
               
               
                   
                   
                   
                   
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                 SYN-UCD38 
                 Wild type 
                 ΔArgR 
                 none 
                 ΔThyA 
                 none 
                 tesB-butyrate 
               
               
                   
                 ARG Box 
                   
                   
                   
                   
                 cassette 
               
               
                   
                   
                   
                   
                   
                   
                 integrated into 
               
               
                   
                   
                   
                   
                   
                   
                 chromosome 
               
               
                   
                   
                   
                   
                   
                   
                 under control of 
               
               
                   
                   
                   
                   
                   
                   
                 FNR promoter; 
               
               
                   
                   
                   
                   
                   
                   
                 Rifaximin 
               
               
                   
                   
                   
                   
                   
                   
                 resistance 
               
               
                   
               
            
           
         
       
     
     In some embodiments, butyrate production by the genetically engineered bacteria can be further enhanced by additional modifications. Butyrate production under anaerobic conditions depends on endogenous NADH pools. In some embodiments, the flux through the butyrate pathway may be enhanced by eliminating competing routes for NADH utilization. A non-limiting example is the mutation/deletion of frdA, which utilizes NADH to catalyze the conversion of phosphoenolpyruvate to succinate. In some embodiments, any of the genetically engineered bacteria described herein further comprise a mutation, which eliminates competing routes for NADH utilization, e.g., a mutation/deletion of frdA. 
     Secretion 
     In some embodiments, the genetically engineered bacteria further comprise a native secretion mechanism (e.g., gram positive bacteria) or non-native secretion mechanism (e.g., gram negative bacteria) that is capable of secreting the protein(s) of interest or therapeutic protein(s), from the bacterial cytoplasm. Many bacteria have evolved sophisticated secretion systems to transport substrates across the bacterial cell envelope. Substrates, such as small molecules, proteins, and DNA, may be released into the extracellular space or periplasm (such as the gut lumen or other space), injected into a target cell, or associated with the bacterial membrane. 
     In Gram-negative bacteria, secretion machineries may span one or both of the inner and outer membranes. In some embodiments, the genetically engineered bacteria further comprise a non-native double membrane-spanning secretion system. Double membrane-spanning secretion systems include, but are not limited to, the type I secretion system (T1SS), the type II secretion system (T2SS), the type III secretion system (T3SS), the type IV secretion system (T4SS), the type VI secretion system (T6SS), and the resistance-nodulation-division (RND) family of multi-drug efflux pumps (Pugsley 1993; Gerlach et al., 2007; Collinson et al., 2015; Costa et al., 2015; Reeves et al., 2015; WO2014138324A1, incorporated herein by reference). Examples of such secretion systems are shown in  FIGS. 69-73 . Mycobacteria, which have a Gram-negative-like cell envelope, may also encode a type VII secretion system (T7SS) (Stanley et al., 2003). With the exception of the T2SS, double membrane-spanning secretions generally transport substrates from the bacterial cytoplasm directly into the extracellular space or into the target cell. In contrast, the T2SS and secretion systems that span only the outer membrane may use a two-step mechanism, wherein substrates are first translocated to the periplasm by inner membrane-spanning transporters, and then transferred to the outer membrane or secreted into the extracellular space. Outer membrane-spanning secretion systems include, but are not limited to, the type V secretion or autotransporter system (T5SS), the curli secretion system, and the chaperone-usher pathway for pili assembly (Saier, 2006; Costa et al., 2015). 
     In some embodiments, the genetically engineered bacteria of the invention further comprise a type III or a type III-like secretion system (T3SS) from  Shigella, Salmonella, E. coli, Bivrio, Burkholderia, Yersinia, Chlamydia , or  Pseudomonas . The T3SS is capable of transporting a protein from the bacterial cytoplasm to the host cytoplasm through a needle complex. The T3SS may be modified to secrete the molecule from the bacterial cytoplasm, but not inject the molecule into the host cytoplasm. Thus, the molecule is secreted into the gut lumen or other extracellular space. In some embodiments, the genetically engineered bacteria comprise said modified T3SS and are capable of secreting the protein(s) of interest or therapeutic protein(s) from the bacterial cytoplasm. In some embodiments, the secreted molecule, such as a heterologous protein or peptide, e.g., the protein of interest or therapeutic protein, comprises a type III secretion sequence that allows the protein(s) of interest or therapeutic protein(s) to be secreted from the bacteria. 
     In some embodiments, a flagellar type III secretion pathway is used to secrete the molecule of interest. In some embodiments, an incomplete flagellum is used to secrete a therapeutic peptide of interest, by recombinantly fusing the peptide to an N-terminal flagellar secretion signal of a native flagellar component. In this manner, the intracellularly expressed chimeric peptide can be mobilized across the inner and outer membranes into the surrounding host environment. 
     In some embodiments, a Type V Autotransporter Secretion System is used to secrete the therapeutic peptide. Due to the simplicity of the machinery and capacity to handle relatively large protein fluxes, the Type V secretion system is attractive for the extracellular production of recombinant proteins. As shown in  FIG. 70 , a therapeutic peptide (star) can be fused to an N-terminal secretion signal, a linker, and the beta-domain of an autotransporter. The N-terminal signal sequence directs the protein to the SecA-YEG machinery which moves the protein across the inner membrane into the periplasm, followed by subsequent cleavage of the signal sequence. The Beta-domain is recruited to the Bam complex (‘Beta-barrel assembly machinery’) where the beta-domain is folded and inserted into the outer membrane as a beta-barrel structure. The therapeutic peptide, is threaded through the hollow pore of the beta-barrel structure ahead of the linker sequence. Once exposed to the extracellular environment, the therapeutic peptide, can be freed from the linker system by an autocatalytic cleavage (left side of Bam complex) or by targeting of a membrane-associated peptidase (black scissors; right side of Barn complex) to a complimentary protease cut site in the linker. Thus, in some embodiments, the secreted molecule, such as a heterologous protein or peptide, e.g., the protein of interest or therapeutic protein, comprises an N-terminal secretion signal, a linker, and beta-domain of an autotransporter so as to allow the molecule to be secreted from the bacteria. 
     In some embodiments, a Hemolysin-based Secretion System is used to secrete the molecule of interest. Type I Secretion systems offer the advantage of translocating their passenger peptide directly from the cytoplasm to the extracellular space, obviating the two-step process of other secretion types.  FIG. 71  shows the alpha-hemolysin (HlyA) of uropathogenic  Escherichia coli . This pathway uses HlyB, an ATP-binding cassette transporter; HlyD, a membrane fusion protein; and TolC, an outer membrane protein. The assembly of these three proteins forms a channel through both the inner and outer membranes. Natively, this channel is used to secrete HlyA, however, to secrete the therapeutic peptide of the present disclosure, the secretion signal-containing C-terminal portion of HlyA is fused to the C-terminal portion of a therapeutic peptide (star) to mediate secretion of this peptide. 
     In alternate embodiments, the genetically engineered bacteria further comprise a non-native single membrane-spanning secretion system. Single membrane-spanning exporters may act as a component of a secretion system, or may export substrates independently. Such exporters include, but are not limited to, ATP-binding cassette translocases, flagellum/virulence-related translocases, conjugation-related translocases, the general secretory system (e.g., the SecYEG complex in  E. coli ), the accessory secretory system in mycobacteria and several types of Gram-positive bacteria (e.g.,  Bacillus anthracis, Lactobacillus johnsonii, Corynebacterium glutamicum, Streptococcus gordonii, Staphylococcus aureus ), and the twin-arginine translocation (TAT) system (Saier, 2006; Rigel and Braunstein, 2008; Albiniak et al., 2013). It is known that the general secretory and TAT systems can both export substrates with cleavable N-terminal signal peptides into the periplasm, and have been explored in the context of biopharmaceutical production. The TAT system may offer particular advantages, however, in that it is able to transport folded substrates, thus eliminating the potential for premature or incorrect folding. In certain embodiments, the genetically engineered bacteria comprise a TAT or a TAT-like system and are capable of secreting the protein(s) of interest or therapeutic protein(s), from the bacterial cytoplasm. One of ordinary skill in the art would appreciate that the secretion systems disclosed herein may be modified to act in different species, strains, and subtypes of bacteria, and/or adapted to deliver different payloads. 
     In order to translocate a protein, e.g., therapeutic polypeptide, to the extracellular space, the polypeptide must first be translated intracellularly, mobilized across the inner membrane and finally mobilized across the outer membrane. Many effector proteins (e.g., therapeutic polypeptides)—particularly those of eukaryotic origin—contain disulphide bonds to stabilize the tertiary and quaternary structures. While these bonds are capable of correctly forming in the oxidizing periplasmic compartment with the help of periplasmic chaperones, in order to translocate the polypeptide across the outer membrane the disulphide bonds must be reduced and the protein unfolded again. 
     One way to secrete properly folded proteins in gram-negative bacteria-particularly those requiring disulphide bonds—is to target the periplasm in a bacterium with a destabilized outer membrane. In this manner the protein is mobilized into the oxidizing environment and allowed to fold properly. In contrast to orchestrated extracellular secretion systems, the protein is then able to escape the periplasmic space in a correctly folded form by membrane leakage. These “leaky” gram-negative mutants are therefore capable of secreting bioactive, properly disulphide-bonded polypeptides. In some embodiments, the genetically engineered bacteria have a “leaky” or destabilized outer membrane. Destabilizing the bacterial outer membrane to induce leakiness can be accomplished by deleting or mutagenizing genes responsible for tethering the outer membrane to the rigid peptidoglycan skeleton, including for example, lpp, ompC, ompA, ompF, tolA, toIB, pal, degS, degP, and nlpI. Lpp is the most abundant polypeptide in the bacterial cell existing at ˜500,000 copies per cell and functions as the primary ‘staple’ of the bacterial cell wall to the peptidoglycan. Silhavy, T. J., Kahne, D. &amp; Walker, S. The bacterial cell envelope. Cold Spring Harb Perspect Biol 2, a000414 (2010). TolA-PAL and OmpA complexes function similarly to Lpp and are other deletion targets to generate a leaky phenotype. Additionally, leaky phenotypes have been observed when periplasmic proteases are deactivated. The periplasm is very densely packed with protein and therefore encode several periplasmic proteins to facilitate protein turnover. Removal of periplasmic proteases such as degS, degP or nlpI can induce leaky phenotypes by promoting an excessive build-up of periplasmic protein. Mutation of the proteases can also preserve the effector polypeptide by preventing targeted degradation by these proteases. Moreover, a combination of these mutations may synergistically enhance the leaky phenotype of the cell without major sacrifices in cell viability. Thus, in some embodiments, the engineered bacteria have one or more deleted or mutated membrane genes. In some embodiments, the engineered bacteria have a deleted or mutated lpp gene. In some embodiments, the engineered bacteria have one or more deleted or mutated gene(s), selected from ompA, ompA, and ompF genes. In some embodiments, the engineered bacteria have one or more deleted or mutated gene(s), selected from tolA, toIB, and pal genes. in some embodiments, the engineered bacteria have one or more deleted or mutated periplasmic protease genes. In some embodiments, the engineered bacteria have one or more deleted or mutated periplasmic protease genes selected from degS, degP, and nlpI. In some embodiments, the engineered bacteria have one or more deleted or mutated gene(s), selected from lpp, ompA, ompA, ompF, tolA, toIB, pal, degS, degP, and nlpI genes. 
     To minimize disturbances to cell viability, the leaky phenotype can be made inducible by placing one or more membrane or periplasmic protease genes, e.g., selected from lpp, ompA, ompA, ompF, tolA, toIB, pal, degS, degP, and nlpI, under the control of an inducible promoter. For example, expression of lpp or other cell wall stability protein or periplasmic protease can be repressed in conditions where the therapeutic polypeptide needs to be delivered (secreted). For instance, under inducing conditions a transcriptional repressor protein or a designed antisense RNA can be expressed which reduces transcription or translation of a target membrane or periplasmic protease gene. Conversely, overexpression of certain peptides can result in a destabilized phenotype, e.g., overexpression of colicins or the third topological domain of TolA, wherein peptide overexpression can be induced in conditions in which the therapeutic polypeptide needs to be delivered (secreted). These sorts of strategies would decouple the fragile, leaky phenotypes from biomass production. Thus, in some embodiments, the engineered bacteria have one or more membrane and/or periplasmic protease genes under the control of an inducible promoter. 
     Table 15 and Table 16 list secretion systems for Gram positive bacteria and Gram negative bacteria. These can be used to secrete polypeptides, proteins of interest or therapeutic protein(s) from the engineered bacteria, which are reviewed in Milton H. Saier, Jr. Microbe/Volume 1, Number 9, 2006 “Protein Secretion Systems in Gram-Negative Bacteria Gram-negative bacteria possess many protein secretion-membrane insertion systems that apparently evolved independently”, the contents of which is herein incorporated by reference in its entirety. 
     
       
         
           
               
             
               
                 TABLE 15 
               
             
            
               
                   
               
               
                 Secretion systems for gram positive bacteria 
               
            
           
           
               
               
               
            
               
                   
                 Bacterial Strain 
                 Relevant Secretion System 
               
               
                   
                   
               
               
                   
                   C. novyi - NT  (Gram+) 
                 Sec pathway 
               
               
                   
                   
                 Twin arginine (TAT) pathway 
               
               
                   
                   C. butryicum  (Gram+) 
                 Sec pathway 
               
               
                   
                   
                 Twin-arginine (TAT) pathway 
               
               
                   
                   Listeria monocytogenes  (Gram+) 
                 Sec pathway 
               
               
                   
                   
                 Twin-arginine (TAT) pathway 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 16 
               
             
            
               
                   
               
               
                 Secretion Systems for Gram negative bacteria 
               
               
                 Protein secretary pathways (SP) in gram-negative bacteria and their descendants 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                   
                 # 
                   
               
               
                 Type 
                   
                   
                   
                   
                   
                 Proteins/ 
                 Energy 
               
               
                 (Abbreviation) 
                 Name 
                 TC# 2   
                 Bacteria 
                 Archaea 
                 Eukarya 
                 System 
                 Source 
               
               
                   
               
            
           
           
               
            
               
                 IMPS-Gram-negative bacterial inner membrane channel-forming translocases 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 ABC (SIP) 
                 ATP binding 
                 3.A.1 
                 + 
                 + 
                 + 
                 3-4 
                 ATP 
               
               
                   
                 cassette 
                   
                   
                   
                   
                   
                   
               
               
                   
                 translocase 
                   
                   
                   
                   
                   
                   
               
               
                 SEC (IISP) 
                 General 
                 3.A.5 
                 + 
                 + 
                 + 
                 ~12 
                 GTP 
               
               
                   
                 secretory 
                   
                   
                   
                   
                   
                 OR 
               
               
                   
                 translocase 
                   
                   
                   
                   
                   
                 ATP + 
               
               
                   
                   
                   
                   
                   
                   
                   
                 PMF 
               
               
                 Fla/Path 
                 Flagellum/ 
                 3.A.6 
                 + 
                 − 
                 − 
                 &gt;10 
                 ATP 
               
               
                 (IIISP) 
                 virulence-related 
                   
                   
                   
                   
                   
                   
               
               
                   
                 translocase 
                   
                   
                   
                   
                   
                   
               
               
                 Conj 
                 Conjugation- 
                 3.A.7 
                 + 
                 − 
                 − 
                 &gt;10 
                 ATP 
               
               
                 (IVSP) 
                 related 
                   
                   
                   
                   
                   
                   
               
               
                   
                 translocase 
                   
                   
                   
                   
                   
                   
               
               
                 Tat (IISP) 
                 Twin-arginine 
                 2.A.64 
                 + 
                 + 
                 + 
                 2-4 
                 PMF 
               
               
                   
                 targeting 
                   
                   
                   
                 (chloroplasts) 
                   
                   
               
               
                   
                 translocase 
                   
                   
                   
                   
                   
                   
               
               
                 Oxa1 
                 Cytochrome 
                 2.A.9 
                 + 
                 + 
                 + 
                 1 
                 None 
               
               
                 (YidC) 
                 oxidase 
                   
                   
                   
                 (mitochondria) 
                   
                 or 
               
               
                   
                 biogenesis 
                   
                   
                   
                   
                   
                 PMF 
               
               
                   
                 family 
                   
                   
                   
                 chloroplasts) 
                   
                   
               
               
                 MscL 
                 Large 
                 1.A.22 
                 + 
                 + 
                 + 
                 1 
                 None 
               
               
                   
                 conductance 
                   
                   
                   
                   
                   
                   
               
               
                   
                 mechanosensitive 
                   
                   
                   
                   
                   
                   
               
               
                   
                 channel family 
                   
                   
                   
                   
                   
                   
               
               
                 Holins 
                 Holin 
                 1.E.1•21 
                 + 
                 − 
                 − 
                 1 
                 None 
               
               
                   
                 functional 
                   
                   
                   
                   
                   
                   
               
               
                   
                 superfamily 
                   
                   
                   
                   
                   
                   
               
            
           
           
               
            
               
                 Eukaryotic Organelles 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 MPT 
                 Mitochondrial 
                 3.A.B 
                 − 
                 − 
                 + 
                 &gt;20 
                 ATP 
               
               
                   
                 protein 
                   
                   
                   
                 (mitochondrial) 
                   
                   
               
               
                   
                 translocase 
                   
                   
                   
                   
                   
                   
               
               
                 CEPT 
                 Chloroplast 
                 3.A.9 
                 (+) 
                 − 
                 + 
                 ≥3 
                 GTP 
               
               
                   
                 envelope 
                   
                   
                   
                 (chloroplasts) 
                   
                   
               
               
                   
                 protein 
                   
                   
                   
                   
                   
                   
               
               
                   
                 translocase 
                   
                   
                   
                   
                   
                   
               
               
                 BcI-2 
                 Eukaryotic Bc1- 
                 1.A.21 
                 − 
                 − 
                 + 
                 1? 
                 None 
               
               
                   
                 2 family 
                   
                   
                   
                   
                   
                   
               
               
                   
                 (programmed 
                   
                   
                   
                   
                   
                   
               
               
                   
                 cell death) 
                   
                   
                   
                   
                   
                   
               
            
           
           
               
            
               
                 Gram-negative bacterial outer membrane channel-forming translocases 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 MTB (IISP) 
                 Main terminal 
                 3.A.15 
                 + b   
                 − 
                 − 
                 ~14 
                 ATP; 
               
               
                   
                 branch of the 
                   
                   
                   
                   
                   
                 PMF 
               
               
                   
                 general 
                   
                   
                   
                   
                   
                   
               
               
                   
                 secretory 
                   
                   
                   
                   
                   
                   
               
               
                   
                 translocase 
                   
                   
                   
                   
                   
                   
               
               
                 FUP AT-1 
                 Fimbrial usher 
                 1.B.11 
                 + b   
                 − 
                 − 
                 1 
                 None 
               
               
                   
                 protein 
                   
                   
                   
                   
                   
                   
               
               
                   
                 Autotransporter-1 
                 1.B.12 
                 + b   
                   
                 − 
                 1 
                 None 
               
               
                 AT-2 OMF 
                 Autotransporter-2 
                 1.B.40 
                 + b   
                 − 
                 − 
                 1 
                 None 
               
               
                 (ISP) 
                   
                 1.B.17 
                 + b   
                   
                 +(?) 
                 1 
                 None 
               
               
                 TPS 
                   
                 1.B.20 
                 + 
                 − 
                 + 
                 1 
                 None 
               
               
                 Secretin 
                   
                 1.B.22 
                 + b   
                   
                 − 
                 1 
                 None 
               
               
                 (IISP and 
                   
                   
                   
                   
                   
                   
                   
               
               
                 IISP) 
                   
                   
                   
                   
                   
                   
                   
               
               
                 OmpIP 
                 Outer 
                 1.B.33 
                 + 
                 − 
                 + 
                 ≥4 
                 None? 
               
               
                   
                 membrane 
                   
                   
                   
                 (mitochondria; 
                   
                   
               
               
                   
                 insertion porin 
                   
                   
                   
                 chloroplasts) 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacterial comprise a native or non-native secretion system described herein for the secretion of therapeutic enzyme. In some embodiments, the secretion system is selected from the modified type III flagellar, type I (e.g., hemolysin secretion system), type II, type IV, type V, type VI, and type VII secretion systems, resistance-nodulation-division (RND) multi-drug efflux pumps, a single membrane secretion system, Sec and, TAT secretion systems. 
     In some embodiments, the therapeutic proteins secreted by the genetically engineered bacteria are modified to increase resistance to proteases, e.g. intestinal proteases. 
     In some embodiments, the one or more proteins of interest or therapeutic proteins for secretion are under the control of an inducible promoter, as described herein. In one example, the one or more proteins of interest or therapeutic proteins are under the control of the FNR promoter and are produced and secreted under anaerobic conditions. In some embodiments, the one or more proteins of interest or therapeutic proteins for secretion are under the control of a constitutive promoter. 
     In some embodiments in which the one or more proteins of interest or therapeutic proteins are secreted or exported from the microorganism, the engineered microorganism comprises gene sequence(s) that includes a secretion tag. In some embodiments, the one or more proteins of interest or therapeutic proteins include a “secretion tag” of either RNA or peptide origin to direct the one or more proteins of interest or therapeutic proteins to specific secretion systems. For example, a secretion tag for the Type I Hemolysin secretion system is encoded in the C-terminal 53 amino acids of the alpha hemolysin protein (HlyA). HlyA secretion signal. 
     HlyB inserts into inner membrane to form a pore, HlyD aligns HlyB with TolC (outer membrane pore) thereby forming a channel through inner and outer membrane. The C-terminal secretion tag can be removed by either an autocatalytic or protease-catalyzed e.g., OmpT cleavage thereby releasing the one or more proteins of interest or therapeutic proteins into the extracellular milieu. 
     The Type V Auto-secretion System utilizes an N-terminal Sec-dependent peptide tag (inner membrane) and C-terminal tag (outer-membrane). This uses Sec-system to get from cytoplasm to periplasm. C-terminal tag then inserts into the outer membrane forming a pore through which the “passenger protein” threads through. Once across the outer membrane, the passenger (anti-cancer molecule) is released from the membrane-embedded C-terminal tag by either an autocatalytic, intein-like mechanism or via a membrane-bound protease (I.e., OmpT). The N-terminal tag is removed by the Sec system. Thus, in some embodiments, the secretion system is able to remove this tag before secreting the one or more proteins of interest or therapeutic proteins, from the engineered bacteria. In the Type V auto-secretion-mediated secretion the N-terminal peptide secretion tag is removed upon translocation of the “passenger” peptide from the cytoplasm into the periplasmic compartment by the native Sec system. Further, once the auto-secretor is translocated across the outer membrane the C-terminal secretion tag can be removed by either an autocatalytic or protease-catalyzed e.g., OmpT cleavage thereby releasing the anti-cancer molecule(s) into the extracellular milieu. 
     In the Flagellar modified Type III Secretion, the tag is encoded in 5′untranslated region of the mRNA and thus there is no peptide tag to cleave/remove. This modified system does not contain the “syringe” portion and instead uses the basal body of the flagella structure as the pore to translocate across both membranes and out through the forming flagella. If the fliC/fliD genes (encoding the flagella “tail”/whip) are disrupted the flagella cannot fully form and this promotes overall secretion. In some embodiments, the tail portion can be removed entirely. In the Type III traditional secretion system, the basal body closely resembles the flagella, however, instead of a “tail”/whip, the traditional T3SS has a syringe to inject the passenger proteins into host cells. The secretion tag is encoded by an N-terminal peptide (lengths vary and there are several different tags, see PCT/US14/020972). The N-terminal tag is not removed from the polypeptides in this secretion system. 
     In some embodiments the one or more proteins of interest or therapeutic proteins contain expressed as fusion protein with the 53 amino acids of the C termini of alpha-hemolysin (hlyA) of  E. coli  CFT073 (C terminal secretion tag). 
     Essential Genes and Auxotrophs 
     As used herein, the term “essential gene” refers to a gene which is necessary to for cell growth and/or survival. Bacterial essential genes are well known to one of ordinary skill in the art, and can be identified by directed deletion of genes and/or random mutagenesis and screening (see, for example, Zhang and Lin, 2009, DEG 5.0, a database of essential genes in both prokaryotes and eukaryotes, Nucl. Acids Res., 37:D455-D458 and Gerdes et al., Essential genes on metabolic maps, Curr. Opin. Biotechnol., 17(5):448-456, the entire contents of each of which are expressly incorporated herein by reference). 
     An “essential gene” may be dependent on the circumstances and environment in which an organism lives. For example, a mutation of, modification of, or excision of an essential gene may result in the recombinant bacteria of the disclosure becoming an auxotroph. An auxotrophic modification is intended to cause bacteria to die in the absence of an exogenously added nutrient essential for survival or growth because they lack the gene(s) necessary to produce that essential nutrient. 
     Exemplary bacterial genes which may be disrupted or deleted to produce an auxotrophic strain are shown below. These include, but are not limited to, genes required for oligonucleotide synthesis, amino acid synthesis, and cell wall synthesis. 
     An auxotrophic modification is intended to cause bacteria to die in the absence of an exogenously added nutrient essential for survival or growth because they lack the gene(s) necessary to produce that essential nutrient. In some embodiments, any of the genetically engineered bacteria described herein also comprise a deletion or mutation in a gene required for cell survival and/or growth. In one embodiment, the essential gene is a DNA synthesis gene, for example, thyA. In another embodiment, the essential gene is a cell wall synthesis gene, for example, dapA. In yet another embodiment, the essential gene is an amino acid gene, for example, serA or MetA. Any gene required for cell survival and/or growth may be targeted, including but not limited to, cysE, glnA, ilvD, leuB, lysA, serA, metA, glyA, hisB, ilvA, pheA, proA, thrC, trpC, tyrA, thyA, uraA, dapA, dapB, dapD, dapE, dapF, flhD, metB, metC, proAB, and thiI, as long as the corresponding wild-type gene product is not produced in the bacteria. Table 17 lists depicts exemplary bacterial genes which may be disrupted or deleted to produce an auxotrophic strain. These include, but are not limited to, genes required for oligonucleotide synthesis, amino acid synthesis, and cell wall synthesis. 
     
       
         
           
               
             
               
                 TABLE 17 
               
             
            
               
                   
               
               
                 Non-limiting Examples of Bacterial Genes Useful for 
               
               
                 Generation of an Auxotroph 
               
            
           
           
               
               
               
               
            
               
                   
                 Amino Acid 
                 Oligonucleotide 
                 Cell Wall 
               
               
                   
                   
               
               
                   
                 cysE 
                 thyA 
                 dapA 
               
               
                   
                 glnA 
                 uraA 
                 dapB 
               
               
                   
                 ilvD 
                   
                 dapD 
               
               
                   
                 leuB 
                   
                 dapE 
               
               
                   
                 lysA 
                   
                 dapF 
               
               
                   
                 serA 
                   
                   
               
               
                   
                 metA 
                   
                   
               
               
                   
                 glyA 
                   
                   
               
               
                   
                 hisB 
                   
                   
               
               
                   
                 ilvA 
                   
                   
               
               
                   
                 pheA 
                   
                   
               
               
                   
                 proA 
                   
                   
               
               
                   
                 thrC 
                   
                   
               
               
                   
                 trpC 
                   
                   
               
               
                   
                 tyrA 
               
               
                   
                   
               
            
           
         
       
     
     Table 18 shows the survival of various amino acid auxotrophs in the mouse gut, as detected 24 hrs and 48 hrs post-gavage. These auxotrophs were generated using BW25113, a non-Nissle strain of  E. coli . 
     
       
         
           
               
             
               
                 TABLE 18 
               
             
            
               
                   
               
               
                 Survival of amino acid auxotrophs in the mouse gut 
               
            
           
           
               
               
               
               
               
            
               
                 Gene 
                 AA Auxotroph 
                 Pre-Gavage 
                 24 hours 
                 48 hours 
               
               
                   
               
               
                 argA 
                 Arginine 
                 Present 
                 Present 
                 Absent 
               
               
                 cysE 
                 Cysteine 
                 Present 
                 Present 
                 Absent 
               
               
                 glnA 
                 Glutamine 
                 Present 
                 Present 
                 Absent 
               
               
                 glyA 
                 Glycine 
                 Present 
                 Present 
                 Absent 
               
               
                 hisB 
                 Histidine 
                 Present 
                 Present 
                 Present 
               
               
                 ilvA 
                 Isoleucine 
                 Present 
                 Present 
                 Absent 
               
               
                 leuB 
                 Leucine 
                 Present 
                 Present 
                 Absent 
               
               
                 lysA 
                 Lysine 
                 Present 
                 Present 
                 Absent 
               
               
                 metA 
                 Methionine 
                 Present 
                 Present 
                 Present 
               
               
                 pheA 
                 Phenylalanine 
                 Present 
                 Present 
                 Present 
               
               
                 proA 
                 Proline 
                 Present 
                 Present 
                 Absent 
               
               
                 serA 
                 Serine 
                 Present 
                 Present 
                 Present 
               
               
                 thrC 
                 Threonine 
                 Present 
                 Present 
                 Present 
               
               
                 trpC 
                 Tryptophan 
                 Present 
                 Present 
                 Present 
               
               
                 tyrA 
                 Tyrosine 
                 Present 
                 Present 
                 Present 
               
               
                 ilvD 
                 Valine/Isoleucine/ 
                 Present 
                 Present 
                 Absent 
               
               
                   
                 Leucine 
                   
                   
                   
               
               
                 thyA 
                 Thiamine 
                 Present 
                 Absent 
                 Absent 
               
               
                 uraA 
                 Uracil 
                 Present 
                 Absent 
                 Absent 
               
               
                 flhD 
                 FlhD 
                 Present 
                 Present 
                 Present 
               
               
                   
               
            
           
         
       
     
     For example, thymine is a nucleic acid that is required for bacterial cell growth; in its absence, bacteria undergo cell death. The thyA gene encodes thimidylate synthetase, an enzyme that catalyzes the first step in thymine synthesis by converting dUMP to dTMP (Sat et al., 2003). In some embodiments, the bacterial cell of the disclosure is a thyA auxotroph in which the thyA gene is deleted and/or replaced with an unrelated gene. A thyA auxotroph can grow only when sufficient amounts of thymine are present, e.g., by adding thymine to growth media in vitro, or in the presence of high thymine levels found naturally in the human gut in vivo. In some embodiments, the bacterial cell of the disclosure is auxotrophic in a gene that is complemented when the bacterium is present in the mammalian gut. Without sufficient amounts of thymine, the thyA auxotroph dies. In some embodiments, the auxotrophic modification is used to ensure that the bacterial cell does not survive in the absence of the auxotrophic gene product (e.g., outside of the gut). 
     Diaminopimelic acid (DAP) is an amino acid synthetized within the lysine biosynthetic pathway and is required for bacterial cell wall growth (Meadow et al., 1959; Clarkson et al., 1971). In some embodiments, any of the genetically engineered bacteria described herein is a dapD auxotroph in which dapD is deleted and/or replaced with an unrelated gene. A dapD auxotroph can grow only when sufficient amounts of DAP are present, e.g., by adding DAP to growth media in vitro. Without sufficient amounts of DAP, the dapD auxotroph dies. In some embodiments, the auxotrophic modification is used to ensure that the bacterial cell does not survive in the absence of the auxotrophic gene product (e.g., outside of the gut). 
     In other embodiments, the genetically engineered bacterium of the present disclosure is a uraA auxotroph in which uraA is deleted and/or replaced with an unrelated gene. The uraA gene codes for UraA, a membrane-bound transporter that facilitates the uptake and subsequent metabolism of the pyrimidine uracil (Andersen et al., 1995). A uraA auxotroph can grow only when sufficient amounts of uracil are present, e.g., by adding uracil to growth media in vitro. Without sufficient amounts of uracil, the uraA auxotroph dies. In some embodiments, auxotrophic modifications are used to ensure that the bacteria do not survive in the absence of the auxotrophic gene product (e.g., outside of the gut). 
     In complex communities, it is possible for bacteria to share DNA. In very rare circumstances, an auxotrophic bacterial strain may receive DNA from a non-auxotrophic strain, which repairs the genomic deletion and permanently rescues the auxotroph. Therefore, engineering a bacterial strain with more than one auxotroph may greatly decrease the probability that DNA transfer will occur enough times to rescue the auxotrophy. In some embodiments, the genetically engineered bacteria of the invention comprise a deletion or mutation in two or more genes required for cell survival and/or growth. 
     Other examples of essential genes include, but are not limited to yhbV, yagG, hemB, secD, secF, ribD, ribE, thiL, dxs, ispA, dnaX, adk, hemH, lpxH, cysS, fold, rplT, infC, thrS, nadE, gapA, yeaZ, aspS, argS, pgsA, yefM, metG, folE, yejM, gyrA, nrdA, nrdB, folC, accD, fabB, gltX, ligA, zipA, dapE, dapA, der, hisS, ispG, suhB, tadA, acpS, era, mc, ftsB, eno, pyrG, chpR, lgt, fbaA, pgk, yqgD, metK, yqgF, plsC, ygiT, pare, ribB, cca, ygjD, tdcF, yraL, yihA, ftsN, murI, murB, birA, secE, nusG, rplJ, rplL, rpoB, rpoC, ubiA, plsB, lexA, dnaB, ssb, alsK, groS, psd, om, yjeE, rpsR, chpS, ppa, valS, yjgP, yjgQ, dnaC, ribF, IspA, ispH, dapB, folA, imp, yabQ, ftsL, ftsl, murE, murF, mraY, murD, ftsW, murG, murC, ftsQ, ftsA, ftsZ, lpxC, secM, secA, can, folk, hemL, yadR, dapD, map, rpsB, infB, nusA, ftsH, obgE, rpmA, rplU, ispB, murA, yrbB, yrbK, yhbN, rpsl, rplM, degS, mreD, mreC, mreB, accB, accC, yrdC, def, fmt, rplQ, rpoA, rpsD, rpsK, rpsM, entD, mrdB, mrdA, nadD, hlepB, rpoE, pssA, yfiO, rplS, trmD, rpsP, ffh, grpE, yfjB, csrA, ispF, ispD, rplVV, rplD, rplC, rpsJ, fusA, rpsG, rpsL, trpS, yrfF, asd, rpoH, ftsX, ftsE, ftsY, frr, dxr, ispU, rfaK, kdtA, coaD, rpmB, dfp, dut, gmk, spot, gyrB, dnaN, dnaA, rpmH, mpA, yidC, tnaB, glmS, glmU, wzyE, hemD, hemC, yigP, ubiB, ubiD, hemG, secY, rplO, rpmD, rpsE, rplR, rplF, rpsH, rpsN, rplE, rplX, rplN, rpsQ, rpmC, rplP, rpsC, rplV, rpsS, rplB, cdsA, yaeL, yaeT, IpxD, fabZ, IpxA, IpxB, dnaE, accA, tilS, proS, yafF, tsf, pyrH, olA, rlpB, leuS, Int, gInS, fldA, cydA, infA, cydC, ftsK, lolA, serS, rpsA, msbA, lpxK, kdsB, mukF, mukE, mukB, asnS, fabA, mviN, me, yceQ, fabD, fabG, acpP, tmk, holB, lolC, loID, lolE, purB, ymfK, minE, mind, pth, rsA, ispE, lolB, hemA, prfA, prmC, kdsA, topA, ribA, fabl, racR, dicA, ydfB, tyrS, rib C, ydiL, pheT, pheS, yhhQ, bcsB, glyQ, yibJ, and gpsA. Other essential genes are known to those of ordinary skill in the art. 
     In some embodiments, the genetically engineered bacterium of the present disclosure is a synthetic ligand-dependent essential gene (SLiDE) bacterial cell. SLiDE bacterial cells are synthetic auxotrophs with a mutation in one or more essential genes that only grow in the presence of a particular ligand (see Lopez and Anderson “Synthetic Auxotrophs with Ligand-Dependent Essential Genes for a BL21 (DE3 Biosafety Strain,”ACS Synthetic Biology (2015) DOI: 10.1021/acssynbio.5b00085, the entire contents of which are expressly incorporated herein by reference). 
     In some embodiments, the SLiDE bacterial cell comprises a mutation in an essential gene. In some embodiments, the essential gene is selected from the group consisting of pheS, dnaN, tyrS, metG, and adk. In some embodiments, the essential gene is dnaN comprising one or more of the following mutations: H191N, R240C, I317S, F319V, L340T, V347I, and S345C. In some embodiments, the essential gene is dnaN comprising the mutations H191N, R240C, I317S, F319V, L340T, V347I, and S345C. In some embodiments, the essential gene is pheS comprising one or more of the following mutations: F125G, P183T, P184A, R186A, and I188L. In some embodiments, the essential gene is pheS comprising the mutations F125G, P183T, P184A, R186A, and I188L. In some embodiments, the essential gene is tyrS comprising one or more of the following mutations: L36V, C38A, and F40G. In some embodiments, the essential gene is tyrS comprising the mutations L36V, C38A, and F40G. In some embodiments, the essential gene is metG comprising one or more of the following mutations: E45Q, N47R, I49G, and A51C. In some embodiments, the essential gene is metG comprising the mutations E45Q, N47R, I49G, and A51C. In some embodiments, the essential gene is adk comprising one or more of the following mutations: I4L, L5I, and L6G. In some embodiments, the essential gene is adk comprising the mutations I4L, L5I, and L6G. 
     In some embodiments, the genetically engineered bacterium is complemented by a ligand. In some embodiments, the ligand is selected from the group consisting of benzothiazole, indole, 2-aminobenzothiazole, indole-3-butyric acid, indole-3-acetic acid, and L-histidine methyl ester. For example, bacterial cells comprising mutations in metG (E45Q, N47R, I49G, and A51C) are complemented by benzothiazole, indole, 2-aminobenzothiazole, indole-3-butyric acid, indole-3-acetic acid or L-histidine methyl ester. Bacterial cells comprising mutations in dnaN (H191N, R240C, I317S, F319V, L340T, V347I, and S345C) are complemented by benzothiazole, indole or 2-aminobenzothiazole. Bacterial cells comprising mutations in pheS (F125G, P183T, P184A, R186A, and I188L) are complemented by benzothiazole or 2-aminobenzothiazole. Bacterial cells comprising mutations in tyrS (L36V, C38A, and F40G) are complemented by benzothiazole or 2-aminobenzothiazole. Bacterial cells comprising mutations in adk (I4L, L5I, and L6G) are complemented by benzothiazole or indole. 
     In some embodiments, the genetically engineered bacterium comprises more than one mutant essential gene that renders it auxotrophic to a ligand. In some embodiments, the bacterial cell comprises mutations in two essential genes. For example, in some embodiments, the bacterial cell comprises mutations in tyrS (L36V, C38A, and F40G) and metG (E45Q, N47R, I49G, and A51C). In other embodiments, the bacterial cell comprises mutations in three essential genes. For example, in some embodiments, the bacterial cell comprises mutations in tyrS (L36V, C38A, and F40G), metG (E45Q, N47R, I49G, and A51C), and pheS (F125G, P183T, P184A, R186A, and I188L). 
     In some embodiments, the genetically engineered bacterium is a conditional auxotroph whose essential gene(s) is replaced using the arabinose system, e.g., as shown in  FIG. 66 . 
     In some embodiments, the genetically engineered bacterium of the disclosure is an auxotroph and also comprises kill-switch circuitry, such as any of the kill-switch components and systems described herein. For example, the recombinant bacteria may comprise a deletion or mutation in an essential gene required for cell survival and/or growth, for example, in a DNA synthesis gene, for example, thyA, cell wall synthesis gene, for example, dapA and/or an amino acid gene, for example, serA or MetA and may also comprise a toxin gene that is regulated by one or more transcriptional activators that are expressed in response to an environmental condition(s) and/or signal(s) (such as the described arabinose system) or regulated by one or more recombinases that are expressed upon sensing an exogenous environmental condition(s) and/or signal(s) (such as the recombinase systems described herein and in  FIGS. 62-65 . Other embodiments are described in Wright et al., “GeneGuard: A Modular Plasmid System Designed for Biosafety,” ACS Synthetic Biology (2015) 4: 307-316, the entire contents of which are expressly incorporated herein by reference). In some embodiments, the genetically engineered bacterium of the disclosure is an auxotroph and also comprises kill-switch circuitry, such as any of the kill-switch components and systems described herein, as well as another biosecurity system, such a conditional origin of replication (Wright et al., 2015). 
     In other embodiments, auxotrophic modifications may also be used to screen for mutant bacteria that consume excess ammonia. In a more specific aspect, auxotrophic modifications may be used to screen for mutant bacteria that consume excess ammonia by overproducing arginine. As described herein, many genes involved in arginine metabolism are subject to repression by arginine via its interaction with ArgR. The astC gene promoter is unique in that the arginine-ArgR complex acts as a transcriptional activator, as opposed to a transcriptional repressor. AstC encodes succinylornithine aminotransferase, the third enzyme of the ammonia-producing arginine succinyltransferase (AST) pathway and the first of the astCADBE operon in  E. coli  (Schneider et al., 1998). In certain embodiments, the genetically engineered bacteria are auxotrophic for a gene, and express the auxotrophic gene product under the control of an astC promoter. In these embodiments, the auxotrophy is subject to a positive feedback mechanism and used to select for mutant bacteria which consume excess ammonia by overproducing arginine. A non-limiting example of a positive feedback auxotroph is shown in  FIGS. 60A and 60B . 
     Genetic Regulatory Circuits 
     In some embodiments, the genetically engineered bacteria comprise multilayered genetic regulatory circuits for expressing the constructs described herein (see, e.g., U.S. Provisional Application No. 62/184,811, incorporated herein by reference in its entirety). 
     In certain embodiments, the invention provides methods for selecting genetically engineered bacteria that overproduce arginine. In some embodiments, the invention provides methods for selecting genetically engineered bacteria that consume excess ammonia via an alternative metabolic pathway, e.g., a histidine biosynthesis pathway, a methionine biosynthesis pathway, a lysine biosynthesis pathway, an asparagine biosynthesis pathway, a glutamine biosynthesis pathway, and a tryptophan biosynthesis pathway. In some embodiments, the invention provides genetically engineered bacteria comprising a mutant arginine regulon and an ArgR-regulated two-repressor activation genetic regulatory circuit. The two-repressor activation genetic regulatory circuit is useful to screen for mutant bacteria that reduce ammonia or rescue an auxotroph. In some constructs, high levels of arginine and the resultant activation of ArgR by arginine can cause expression of a detectable label or an essential gene that is required for cell survival. 
     The two-repressor activation regulatory circuit comprises a first ArgR and a second repressor, e.g., the Tet repressor. In one aspect of these embodiments, ArgR inhibits transcription of a second repressor, which inhibits the transcription of a particular gene of interest, e.g., a detectable product, which may be used to screen for mutants that consume excess ammonia, and/or an essential gene that is required for cell survival. Any detectable product may be used, including but not limited to, luciferase, β-galactosidase, and fluorescent proteins such as GFP. In some embodiments, the second repressor is a Tet repressor protein (TetR). In this embodiment, an ArgR-repressible promoter comprising wild-type ARG boxes drives the expression of TetR, and a TetR-repressible promoter drives the expression of at least one gene of interest, e.g., GFP. In the absence of ArgR binding (which occurs at low arginine concentrations), tetR is transcribed, and TetR represses GFP expression. In the presence of ArgR binding (which occurs at high arginine concentrations), tetR expression is repressed, and GFP is generated. Examples of other second repressors useful in these embodiments include, but are not limited to, ArsR, AscG, LacI, CscR, DeoR, DgoR, FruR, GalR, GatR, CI, LexA, RafR, QacR, and PtxS (US20030166191). In some embodiments, the mutant arginine regulon comprising a switch is subjected to mutagenesis, and mutants that reduce ammonia by overproducing arginine are selected based upon the level of detectable product, e.g., by flow cytometry, fluorescence-activated cell sorting (FACS) when the detectable product fluoresces. 
     In some embodiments, the gene of interest is one required for survival and/or growth of the bacteria. Any such gene may be used, including but not limited to, cysE, glnA, ilvD, leuB, lysA, serA, metA, glyA, hisB, ilvA, pheA, proA, thrC, trpC, tyrA, thyA, uraA, dapA, dapB, dapD, dapE, dapF, flhD, metB, metC, proAB, and thiI, as long as the corresponding wild-type gene has been removed or mutated so as not to produce the gene product except under control of ArgR. In some embodiments, an ArgR-repressible promoter comprising wild-type ARG boxes drives the expression of a TetR protein, and a TetR-repressible promoter drives the expression of at least one gene required for survival and/or growth of the bacteria, e.g., thyA, uraA (Sat et al., 2003). In some embodiments, the genetically engineered bacterium is auxotrophic in a gene that is not complemented when the bacterium is present in the mammalian gut, wherein said gene is complemented by a second inducible gene present in the bacterium; transcription of the second gene is ArgR-repressible and induced in the presence of sufficiently high concentrations of arginine (thus complementing the auxotrophic gene). In some embodiments, the mutant arginine regulon comprising a two-repressor activation circuit is subjected to mutagenesis, and mutants that reduce excess ammonia are selected by growth in the absence of the gene product required for survival and/or growth. In some embodiments, the mutant arginine regulon comprising a two-repressor activation circuit is used to ensure that the bacteria do not survive in the absence of high levels of arginine (e.g., outside of the gut). 
     Host-Plasmid Mutual Dependency 
     In some embodiments, the genetically engineered bacteria of the invention also comprise a plasmid that has been modified to create a host-plasmid mutual dependency. In certain embodiments, the mutually dependent host-plasmid platform is GeneGuard (Wright et al., 2015). In some embodiments, the GeneGuard plasmid comprises (i) a conditional origin of replication, in which the requisite replication initiator protein is provided in trans; (ii) an auxotrophic modification that is rescued by the host via genomic translocation and is also compatible for use in rich media; and/or (iii) a nucleic acid sequence which encodes a broad-spectrum toxin. The toxin gene may be used to select against plasmid spread by making the plasmid DNA itself disadvantageous for strains not expressing the anti-toxin (e.g., a wild-type bacterium). In some embodiments, the GeneGuard plasmid is stable for at least 100 generations without antibiotic selection. In some embodiments, the GeneGuard plasmid does not disrupt growth of the host. The GeneGuard plasmid is used to greatly reduce unintentional plasmid propagation in the genetically engineered bacteria of the invention. 
     The mutually dependent host-plasmid platform may be used alone or in combination with other biosafety mechanisms, such as those described herein (e.g., kill switches, auxotrophies). In some embodiments, the genetically engineered bacteria comprise a GeneGuard plasmid. In other embodiments, the genetically engineered bacteria comprise a GeneGuard plasmid and/or one or more kill switches. In other embodiments, the genetically engineered bacteria comprise a GeneGuard plasmid and/or one or more auxotrophies. In still other embodiments, the genetically engineered bacteria comprise a GeneGuard plasmid, one or more kill switches, and/or one or more auxotrophies. 
     Synthetic gene circuits express on plasmids may function well in the short term but lose ability and/or function in the long term (Danino et al., 2015). In some embodiments, the genetically engineered bacteria comprise stable circuits for expressing genes of interest over prolonged periods. In some embodiments, the genetically engineered bacteria are capable of producing a gut enhancer molecule and further comprise a toxin-anti-toxin system that simultaneously produces a toxin (hok) and a short-lived anti-toxin (sok), wherein loss of the plasmid causes the cell to be killed by the long-lived toxin (Danino et al., 2015;  FIG. 68 ). In some embodiments, the genetically engineered bacteria further comprise alp7 from  B. subtilis  plasmid pL20 and produces filaments that are capable of pushing plasmids to the poles of the cells in order to ensure equal segregation during cell division (Danino et al., 2015). 
     Kill Switch 
     In some embodiments, the genetically engineered bacteria of the invention also comprise a kill switch (see, e.g., U.S. Provisional Application Nos. 62/183,935, 62/263,329, and 62/277,654, each of which is incorporated herein by reference in their entireties). The kill switch is intended to actively kill engineered microbes in response to external stimuli. As opposed to an auxotrophic mutation where bacteria die because they lack an essential nutrient for survival, the kill switch is triggered by a particular factor in the environment that induces the production of toxic molecules within the microbe that cause cell death. 
     Bacteria engineered with kill switches have been engineered for in vitro research purposes, e.g., to limit the spread of a biofuel-producing microorganism outside of a laboratory environment. Bacteria engineered for in vivo administration to treat a disease or disorder may also be programmed to die at a specific time after the expression and delivery of a heterologous gene or genes, for example, a therapeutic gene(s) or after the subject has experienced the therapeutic effect. For example, in some embodiments, the kill switch is activated to kill the bacteria after a period of time following oxygen level-dependent expression of arg Afbr . In some embodiments, the kill switch is activated in a delayed fashion following oxygen level-dependent expression of arg Afbr , for example, after the production of arginine or citrulline. Alternatively, the bacteria may be engineered to die after the bacteria has spread outside of a disease site. Specifically, it may be useful to prevent long-term colonization of subjects by the microorganism, spread of the microorganism outside the area of interest (for example, outside the gut) within the subject, or spread of the microorganism outside of the subject into the environment (for example, spread to the environment through the stool of the subject). Examples of such toxins that can be used in kill-switches include, but are not limited to, bacteriocins, lysins, and other molecules that cause cell death by lysing cell membranes, degrading cellular DNA, or other mechanisms. Such toxins can be used individually or in combination. The switches that control their production can be based on, for example, transcriptional activation (toggle switches; see, e.g., Gardner et al., 2000), translation (riboregulators), or DNA recombination (recombinase-based switches), and can sense environmental stimuli such as anaerobiosis or reactive oxygen species. These switches can be activated by a single environmental factor or may require several activators in AND, OR, NAND and NOR logic configurations to induce cell death. For example, an AND riboregulator switch is activated by tetracycline, isopropyl β-D-1-thiogalactopyranoside (IPTG), and arabinose to induce the expression of lysins, which permeabilize the cell membrane and kill the cell. IPTG induces the expression of the endolysin and holin mRNAs, which are then derepressed by the addition of arabinose and tetracycline. All three inducers must be present to cause cell death. Examples of kill switches are known in the art (Callura et al., 2010). In some embodiments, the kill switch is activated to kill the bacteria after a period of time following oxygen level-dependent expression of arg Afbr . In some embodiments, the kill switch is activated in a delayed fashion following oxygen level-dependent expression of argA fbr . 
     Kill-switches can be designed such that a toxin is produced in response to an environmental condition or external signal (e.g., the bacteria is killed in response to an external cue) or, alternatively designed such that a toxin is produced once an environmental condition no longer exists or an external signal is ceased. 
     Thus, in some embodiments, the genetically engineered bacteria of the disclosure are further programmed to die after sensing an exogenous environmental signal, for example, in a low-oxygen environment. In some embodiments, the genetically engineered bacteria of the present disclosure, e.g., bacteria expressing argA fbr  and repressor ArgR, comprise one or more genes encoding one or more recombinase(s), whose expression is induced in response to an environmental condition or signal and causes one or more recombination events that ultimately leads to the expression of a toxin which kills the cell. In some embodiments, the at least one recombination event is the flipping of an inverted heterologous gene encoding a bacterial toxin which is then constitutively expressed after it is flipped by the first recombinase. In one embodiment, constitutive expression of the bacterial toxin kills the genetically engineered bacterium. In these types of kill-switch systems once the engineered bacterial cell senses the exogenous environmental condition and expresses the heterologous gene of interest, the recombinant bacterial cell is no longer viable. 
     In another embodiment in which the genetically engineered bacteria of the present disclosure, e.g., bacteria expressing argA fbr  and repressor ArgR, express one or more recombinase(s) in response to an environmental condition or signal causing at least one recombination event, the genetically engineered bacterium further expresses a heterologous gene encoding an anti-toxin in response to an exogenous environmental condition or signal. In one embodiment, the at least one recombination event is flipping of an inverted heterologous gene encoding a bacterial toxin by a first recombinase. In one embodiment, the inverted heterologous gene encoding the bacterial toxin is located between a first forward recombinase recognition sequence and a first reverse recombinase recognition sequence. In one embodiment, the heterologous gene encoding the bacterial toxin is constitutively expressed after it is flipped by the first recombinase. In one embodiment, the anti-toxin inhibits the activity of the toxin, thereby delaying death of the genetically engineered bacterium. In one embodiment, the genetically engineered bacterium is killed by the bacterial toxin when the heterologous gene encoding the anti-toxin is no longer expressed when the exogenous environmental condition is no longer present. 
     In another embodiment, the at least one recombination event is flipping of an inverted heterologous gene encoding a second recombinase by a first recombinase, followed by the flipping of an inverted heterologous gene encoding a bacterial toxin by the second recombinase. In one embodiment, the inverted heterologous gene encoding the second recombinase is located between a first forward recombinase recognition sequence and a first reverse recombinase recognition sequence. In one embodiment, the inverted heterologous gene encoding the bacterial toxin is located between a second forward recombinase recognition sequence and a second reverse recombinase recognition sequence. In one embodiment, the heterologous gene encoding the second recombinase is constitutively expressed after it is flipped by the first recombinase. In one embodiment, the heterologous gene encoding the bacterial toxin is constitutively expressed after it is flipped by the second recombinase. In one embodiment, the genetically engineered bacterium is killed by the bacterial toxin. In one embodiment, the genetically engineered bacterium further expresses a heterologous gene encoding an anti-toxin in response to the exogenous environmental condition. In one embodiment, the anti-toxin inhibits the activity of the toxin when the exogenous environmental condition is present, thereby delaying death of the genetically engineered bacterium. In one embodiment, the genetically engineered bacterium is killed by the bacterial toxin when the heterologous gene encoding the anti-toxin is no longer expressed when the exogenous environmental condition is no longer present. 
     In one embodiment, the at least one recombination event is flipping of an inverted heterologous gene encoding a second recombinase by a first recombinase, followed by flipping of an inverted heterologous gene encoding a third recombinase by the second recombinase, followed by flipping of an inverted heterologous gene encoding a bacterial toxin by the third recombinase. 
     In one embodiment, the at least one recombination event is flipping of an inverted heterologous gene encoding a first excision enzyme by a first recombinase. In one embodiment, the inverted heterologous gene encoding the first excision enzyme is located between a first forward recombinase recognition sequence and a first reverse recombinase recognition sequence. In one embodiment, the heterologous gene encoding the first excision enzyme is constitutively expressed after it is flipped by the first recombinase. In one embodiment, the first excision enzyme excises a first essential gene. In one embodiment, the programmed recombinant bacterial cell is not viable after the first essential gene is excised. 
     In one embodiment, the first recombinase further flips an inverted heterologous gene encoding a second excision enzyme. In one embodiment, the wherein the inverted heterologous gene encoding the second excision enzyme is located between a second forward recombinase recognition sequence and a second reverse recombinase recognition sequence. In one embodiment, the heterologous gene encoding the second excision enzyme is constitutively expressed after it is flipped by the first recombinase. In one embodiment, the genetically engineered bacterium dies or is no longer viable when the first essential gene and the second essential gene are both excised. In one embodiment, the genetically engineered bacterium dies or is no longer viable when either the first essential gene is excised or the second essential gene is excised by the first recombinase. 
     In one embodiment, the genetically engineered bacterium dies after the at least one recombination event occurs. In another embodiment, the genetically engineered bacterium is no longer viable after the at least one recombination event occurs. 
     In any of these embodiment, the recombinase can be a recombinase selected from the group consisting of: BxbI, PhiC31, TP901, BxbI, PhiC31, TP901, HK022, HP1, R4, Int1, Int2, Int3, Int4, Int5, Int6, Int7, Int8, Int9, Int10, Int11, Int12, Int13, Int14, Int15, Int16, Int17, Int18, Int19, Int20, Int21, Int22, Int23, Int24, Int25, Int26, Int27, Int28, Int29, Int30, Int31, Int32, Int33, and Int34, or a biologically active fragment thereof. 
     In the above-described kill-switch circuits, a toxin is produced in the presence of an environmental factor or signal. In another aspect of kill-switch circuitry, a toxin may be repressed in the presence of an environmental factor (not produced) and then produced once the environmental condition or external signal is no longer present. An exemplary kill-switch in which the toxin is repressed in the presence of an external factor or signal (and activated once the external signal is removed) is shown in  FIGS. 66-68 . The disclosure provides recombinant bacterial cells which express one or more heterologous gene(s) upon sensing arabinose or other sugar in the exogenous environment. In this aspect, the recombinant bacterial cells contain the araC gene, which encodes the AraC transcription factor, as well as one or more genes under the control of the araBAD promoter. In the absence of arabinose, the AraC transcription factor adopts a conformation that represses transcription of genes under the control of the araBAD promoter. In the presence of arabinose, the AraC transcription factor undergoes a conformational change that allows it to bind to and activate the araBAD promoter, which induces expression of the desired gene, for example tetR, which represses expression of a toxin gene. In this embodiment, the toxin gene is repressed in the presence of arabinose or other sugar. In an environment where arabinose is not present, the tetR gene is not activated and the toxin is expressed, thereby killing the bacteria. The arabinose system can also be used to express an essential gene, in which the essential gene is only expressed in the presence of arabinose or other sugar and is not expressed when arabinose or other sugar is absent from the environment. 
     Thus, in some embodiments in which one or more heterologous gene(s) are expressed upon sensing arabinose in the exogenous environment, the one or more heterologous genes are directly or indirectly under the control of the araBAD promoter. In some embodiments, the expressed heterologous gene is selected from one or more of the following: a heterologous therapeutic gene, a heterologous gene encoding an anti-toxin, a heterologous gene encoding a repressor protein or polypeptide, for example, a TetR repressor, a heterologous gene encoding an essential protein not found in the bacterial cell, and/or a heterologous encoding a regulatory protein or polypeptide. 
     In some embodiments, the argA fbr  gene is directly or indirectly under the control of the araBAD promoter.  FIG. 13  depicts a schematic diagram of an exemplary BAD promoter-driven argA fbr  construct. In this embodiment, the argA fbr  gene is inserted between the araC and araD genes. ArgA fbr  is flanked by a ribosome binding site, a FRT site, and one or more transcription terminator sequences. The nucleic acid sequence of an exemplary BAD promoter-driven argA fbr  construct is shown in Table 19. All bolded sequences are Nissle genomic DNA. A portion of the araC gene is bolded and underlined, the argA fbr  gene is  , and the bolded sequence in between is the promoter that is activated by the presence of arabinose. The ribosome binding site is in italics, the terminator sequences are highlighted, and the FRT site is boxed. A portion of the araD gene is   in dashes. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the BAD promoter sequence of SEQ ID NO: 67 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise the BAD promoter sequence of SEQ ID NO: 67 or a functional fragment thereof. 
     
       
         
           
               
             
               
                 Table 19 
               
               
                   
               
               
                 Nucleotide sequence of exemplary BAD promoter-driven argA fbr   
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 (SEQ ID NO: 67) 
               
               
                 
                   
                     cgacggtggcgataggcatccgggtggtgctcaaaagcagcttcgcctgactgatgcgc 
                   
                 
               
               
                   
               
               
                 
                   
                     tggtcctcgcgccagcttaatacgctaatccctaactgctggcggaacaaatgcgacag 
                   
                 
               
               
                   
               
               
                 
                   
                     acgcgacggcgacaggcagacatgctgtgcgacgctggcgatatcaaaattactgtctg 
                   
                 
               
               
                   
               
               
                 
                   
                     ccaggtgatcgctgatgtactgacaagcctcgcgtacccgattatccatcggtggatgg 
                   
                 
               
               
                   
               
               
                 
                   
                     agcgactcgttaatcgcttccatgcgccgcagtaacaattgctcaagcagatttatcgc 
                   
                 
               
               
                   
               
               
                 
                   
                     cagcaattccgaatagcgcccttccccttgtccggcattaatgatttgcccaaacaggt 
                   
                 
               
               
                   
               
               
                 
                   
                     cgctgaaatgcggctggtgcgcttcatccgggcgaaagaaaccggtattggcaaatatc 
                   
                 
               
               
                   
               
               
                 
                   
                     gacggccagttaagccattcatgccagtaggcgcgcggacgaaagtaaacccactggtg 
                   
                 
               
               
                   
               
               
                 
                   
                     ataccattcgtgagcctccggatgacgaccgtagtgatgaatctctccaggcgggaaca 
                   
                 
               
               
                   
               
               
                 
                   
                     gcaaaatatcacccggtcggcagacaaattctcgtccctgatttttcaccaccccctga 
                   
                 
               
               
                   
               
               
                 
                   
                     ccgcgaatggtgagattgagaatataacctttcattcccagcggtcggtcgataaaaaa 
                   
                 
               
               
                   
               
               
                 
                   
                     atcgagataaccgttggcctcaatcggcgttaaacccgccaccagatgggcgttaaacg 
                   
                 
               
               
                   
               
               
                 
                   
                     agtatcccggcagcaggggatcattttgcgcttcagccatacttttcatactcccgcca 
                   
                 
               
               
                   
               
               
                 
                   
                     ttcagagaagaaaccaattgtccatattgcat 
                   
                   cagacattgccgtcactgcgtctttta 
                 
               
               
                   
               
               
                 
                   ctggctcttctcgctaacccaaccggtaaccccgcttattaaaagcattctgtaacaaa 
                 
               
               
                   
               
               
                 
                   gcgggaccaaagccatgacaaaaacgcgtaacaaaagtgtctataatcacggcagaaaa 
                 
               
               
                   
               
               
                 
                   gtccacattgattatttgcacggcgtcacactttgctatgccatagcatttttatccat 
                 
               
               
                   
               
               
                 
                   aagattagcggatccagcctgacgctttttttcgcaactctctactgtttctccata 
                   cc 
                 
               
               
                   
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 GGGAATTAGCCATGGTCCATATGAATATCCTCCTTAGTTCCTATTCC gaagttcctatt 
               
               
                   
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
            
           
         
       
     
     Arabinose inducible promoters are known in the art, including P ara , P araB , P araC , and P araBAD . In one embodiment, the arabinose inducible promoter is from  E. coli. In some embodiments, the P   araC  promoter and the P araBAD  promoter operate as a bidirectional promoter, with the P araBAD  promoter controlling expression of a heterologous gene(s) in one direction, and the P araC  (in close proximity to, and on the opposite strand from the P araBAD  promoter), controlling expression of a heterologous gene(s) in the other direction. In the presence of arabinose, transcription of both heterologous genes from both promoters is induced. However, in the absence of arabinose, transcription of both heterologous genes from both promoters is not induced. 
     In one exemplary embodiment of the disclosure, the engineered bacteria of the present disclosure contains a kill-switch having at least the following sequences: a P araBAD  promoter operably linked to a heterologous gene encoding a tetracycline repressor protein (TetR), a P araC  promoter operably linked to a heterologous gene encoding AraC transcription factor, and a heterologous gene encoding a bacterial toxin operably linked to a promoter which is repressed by the tetracycline repressor protein (P TetR ). In the presence of arabinose, the AraC transcription factor activates the P araBAD  promoter, which activates transcription of the TetR protein which, in turn, represses transcription of the toxin. In the absence of arabinose, however, AraC suppresses transcription from the the P araBAD  promoter and no TetR protein is expressed. In this case, expression of the heterologous toxin gene is activated, and the toxin is expressed. The toxin builds up in the recombinant bacterial cell, and the recombinant bacterial cell is killed. In one embodiment, the araC gene encoding the AraC transcription factor is under the control of a constitutive promoter and is therefore constitutively expressed. 
     In one embodiment of the disclosure, the recombinant bacterial cell further comprises an anti-toxin under the control of a constitutive promoter. In this situation, in the presence of arabinose, the toxin is not expressed due to repression by TetR protein, and the anti-toxin protein builds-up in the cell. However, in the absence of arabinose, TetR protein is not expressed, and expression of the toxin is induced. The toxin begins to build-up within the recombinant bacterial cell. The recombinant bacterial cell is no longer viable once the toxin protein is present at either equal or greater amounts than that of the anti-toxin protein in the cell, and the recombinant bacterial cell will be killed by the toxin. 
     In another embodiment of the disclosure, the recombinant bacterial cell further comprises an anti-toxin under the control of the P araBAD  promoter. In this situation, in the presence of arabinose, TetR and the anti-toxin are expressed, the anti-toxin builds up in the cell, and the toxin is not expressed due to repression by TetR protein. However, in the absence of arabinose, both the TetR protein and the anti-toxin are not expressed, and expression of the toxin is induced. The toxin begins to build-up within the recombinant bacterial cell. The recombinant bacterial cell is no longer viable once the toxin protein is expressed, and the recombinant bacterial cell will be killed by the toxin. 
     In another exemplary embodiment of the disclosure, the engineered bacteria of the present disclosure contain a kill-switch having at least the following sequences: a P araBAD  promoter operably linked to a heterologous gene encoding an essential polypeptide not found in the recombinant bacterial cell (and required for survival), and a P araC  promoter operably linked to a heterologous gene encoding the AraC transcription factor. In the presence of arabinose, the AraC transcription factor activates the P araBAD  promoter, which activates transcription of the heterologous gene encoding the essential polypeptide, allowing the recombinant bacterial cell to survive. In the absence of arabinose, however, AraC suppresses transcription from the the P araBAD  promoter and the essential protein required for survival is not expressed. In this case, the recombinant bacterial cell dies in the absence of arabinose. In some embodiments, the sequence of P araBAD  promoter operably linked to a heterologous gene encoding an essential polypeptide not found in the recombinant bacterial cell can be present in the bacterial cell in conjunction with the TetR/toxin kill-switch system described directly above. In some embodiments, the sequence of P araBAD  promoter operably linked to a heterologous gene encoding an essential polypeptide not found in the recombinant bacterial cell can be present in the bacterial cell in conjunction with the TetR/toxin/anti-toxin kill-switch system described directly above. 
     In yet other embodiments, the bacteria may comprise a plasmid stability system with a plasmid that produces both a short-lived anti-toxin and a long-lived toxin. In this system, the bacterial cell produces equal amounts of toxin and anti-toxin to neutralize the toxin. However, if/when the cell loses the plasmid, the short-lived anti-toxin begins to decay. When the anti-toxin decays completely the cell dies as a result of the longer-lived toxin killing it. 
     In some embodiments, the engineered bacteria of the present disclosure, for example, bacteria expressing argA fbr  and repressor ArgR further comprise the gene(s) encoding the components of any of the above-described kill-switch circuits. 
     In any of the above-described embodiments, the bacterial toxin is selected from the group consisting of a lysin, Hok, Fst, TisB, LdrD, Kid, SymE, MazF, FImA, Ibs, XCV2162, dinJ, CcdB, MazF, ParE, YafO, Zeta, hicB, relB, yhaV, yoeB, chpBK, hipA, microcin B, microcin B17, microcin C, microcin C7-051, microcin J25, microcin ColV, microcin 24, microcin L, microcin D93, microcin L, microcin E492, microcin H47, microcin 147, microcin M, colicin A, colicin E1, colicin K, colicin N, colicin U, colicin B, colicin Ia, colicin Ib, colicin 5, colicin10, colicin S4, colicin Y, colicin E2, colicin E7, colicin E8, colicin E9, colicin E3, colicin E4, colicin E6; colicin E5, colicin D, colicin M, and cloacin DF13, or a biologically active fragment thereof. 
     In any of the above-described embodiments, the anti-toxin is selected from the group consisting of an anti-lysin, Sok, RNAII, LstR, RdID, Kis, SymR, MazE, FlmB, Sib, ptaRNA1, yafQ, CcdA, MazE, ParD, yafN, Epsilon, HicA, relE, prIF, yefM, chpBI, hipB, MccE, MccE cTD , MccF, Cai, ImmE1, Cki, Cni, Cui, Cbi, Iia, Imm, Cfi, Im10, Csi, Cyi, Im2, Im7, Im8, Im9, Im3, Im4, ImmE6, cloacin immunity protein (Cim), ImmE5, ImmD, and Cmi, or a biologically active fragment thereof. 
     In one embodiment, the bacterial toxin is bactericidal to the genetically engineered bacterium. In one embodiment, the bacterial toxin is bacteriostatic to the genetically engineered bacterium. 
     In some embodiments, the engineered bacteria provided herein have an arginine regulon comprising one or more nucleic acid mutations that reduce or eliminate arginine-mediated repression of each of the operons that encode the enzymes responsible for converting glutamate to arginine and/or an intermediate byproduct, e.g., citrulline, in the arginine biosynthesis pathway, such that the mutant arginine regulon produces more arginine and/or intermediate byproduct than an unmodified regulon from the same bacterial subtype under the same conditions. In some embodiments, the genetically engineered bacteria comprise an arginine feedback resistant N-acetylglutamate synthase mutant, e.g., argA fbr . In some embodiments, the genetically engineered bacteria comprise a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamylphosphate reductase, acetylornithine am inotransferase, N-acetylornithinase, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase, and carbamoylphosphate synthase, thereby derepressing the regulon and enhancing arginine and/or intermediate byproduct biosynthesis. In some embodiments, the genetically engineered bacteria further comprise an arginine feedback resistant N-acetylglutamate synthase mutant. In some embodiments, the arginine feedback resistant N-acetylglutamate synthase mutant is controlled by an oxygen level-dependent promoter. In some embodiments, the arginine feedback resistant N-acetylglutamate synthase mutant is controlled by a promoter that is induced under low-oxygen or anaerobic conditions. In some embodiments, the promoter is selected from the fumarate and nitrate reductase regulator (FNR) promoter, arginine deiminiase and nitrate reduction (ANR) promoter, and dissimilatory nitrate respiration regulator (DNR) promoter. In some embodiments, the arginine feedback resistant N-acetylglutamate synthase mutant is argA fbr . 
     In some embodiments, the genetically engineered bacteria comprise a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes and an arginine feedback resistant N-acetylglutamate synthase mutant. In some embodiments, the genetically engineered bacteria comprise a mutant arginine regulon, wherein the bacterium comprises a gene encoding a functional N-acetylglutamate synthetase that is mutated to reduce arginine feedback inhibition as compared to a wild-type N-acetylglutamate synthetase from the same bacterial subtype under the same conditions, wherein expression of the gene encoding the mutated N-acetylglutamate synthetase is controlled by a promoter that is induced under low-oxygen or anaerobic conditions, wherein the mutant arginine regulon comprises one or more operons comprising genes that encode arginine biosynthesis enzymes N-acetylglutamate kinase, N-acetylglutamate phosphate reductase, acetylornithine aminotransferase, N-acetylornithinase, carbamoylphosphate synthase, ornithine transcarbamylase, argininosuccinate synthase, and argininosuccinate lyase, and wherein each operon comprises one or more mutated ARG box(es) characterized by one or more nucleic acid mutations that reduces arginine-mediated repression of the operon via ArgR repressor binding, and retains RNA polymerase binding with sufficient affinity to promote transcription of the genes in the operon. 
     In some embodiments, the genetically engineered bacteria is an auxotroph comprising a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes and an arginine feedback resistant N-acetylglutamate synthase mutant. In one embodiment, the genetically engineered bacteria comprising a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes and an arginine feedback resistant N-acetylglutamate synthase mutant is an auxotroph selected from a cysE, glnA, ilvD, leuB, lysA, serA, metA, glyA, hisB, ilvA, pheA, proA, thrC, trpC, tyrA, thyA, uraA, dapA, dapB, dapD, dapE, dapF, flhD, metB, metC, proAB, and thiI auxotroph. In some embodiments, the engineered bacteria have more than one auxotrophy, for example, they may be a ΔthyA and ΔdapA auxotroph. 
     In some embodiments, the genetically engineered bacteria comprising a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes and an arginine feedback resistant N-acetylglutamate synthase mutant further comprises a kill-switch circuit, such as any of the kill-switch circuits provided herein. For example, in some embodiments, the genetically engineered bacteria further comprise one or more genes encoding one or more recombinase(s) under the control of an inducible promoter and an inverted toxin sequence. In some embodiments, the genetically engineered bacteria further comprise one or more genes encoding an anti-toxin. In some embodiments, the engineered bacteria further comprise one or more genes encoding one or more recombinase(s) under the control of an inducible promoter and one or more inverted excision genes, wherein the excision gene(s) encode an enzyme that deletes an essential gene. In some embodiments, the genetically engineered bacteria further comprise one or more genes encoding an anti-toxin. In some embodiments, the engineered bacteria further comprise one or more genes encoding a toxin under the control of a promoter having a TetR repressor binding site and a gene encoding the TetR under the control of an inducible promoter that is induced by arabinose, such as P araBAD . In some embodiments, the genetically engineered bacteria further comprise one or more genes encoding an anti-toxin. 
     In some embodiments, the genetically engineered bacteria is an auxotroph comprising a mutant arginine regulon comprising one or more nucleic acid mutations in at least one ARG box for each of the operons that encode the arginine biosynthesis enzymes and an arginine feedback resistant N-acetylglutamate synthase mutant and further comprises a kill-switch circuit, such as any of the kill-switch circuits described herein. 
     In some embodiments of the above described genetically engineered bacteria, the gene encoding the arginine feedback resistant N-acetylglutamate synthetase is present on a plasmid in the bacterium and operatively linked on the plasmid to the promoter that is induced under low-oxygen or anaerobic conditions. In other embodiments, the gene encoding the arginine feedback resistant N-acetylglutamate synthetase is present in the bacterial chromosome and is operatively linked in the chromosome to the promoter that is induced under low-oxygen or anaerobic conditions. 
     In some embodiments, the genetically engineered bacteria comprise a mutant arginine repressor comprising one or more nucleic acid mutations such that arginine repressor function is decreased or inactive, or the genetically engineered bacteria do not have an arginine repressor (e.g., the arginine repressor gene has been deleted), resulting in derepression of the regulon and enhancement of arginine and/or intermediate byproduct biosynthesis. In some embodiments, the genetically engineered bacteria further comprise an arginine feedback resistant N-acetylglutamate synthase mutant. In some embodiments, the arginine feedback resistant N-acetylglutamate synthase mutant is controlled by an oxygen level-dependent promoter. In some embodiments, the arginine feedback resistant N-acetylglutamate synthase mutant is controlled by a promoter that is induced under low-oxygen or anaerobic conditions. In some embodiments, the promoter is selected from the fumarate and nitrate reductase regulator (FNR) promoter, arginine deiminiase and nitrate reduction (ANR) promoter, and dissimilatory nitrate respiration regulator (DNR) promoter. In some embodiments, the arginine feedback resistant N-acetylglutamate synthase mutant is argA fbr . 
     In some embodiments, the genetically engineered bacteria comprise a mutant or deleted arginine repressor and an arginine feedback resistant N-acetylglutamate synthase mutant. In some embodiments, the genetically engineered bacterium comprise an arginine regulon, wherein the bacterium comprises a gene encoding a functional N-acetylglutamate synthetase with reduced arginine feedback inhibition as compared to a wild-type N-acetylglutamate synthetase from the same bacterial subtype under the same conditions, wherein expression of the gene encoding arginine feedback resistant N-acetylglutamate synthetase is controlled by a promoter that is induced by exogenous environmental conditions and wherein the bacterium has been genetically engineered to lack a functional ArgR repressor. 
     In some embodiments, the genetically engineered bacteria comprising a mutant or deleted arginine repressor and an arginine feedback resistant N-acetylglutamate synthase mutant is an auxotroph. In one embodiment, the genetically engineered bacteria comprising a mutant or deleted arginine repressor and an arginine feedback resistant N-acetylglutamate synthase mutant is an auxotroph selected from a cysE, glnA, ilvD, leuB, lysA, serA, metA, glyA, hisB, ilvA, pheA, proA, thrC, trpC, tyrA, thyA, uraA, dapA, dapB, dapD, dapE, dapF, flhD, metB, metC, proAB, and thiI auxotroph. In some embodiments, the engineered bacteria have more than one auxotrophy, for example, they may be a ΔthyA and ΔdapA auxotroph. 
     In some embodiments, the genetically engineered bacteria comprising a mutant or deleted arginine repressor and an arginine feedback resistant N-acetylglutamate synthase mutant further comprise a kill-switch circuit, such as any of the kill-switch circuits provided herein. For example, in some embodiments, the genetically engineered bacteria further comprise one or more genes encoding one or more recombinase(s) under the control of an inducible promoter, and an inverted toxin sequence. In some embodiments, the genetically engineered bacteria further comprise one or more genes encoding an anti-toxin. In some embodiments, the engineered bacteria further comprise one or more genes encoding one or more recombinase(s) under the control of an inducible promoter and one or more inverted excision genes, wherein the excision gene(s) encode an enzyme that deletes an essential gene. In some embodiments, the genetically engineered bacteria further comprise one or more genes encoding an anti-toxin. In some embodiments, the engineered bacteria further comprise one or more genes encoding a toxin under the control of a promoter having a TetR repressor binding site and a gene encoding the TetR under the control of an inducible promoter that is induced by arabinose, such as P araBAD . In some embodiments, the genetically engineered bacteria further comprise one or more genes encoding an anti-toxin. 
     In some embodiments, the genetically engineered bacterium is an auxotroph comprising a mutant or deleted arginine repressor and an arginine feedback resistant N-acetylglutamate synthase mutant and further comprises a kill-switch circuit, such as any of the kill-switch circuits described herein. 
     In some embodiments of the above described genetically engineered bacteria, the gene encoding the arginine feedback resistant N-acetylglutamate synthetase is present on a plasmid in the bacterium and operatively linked on the plasmid to the promoter that is induced under low-oxygen or anaerobic conditions. In other embodiments, the gene encoding the arginine feedback resistant N-acetylglutamate synthetase is present in the bacterial chromosome and is operatively linked in the chromosome to the promoter that is induced under low-oxygen or anaerobic conditions. 
     Ammonia Transport 
     Ammonia transporters may further be expressed or modified in the genetically engineered bacteria of the invention in order to enhance ammonia transport into the cell. AmtB is a membrane transport protein that transports ammonia into bacterial cells. In some embodiments, the genetically engineered bacteria of the invention also comprise multiple copies of the native amtB gene. In some embodiments, the genetically engineered bacteria of the invention also comprise an amtB gene from a different bacterial species. In some embodiments, the genetically engineered bacteria of the invention comprise multiple copies of an amtB gene from a different bacterial species. In some embodiments, the native amtB gene in the genetically engineered bacteria of the invention is not modified. In some embodiments, the genetically engineered bacteria of the invention comprise an amtB gene that is controlled by its native promoter, an inducible promoter, or a promoter that is stronger than the native promoter, e.g., a GlnRS promoter, a P(Bla) promoter, or a constitutive promoter. 
     In some embodiments, the native amtB gene in the genetically engineered bacteria is not modified, and one or more additional copies of the native amtB gene are inserted into the genome under the control of the same inducible promoter that controls expression of argA fbr , e.g., a FNR promoter, or a different inducible promoter than the one that controls expression of argA fbr  or a constitutive promoter. In alternate embodiments, the native amtB gene is not modified, and a copy of a non-native amtB gene from a different bacterial species is inserted into the genome under the control of the same inducible promoter that controls expression of argA fbr , e.g., a FNR promoter, or a different inducible promoter than the one that controls expression of argA fbr  or a constitutive promoter. 
     In some embodiments, the native amtB gene in the genetically engineered bacteria is not modified, and one or more additional copies of the native amtB gene are present in the bacteria on a plasmid and under the control of the same inducible promoter that controls expression of argA fbr , e.g., a FNR promoter, or a different inducible promoter than the one that controls expression of argA fbr  or a constitutive promoter. In alternate embodiments, the native amtB gene is not modified, and a copy of a non-native amtB gene from a different bacterial species is present in the bacteria on a plasmid and under the control of the same inducible promoter that controls expression of argA fbr , e.g., a FNR promoter, or a different inducible promoter than the one that controls expression of argA fbr  or a constitutive promoter. 
     In some embodiments, the native amtB gene is mutagenized, the mutants exhibiting increased ammonia transport are selected, and the mutagenized amtB gene is isolated and inserted into the genetically engineered bacteria. In some embodiments, the native amtB gene is mutagenized, mutants exhibiting increased ammonia transport are selected, and those mutants are used to produce the bacteria of the invention. The ammonia transporter modifications described herein may be present on a plasmid or chromosome. 
     In some embodiments, the genetically engineered bacterium is  E. coli  Nissle, and the native amtB gene in  E. coli  Nissle is not modified; one or more additional copies the native  E. coli  Nissle amtB genes are inserted into the  E. coli  Nissle genome under the control of the same inducible promoter that controls expression of argA fbr , e.g., a FNR promoter, or a different inducible promoter than the one that controls expression of argA fbr  or a constitutive promoter. In an alternate embodiment, the native amtB gene in  E. coli  Nissle is not modified, and a copy of a non-native amtB gene from a different bacterium, e.g.,  Lactobacillus plantarum , is inserted into the  E. coli  Nissle genome under the control of the same inducible promoter that controls expression of argA fbr , e.g., a FNR promoter, or a different inducible promoter than the one that controls expression of argA fbr  or a constitutive promoter. 
     In some embodiments, the genetically engineered bacterium is  E. coli  Nissle, and the native amtB gene in  E. coli  Nissle is not modified; one or more additional copies the native  E. coli  Nissle amtB genes are present in the bacterium on a plasmid and under the control of the same inducible promoter that controls expression of argA fbr , e.g., a FNR promoter, or a different inducible promoter than the one that controls expression of argA fbr , or a constitutive promoter. In an alternate embodiment, the native amtB gene in  E. coli  Nissle is not modified, and a copy of a non-native amtB gene from a different bacterium, e.g.,  Lactobacillus plantarum , are present in the bacterium on a plasmid and under the control of the same inducible promoter that controls expression of argA fbr , e.g., a FNR promoter, or a different inducible promoter than the one that controls expression of argA fbr , or a constitutive promoter. 
     Pharmaceutical Compositions and Formulations 
     Pharmaceutical compositions comprising the genetically engineered bacteria described herein may be used to treat, manage, ameliorate, and/or prevent a disorder associated with hyperammonemia or symptom(s) associated with hyperammonemia. Pharmaceutical compositions comprising one or more genetically engineered bacteria, alone or in combination with prophylactic agents, therapeutic agents, and/or pharmaceutically acceptable carriers are provided. 
     In certain embodiments, the pharmaceutical composition comprises one species, strain, or subtype of bacteria that are engineered to comprise the genetic modifications described herein. In alternate embodiments, the pharmaceutical composition comprises two or more species, strains, and/or subtypes of bacteria that are each engineered to comprise the genetic modifications described herein. 
     The pharmaceutical compositions described herein may be formulated in a conventional manner using one or more physiologically acceptable carriers comprising excipients and auxiliaries, which facilitate processing of the active ingredients into compositions for pharmaceutical use. Methods of formulating pharmaceutical compositions are known in the art (see, e.g., “Remington&#39;s Pharmaceutical Sciences,” Mack Publishing Co., Easton, Pa.). In some embodiments, the pharmaceutical compositions are subjected to tabletting, lyophilizing, direct compression, conventional mixing, dissolving, granulating, levigating, emulsifying, encapsulating, entrapping, or spray drying to form tablets, granulates, nanoparticles, nanocapsules, microcapsules, microtablets, pellets, or powders, which may be enterically coated or uncoated. Appropriate formulation depends on the route of administration. 
     The genetically engineered bacteria described herein may be formulated into pharmaceutical compositions in any suitable dosage form (e.g., liquids, capsules, sachet, hard capsules, soft capsules, tablets, enteric coated tablets, suspension powders, granules, or matrix sustained release formations for oral administration) and for any suitable type of administration (e.g., oral, topical, injectable, immediate-release, pulsatile-release, delayed-release, or sustained release). Suitable dosage amounts for the genetically engineered bacteria may range from about 10 5  to 10 12  bacteria, e.g., approximately 10 5  bacteria, approximately 10 6  bacteria, approximately 10 7  bacteria, approximately 10 8  bacteria, approximately 10 9  bacteria, approximately 10 10  bacteria, approximately 10 11  bacteria, or approximately 10 11  bacteria. The composition may be administered once or more daily, weekly, or monthly. The composition may be administered before, during, or following a meal. In one embodiment, the pharmaceutical composition is administered before the subject eats a meal. In one embodiment, the pharmaceutical composition is administered currently with a meal. In one embodiment, the pharmaceutical composition is administered after the subject eats a meal. 
     The composition may be administered once or more daily, weekly, or monthly. The genetically engineered bacteria may be formulated into pharmaceutical compositions comprising one or more pharmaceutically acceptable carriers, thickeners, diluents, buffers, buffering agents, surface active agents, neutral or cationic lipids, lipid complexes, liposomes, penetration enhancers, carrier compounds, and other pharmaceutically acceptable carriers or agents. For example, the pharmaceutical composition may include, but is not limited to, the addition of calcium bicarbonate, sodium bicarbonate, calcium phosphate, various sugars and types of starch, cellulose derivatives, gelatin, vegetable oils, polyethylene glycols, and surfactants, including, for example, polysorbate 20. In some embodiments, the genetically engineered bacteria of the invention may be formulated in a solution of sodium bicarbonate, e.g., 1 molar solution of sodium bicarbonate (to buffer an acidic cellular environment, such as the stomach, for example). The genetically engineered bacteria may be administered and formulated as neutral or salt forms. Pharmaceutically acceptable salts include those formed with anions such as those derived from hydrochloric, phosphoric, acetic, oxalic, tartaric acids, etc., and those formed with cations such as those derived from sodium, potassium, ammonium, calcium, ferric hydroxides, isopropylamine, triethylamine, 2-ethylamino ethanol, histidine, procaine, etc. 
     The genetically engineered bacteria disclosed herein may be administered topically and formulated in the form of an ointment, cream, transdermal patch, lotion, gel, shampoo, spray, aerosol, solution, emulsion, or other form well-known to one of skill in the art. See, e.g., “Remington&#39;s Pharmaceutical Sciences,” Mack Publishing Co., Easton, Pa. In an embodiment, for non-sprayable topical dosage forms, viscous to semi-solid or solid forms comprising a carrier or one or more excipients compatible with topical application and having a dynamic viscosity greater than water are employed. Suitable formulations include, but are not limited to, solutions, suspensions, emulsions, creams, ointments, powders, liniments, salves, etc., which may be sterilized or mixed with auxiliary agents (e.g., preservatives, stabilizers, wetting agents, buffers, or salts) for influencing various properties, e.g., osmotic pressure. Other suitable topical dosage forms include sprayable aerosol preparations wherein the active ingredient in combination with a solid or liquid inert carrier, is packaged in a mixture with a pressurized volatile (e.g., a gaseous propellant, such as freon) or in a squeeze bottle. Moisturizers or humectants can also be added to pharmaceutical compositions and dosage forms. Examples of such additional ingredients are well known in the art. In one embodiment, the pharmaceutical composition comprising the recombinant bacteria of the invention may be formulated as a hygiene product. For example, the hygiene product may be an antibacterial formulation, or a fermentation product such as a fermentation broth. Hygiene products may be, for example, shampoos, conditioners, creams, pastes, lotions, and lip balms. 
     The genetically engineered bacteria disclosed herein may be administered orally and formulated as tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions, etc. Pharmacological compositions for oral use can be made using a solid excipient, optionally grinding the resulting mixture, and processing the mixture of granules, after adding suitable auxiliaries if desired, to obtain tablets or dragee cores. Suitable excipients include, but are not limited to, fillers such as sugars, including lactose, sucrose, mannitol, or sorbitol; cellulose compositions such as maize starch, wheat starch, rice starch, potato starch, gelatin, gum tragacanth, methyl cellulose, hydroxypropylmethyl-cellulose, sodium carbomethylcellulose; and/or physiologically acceptable polymers such as polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG). Disintegrating agents may also be added, such as cross-linked polyvinylpyrrolidone, agar, alginic acid or a salt thereof such as sodium alginate. 
     Tablets or capsules can be prepared by conventional means with pharmaceutically acceptable excipients such as binding agents (e.g., pregelatinised maize starch, polyvinylpyrrolidone, hydroxypropyl methylcellulose, carboxymethylcellulose, polyethylene glycol, sucrose, glucose, sorbitol, starch, gum, kaolin, and tragacanth); fillers (e.g., lactose, microcrystalline cellulose, or calcium hydrogen phosphate); lubricants (e.g., calcium, aluminum, zinc, stearic acid, polyethylene glycol, sodium lauryl sulfate, starch, sodium benzoate, L-leucine, magnesium stearate, talc, or silica); disintegrants (e.g., starch, potato starch, sodium starch glycolate, sugars, cellulose derivatives, silica powders); or wetting agents (e.g., sodium lauryl sulphate). The tablets may be coated by methods well known in the art. A coating shell may be present, and common membranes include, but are not limited to, polylactide, polyglycolic acid, polyanhydride, other biodegradable polymers, alginate-polylysine-alginate (APA), alginate-polymethylene-co-guanidine-alginate (A-PMCG-A), hydroymethylacrylate-methyl methacrylate (HEMA-MMA), multilayered HEMA-MMA-MAA, polyacrylonitrilevinylchloride (PAN-PVC), acrylonitrile/sodium methallylsulfonate (AN-69), polyethylene glycol/poly pentamethylcyclopentasiloxane/polydimethylsiloxane (PEG/PD5/PDMS), poly N,N-dimethyl acrylamide (PDMAAm), siliceous encapsulates, cellulose sulphate/sodium alginate/polymethylene-co-guanidine (CS/A/PMCG), cellulose acetate phthalate, calcium alginate, k-carrageenan-locust bean gum gel beads, gellan-xanthan beads, poly(lactide-co-glycolides), carrageenan, starch polyanhydrides, starch polymethacrylates, polyamino acids, and enteric coating polymers. 
     In some embodiments, the genetically engineered bacteria are enterically coated for release into the gut or a particular region of the gut, for example, the large intestine. The typical pH profile from the stomach to the colon is about 1-4 (stomach), 5.5-6 (duodenum), 7.3-8.0 (ileum), and 5.5-6.5 (colon). In some diseases, the pH profile may be modified. In some embodiments, the coating is degraded in specific pH environments in order to specify the site of release. In some embodiments, at least two coatings are used. In some embodiments, the outside coating and the inside coating are degraded at different pH levels. 
     Liquid preparations for oral administration may take the form of solutions, syrups, suspensions, or a dry product for constitution with water or other suitable vehicle before use. Such liquid preparations may be prepared by conventional means with pharmaceutically acceptable agents such as suspending agents (e.g., sorbitol syrup, cellulose derivatives, or hydrogenated edible fats); emulsifying agents (e.g., lecithin or acacia); non-aqueous vehicles (e.g., almond oil, oily esters, ethyl alcohol, or fractionated vegetable oils); and preservatives (e.g., methyl or propyl-p-hydroxybenzoates or sorbic acid). The preparations may also contain buffer salts, flavoring, coloring, and sweetening agents as appropriate. Preparations for oral administration may be suitably formulated for slow release, controlled release, or sustained release of the genetically engineered bacteria described herein. 
     In one embodiment, the genetically engineered bacteria of the disclosure may be formulated in a composition suitable for administration to pediatric subjects. As is well known in the art, children differ from adults in many aspects, including different rates of gastric emptying, pH, gastrointestinal permeability, etc. (Ivanovska et al., 2014). Moreover, pediatric formulation acceptability and preferences, such as route of administration and taste attributes, are critical for achieving acceptable pediatric compliance. Thus, in one embodiment, the composition suitable for administration to pediatric subjects may include easy-to-swallow or dissolvable dosage forms, or more palatable compositions, such as compositions with added flavors, sweeteners, or taste blockers. In one embodiment, a composition suitable for administration to pediatric subjects may also be suitable for administration to adults. 
     In one embodiment, the composition suitable for administration to pediatric subjects may include a solution, syrup, suspension, elixir, powder for reconstitution as suspension or solution, dispersible/effervescent tablet, chewable tablet, gummy candy, lollipop, freezer pop, troche, chewing gum, oral thin strip, orally disintegrating tablet, sachet, soft gelatin capsule, sprinkle oral powder, or granules. In one embodiment, the composition is a gummy candy, which is made from a gelatin base, giving the candy elasticity, desired chewy consistency, and longer shelf-life. In some embodiments, the gummy candy may also comprise sweeteners or flavors. 
     In one embodiment, the composition suitable for administration to pediatric subjects may include a flavor. As used herein, “flavor” is a substance (liquid or solid) that provides a distinct taste and aroma to the formulation. Flavors also help to improve the palatability of the formulation. Flavors include, but are not limited to, strawberry, vanilla, lemon, grape, bubble gum, and cherry. 
     In certain embodiments, the genetically engineered bacteria may be orally administered, for example, with an inert diluent or an assimilable edible carrier. The compound may also be enclosed in a hard or soft shell gelatin capsule, compressed into tablets, or incorporated directly into the subject&#39;s diet. For oral therapeutic administration, the compounds may be incorporated with excipients and used in the form of ingestible tablets, buccal tablets, troches, capsules, elixirs, suspensions, syrups, wafers, and the like. To administer a compound by other than parenteral administration, it may be necessary to coat the compound with, or co-administer the compound with, a material to prevent its inactivation. 
     In another embodiment, the pharmaceutical composition comprising the recombinant bacteria of the invention may be a comestible product, for example, a food product. In one embodiment, the food product is milk, concentrated milk, fermented milk (yogurt, sour milk, frozen yogurt, lactic acid bacteria-fermented beverages), milk powder, ice cream, cream cheeses, dry cheeses, soybean milk, fermented soybean milk, vegetable-fruit juices, fruit juices, sports drinks, confectionery, candies, infant foods (such as infant cakes), nutritional food products, animal feeds, or dietary supplements. In one embodiment, the food product is a fermented food, such as a fermented dairy product. In one embodiment, the fermented dairy product is yogurt. In another embodiment, the fermented dairy product is cheese, milk, cream, ice cream, milk shake, or kefir. In another embodiment, the recombinant bacteria of the invention are combined in a preparation containing other live bacterial cells intended to serve as probiotics. In another embodiment, the food product is a beverage. In one embodiment, the beverage is a fruit juice-based beverage or a beverage containing plant or herbal extracts. In another embodiment, the food product is a jelly or a pudding. Other food products suitable for administration of the recombinant bacteria of the invention are well known in the art. For example, see U.S. 2015/0359894 and US 2015/0238545, the entire contents of each of which are expressly incorporated herein by reference. In yet another embodiment, the pharmaceutical composition of the invention is injected into, sprayed onto, or sprinkled onto a food product, such as bread, yogurt, or cheese. 
     In some embodiments, the composition is formulated for intraintestinal administration, intrajejunal administration, intraduodenal administration, intraileal administration, gastric shunt administration, or intracolic administration, via nanoparticles, nanocapsules, microcapsules, or microtablets, which are enterically coated or uncoated. The pharmaceutical compositions may also be formulated in rectal compositions such as suppositories or retention enemas, using, e.g., conventional suppository bases such as cocoa butter or other glycerides. The compositions may be suspensions, solutions, or emulsions in oily or aqueous vehicles, and may contain suspending, stabilizing and/or dispersing agents. 
     The genetically engineered bacteria described herein may be administered intranasally, formulated in an aerosol form, spray, mist, or in the form of drops, and conveniently delivered in the form of an aerosol spray presentation from pressurized packs or a nebuliser, with the use of a suitable propellant (e.g., dichlorodifluoromethane, trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide or other suitable gas). Pressurized aerosol dosage units may be determined by providing a valve to deliver a metered amount. Capsules and cartridges (e.g., of gelatin) for use in an inhaler or insufflator may be formulated containing a powder mix of the compound and a suitable powder base such as lactose or starch. 
     The genetically engineered bacteria may be administered and formulated as depot preparations. Such long acting formulations may be administered by implantation or by injection, including intravenous injection, subcutaneous injection, local injection, direct injection, or infusion. For example, the compositions may be formulated with suitable polymeric or hydrophobic materials (e.g., as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives (e.g., as a sparingly soluble salt). 
     In some embodiments, disclosed herein are pharmaceutically acceptable compositions in single dosage forms. Single dosage forms may be in a liquid or a solid form. Single dosage forms may be administered directly to a patient without modification or may be diluted or reconstituted prior to administration. In certain embodiments, a single dosage form may be administered in bolus form, e.g., single injection, single oral dose, including an oral dose that comprises multiple tablets, capsule, pills, etc. In alternate embodiments, a single dosage form may be administered over a period of time, e.g., by infusion. 
     Single dosage forms of the pharmaceutical composition may be prepared by portioning the pharmaceutical composition into smaller aliquots, single dose containers, single dose liquid forms, or single dose solid forms, such as tablets, granulates, nanoparticles, nanocapsules, microcapsules, microtablets, pellets, or powders, which may be enterically coated or uncoated. A single dose in a solid form may be reconstituted by adding liquid, typically sterile water or saline solution, prior to administration to a patient. 
     In other embodiments, the composition can be delivered in a controlled release or sustained release system. In one embodiment, a pump may be used to achieve controlled or sustained release. In another embodiment, polymeric materials can be used to achieve controlled or sustained release of the therapies of the present disclosure (see, e.g., U.S. Pat. No. 5,989,463). Examples of polymers used in sustained release formulations include, but are not limited to, poly(2-hydroxy ethyl methacrylate), poly(methyl methacrylate), poly(acrylic acid), poly(ethylene-co-vinyl acetate), poly(methacrylic acid), polyglycolides (PLG), polyanhydrides, poly(N-vinyl pyrrolidone), poly(vinyl alcohol), polyacrylamide, poly(ethylene glycol), polylactides (PLA), poly(lactide-co-glycolides) (PLGA), and polyorthoesters. The polymer used in a sustained release formulation may be inert, free of leachable impurities, stable on storage, sterile, and biodegradable. In some embodiments, a controlled or sustained release system can be placed in proximity of the prophylactic or therapeutic target, thus requiring only a fraction of the systemic dose. Any suitable technique known to one of skill in the art may be used. 
     Dosage regimens may be adjusted to provide a therapeutic response. Dosing can depend on several factors, including severity and responsiveness of the disease, route of administration, time course of treatment (days to months to years), and time to amelioration of the disease. For example, a single bolus may be administered at one time, several divided doses may be administered over a predetermined period of time, or the dose may be reduced or increased as indicated by the therapeutic situation. The specification for the dosage is dictated by the unique characteristics of the active compound and the particular therapeutic effect to be achieved. Dosage values may vary with the type and severity of the condition to be alleviated. For any particular subject, specific dosage regimens may be adjusted over time according to the individual need and the professional judgment of the treating clinician. Toxicity and therapeutic efficacy of compounds provided herein can be determined by standard pharmaceutical procedures in cell culture or animal models. For example, LD 50 , ED 50 , EC 50 , and IC 50  may be determined, and the dose ratio between toxic and therapeutic effects (LD 50 /ED 50 ) may be calculated as the therapeutic index. Compositions that exhibit toxic side effects may be used, with careful modifications to minimize potential damage to reduce side effects. Dosing may be estimated initially from cell culture assays and animal models. The data obtained from in vitro and in vivo assays and animal studies can be used in formulating a range of dosage for use in humans. 
     The ingredients are supplied either separately or mixed together in unit dosage form, for example, as a dry lyophilized powder or water-free concentrate in a hermetically sealed container such as an ampoule or sachet indicating the quantity of active agent. If the mode of administration is by injection, an ampoule of sterile water for injection or saline can be provided so that the ingredients may be mixed prior to administration. 
     The pharmaceutical compositions may be packaged in a hermetically sealed container such as an ampoule or sachet indicating the quantity of the agent. In one embodiment, one or more of the pharmaceutical compositions is supplied as a dry sterilized lyophilized powder or water-free concentrate in a hermetically sealed container and can be reconstituted (e.g., with water or saline) to the appropriate concentration for administration to a subject. In an embodiment, one or more of the prophylactic or therapeutic agents or pharmaceutical compositions is supplied as a dry sterile lyophilized powder in a hermetically sealed container stored between 2° C. and 8° C. and administered within 1 hour, within 3 hours, within 5 hours, within 6 hours, within 12 hours, within 24 hours, within 48 hours, within 72 hours, or within one week after being reconstituted. Cryoprotectants can be included for a lyophilized dosage form, principally 0-10% sucrose (optimally 0.5-1.0%). Other suitable cryoprotectants include trehalose and lactose. Other suitable bulking agents include glycine and arginine, either of which can be included at a concentration of 0-0.05%, and polysorbate-80 (optimally included at a concentration of 0.005-0.01%). Additional surfactants include but are not limited to polysorbate 20 and BRIJ surfactants. The pharmaceutical composition may be prepared as an injectable solution and can further comprise an agent useful as an adjuvant, such as those used to increase absorption or dispersion, e.g., hyaluronidase. 
     Methods of Treatment 
     Another aspect of the invention provides methods of treating a disease or disorder associated with hyperammonemia. In some embodiments, the invention provides methods for reducing, ameliorating, or eliminating one or more symptom(s) associated with these diseases or disorders. In some embodiments, the disorder is a urea cycle disorder such as argininosuccinic aciduria, arginase deficiency, carbamoylphosphate synthetase deficiency, citrullinemia, N-acetylglutamate synthetase deficiency, and ornithine transcarbamylase deficiency. In alternate embodiments, the disorder is a liver disorder such as hepatic encephalopathy, acute liver failure, or chronic liver failure; organic acid disorders; isovaleric aciduria; 3-methylcrotonylglycinuria; methylmalonic acidemia; propionic aciduria; fatty acid oxidation defects; carnitine cycle defects; carnitine deficiency; β-oxidation deficiency; lysinuric protein intolerance; pyrroline-5-carboxylate synthetase deficiency; pyruvate carboxylase deficiency; ornithine aminotransferase deficiency; carbonic anhydrase deficiency; hyperinsulinism-hyperammonemia syndrome; mitochondrial disorders; valproate therapy; asparaginase therapy; total parenteral nutrition; cystoscopy with glycine-containing solutions; post-lung/bone marrow transplantation; portosystemic shunting; urinary tract infections; ureter dilation; multiple myeloma; chemotherapy; infection; neurogenic bladder; or intestinal bacterial overgrowth. In some embodiments, the symptom(s) associated thereof include, but are not limited to, seizures, ataxia, stroke-like lesions, coma, psychosis, vision loss, acute encephalopathy, cerebral edema, as well as vomiting, respiratory alkalosis, and hypothermia. 
     The method may comprise preparing a pharmaceutical composition with at least one genetically engineered species, strain, or subtype of bacteria described herein, and administering the pharmaceutical composition to a subject in a therapeutically effective amount. In some embodiments, the genetically engineered bacteria of the invention are administered orally, e.g., in a liquid suspension. In some embodiments, the genetically engineered bacteria of the invention are lyophilized in a gel cap and administered orally. In some embodiments, the genetically engineered bacteria of the invention are administered via a feeding tube or gastric shunt. In some embodiments, the genetically engineered bacteria of the invention are administered rectally, e.g., by enema. In some embodiments, the genetically engineered bacteria of the invention are administered topically, intraintestinally, intrajejunally, intraduodenally, intraileally, and/or intracolically. 
     In certain embodiments, administering the pharmaceutical composition to the subject reduces ammonia concentrations in a subject. In some embodiments, the methods of the present disclosure may reduce the ammonia concentration in a subject by at least about 10%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, or more as compared to levels in an untreated or control subject. In some embodiments, reduction is measured by comparing the ammonia concentration in a subject before and after administration of the pharmaceutical composition. In some embodiments, the method of treating or ameliorating hyperammonemia allows one or more symptoms of the condition or disorder to improve by at least about 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or more. 
     Before, during, and after the administration of the pharmaceutical composition, ammonia concentrations in the subject may be measured in a biological sample, such as blood, serum, plasma, urine, fecal matter, peritoneal fluid, intestinal mucosal scrapings, a sample collected from a tissue, and/or a sample collected from the contents of one or more of the following: the stomach, duodenum, jejunum, ileum, cecum, colon, rectum, and anal canal. In some embodiments, the methods may include administration of the compositions of the invention to reduce ammonia concentrations in a subject to undetectable levels, or to less than about 1%, 2%, 5%, 10%, 20%, 25%, 30%, 40%, 50%, 60%, 70%, 75%, or 80% of the subject&#39;s ammonia concentrations prior to treatment. 
     In certain embodiments, the genetically engineered bacteria comprising the mutant arginine regulon is  E. coli  Nissle. The genetically engineered bacteria may be destroyed, e.g., by defense factors in the gut or blood serum (Sonnenborn et al., 2009), or by activation of a kill switch, several hours or days after administration. Thus, the pharmaceutical composition comprising the mutant arginine regulon may be re-administered at a therapeutically effective dose and frequency. Length of Nissle residence in vivo in mice is shown in  FIGS. 34 and 35 . In alternate embodiments, the genetically engineered bacteria are not destroyed within hours or days after administration and may propagate and colonize the gut. 
     The pharmaceutical composition may be administered alone or in combination with one or more additional therapeutic agents, including but not limited to, sodium phenylbutyrate, sodium benzoate, and glycerol phenylbutyrate. An important consideration in the selection of the one or more additional therapeutic agents is that the agent(s) should be compatible with the genetically engineered bacteria of the invention, e.g., the agent(s) must not kill the bacteria. 
     In one embodiment, the genetically engineered bacteria are administered for prevention, treatment or management of HE. In some embodiments, the genetically engineered bacteria are administered in combination with another therapeutic approach to prevent HE reoccurrence. In one embodiment, the genetically engineered bacteria are administered in combination with branched-chain amino acid supplementation. In one embodiment, the genetically engineered bacteria are administered in combination with acetyl-1-carnitine and/or sodium benzoate and/or zinc and/or acarbose and/or ornithine aspartate. In one embodiment, the genetically engineered bacteria are administered in combination with non-absorbable disaccharides, which are commonly applied to both treat and prevent HE in patients. In one embodiment, the genetically engineered bacteria are administered in combination with lactulose and/or lactitol. 
     In one embodiment, the genetically engineered bacteria are administered in combination with one or more antibiotics, for example for the treatment of HE. Examples of such antibiotics include, but are not limited to, non-absorbable antibiotics, such as aminoglicosides, e.g., neomycin and/or paramomycin. In one embodiment, the antibiotic is rifamycin. In one embodiment, the antibiotic is a rifamycin derivative, e.g., a synthetic derivative, including but not limited to, rifaximin. 
     Rifaximin has been shown to significantly reduce the risk of an episode of hepatic encephalopathy, as compared with placebo, over a 6-month period (Bass et a., Rifaximin Treatment in Hepatic Encephalopathy; N Engl J Med 2010; 362:1071-1081). Rifaximin is a semi-synthetic derivative of rifampin and acts by binding to the beta-subunit of bacterial DNA-dependent RNA polymerase, and thereby blocking transcription. As a result, bacterial protein synthesis and growth is inhibited. 
     Rifaximin has been shown to be active against  E. coli  both in vitro and in clinical studies. It therefore is understood that, for a combination treatment with rifaximin to be effective, the genetically engineered bacteria must further comprise a rifaximin resistance. 
     Resistance to rifaximin is caused primarily by mutations in the rpoB gene. This changes the binding site on DNA dependent RNA polymerase and decreases rifaximin binding affinity, thereby reducing efficacy. In one embodiment, the rifaximin resistance is a mutation in the rpoB gene. Non-limiting examples of such mutations are described in e.g., Rodriguez-Verdugo, Evolution of  Escherichia coli  rifampicin resistance in an antibiotic-free environment during thermal stress. BMC Evol Biol. 2013 Feb. 22; 13:50. Of note, mutations in the same three codons of the rpoB consensus sequence occur repeatedly in unrelated rifaximin-resistant clinical isolates of several different bacterial species (as reviewed in Goldstein, Resistance to rifampicin: a review; The Journal of Antibiotics (2014), 1-6, the contents of which is herein incorporated by reference in its entirety. In some embodiments, the genetically engineered bacteria comprise a known rifaximin resistance mutation, e.g., in the rpoB gene. In other embodiments, a screen can be employed, exposing the genetically engineered bacteria to increasing amounts of rifaximin, to identify a useful mutation which confers rifaximin resistance. 
     In some embodiments, the pharmaceutical composition is administered with food. In alternate embodiments, the pharmaceutical composition is administered before or after eating food. The pharmaceutical composition may be administered in combination with one or more dietary modifications, e.g., low-protein diet and amino acid supplementation. The dosage of the pharmaceutical composition and the frequency of administration may be selected based on the severity of the symptoms and the progression of the disorder. The appropriate therapeutically effective dose and/or frequency of administration can be selected by a treating clinician. 
     Table 20 shows non-limiting examples of target degradation rates, based on levels of phenylalanine on average in) in hyperammonemic patients (UCD&lt;HE). 
     
       
         
           
               
             
               
                 TABLE 20 
               
             
            
               
                   
               
               
                 Target Ammonia Degradation/Arginine Production Rates 
               
            
           
           
               
               
            
               
                 Parameter 
                 Value 
               
               
                   
               
               
                 Maximum burden of 
                 825 pmols total excess NH 4   +   
               
               
                 NH 4   +  (in blood) in 
                 Total blood ammonia 
               
               
                 hyperammonemic 
                 levels: ~1000 μmols; 
               
               
                 patients (UCD&lt;HE) 
                 5L blood (adult) 
               
               
                 Arginine production target: 
                 275 μmol/day 
               
               
                 NH 4   +  burden 
                 (1 Arg = 3 NH 4   + ) 
               
               
                 Target arginine production rate: 
                 275 μmol/day/10 11  bacteria 
               
               
                 NH 4   +  burden 
                   
               
               
                 Lab assay target: NH 4   +  burden 
                 0.11 μmol/hr/10 9  bacteria 
               
               
                 Current arginine production rate 
                 1.25 μmol/hr/10 9  bacteria 
               
               
                 Maximum flux of NH 4   +  (in blood from 
                 800 μmols/hr 
               
               
                 colon); in healthy individuals &gt;UCD 
                   
               
               
                 Arginine production target: NH 4   +  flux 
                 267 μmols/hr 
               
               
                 Target arginine production rate: 
                 267 μmols/hr/10 11  bacteria 
               
               
                 NH 4   +  flux 
                   
               
               
                 Lab assay target: NH 4   +  flux 
                 2.67 mol/hr/10 9  bacteria 
               
               
                   
               
            
           
         
       
     
     Treatment In Vivo 
     The genetically engineered bacteria of the invention may be evaluated in vivo, e.g., in an animal model. Any suitable animal model of a disease or condition associated with hyperammonemia may be used (see, e.g., Deignan et al., 2008; Nicaise et al., 2008), for example, a mouse model of acute liver failure and hyperammonemia. This acute liver failure and hyperammonemia may be induced by treatment with thiol acetamide (TAA) (Basile et al., 1990; Nicaise et al., 2008). Alternatively, liver damage may be modeled using physical bile duct ligation (Rivera-Mancia et al., 2012). Hyperammonemia may also be induced by oral supplementation with ammonium acetate and/or magnesium chloride (Azorin et al., 1989; Rivera-Mancia et al., 2012). 
     Additionally, CCl4 is often used to induce hepaticfibrosis and cirrhosis in animals (Nhung et al., Establishment of a standardized mouse model of hepatic fibrosis for biomedical research; Biomedical Research and Therapy 2014, 1(2):43-49). 
     The genetically engineered bacteria of the invention may be administered to the animal, e.g., by oral gavage, and treatment efficacy determined, e.g., by measuring ammonia in blood samples and/or arginine, citrulline, or other byproducts in fecal samples. 
     Full citations for the references cited throughout the specification include:
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Delivery of glutamine synthetase gene by baculovirus vectors: a proof of concept for the treatment of acute hyperammonemia. Gene Ther. 2014 Oct. 23; 22(1):58-64. PMID: 25338921.   84. Trunk et al. Anaerobic adaptation in  Pseudomonas aeruginosa : definition of the Anr and Dnr regulons. Environ Microbiol. 2010 June; 12(6):1719-33. PMID: 20553552.   85. Tuchman et al. Enhanced production of arginine and urea by genetically engineered  Escherichia coli  K-12 strains. Appl Environ Microbiol. 1997 January; 63(1):33-8. PMID: 8979336.   86. Ukena et al. Probiotic  Escherichia coli  Nissle 1917 inhibits leaky gut by enhancing mucosal integrity. PLoS One. 2007 Dec. 12; 2(12):e1308. PMID: 18074031.   87. Unden et al. Alternative respiratory pathways of  Escherichia coli : energetics and transcriptional regulation in response to electron acceptors. Biochim Biophys Acta. 1997 Jul. 4; 1320(3):217-34. Review. PMID: 9230919.   88. Vander Wauven et al.  Pseudomonas aeruginosa  mutants affected in anaerobic growth on arginine: evidence for a four-gene cluster encoding the arginine deiminase pathway. J Bacteriol. 1984 December; 160(3):928-34. PMID: 6438064.   89. Walker. Severe hyperammonaemia in adults not explained by liver disease. Ann Clin Biochem. 2012 May; 49(Pt 3):214-28. Review. PMID: 22349554.   90. Winteler et al. The homologous regulators ANR of  Pseudomonas aeruginosa  and FNR of  Escherichia coli  have overlapping but distinct specificities for anaerobically inducible promoters. Microbiology. 1996 March; 142 (Pt 3):685-93. PMID: 8868444.   91. Wu et al. Direct regulation of the natural competence regulator gene tfoX by cyclic AMP (cAMP) and cAMP receptor protein in Vibrios. Sci Rep. 2015 Oct. 7; 5:14921. PMID: 26442598.   92. Zimmermann et al. Anaerobic growth and cyanide synthesis of  Pseudomonas aeruginosa  depend on anr, a regulatory gene homologous with fnr of  Escherichia coli . Mol Microbiol. 1991 June; 5(6):1483-90. PMID: 1787798.   93. Wright O, Delmans M, Stan G B, Ellis T. GeneGuard: A modular plasmid system designed for biosafety. ACS Synth Biol. 2015 Mar. 20; 4(3):307-16. PMID: 24847673.   94. Liu Y, White R H, Whitman W B. Methanococci use the diaminopimelate aminotransferase (DapL) pathway for lysine biosynthesis. J Bacteriol. 2010 July; 192(13):3304-10. PMID: 20418392.   95. Dogovski et al. (2012) Enzymology of Bacterial Lysine Biosynthesis, Biochemistry, Prof. Deniz Ekinci (Ed.), ISBN: 978-953-51-0076-8, InTech, Available from:   96. http://www.intechopen.com/books/biochemistry/enzymology-of-bacterial-lysine-biosynthesis.   97. Feng et al. Role of phosphorylated metabolic intermediates in the regulation of glutamine synthetase synthesis in  Escherichia coli . J Bacteriol. 1992 October; 174(19):6061-70. PMID: 1356964.   98. Lodeiro et al. Robustness in  Escherichia coli  glutamate and glutamine synthesis studied by a kinetic model. J Biol Phys. 2008 April; 34(1-2):91-106. PMID: 19669495.   99. Reboul et al. Structural and dynamic requirements for optimal activity of the essential bacterial enzyme dihydrodipicolinate synthase. PLoS Comput Biol. 2012; 8(6):e1002537. PMID: 22685390.   100. Saint-Girons et al. Structure and autoregulation of the metJ regulatory gene in  Escherichia coli . J Biol Chem. 1984 Nov. 25; 259(22):14282-5. PMID: 6094549.   101. Shoeman et al. Regulation of methionine synthesis in  Escherichia coli : Effect of metJ gene product and S-adenosylmethionine on the expression of the metF gene. Proc Natl Acad Sci USA. 1985 June; 82(11):3601-5. PMID: 16593564.   102. van Heeswijk et al. Nitrogen assimilation in  Escherichia coli : putting molecular data into a systems perspective. Microbiol Mol Biol Rev. 2013 December; 77(4):628-95. PMID: 24296575.   

     EXAMPLES 
     The following examples provide illustrative embodiments of the disclosure. One of ordinary skill in the art will recognize the numerous modifications and variations that may be performed without altering the spirit or scope of the disclosure. Such modifications and variations are encompassed within the scope of the disclosure. The Examples do not in any way limit the disclosure. 
     Arginine Repressor Binding Sites (ARG Boxes) 
     Example 1. ARG Box Mutations 
     The wild-type genomic sequences comprising ArgR binding sites for each arginine biosynthesis operon in  E. coli  Nissle is shown in Table 3. Modifications to those sequences are designed according to the following parameters. For each wild-type sequence, the ARG boxes are shown in italics. The ARG boxes of the arginine regulon overlap with the promoter region of each operon. The underlined sequences represent RNA polymerase binding sites and those sequences were not altered. Bases that are protected from DNA methylation during ArgR binding are highlighted, and bases that are protected from hydroxyl radical attack during ArgR binding are bolded. The highlighted and bolded bases were the primary targets for mutations to disrupt ArgR binding. 
     Example 2. Lambda Red Recombination 
     Lambda red recombination is used to make chromosomal modifications, e.g., ARG box mutations. Lambda red is a procedure using recombination enzymes from a bacteriophage lambda to insert a piece of custom DNA into the chromosome of  E. coli . A pKD46 plasmid is transformed into the  E. coli  Nissle host strain.  E. coli  Nissle cells are grown overnight in LB media. The overnight culture is diluted 1:100 in 5 mL of LB media and grown until it reaches an OD 600  of 0.4-0.6. All tubes, solutions, and cuvettes are pre-chilled to 4° C. The  E. coli  cells are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 1 mL of 4° C. water. The  E. coli  are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.5 mL of 4° C. water. The  E. coli  are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.1 mL of 4° C. water. The electroporator is set to 2.5 kV. 1 ng of pKD46 plasmid DNA is added to the  E. coli  cells, mixed by pipetting, and pipetted into a sterile, chilled cuvette. The dry cuvette is placed into the sample chamber, and the electric pulse is applied. 1 mL of room-temperature SOC media is immediately added, and the mixture is transferred to a culture tube and incubated at 30° C. for 1 hr. The cells are spread out on a selective media plate and incubated overnight at 30° C. 
     DNA sequences comprising the desired ARG box sequences shown in Table 3 were ordered from a gene synthesis company. For the argA operon, the mutant regulatory region comprises the following nucleic acid sequence (SEQ ID NO: 2): 
     
       
         
           
               
               
            
               
                   
                 gcaaaaaaacaCTTtaaaaaCTTaataatttc 
               
               
                   
                   
               
               
                   
                 CTTtaatcaCTTaaagaggtgtaccgtg. 
               
            
           
         
       
     
     The lambda enzymes are used to insert this construct into the genome of  E. coli  Nissle through homologous recombination. The construct is inserted into a specific site in the genome of  E. coli  Nissle based on its DNA sequence. To insert the construct into a specific site, the homologous DNA sequence flanking the construct is identified. The homologous sequence of DNA includes approximately 50 bases on either side of the mutated sequence. The homologous sequences are ordered as part of the synthesized gene. Alternatively, the homologous sequences may be added by PCR. The construct is used to replace the natural sequence upstream of argA in the  E. coli  Nissle genome. The construct includes an antibiotic resistance marker that may be removed by recombination. The resulting mutant argA construct comprises approximately 50 bases of homology upstream of argA, a kanamycin resistance marker that can be removed by recombination, gcaaaaaaacaCTTtaaaaaCTTaataatttcCTTtaatcaCTTaaagaggtgtaccgtg (SEQ ID NO: 2), and approximately 50 bases of homology to argA. 
     In some embodiments, the ARG boxes were mutated in the argG regulatory region as described above, and a BBa_J23100 constitutive promoter was inserted into the regulatory region using lambda red recombination (SYN-UCD105). These bacteria were capable of producing arginine. In alternate embodiments, the argG regulatory region (SEQ ID NO: 16) remained ArgR-repressible (SYN-UCD104), and the bacteria were capable of producing citrulline. 
     Example 3. Transforming  E. coli  Nissle 
     The mutated ARG box construct is transformed into  E. coli  Nissle comprising pKD46. All tubes, solutions, and cuvettes are pre-chilled to 4° C. An overnight culture is diluted 1:100 in 5 mL of LB media containing ampicillin and grown until it reaches an OD 600  of 0.1. 0.05 mL of 100×L-arabinose stock solution is added to induce pKD46 lambda red expression. The culture is grown until it reaches an OD 600  of 0.4-0.6. The  E. coli  cells are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 1 mL of 4° C. water. The  E. coli  are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.5 mL of 4° C. water. The  E. coli  are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.1 mL of 4° C. water. The electroporator is set to 2.5 kV. 0.5 μg of the mutated ARG box construct is added to the cells, mixed by pipetting, and pipetted into a sterile, chilled cuvette. The dry cuvette is placed into the sample chamber, and the electric pulse is applied. 1 mL of room-temperature SOC media is immediately added, and the mixture is transferred to a culture tube and incubated at 37° C. for 1 hr. The cells are spread out on an LB plate containing kanamycin and incubated overnight. 
     Example 4. Verifying Mutants 
     The presence of the mutation is verified by colony PCR. Colonies are picked with a pipette tip and resuspended in 20 μl of cold ddH 2 O by pipetting up and down. 3 μL of the suspension is pipetted onto an index plate with appropriate antibiotic for use later. The index plate is grown at 37° C. overnight. A PCR master mix is made using 5 μL of 10×PCR buffer, 0.6 μl of 10 mM dNTPs, 0.4 μL of 50 mM Mg 2 SO 4 , 6.0 μL of 10× enhancer, and 3.0 μL of ddH 2 O (15 μL of master mix per PCR reaction). A 10 μM primer mix is made by mixing 2 μL of primers unique to the argA mutant construct (100 μM stock) into 16 μL of ddH 2 O. For each 20 μL reaction, 15 μL of the PCR master mix, 2.0 μL of the colony suspension (template), 2.0 μL of the primer mix, and 1.0 μL of Pfx Platinum DNA Pol are mixed in a PCR tube. The PCR thermocycler is programmed as follows, with steps 2-4 repeating 34 times: 1) 94° C. at 5:00 min., 2) 94° C. at 0:15 min., 3) 55° C. at 0:30 min., 4) 68° C. at 2:00 min., 5) 68° C. at 7:00 min., and then cooled to 4° C. The PCR products are analyzed by gel electrophoresis using 10 μL of each amplicon and 2.5 μL 5× dye. The PCR product only forms if the mutation has inserted into the genome. 
     Example 5. Removing Selection Marker 
     The antibiotic resistance gene is removed with pCP20. Each strain with the mutated ARG boxes is grown in LB media containing antibiotics at 37° C. until it reaches an OD 600  of 0.4-0.6. All tubes, solutions, and cuvettes are pre-chilled to 4° C. The cells are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 1 mL of 4° C. water. The  E. coli  are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.5 mL of 4° C. water. The  E. coli  are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.1 mL of 4° C. water. The electroporator is set to 2.5 kV. 1 ng of pCP20 plasmid DNA is added to the cells, mixed by pipetting, and pipetted into a sterile, chilled cuvette. The dry cuvette was placed into the sample chamber, and the electric pulse was applied. 1 mL of room-temperature SOC media is immediately added, and the mixture is transferred to a culture tube and incubated at 30° C. for 1-3 hrs. The cells are spread out on an LB plate containing kanamycin and incubated overnight. Colonies that do not grow to a sufficient OD 600  overnight are further incubated for an additional 24 hrs. 200 μL of cells are spread on ampicillin plates, 200 μL of cells are spread on kanamycin plates, and both are grown at 37° C. overnight. The ampicillin plate contains cells with pCP20. The kanamycin plate provides an indication of how many cells survived the electroporation. Transformants from the ampicillin plate are purified non-selectively at 43° C. and allowed to grow overnight. 
     Example 6. Verifying Transformants 
     The purified transformants are tested for sensitivity to ampicillin and kanamycin. A colony from the plate grown at 43° C. is picked and and resuspended in 10 μL of LB media. 3 μL of the cell suspension is pipetted onto each of three plates: 1) an LB plate with kanamycin incubated at 37° C., which tests for the presence or absence of the kanR gene in the genome of the host strain; 2) an LB plate with ampicillin incubated at 30° C., which tests for the presence or absence of the ampR gene from the pCP20 plasmid; and 3) an LB plate without antibiotic incubated at 37° C. If no growth is observed on the kanamycin or ampicillin plates for a particular colony, then both the kanR gene and the pCP20 plasmid were lost, and the colony is saved for further analysis. The saved colonies are restreaked onto an LB plate to obtain single colonies and grown overnight at 37° C. The presence of the mutated genomic ARG box is confirmed by sequencing the argA region of the genome. 
     The methods for lambda red recombination, transforming  E. coli  Nissle, verifying the mutation, removing the selection marker, and verifying/sequencing the transformants are repeated for each of the ARG box mutations and operons shown in Table 3. The resulting bacteria comprise mutations in each ARG box for one or more operons encoding the arginine biosynthesis enzymes, such that ArgR binding to the ARG boxes is reduced and total ArgR binding to the regulatory region of said operons is reduced. 
     Example 7. Arginine Feedback Resistant N-Acetylglutamate Synthetase (argA fbr ) 
     In addition to the ARG box mutations described above, the  E. coli  Nissle bacteria further comprise an arginine feedback resistant N-acetylglutamate synthetase (argA fbr , SEQ ID NO: 30) gene expressed under the control of each of the following promoters: tetracycline-inducible promoter, FNR promoter selected from SEQ ID NOs: 18-29. As discussed herein, other promoters may be used. 
     The argA fbr  gene is expressed on a high-copy plasmid, a low-copy plasmid, or a chromosome. SYN-UCD101 comprises wild-type ArgR, wild-type ArgA, tetracycline-inducible argA fbr  on a plasmid, and mutations in each ARG box for each arginine biosynthesis operon. The plasmid does not comprise functional ArgR binding sites, i.e., ARG boxes. SYN-UCD101 was used to generate SYN-UCD102, which comprises wild-type ArgR, wild-type ArgA, tetracycline-inducible argA fbr  on a plasmid, and mutations in each ARG box for each arginine biosynthesis operon. The plasmid further comprises functional ArgR binding sites, i.e., ARG boxes. In some instances, the presence and/or build-up of functional ArgR may result in off-target binding at sites other than the ARG boxes. Introducing functional ARG boxes in this plasmid may be useful for reducing or eliminating off-target ArgR binding, i.e., by acting as an ArgR sink. SYN-UCD104 comprises wild-type ArgR, wild-type ArgA, tetracycline-inducible argA fbr  on a low-copy plasmid, tetracycline-inducible argG, and mutations in each ARG box for each arginine biosynthesis operon except for argG. SYN-UCD105 comprises wild-type ArgR, wild-type ArgA, tetracycline-inducible argA fbr  on a low-copy plasmid, constitutively expressed argG (SEQ ID NO: 17 comprising the BBa_J23100 constitutive promoter), and mutations in each ARG box for each arginine biosynthesis operon. SYN-UCD103 is a control Nissle construct. 
     The argA fbr  gene is inserted into the bacterial genome at one or more of the following insertion sites in  E. coli  Nissle: malE/K, araC/BAD, lacZ, thyA, malP/T. Any suitable insertion site may be used, see, e.g.,  FIG. 18 . The insertion site may be anywhere in the genome, e.g., in a gene required for survival and/or growth, such as thyA (to create an auxotroph); in an active area of the genome, such as near the site of genome replication; and/or in between divergent promoters in order to reduce the risk of unintended transcription, such as between AraB and AraC of the arabinose operon. At the site of insertion, DNA primers that are homologous to the site of insertion and to the argA fbr  construct are designed. A linear DNA fragment containing the construct with homology to the target site is generated by PCR, and lambda red recombination is performed as described above. 
     The resulting  E. coli  Nissle bacteria are genetically engineered to include nucleic acid mutations that reduce arginine-mediated repression—via ArgR binding and arginine binding to N-acetylglutamate synthetase—of one or more of the operons that encode the arginine biosynthesis enzymes, thereby enhancing arginine and/or citrulline biosynthesis. 
     Arginine Repressor (ArgR) sequences The wild-type argR nucleotide sequence in  E. coli  Nissle and the nucleotide sequence following argR deletion are shown below in Table 21 and Table 22. 
     
       
         
           
               
             
               
                 TABLE 21 
               
             
            
               
                   
               
               
                 Wild-type argR nucleotide sequence 
               
            
           
           
               
               
               
            
               
                   
                 SEQ ID NO: 69 
                 Sequence 
               
               
                   
                   
               
               
                   
                 argR 
                 atgcgaagctcggctaagcaagaagaactag 
               
               
                   
                 nucleotide 
                 ttaaagcatttaaagcattacttaaagaaga 
               
               
                   
                 sequence 
                 gaaatttagctcccagggcgaaatcgtcgcc 
               
               
                   
                   
                 gcgttgcaggagcaaggctttgacaatatta 
               
               
                   
                   
                 atcagtctaaagtctcgcggatgttgaccaa 
               
               
                   
                   
                 gtttggtgctgtacgtacacgcaatgccaaa 
               
               
                   
                   
                 atggaaatggtttactgcctgccagctgaac 
               
               
                   
                   
                 tgggtgtaccaaccacctccagtccattgaa 
               
               
                   
                   
                 gaatctggtactggatatcgactacaacgat 
               
               
                   
                   
                 gcagttgtcgtgattcataccagccctggtg 
               
               
                   
                   
                 cggcgcagttaattgctcgcctgctggactc 
               
               
                   
                   
                 actgggcaaagcagaaggtattctgggcacc 
               
               
                   
                   
                 atcgctggcgatgacaccatctttactaccc 
               
               
                   
                   
                 ctgctaacggtttcaccgtcaaagagctgta 
               
               
                   
                   
                 cgaagcgattttagagctgttc 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 22 
               
             
            
               
                   
               
               
                 Nucleotide sequence following argR deletion 
               
            
           
           
               
               
            
               
                 SEQ ID NO: 124 
                 Sequence 
               
               
                   
               
               
                 argR-deleted 
                 atgcgaagctcggctaagcaagaagagagctgttc 
               
               
                 nucleotide 
                 gaccaggagctttaa 
               
               
                 sequence 
               
               
                   
               
            
           
         
       
     
     Example 9. Deleting ArgR 
     A pKD46 plasmid is transformed into the  E. coli  Nissle host strain.  E. coli  Nissle cells are grown overnight in LB media. The overnight culture is diluted 1:100 in 5 mL of LB media and grown until it reaches an OD 600  of 0.4-0.6. All tubes, solutions, and cuvettes are pre-chilled to 4° C. The  E. coli  cells are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 1 mL of 4° C. water. The  E. coli  are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.5 mL of 4° C. water. The  E. coli  are centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.1 mL of 4° C. water. The electroporator is set to 2.5 kV. 1 ng of pKD46 plasmid DNA is added to the  E. coli  cells, mixed by pipetting, and pipetted into a sterile, chilled cuvette. The dry cuvette is placed into the sample chamber, and the electric pulse is applied. 1 mL of room-temperature SOC media is immediately added, and the mixture is transferred to a culture tube and incubated at 30° C. for 1 hr. The cells are spread out on a selective media plate and incubated overnight at 30° C. 
     Approximately 50 bases of homology upstream and downstream of the ArgR gene are added by PCR to the kanamycin resistance gene in the pKD4 plasmid to generate the following KanR construct: (˜50 bases upstream of ArgR) (terminator) (kanR gene flanked by FRT sites from pKD4) (DNA downstream of argR). 
     In some embodiments, both argR and argG genes are deleted using lambda red recombination as described above, and the bacteria are capable of producing citrulline. 
     Example 10. Bacterial Strains Having Arginine Feedback Resistant N-Acetylglutamate Synthetase (argA fbr ) and ArgR Deletion 
     In addition to the ArgR deletion described above, the  E. coli  Nissle bacteria further comprise an arginine feedback resistant N-acetylglutamate synthetase (argA fbr , SEQ ID NO: 30) gene expressed under the control of each of the following promoters: tetracycline-inducible promoter, FNR promoter selected from SEQ ID NOs: 18-29. As discussed herein, other promoters may be used. 
     The argA fbr  gene is expressed on a high-copy plasmid, a low-copy plasmid, or a chromosome. ArgR is deleted (ΔArgR) in each of SYN-UCD201, SYN-UCD202, and SYN-UCD203. SYN-UCD201 further comprises wild-type argA, but lacks inducible argA fbr . SYN-UCD202 comprises ArgR and argA fbr  expressed under the control of a tetracycline-inducible promoter on a high-copy plasmid. SYN-UCD203 comprises ArgR and argA fbr  expressed under the control of a tetracycline-inducible promoter on a low-copy plasmid. SYN-UCD204 comprises ArgR and argA fbr  expressed under the control of a tetracycline-inducible promoter on a low-copy plasmid. SYN-UCD205 comprises ArgR and argA fbr  expressed under the control of a FNR-inducible promoter (fnrS2) on a low-copy plasmid. 
     The argA fbr  gene is inserted into the bacterial genome at one or more of the following insertion sites in  E. coli  Nissle: malE/K, araC/BAD, lacZ, thyA, malP/T. Any suitable insertion site may be used, see, e.g.,  FIG. 18 . The insertion site may be anywhere in the genome, e.g., in a gene required for survival and/or growth, such as thyA (to create an auxotroph); in an active area of the genome, such as near the site of genome replication; and/or in between divergent promoters in order to reduce the risk of unintended transcription, such as between AraB and AraC of the arabinose operon. At the site of insertion, DNA primers that are homologous to the site of insertion and to the argA fbr  construct are designed. A linear DNA fragment containing the construct with homology to the target site is generated by PCR, and lambda red recombination is performed as described above. The resulting  E. coli  Nissle bacteria have deleted ArgR and inserted feedback resistant N-acetylglutamate synthetase, thereby increasing arginine or citrulline biosynthesis. 
     Example 11. Generation of ΔThyA 
     An auxotrophic mutation causes bacteria to die in the absence of an exogenously added nutrient essential for survival or growth because they lack the gene(s) necessary to produce that essential nutrient. In order to generate genetically engineered bacteria with an auxotrophic modification, the thyA, a gene essential for oligonucleotide synthesis was deleted. Deletion of the thyA gene in  E. coli  Nissle yields a strain that cannot form a colony on LB plates unless they are supplemented with thymidine. 
     A thyA::cam PCR fragment was amplified using 3 rounds of PCR as follows. Sequences of the primers used at a 100 um concentration are found in Table 23. 
     
       
         
           
               
             
               
                 TABLE 23 
               
             
            
               
                   
               
               
                 Primer Sequences 
               
            
           
           
               
               
               
               
            
               
                   
                   
                   
                 SEQ ID 
               
               
                 Name 
                 Sequence 
                 Description 
                 NO 
               
               
                   
               
               
                 SR36 
                 tagaactgatgcaaaaagtgctcgacgaaggcacaca 
                 Round 1: binds 
                 SEQ ID 
               
               
                   
                 gaTGTGTAGGCTGGAGCTGCTTC 
                 on pKD3 
                 NO: 68 
               
               
                   
               
               
                 SR38 
                 gtttcgtaattagatagccaccggcgctttaatgcccgga 
                 Round 1: binds 
                 SEQ ID 
               
               
                   
                 CATATGAATATCCTCCTTAG 
                 on pKD3 
                 NO: 125 
               
               
                   
               
               
                 SR33 
                 caacacgtttcctgaggaaccatgaaacagtatttagaac 
                 Round 2: binds 
                 SEQ ID 
               
               
                   
                 tgatgcaaaaag 
                 to round 1 PCR 
                 NO: 70 
               
               
                   
                   
                 product 
                   
               
               
                   
               
               
                 SR34 
                 cgcacactggcgtcggctctggcaggatgtttcgtaattag 
                 Round 2: binds 
                 SEQ ID 
               
               
                   
                 atagc 
                 to round 1 PCR 
                 NO: 71 
               
               
                   
                   
                 product 
                   
               
               
                   
               
               
                 SR43 
                 atatcgtcgcagcccacagcaacacgtttcctgagg 
                 Round 3: binds 
                 SEQ ID 
               
               
                   
                   
                 to round 2 PCR 
                 NO: 72 
               
               
                   
                   
                 product 
                   
               
               
                   
               
               
                 SR44 
                 aagaatttaacggagggcaaaaaaaaccgacgcaca 
                 Round 3: binds 
                 SEQ ID 
               
               
                   
                 ctggcgtcggc 
                 to round 2 PCR 
                 NO: 73 
               
               
                   
                   
                 product 
               
               
                   
               
            
           
         
       
     
     For the first PCR round, 4×50 ul PCR reactions containing 1 ng pKD3 as template, 25 ul 2×phusion, 0.2 ul primer SR36 and SR38, and either 0, 0.2, 0.4 or 0.6 ul DMSO were brought up to 50 ul volume with nuclease free water and amplified under the following cycle conditions: 
     step1: 98c for 30 s 
     step2: 98c for 10 s 
     step3: 55c for 15 s 
     step4: 72c for 20 s 
     repeat step 2-4 for 30 cycles 
     step5: 72c for 5 min 
     Subsequently, 5 ul of each PCR reaction was run on an agarose gel to confirm PCR product of the appropriate size. The PCR product was purified from the remaining PCR reaction using a Zymoclean gel DNA recovery kit according to the manufacturer&#39;s instructions and eluted in 30 ul nuclease free water. 
     For the second round of PCR, 1 ul purified PCR product from round 1 was used as template, in 4×50 ul PCR reactions as described above except with 0.2 ul of primers SR33 and SR34. Cycle conditions were the same as noted above for the first PCR reaction. The PCR product run on an agarose gel to verify amplification, purified, and eluted in 30 ul as described above. 
     For the third round of PCR, 1 ul of purified PCR product from round 2 was used as template in 4×50 ul PCR reactions as described except with primer SR43 and SR44. Cycle conditions were the same as described for rounds 1 and 2. Amplification was verified, the PCR product purified, and eluted as described above. The concentration and purity was measured using a spectrophotometer. The resulting linear DNA fragment, which contains 92 bp homologous to upstream of thyA, the chloramphenicol cassette flanked by frt sites, and 98 bp homologous to downstream of the thyA gene, was transformed into a  E. coli  Nissle 1917 strain containing pKD46 grown for recombineering. Following electroporation, 1 ml SOC medium containing 3 mM thymidine was added, and cells were allowed to recover at 37 C for 2 h with shaking. Cells were then pelleted at 10,000×g for 1 minute, the supernatant was discarded, and the cell pellet was resuspended in 100 ul LB containing 3 mM thymidine and spread on LB agar plates containing 3 mM thy and 20 ug/ml chloramphenicol. Cells were incubated at 37 C overnight. Colonies that appeared on LB plates were restreaked. + cam 20 ug/ml + or − thy 3 mM. (thyA auxotrophs will only grow in media supplemented with thy 3 mM). 
     Next, the antibiotic resistance was removed with pCP20 transformation. pCP20 has the yeast Flp recombinase gene, FLP, chloramphenicol and ampicillin resistant genes, and temperature sensitive replication. Bacteria were grown in LB media containing the selecting antibiotic at 37° C. until OD600=0.4-0.6. 1 mL of cells were washed as follows: cells were pelleted at 16,000×g for 1 minute. The supernatant was discarded and the pellet was resuspended in 1 mL ice-cold 10% glycerol. This wash step was repeated 3× times. The final pellet was resuspended in 70 ul ice-cold 10% glycerol. Next, cells were electroporated with 1 ng pCP20 plasmid DNA, and 1 mL SOC supplemented with 3 mM thymidine was immediately added to the cuvette. Cells were resuspended and transferred to a culture tube and grown at 30° C. for 1 hours. Cells were then pelleted at 10,000×g for 1 minute, the supernatant was discarded, and the cell pellet was resuspended in 100 ul LB containing 3 mM thymidine and spread on LB agar plates containing 3 mM thy and 100 ug/ml carbenicillin and grown at 30° C. for 16-24 hours. Next, transformants were colony purified non-selectively (no antibiotics) at 42° C. 
     To test the colony-purified transformants, a colony was picked from the 42° C. plate with a pipette tip and resuspended in 10 μL LB. 3 μL of the cell suspension was pipetted onto a set of 3 plates: Cam, (37° C.; tests for the presence/absence of CamR gene in the genome of the host strain), Amp, (30° C., tests for the presence/absence of AmpR from the pCP20 plasmid) and LB only (desired cells that have lost the chloramphenicol cassette and the pCP20 plasmid), 37° C. Colonies were considered cured if there is no growth in neither the Cam or Amp plate, picked, and restreaked on an LB plate to get single colonies, and grown overnight at 37° C. 
     Example 12. Quantifying Ammonia 
     The genetically engineered bacteria described above were grown overnight in 5 mL LB. The next day, cells were pelleted and washed in M9+glucose, pelleted, and resuspended in 3 mL M9+glucose. Cell cultures were incubated with shaking (250 rpm) for 4 hrs and incubated aerobically or anaerobically in a Coy anaerobic chamber (supplying 90% N 2 , 5% CO 2 , 5% H 2 ) at 37° C. At baseline (t=0), 2 hours, and 4 hours, the OD 600  of each cell culture was measured in order to determine the relative abundance of each cell. 
     At t=0, 2 hrs, and 4 hrs, a 1 mL aliquot of each cell culture was analyzed on the Nova Biomedical Bioprofile Analyzer 300 in order to determine the concentration of ammonia in the media. Both SYN-UCD101 and SYN-UCD102 were capable of consuming ammonia in vitro ( FIG. 26 ).  FIGS. 25, 26, and 27  depict bar graphs of ammonia concentrations using SYN-UCD202, SYN-UCD204, SYN-UCD103, and blank controls. 
     Example 13. Quantifying Arginine and Citrulline 
     In some embodiments, the genetically engineered bacteria described above are grown overnight in LB at 37° C. with shaking. The bacteria are diluted 1:100 in 5 mL LB and grown at 37° C. with shaking for 1.5 hr. The bacteria cultures are induced as follows: (1) bacteria comprising FNR-inducible argA fbr  are induced in LB at 37° C. for up to 4 hrs in anaerobic conditions in a Coy anaerobic chamber (supplying 90% N 2 , 5% CO 2 , 5% H 2 , and 20 mM nitrate) at 37° C.; (2) bacteria comprising tetracycline-inducible argA fbr  are induced with anhydrotetracycline (100 ng/mL); (3) bacteria comprising arabinose-inducible argA fbr  are induced with 1% arabinose in media lacking glucose. After induction, bacterial cells are removed from the incubator and spun down at maximum speed for 5 min. The cells are resuspended in 1 mL M9 glucose, and the OD 600  is measured. Cells are diluted until the OD 600  is between 0.6-0.8. Resuspended cells in M9 glucose media are grown aerobically with shaking at 37 C. 100 μL of the cell resuspension is removed and the OD 600  is measured at time=0. A 100 μL aliquot is frozen at −20° C. in a round-bottom 96-well plate for mass spectrometry analysis (LC-MS/MS). At each subsequent time point, 100 μL of the cell suspension is removed and the OD 600  is measured; a 100 μL aliquot is frozen at −20C in a round-bottom 96-well plate for mass spectrometry analysis. Samples are analyzed for arginine and/or citrulline concentrations. At each time point, normalized concentrations as determined by mass spectrometry vs. OD 600  are used to determine the rate of arginine and/or citrulline production per cell per unit time. 
     In some embodiments, the genetically engineered bacteria described above are streaked from glycerol stocks for single colonies on agar. A colony is picked and grown in 3 mL LB for 4 hrs or overnight, then centrifuged for 5 min at 2,500 rcf. The cultures are washed in M9 media with 0.5% glucose. The cultures are resuspended in 3 mL of M9 media with 0.5% glucose, and the OD 600  is measured. The cultures are diluted in M9 media with 0.5% glucose, with or without ATC (100 ng/mL), with or without 20 mM glutamine, so that all of the OD 600  are between 0.4 and 0.5. A 0.5 mL aliquot of each sample is removed, centrifuged for 5 min. at 14,000 rpm, and the supernatant is removed and saved. The supernatant is frozen at −80° C., and the cell pellets are frozen at −80° C. (t=0). The remaining cells are grown with shaking (250 rpm) for 4-6 hrs and incubated aerobically or anaerobically in a Coy anaerobic chamber (supplying 90% N 2 , 5% CO 2 , 5% H 2 ) at 37° C. One 0.5 mL aliquot is removed from each sample every two hours and the OD 600  is measured. The aliquots are centrifuged for 5 min at 14,000 rpm, and the supernatant is removed. The supernatant is frozen at −80° C., and the cell pellets are frozen at −80° C. (t=2, 4, and 6 hrs). The samples are placed on ice, and arginine and citrulline levels are determined using mass spectrometry. 
     For bacterial culture supernatants, samples of 500, 100, 20, 4, and 0.8 μg/mL arginine and citrulline standards in water are prepared. In a round-bottom 96-well plate, 20 μL of sample (bacterial supernatant or standards) is added to 80 μL of water with L-Arginine- 13 C 6 ,  15 N 4  (Sigma) and L-Citrulline-2,3,3,4,4,5,5-d7 (CDN isotope) internal standards at a final 2 μg/mL concentration. The plate is heat-sealed with a PierceASeal foil and mixed well. In a V-bottom 96-well polypropylene plate, 5 μL of diluted samples is added to 95 μL of derivatization mix (85 μL 10 mM NaHCO 3  pH 9.7 and 10 μL 10 mg/mL dansyl-chloride (diluted in acetonitrile). The plate is heat-sealed with a ThermASeal foil and mixed well. The samples are incubated at 60° C. for 45 min for derivatization and centrifuged at 4000 rpm for 5 min. In a round-bottom 96-well plate, 20 μL of the derivatized samples are added to 180 μL of water with 0.1% formic acid. The plate is heat-sealed with a ClearASeal sheet and mixed well. 
     Arginine and citrulline are measured by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using a Thermo TSQ Quantum Max triple quadrupole mass spectrometer. Table 24 below provides a summary of a LC-MS/MS method. 
     
       
         
           
               
             
               
                 TABLE 24 
               
               
                   
               
               
                 a LC-MS/MS Method Summary 
               
               
                   
               
             
            
               
                 HPLC 
               
               
                   
               
            
           
           
               
               
            
               
                 Column 
                 Luna C18 (2) column, 5 μm (50 × 2.1 mm) 
               
               
                 Mobile Phase A 
                 100% H 2 O, 0.1% Formic Acid) 
               
               
                 Mobile Phase B 
                 100% ACN, 0.1% Formic Acid 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Total Time 
                 Flow Rate 
                   
                   
               
               
                 HPLC Method 
                 (min) 
                 (μL/min) 
                 A% 
                 B% 
               
               
                   
               
               
                   
                 0.00 
                 400 
                 90.0 
                 10.0 
               
               
                   
                 0.50 
                 400 
                 90.0 
                 10.0 
               
               
                   
                 2.00 
                 400 
                 10.0 
                 90.0 
               
               
                   
                 3.25 
                 400 
                 10.0 
                 90.0 
               
               
                   
                 3.26 
                 400 
                 90.0 
                 10.0 
               
               
                   
                 4.30 
                 400 
                 90.0 
                 10.0 
               
               
                 Injection Volume 
                 10 μL 
               
               
                   
               
            
           
           
               
            
               
                 Tandem Mass Spectrometry 
               
               
                   
               
            
           
           
               
               
            
               
                 Ion Source 
                 HESI-II 
               
               
                 Polarity 
                 Positive 
               
               
                 SRM transitions 
                 L-Arginine: 408.1/170.1 
               
               
                   
                 L-Arginine- 13 C 6 , 15 N 4 : 418.1/170.0 
               
               
                   
                 L-Citrulline: 409.1/170.2 
               
               
                   
                 L-Citrulline-2,3,3,4,4,5,5-d7: 416.1/170.1 
               
               
                   
               
            
           
         
       
     
     Intracellular arginine and secreted (supernatant) arginine production in the genetically engineered bacteria in the presence or absence an ATC or anaerobic inducer is measured and compared to control bacteria of the same strain under the same conditions. 
     Total arginine production over 6 hrs in the genetically engineered bacteria in the genetically engineered bacteria in the presence or absence an ATC or anaerobic inducer is measured and compared to control bacteria of the same strain under the same conditions. 
     Example 14. Efficacy of Genetically Engineered Bacteria in a Mouse Model of Hyperammonemia and Acute Liver Failure 
     Wild-type C57BL6/J mice are treated with thiol acetamide (TAA), which causes acute liver failure and hyperammonemia (Nicaise et al., 2008). The TAA mouse model is an industry-accepted in vivo model for HE. Mice are treated with unmodified control Nissle bacteria or Nissle bacteria engineered to produce high levels of arginine or citrulline as described above. 
     On day 1, 50 mL of the bacterial cultures are grown overnight and pelleted. The pellets are resuspended in 5 mL of PBS at a final concentration of approximately 10 11  CFU/mL. Blood ammonia levels in mice are measured by mandibular bleed, and ammonia levels are determined by the PocketChem Ammonia Analyzer (Arkray). Mice are gavaged with 100 μL of bacteria (approximately 10 10  CFU). Drinking water for the mice is changed to contain 0.1 mg/mL anhydrotetracycline (ATC) and 5% sucrose for palatability. 
     On day 2, the bacterial gavage solution is prepared as described above, and mice are gavaged with 100 μL of bacteria. The mice continue to receive drinking water containing 0.1 mg/mL ATC and 5% sucrose. 
     On day 3, the bacterial gavage solution is prepared as described above, and mice are gavaged with 100 μL of bacteria. The mice continue to receive drinking water containing 0.1 mg/mL ATC and 5% sucrose. Mice receive an intraperitoneal (IP) injection of 100 μL of TAA (250 mg/kg body weight in 0.5% NaCl). 
     On day 4, the bacterial gavage solution is prepared as described above, and mice are gavaged with 100 μL of bacteria. The mice continue to receive drinking water containing 0.1 mg/mL ATC and 5% sucrose. Mice receive another IP injection of 100 μL of TAA (250 mg/kg body weight in 0.5% NaCl). Blood ammonia levels in the mice are measured by mandibular bleed, and ammonia levels are determined by the PocketChem Ammonia Analyzer (Arkray). 
     On day 5, blood ammonia levels in mice are measured by mandibular bleed, and ammonia levels are determined by the PocketChem Ammonia Analyzer (Arkray). Fecal pellets are collected from mice to determine arginine content by liquid chromatography-mass spectrometry (LC-MS). Ammonia levels in mice treated with genetically engineered Nissle and unmodified control Nissle are compared. 
     Example 15. Efficacy of Genetically Engineered Bacteria in a Mouse Model of Hyperammonemia and UCD 
     Ornithine transcarbamylase is urea cycle enzyme, and mice comprising an spf-ash mutation exhibit partial ornithine transcarbamylase deficiency, which serves as a model for human UCD. Mice are treated with unmodified control Nissle bacteria or Nissle bacteria engineered to produce high levels of arginine or citrulline as described above. 
     [0518]60 spf-ash mice were treated with the genetically engineered bacteria of the invention (SYN-UCD103, SYN-UCD204) or H2O control at 100 ul PO QD: H2O control, normal chow (n=15); H2O control, high protein chow (n=15); SYN-UCD103, high protein chow (n=15); SYN-UCD204, high protein chow (n=15). On Day 1, mice were weighed and sorted into groups to minimize variance in mouse weight per cage. Mice were gavaged and water with 20 mg/L ATC was added to the cages. On day 2, mice were gavaged in the morning and afternoon. On day 3, mice were gavaged in the morning and weighed, and blood was drawn 4 h post-dosing to obtain baseline ammonia levels. Mice were gavaged in the afternoon and chow changed to 70% protein chow. On day 4, mice were gavaged in the morning and afternoon. On day 5, mice were gavaged in the morning and weighed, and blood was drawn 4 h post-dosing to obtain ammonia levels. On days 6 and 7, mice were gavaged in the morning. On day 8, mice were gavaged in the morning and weighed, and blood was drawn 4 h post-dosing to obtain ammonia levels. On day 9, mice were gavaged in the morning and afternoon. On day 10, mice were gavaged in the morning and weighed, and blood was drawn 4 h post-dosing to obtain ammonia levels. On day 12, mice were gavaged in the morning and afternoon. On day 13, mice were gavaged in the morning and weighed, and blood was drawn 4 h post-dosing to obtain ammonia levels. Blood ammonia levels, body weight, and survival rates are analyzed ( FIG. 29 ). 
     Example 16. Efficacy of Genetically Engineered Bacteria in a Mouse Model of Hyperammonemia and UCD (Spf-Ash) Maintained on a High Protein Diet 
     The hyperammonia/UCD (spf-ash) model described in Example 14 was used to assess the in vivo efficacy of genetically engineered bacteria encoding ArgAfbr driven by a fnr promoter on a low copy plasmid on ammonia levels upon administration of a high protein diet. 
     Two strains encoding ArgAfbr driven by a fnr promoter on a low copy plasmid, SYN-UCD206 (comprising ΔArgR and ΔThyA and argAfbr expressed under the control of a FNR-inducible promoter (fnrS2) on a low-copy plasmid) and SYN-UCD205 (comprising ΔArgR and argAfbr expressed under the control of a FNR-inducible promoter (fnrS2) on a low-copy plasmid) were compared to determine whether thymidine auxotrophy can influence the efficacy of ammonia removal from the blood. 
     Spf-ash mice were treated by oral administration with the genetically engineered bacteria (SYN-UCD205, SYN-UCD206) or H2O control. Normal or high protein chow was provided as follows: SYN-UCD205, high protein chow (n=10); SYN-UCD206, high protein chow (n=10); H2O control, normal chow (n=10); H2O control, high protein chow (n=10). For SYN-UCD205 and SYN-UCD206, a dose of 100 ul of &gt;1×10 10  cells/ml was administered twice a day for 12 days, with the exception of days 1, 5, 6, and 7, where bacteria were administered once. On Day 1, mice were weighed and randomized. T=0 NH4 levels were determined from mandibular bleeds using the PocketChem Ammonia Analyzer (Arkray), and mice were subsequently and gavaged. On day 2, mice were gavaged in the morning and afternoon. On day 3, mice were gavaged in the morning and afternoon and the chow was changed from normal chow to 70% protein chow. On day 4, mice were gavaged in the morning and afternoon. On day 5, mice were gavaged in the morning and weighed, and blood was drawn 4 h post-dosing to obtain ammonia levels. On days 8 through 12, mice were gavaged in the morning and afternoon. 
     As seen in  FIG. 30 , ammonia levels of spf-ash mice in a high protein diet were reduced 48 hours after switch to high protein chow in the SYN-UCD205 and SYN-UCD206 groups as compared to the H2O high protein diet control group, indicating that the FNR inducible promoter can drive ArgAfbr expression, resulting in decreased ammonia levels in the blood of the mice treated with the engineered bacteria. The observed reduction in ammonia levels was similar in both SYN-UCD205 and SYN-UCD206, indicating that ThyA auxotrophy does not have a significant effect on efficacy of SYN-UCD206. 
     Example 17. Engineering Bacterial Strains Using Chromosomal Insertions 
     Bacterial strains, in which ArgAfbr is integrated directly into the  E. coli  Nissle genome under the control of an FNR-responsive promoter at the MALEK site were constructed. 
     To create a vector capable of integrating the PfnrS-ArgAfbr into the chromosome at the Nissle MalE and MalK loci, Gibson assembly was used to add 1000 bp sequences of DNA homologous to the Nissle MALE/K locus to both sides of a flippase recombination target (FRT) site-flanked chloramphenicol resistance (cmR) cassette on a knock-in knock-out (KIKO) plasmid. Gibson assembly was then used to clone the PfnrS-ArgAfbr DNA sequence between these homology arms, adjacent to the FRT-cmR-FRT site. Successful insertion of the fragment was validated by sequencing. PCR is used to amplify the entire MalEK::FRT-cmR-FRT::PfnrS-ArgAfbr::MalK region. This knock-in PCR fragment was used to transform an electrocompetent Nissle strain that contains a temperature-sensitive plasmid encoding the lambda red recombinase genes. After transformation, cells were grown for 2 hrs at 37° C. Growth at 37° C. cures the temperature-sensitive plasmid. Transformants with successful chromosomal integration of the fragment were selected on chloramphenicol at 20 μg/mL. 
     In some embodiments, recombinase-based switches may be used to activate PfnrS-ArgAfbr expression. To construct a strain allowing recombinase-based switches to regulate ArgAfbr expression, the PfnrS-driven Int5 gene and the rrnBUP-driven, recombinase site-flanked ArgAfbrare synthesized by Genewiz (Cambridge, Mass.). Gibson assembly is used to add 1000 bp sequences of DNA homologous to the Nissle malE and malK loci on either side of the PfnrS-Int5, rrnBUP-ArgAfbr sequence and to clone this sequence between the homology arms. Successful insertion of the fragment into a KIKO plasmid is validated by sequencing. PCR is used to amplify the entire PfnrS-Int5, rrnBUP-ArgAfbr region. This knock-in PCR fragment is used to transform an electrocompetent Nissle strain expressing the lambda red recombinase genes. After transformation, cells are grown for 2 hrs at 37° C. Transformants with successful integration of the PfnrS-ArgAfbr at the malEK intergenic region are selected on kanamycin at 50 μg/mL. This strategy may also be used to construct a recombinase-based strain requiring T7 polymerase activity for ArgAfbr expression. 
     Example 18. Comparison of In Vitro Efficacy of Chromosomal Insertion and Plasmid-Bearing Engineered Bacterial Strains 
     To compare the in vitro efficacy between engineered bacterial strains harboring a chromosomal insertion of ArgAfbr driven by an fnr inducible promoter at the malEK locus and strains with a low copy plasmid comprising ArgAfbr driven by an fnr inducible promoter, arginine levels in the media were measured at various time points post anaerobic induction. Additionally, to assess whether auxotrophy for thymidine may have an effect on arginine production efficiency, arginine production of engineered bacterial strains with or without a ThyA deletion, comprising the fnr-ArgAfbr on a low copy plasmid or integrated on the chromosome, were compared. 
     Overnight cultures were diluted 1:100 in LB and grown with shaking (250 rpm) at 37° C. After 1.5 hrs of growth, the bacteria cultures were induced as follows: (1) bacteria comprising FNR-inducible argAfbr were induced in LB at 37° C. for 4 hrs in anaerobic conditions in a Coy anaerobic chamber (supplying 90% N2, 5% CO2, 5% H2, and 20 mM nitrate) at 37° C.; (2) bacteria comprising tetracycline-inducible argAfbr were induced with anhydrotetracycline (100 ng/mL). After induction, bacteria were removed from the incubator and spun down at maximum speed for 5 min. The cells were resuspended in 1 mL M9 glucose, and the OD600 was measured. Cells were diluted until the OD600 was between 0.6-0.8. Resuspended cells in M9 glucose media were grown aerobically with shaking at 37 C. 100 μL of the cell resuspension was removed and the OD600 is measured at time=0. A 100 μL aliquot was frozen at −20° C. in a round-bottom 96-well plate for mass spectrometry analysis (LC-MS/MS). At each subsequent time point (e.g., 30, 60, and 120 min), 100 μL of the cell suspension was removed and the OD600 was measured; a 100 μL aliquot was frozen at −20C in a round-bottom 96-well plate for mass spectrometry analysis. Samples were analyzed for arginine concentrations. At each time point, normalized concentrations as determined by mass spectrometry vs. OD600 were used to determine the rate of arginine production per cell per unit time. A summary of the LC-MS/MS method is provided above. 
     Arginine production at 30, 60, and 120 min post induction was compared between (1) Syn-UCD301 (SYN825; comprising ΔArgR and argAfbr expressed under the control of a FNR-inducible promoter integrated into the chromosome at the malEK locus), (2) SYN-UCD205 (comprising ΔArgR and argAfbr expressed under the control of a FNR-inducible promoter on a low-copy plasmid), and (3) SYN-UCD206 (comprising ΔArgR and ΔThyA and argAfbr expressed under the control of a FNR-inducible promoter on a low-copy plasmid. SYN-UCD103 was used as is a control Nissle construct and results are shown in  FIG. 31A . 
       FIG. 31A  shows the levels of arginine production of SYN-UCD205, SYN-UCD206, and SYN-UCD301 measured at 0, 30, 60, and 120 minutes. Arginine production was comparable between all three strains, with the greatest arginine production seen with SYN-UCD301 at 120 minutes, indicating that chromosomal integration of FNR ArgA fbr results in similar levels of arginine production as seen with the low copy plasmid strains expressing the same construct, and may even slightly increase the rate of arginine production. SYN-UCD206 exhibited attenuated arginine production as compared to SYN-UCD205 and SYN-UCD-301 (lower arginine levels at 60 minutes), but reached comparable arginine production levels at 120 minutes, indicating that ΔThyA may have a slight attenuating effect on arginine production. No arginine production was detected for the SYN-UCD103 control. 
     Next, samples were prepared as described above and arginine production at 120 min post induction was compared between (1) SYN-UCD204 (comprising ΔArgR and argAfbr expressed under the control of a tetracycline-inducible promoter on a low-copy plasmid), and (2) SYN-UCD301 (comprising ΔArgR, CmR and argAfbr expressed under the control of a FNR-inducible promoter integrated into the chromosome at the malEK locus), (3) SYN-UCD302 (comprising ΔArgR, ΔThyA, CmR (chloramphenicol resistance) and argAfbr expressed under the control of a FNR-inducible promoter integrated into the chromosome at the malEK locus), and (4) SYN-UCD303 (comprising ΔArgR, ΔThyA, KanR (kanamycin resistance) and argAfbr expressed under the control of a FNR-inducible promoter integrated into the chromosome at the malEK locus). 
     SYN-UCD106, comprising ΔArgR and ΔThyA was used as is a control Nissle construct. Results are shown in  FIG. 31B . As seen in  FIG. 31B , arginine production was elevated to between 0.7 and 0.9 umol/1×109 cells, indicating that arginine production is at similar levels in strains bearing ArgAfbr on a plasmid and strains with integrated copies of ArgAfbr. 
     Example 19. Efficacy of Genetically Engineered Bacteria in a Mouse Model of Hyperammonemia and UCD (Spf-Ash) Maintained on a High Protein Diet 
     The hyperammonia/UCD (spf-ash) model described in Example 14 was used to assess the in vivo efficacy of genetically engineered bacteria encoding ArgAfbr driven by a fnr promoter integrated into the bacterial chromosome on ammonia levels upon administration of a high protein diet. Mice were treated with unmodified control Nissle bacteria or Nissle bacteria engineered to produce high levels of arginine or citrulline as described above. 
     Two strains, one with a ThyA deletion (SYN-UCD303) and one without a ThyA deletion (SYN-UCD301) were tested for efficacy and compared to determine whether ThyA may influence the efficacy of ammonia removal from the blood with these stains harboring chromosomal fnr-ArgAfbr. 
     Spf-ash mice were treated by oral administration with the genetically engineered bacteria (SYN-UCD301, SYN-UCD303) or H2O control. Normal and high protein chow was provided as follows: SYN-UCD301, high protein chow (n=10); SYN-UCD303, high protein chow (n=10); H2O control, normal chow (n=10); H2O control, high protein chow (n=10). For SYN-UCD301, SYN-UCD303, and SYN-UCD106, a dose of 100 ul of &gt;1×10 10  cells/ml was administered twice a day for 12 days, with the exception of days 1, 5, 6, and 7, where bacteria were administered once. Essentially the same protocol was followed as described in Example 16, with blood being drawn on day 5 to obtain ammonia levels ( FIG. 32A ). On day 10, survival rates were analyzed and a time course of survival is shown in  FIG. 32B . 
     As depicted in  FIG. 32A , ammonia levels of spf-ash mice in a high protein diet were reduced in the SYN-UCD301 and SYN-UCD303 groups as compared to the H2O high protein diet control group, indicating that the FNR inducible promoter can drive ArgAfbr expression when the construct is integrated into the chromosome, resulting in decreased ammonia levels in the blood of the mice treated with the engineered bacteria. The observed reduction in ammonia levels was similar in both SYN-UCD301 and SYN-UCD303, indicating that ThyA auxotrophy does not have a significant effect on efficacy of SYN-UCD303. As seen in  FIG. 32B , SYN-UCD301 and SYN-UCD303 showed prolonged survival as compared to controls. Experiments were conducted twice sequentially with similar results. 
     Example 20. Comparison of Efficacy at Various Doses 
     To determine the lowest dose which can be used, while achieving optimal arginine production in the hyperammonia/UCD (spf-ash) model described in Example 14, three doses of SYN-UCD303 were administered. 
     Spf-ash mice were treated by gavage with the genetically engineered bacteria (SYN-UCD303) or H2O control. For SYN-UCD303, doses of 1×10 7 , 1×10 8 , 1×10 9 , and 1×10 10  CFUs were administered in a volume of 100 ul twice a day for 12 days, with the exception of days 1, 5, 6, and 7, where bacteria were administered once. Normal chow or high protein chow was provided as follows: SYN-UCD303 (1×10 7  CFU), high protein chow (n=10); SYN-UCD303 (1×10 8  CFU), high protein chow (n=10); SYN-UCD303 (1×10 9  CFU), high protein chow (n=10); H2O control, normal chow (n=10); H2O control, high protein chow (n=10). Essentially the same protocol was followed as described in Example 16, with blood being drawn on day 5 to obtain ammonia levels. Blood ammonia levels were analyzed for each dose on day 5. Results are depicted in  FIG. 33 . Both doses of 1×10 8  and 1×10 9  were sufficient to result in a significant reduction of blood ammonia levels in this model. 
     Example 21. Nissle Residence 
     Unmodified  E. coli  Nissle and the genetically engineered bacteria of the invention may be destroyed, e.g., by defense factors in the gut or blood serum. The residence time of bacteria in vivo may be calculated. A non-limiting example using a streptomycin-resistant strain of  E. coli  Nissle is described below. In alternate embodiments, residence time is calculated for the genetically engineered bacteria of the invention. 
     C57BL/6 mice were acclimated in the animal facility for 1 week. After one week of acclimation (i.e., day 0), streptomycin-resistant Nissle (SYN-UCD103) was administered to the mice via oral gavage on days 1-3. Mice were not pre-treated with antibiotic. The amount of bacteria administered, i.e., the inoculant, is shown in Table 25. In order to determine the CFU of the inoculant, the inoculant was serially diluted, and plated onto LB plates containing streptomycin (300 μg/mL). The plates were incubated at 37° C. overnight, and colonies were counted. 
     
       
         
           
               
             
               
                 TABLE 25 
               
             
            
               
                   
               
               
                 CFU administered via oral gavage 
               
            
           
           
               
               
               
               
            
               
                 Strain 
                 Day 1 
                 Day 2 
                 Day 3 
               
               
                   
               
               
                 SYN-UCD103 
                 1.30E+08 
                 8.50E+08 
                 1.90E+09 
               
               
                   
               
            
           
         
       
     
     On days 2-10, fecal pellets were collected from up to 6 mice (ID NOs. 1-6; Table 14). The pellets were weighed in tubes containing PBS and homogenized. In order to determine the CFU of Nissle in the fecal pellet, the homogenized fecal pellet was serially diluted, and plated onto LB plates containing streptomycin (300 μg/mL). The plates were incubated at 37° C. overnight, and colonies were counted. 
     Fecal pellets from day 1 were also collected and plated on LB plates containing streptomycin (300 μg/mL) to determine if there were any strains native to the mouse gastrointestinal tract that were streptomycin resistant. The time course and amount of administered Nissle still residing within the mouse gastrointestinal tract is shown in Table 26. 
       FIG. 34  depicts a graph of Nissle residence in vivo. Streptomycin-resistant Nissle was administered to mice via oral gavage without antibiotic pre-treatment. Fecal pellets from six total mice were monitored post-administration to determine the amount of administered Nissle still residing within the mouse gastrointestinal tract. The bars represent the number of bacteria administered to the mice. The line represents the number of Nissle recovered from the fecal samples each day for 10 consecutive days. 
     
       
         
           
               
             
               
                 TABLE 26 
               
               
                   
               
               
                 Nissle residence in vivo 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 ID 
                 Day 2 
                 Day 3 
                 Day 4 
                 Day 5 
               
               
                   
               
               
                 1 
                 2.40E+05 
                 6.50E+03 
                 6.00E+04 
                 2.00E+03 
               
               
                 2 
                 1.00E+05 
                 1.00E+04 
                 3.30E+04 
                 3.00E+03 
               
               
                 3 
                 6.00E+04 
                 1.70E+04 
                 6.30E+04 
                 2.00E+02 
               
               
                 4 
                 3.00E+04 
                 1.50E+04 
                 1.10E+05 
                 3.00E+02 
               
               
                 5 
                   
                 1.00E+04 
                 3.00E+05 
                 1.50E+04 
               
               
                 6 
                   
                 1.00E+06 
                 4.00E+05 
                 2.30E+04 
               
               
                 Avg 
                 1.08E+05 
                 1.76E+05 
                 1.61E+05 
                 7.25E+03 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 ID 
                 Day 6 
                 Day 7 
                 Day 8 
                 Day 9 
                 Day 10 
               
               
                   
               
               
                 1 
                 9.10E+03 
                 1.70E+03 
                 4.30E+03 
                 6.40E+03 
                 2.77E+03 
               
               
                 2 
                 6.00E+03 
                 7.00E+02 
                 6.00E+02 
                 0.00E+00 
                 0.00E+00 
               
               
                 3 
                 1.00E+02 
                 2.00E+02 
                 0.00E+00 
                 0.00E+00 
                 0.00E+00 
               
               
                 4 
                 1.50E+03 
                 1.00E+02 
                   
                 0.00E+00 
                 0.00E+00 
               
               
                 5 
                 3.10E+04 
                 3.60E+03 
                   
                 0.00E+00 
                 0.00E+00 
               
               
                 6 
                 1.50E+03 
                 1.40E+03 
                 4.20E+03 
                 1.00E+02 
                 0.00E+00 
               
               
                 Avg 
                 8.20E+03 
                 1.28E+03 
                 2.28E+03 
                 1.08E+03 
                 4.62E+02 
               
               
                   
               
            
           
         
       
     
     Example 22. Intestinal Residence and Survival of Bacterial Strains In Vivo 
     Localization and intestinal residence time of SYN-UCD303 (integrated fnrS inducible promoter driving ArgAfbr, kanamycin resistance, ΔThyA,  FIG. 35C ) was compared to SYN-UCD106 (ΔArgR, ΔThyA, and chloramphenicol resistance,  FIG. 35B ) and SYN-UCD103 (streptomycin resistant Nissle,  FIG. 35A ). Mice were gavaged, sacrificed at various time points, and effluents were collected from various areas of the small intestine cecum and colon. 
     Bacterial cultures were grown overnight and pelleted. The pellets were resuspended in PBS at a final concentration of approximately 10 10  CFU/mL. Mice (C57BL6/J, 10-12 weeks old) were gavaged with 100 μL of bacteria (approximately 109 CFU). Drinking water for the mice was changed to contain 0.1 mg/mL anhydrotetracycline (ATC) and 5% sucrose for palatability. At each timepoint (1, 4, 8, 12, 24, and 30 hours post-gavage), animals (n=4) were euthanized, and intestine, cecum, and colon were removed. The small intestine was cut into three sections, and the large intestine and colon each into two sections. Each section was flushed with 0.5 ml cold PBS and collected in separate 1.5 ml tubes. The cecum was harvested, contents were squeezed out, and flushed with 0.5 ml cold PBS and collected in a 1.5 ml tube. Intestinal effluents were placed on ice for serial dilution plating. 
     In order to determine the CFU of bacteria in each effluent, the effluent was serially diluted, and plated onto LB plates containing kanamycin. The plates were incubated at 37° C. overnight, and colonies were counted. The amount of bacteria and residence time of SYN-UCD103, SYN-UCD106, and SYN-UCD303 seen in each compartment is shown in  FIG. 35 . As seen in  FIG. 35 , all three strains behave in a similar manner. Comparing  FIG. 35A  with  FIG. 35B , ΔThyA auxotrophy and ΔArgR does not seem to have any substantial effect on residency and transit time. 
     Example 23. Effect of Auxotrophy on Intestinal Residence Time 
     To determine if auxotrophy may have an effect on localization and time of residence, the mouse model described above is used to compare the residency of SYN-UCD303 (ΔThyA) with SYN-UCD304 (wild type ThyA). SYN-UCD103 (streptomycin resistant control Nissle) is administered in parallel to determine whether the Arg R deletion and argAfbr have an effect on residence. 
     Bacteria are prepared and mice are gavaged, euthanized and intestinal effluents collected at various time points as described in Example 22. To determine the CFU of bacteria in each effluent, the effluent is serially diluted and plated as described in Example 20. For SYN-UCD103 streptomycin containing plates and for SYN-UCD301 chloramphenicol containing plates are used. 
     Example 24. TAA Model of Hyperammonemia 
     TAA treatment of mice has previously been employed in the literature to model increased blood ammonia levels associated with UCDs, acute and chronic liver disease and HE (Wallace M C, et al., Lab Anim. 2015 April; 49(1 Suppl):21-9. Standard operating procedures in experimental liver research: thioacetamide model in mice and rat)s. In some embodiments, a TAA-induced mouse model of hyperammonemia is employed to investigate the ability of the genetically engineered bacteria to reduce blood ammonia levels. The TAA serves as an alternative to the spf-ash model. Because spf-ash is a genetic model, the numbers of mice are limiting so developing an inducible model in wild-type mice would greatly facilitate in vivo testing of potential strains of interest. 
     To investigate the effects of engineered bacteria on prolonged elevations of blood ammonia, the bacteria are administered to C57BL6 mice that are also administered a dose of 300 mpk thioacetamide (TAA). 
     C57BL6 (10 weeks old) are administered one daily dose of SYN-UCD103 or SYN-UCD303 (100 ul of &gt;1×10 10  cells/ml) or vehicle control. Alternatively, mice are administered 2 daily doses of bacteria (100 ul of &gt;1×10 10  cells/ml) (n=5 for each treatment group), once in the AM and once in the PM. After three days of pre-dosing with the bacteria, the mice are treated intraperitoneally with thioacetamide (TAA) at 300 mpk or with H2O as control. Alternatively, the mice are treated twice daily, once in the AM and once in the PM with 250 mpk. The duration of the study is five days. Ammonium levels are measured and overall health survival, body weight change is monitored. 
     In brief, animals are acclimated for 7 days. On day 1 of the time course, animals are weighed, bled to measure baseline ammonia and collect fecal pellets (per cage), and are randomized based on initial blood ammonia levels. Animals are dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD103 or SYN-UCD303 (100 ul/dose/animal). Water is changed to H2O(+)20 mg/ml ATC. On day 2, animals are dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD103 or SYN-UCD303 (100 ul/dose/animal). On day 3, animals are weighed and dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD103 or SYN-UCD303 (100 ul/dose/animal). Additionally, animals are dosed intraperitoneally with 300 mpk TAA (or saline control). Alternatively, animals are dosed with 250 mpk TAA (or saline control) once in the AM and once in the PM. On day 4, animals are weighed, bled, and blood ammonia is measured. Fecal pellets are collected per cage. Animals are dosed per oral gavage either once or twice (AM and PM) with H2O, SYN-UCD103 or SYN-UCD303 (100 ul/dose/animal). Animals may also be dosed with 250 mpk TAA (or saline control). On day 5, animals are weighed, bled, and blood ammonia levels are measured. Fecal pellets are collected (per cage). Animals are dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD103 or SYN-UCD303 (100 ul/dose/animal). Ammonium levels, bacterial load in the fecal pellets, and overall health survival, and body weight changes are monitored. 
     Example 25. Model of Hyperammonemia Using Arginase Inhibitors 
     As an alternative to the genetic spf-ash model, arginase inhibitors+/−high protein chow are used as an inducible model of hyperammonemia. Arginase inhibitors fall into at least 2 classes (described in Steppan et al., Front Immunol. 2013; 4: 278. Development of Novel Arginase Inhibitors for Therapy of Endothelial Dysfunction). The first group of arginase inhibitors consisted of the boronic acid analogs of 1-arginine (2)S-amino-6-hexanoic acid (ABH) and S-2-BEC both of which inhibit the catalytic activity of arginase. Another category of arginase inhibitors, that is mainly represented by N-hydroxy-1-arginine (NOHA) and N-hydroxy-nor-1-arginine (nor-NOHA), is characterized by N-hydroxy-guanidinium side chains and inhibit arginase by displacing the metal-bridging hydroxide ion of arginase with their N-hydroxy group. The model development study employs an arginase inhibitor from each group, BEC and nor-NOHA+/−high protein chow (70% protein). 
     To determine if engineered bacteria can change ammonium levels in the blood, inducible models using an arginase inhibitor from each group, BEC and nor-NOHA, +/− high protein chow (70% protein) (70% protein) in wild type mice are employed. C57BL6 (Female, 8 weeks) are treated by oral gavage with the genetically engineered bacteria (100 ul of &gt;1×10 10  cells/ml) or a vehicle control and intraperitoneally either with BEC or norNOHA, and are kept either on a normal chow (n=5 per treatment group) or a high protein chow diet (n=5 per treatment group). Administration groups are as follows for SYN-UCD303 and a vehicle control-treated animals: normal chow (n=5); high protein chow (70% protein chow; n=5); high protein chow (+)BEC (n=5); high protein chow (+)norNOHA (n=5). 
     On day 1 of the time course, animals are weighed, bled to measure baseline ammonia, and are randomized based on initial blood ammonia levels. Fecal pellets are collected (per cage). Animals are dosed by oral gavage with H2O, SYN-UCD303 or SYN-UCD103 (100 ul/dose/animal). Water is changed to H2O(+)20 mg/ml ATC. On day 2, animals are dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD303 or SYN-UCD103 (100 ul/dose/animal). On day 3, animals are weighed and dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD303 or SYN-UCD103 (100 ul/dose/animal). Additionally, animals are dosed intraperitoneally with BEC (25 mpk) or norNOHA (100 mpk) or saline control. For the high protein diet groups, the chow is changed from normal chow to 70% protein chow. On day 4, animals are weighed, bled, and blood ammonia is measured. Fecal pellets are collected per cage. Animals are dosed per oral gavage either once or twice (AM and PM) with H2O, SYN-UCD303 or SYN-UCD103 (100 ul/dose/animal). Animals are dosed intraperitoneally with BEC (25 mpk) or norNOHA (100 mpk). On day 4, animals are dosed per oral gavage either once or twice (AM and PM) with H2O, SYN-UCD303 or SYN-UCD103 (100 ul/dose/animal). Animals are weighed, bled 1 h post dose, and blood ammonia is measured. Fecal pellets are collected per cage. Animals are also dosed intraperitoneally with BEC (25 mpk) or norNOHA (100 mpk). On day 5, Animals are dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD303 or SYN-UCD103 (100 ul/dose/animal). Animals are weighed, bled 1 h post dose, and ammonia levels are measured. 
     A similar study was conducted using strains SYN-UCD202, SYN-UCD204, and SYN-UCD103, and results are shown in  FIG. 28 . 
     Example 26. Effect of Proliferation Potential and Metabolic Activity on Arginine Production 
     The requirement of cell division and/or active metabolism for arginine production from the genetically engineered bacteria was investigated in strain SYNUCD-303. 
     SYNUCD-301 were incubated with 70% isopropanol or phosphate buffered saline (PBS) as a control for 1 hour with shaking. 70% isopropanol disrupted the cellular membrane, which prevented cell division, but should allow cell metabolism. PBS incubation had no effect on the cells (not shown). After treatment, the cells were mixed at specific ratios in M9 media supplemented with 0.5% glucose and 3 mM thymidine. Cells were incubated with shaking at 37 C for 2 hours. Cells can use the ammonium chloride contained in the M9 media to form arginine. Arginine concentration was measured in the media at time zero and again after the 2 hour incubation, and the amount of arginine produced per hour per billion cells was calculated. As seen in  FIGS. 36A and 36B , a greater ratio of isopropanol treated cells to untreated in a culture results in fewer CFUs as determined by plating, and lower levels of arginine production. Arginine production relative to amount of bacteria present remained constant across the various cultures ( FIG. 36C ). These results indicate that only viable bacteria are contributing to arginine production. 
     Example 27. Repeat-Dose Pharmacokinetic and Pharmacodynamic Study of SYN-UCD-303 Following Daily Nasogastric Gavage Dose Administration for 28-Days in Cynomolgus Monkeys (Non-GLP) 
     To evaluate any potential toxicities arising from administration of the genetically engineered bacteria or  E coli  Nissle alone, the pharmacokinetics and pharmacodynamics of SYN-UCD303 and an  E. coli  Nissle with kanamycin resistance (SYN-UCD107) were studied following daily nasogastric gavage (NG) dose administration for 28-days to female cynomolgus monkeys. Cynomolgus monkeys were selected because this species is closely related, both phylogenetically and physiologically, to humans and is a species commonly used for nonclinical toxicity evaluations. The genetically engineered bacteria were administered by nasal gastric gavage, consistent with the proposed route of administration in humans. Animals overall well-being (clinical observations), weight clinical pathology (serum chemistry, hematology, and coagulation) were tracked. Fecal samples were examined for bacterial load. Plasma is analyzed for ammonia levels. 
     A. Materials, Animals and Dosing Regimen: 
     The study was conducted in compliance with nonclinical Laboratory Studies Good Laboratory Practice Regulations issued by the U.S. Food and Drug Administration (Title 21 of the Code of Federal Regulations, Part 58; effective Jun. 20, 1979) and the OECD Principles on Good Laboratory Practice (C[97]186/Final; effective 1997). The animals were individually housed based on the recommendations set forth in the Guide for the Care and Use of Laboratory Animals (National Research Council 2011). 
     Animals used in the study were Female Purpose-bred, non-naive cynomolgus monkey ( Macaca fascicularis ) with 3 to 6 kg (at initial physical exam) 3 to 8 years (at initial physical exam) of age (SNBL USA stock, Origin: Cambodia). 
     For control of bias, animals were randomized to groups in a weight-stratified manner to achieve similar group body weight distributions. The number of animals selected for randomization and their weights and ages are included in Table 
                     TABLE 27                  Animals for randomization                                         Number of                   Sex   Animals   Age   Weight                       Female   17   3 to 6 years   3.1 to 4.7 kg                        
Animals were identified by unique tattoo numbers.
 
     Seventeen animals were acclimated for 7 days prior to dose initiation and fifteen animals were assigned to treatment groups. Spare animals were removed from the study after Day 1. 
     For the duration of the study, animals were offered PMI LabDiet® Fiber-Plus® Monkey Diet 5049 biscuits twice daily. Animal were fasted for at least 2 hours prior to dose administration and fed within 1 hour post dose. Animals also were fasted as required by specific procedures (e.g., prior to blood draws for serum chemistry, fecal collection). The diet was routinely analyzed for contaminants and found to be within manufacturer&#39;s specifications. No contaminants were expected to be present at levels that would interfere with the outcome of the study. 
     Fresh drinking water was provided ad libitum to all animals. The water was routinely analyzed for contaminants. No contaminants were present at levels that would interfere with the outcome of the study. Animals were given fruits, vegetables, other dietary supplements, and cage enrichment devices throughout the course of the study. 
     Previously quarantined animals were acclimated to the study room for 7 days prior to initiation of dosing (day 1). The last dosing occurred on day 28. A stratified randomization scheme incorporating body weights was used to assign animals to study groups. Animals were assigned to groups and treated as indicated in Table 28. 
     
       
         
           
               
             
               
                 TABLE 28 
               
             
            
               
                   
               
               
                 Group Assignments 
               
            
           
           
               
               
               
               
            
               
                   
                 Dose 
                 Flush* 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Test/ 
                   
                   
                 Volume 
                 Bicarb. 
                 Volume 
                 Number of 
               
               
                   
                 Control 
                 Dose Level 
                 Conc. 
                 (mL/ 
                 Conc.  
                 (mL/ 
                 Females 
               
               
                 Group 
                 Articles 
                 (cfu/Animal) 
                 (cfu/mL) 
                 Animal) 
                 (M) 
                 Animal) 
                 (Animal NO.) 
               
               
                   
               
               
                 1 
                 Control 
                 0 
                 0 
                 10 
                 0.36 
                  5 
                 3 (1, 3, 5) 
               
               
                   
                 Article* 
                   
                   
                   
                   
                   
                   
               
               
                 2 
                 SYN- 
                 1 × 10 9   
                 1 × 10 9   
                  1 
                 0.12 
                 14 
                 3 (1, 3, 5) 
               
               
                   
                 UCD107 
                   
                   
                   
                   
                   
                   
               
               
                 3 
                 SYN- 
                 1 × 10 12   
                 1 × 10 11   
                 10 
                 0.36 
                  5 
                 3 (1, 3, 5) 
               
               
                   
                 UCD107 
                   
                   
                   
                   
                   
                   
               
               
                 4 
                 SYN- 
                 1 × 10 9   
                 1 × 10 9   
                  1 
                 0.12 
                 14 
                 3 (19, 21, 23) 
               
               
                   
                 UCD303 
                   
                   
                   
                   
                   
                   
               
               
                 5 
                 SYN- 
                 1 × 10 12   
                 1 × 10 11   
                 10 
                 0.36 
                  5 
                 3 (25, 27, 29) 
               
               
                   
                 UCD303 
               
               
                   
               
               
                 *Concentration of Sodium Bicarbonate: .36M or 0.12M (0.36M for the control article) 
               
            
           
         
       
     
     SYN-UCD107 and SYN-UCD303 stocks were prepared at 1×109 cfu/mL and 1×10 11  cfu/mL in 15% glycerol in 1×PBS with 2.2% glucose and 3 mM thymidine and were kept at 86 to −60° C. (see Table 28). PBS made in 20% glycerol with sodium bicarbonate was used as a control vehicle. Carbonate concentration was 0.36M and 0.12M for sodium bicarbonate (see Table 28). On the day of each dosing, bacteria and vehicle control were removed from the freezer and put on ice and thawed and placed on ice until dosing. 
     Animals were dosed at 0, 1×10 9 , or 1×10 12  cfu/animal. All animals were dosed via nasal gastric gavage (NG) followed by control/vehicle flush once daily for 28-days. The concentration of bicarbonate and volume for each group is specified in Table 28. Vials were inverted at least 3 times prior to drawing the dose in the syringe. The dose site and dose time (end of flush time) was recorded. On Day 6, Animals 19, 21, and 23 in Group 4 (SYN-UCD303, 1×109/animal) received 5 mL bicarbonate flush instead of 14 mL followed by test article dose administration. 
     B. Analysis 
     Overall Condition and Weight 
     Overall condition: Clinical observations were performed twice daily, beginning on Day −6 through 44. The first observation was in the AM. The second observation was no sooner than 4 hours after the AM observation. During the dosing phase, the second observation was performed 4 hour (±10 minutes) post dose administration. Additional clinical observations were performed, as necessary. 
     No test article-related clinical observations were identified in this study. 
     Incidental and/or procedural findings, commonly noted in similarly housed animals, occurred sporadically among individuals, were noted in control animals, were also present during the acclimation phase, and did not increase in severity and incidence among dose groups. These included findings related to skin (scab/crust, wounds, abrasions, abnormal skin discoloration, bruising), hair loss, kinked tail, sunken eyes, inappetence, emesis, and urogenital discharge. 
     Weight: Body weights were measured on Days −6, 1, 8, 11, 15, 22, 29, 36, and 43 prior to the first feeding and dose administration, as applicable. 
     No test article-related effects on body weights were identified in this study. Decreases of 5 to 10% body weight, relative to baseline (Day 1), was apparent across all groups, including control, by Day 36 and determined to be study procedure-related. Compared to Day 36, an upward trend was noted in the available body weight data on Day 43, albeit values did not completely return to baseline. 
     Clinical Pathology 
     Blood Collection: Animals were fasted overnight prior to daily dose administration and at least 4 hours prior to each series of collections that included specimens for serum chemistry and plasma bioanalysis. In these instances, associated clinical pathology evaluations were from fasted animals. Blood was collected by venipuncture from a peripheral vein of restrained, conscious animals via a single draw (if possible) and divided into appropriate tubes for analysis, as follows: Hematology: approximately 1.3 mL, K2EDTA tube; Coagulation: approximately 1.8 mL, 3.2% sodium citrate tube; Serum chemistry: approximately 1.0 mL, serum separator tube (SST); Plasma sample: approximately 1.0 mL, Lithium Heparin; The blood for clinical pathology assessment was processed to serum or plasma, or used intact, according to SNBL USA SOPs. 
     Whenever possible, blood was collected via a single draw and then divided appropriately. Specimen collection frequency is summarized in Table 29. 
     
       
         
           
               
             
               
                 TABLE 29 
               
             
            
               
                   
               
               
                 Specimen collection frequency 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                 Plasma 
                 Fecal 
               
               
                   
                   
                   
                 Serum 
                 Sample 
                 sample  
               
               
                 Time Point 
                 Hematology 
                 Coagulation 
                 Chemistry 
                 (on ice) 
                 (on ice) 
               
               
                   
               
               
                 Acclimation 
                 1x 
                 1x 
                 1x 
                 1x 
                 1x 
               
               
                 Week 1 
                   
                   
                   
                   
                   
               
               
                 Dosing 
                 Day 2 
                 Day 2 
                 Day 2 
                 Days 2 and 7 
                 Days 2, 4 
               
               
                 Week 1 
                 (Predose) 
                 (Predose) 
                 (Predose) 
                 (Predose) 
                 and 7 
               
               
                   
                   
                   
                   
                   
                 (Postdose) 
               
               
                 Dosing 
                 Day 14 
                 Day 14 
                 Day 14 
                 Day 14 
                 Day 14 
               
               
                 Week 2 
                 (Predose) 
                 (Predose) 
                 (Predose) 
                 (Predose) 
                 (Postdose) 
               
               
                 Dosing 
                 — 
                 — 
                 — 
                 — 
                 Once daily 
               
               
                 Week 3 
                   
                   
                   
                   
                 Days 18 
               
               
                   
                   
                   
                   
                   
                 through 21 
               
               
                   
                   
                   
                   
                   
                 (Predose) 
               
               
                 Dosing 
                 — 
                 — 
                 — 
                 Day 28 
                 Once daily 
               
               
                 Week 4 
                   
                   
                   
                 (Predose) 
                 Days 22 
               
               
                   
                   
                   
                   
                   
                 through 28 
               
               
                   
                   
                   
                   
                   
                 (Predose) 
               
               
                 Dosing 
                 Day 30 
                 Day 30 
                 Day 30 
                 Day 30 
                 Once daily 
               
               
                 Weeks 5 
                   
                   
                   
                   
                 Days 29, 30, 
               
               
                   
                   
                   
                   
                   
                 and 35 
               
               
                 Dosing 
                 — 
                 — 
                 — 
                 — 
                 Day 40 
               
               
                 Weeks 6 
                   
                   
                   
                   
                   
               
               
                 Dosing 
                 — 
                 — 
                 — 
                 — 
                 Days 46 
               
               
                 Weeks 6 
                   
                   
                   
                   
                 and 50 
               
               
                   
               
               
                 — = Not applicable 
               
               
                 x = Number of times procedure performed within the week 
               
            
           
         
       
     
     Table 30 Summarizes the Clinical Pathology Assay Information. 
     
       
         
           
               
             
               
                 TABLE 30 
               
             
            
               
                   
               
               
                 Clinical pathology assay information 
               
            
           
           
               
               
               
               
            
               
                   
                 Analyzed 
                   
                   
               
               
                   
                 Sample 
                   
                 Residual 
               
               
                   
                 Collection 
                 Parameters 
                 Sample 
               
               
                 Assay 
                 Days 
                 Measured 
                 Disposition 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Hematology 
                 Days −6, 
                 Hematocrit, Hemoglobin, Mean 
                 Stored at 
               
               
                   
                 2, 14, 
                 corpuscular hemoglobin, Mean 
                 2 to 8° C. a   
               
               
                   
                 and 30 
                 corpuscular hemoglobin 
                   
               
               
                   
                   
                 concentration, Mean 
                   
               
               
                   
                   
                 corpuscular volume, Mean 
                   
               
               
                   
                   
                 platelet volume, Platelets, 
                   
               
               
                   
                   
                 Red blood cells, Red cell 
                   
               
               
                   
                   
                 distribution width, Reticulocyte 
                   
               
               
                   
                   
                 absolute count, Reticulocyte 
                   
               
               
                   
                   
                 percent, White blood 
                   
               
               
                   
                   
                 cells, and Differential leukocyte 
                   
               
               
                   
                   
                 absolute count: Basophils, 
                   
               
               
                   
                   
                 Eosinophils, Lymphocytes, 
                   
               
               
                   
                   
                 Monocytes, and Neutrophils 
                   
               
               
                 Coagulation 
                 Days −6, 
                 Activated partial 
                 Stored 
               
               
                   
                 2, 14, 
                 thromboplastin time, Fibrinogen, 
                 at −60 
               
               
                   
                 and 30 
                 and Prothrombin time 
                 to −86° C. a   
               
               
                 Serum 
                 Days −6, 
                 Alanine Aminotransferase, 
                 Stored 
               
               
                 Chemistry 
                 2, 14, 
                 Albumin, Albumin/ 
                 at −60 
               
               
                   
                 and 30 
                 Globulin Ratio, Alkaline 
                 to −86° C. a   
               
               
                   
                   
                 Phosphatase, Aspartate 
                   
               
               
                   
                   
                 Aminotransferase, Blood Urea 
                   
               
               
                   
                   
                 Nitrogen, Calcium, 
                   
               
               
                   
                   
                 Chloride, Creatine 
                   
               
               
                   
                   
                 Kinase, Creatinine, Gamma 
                   
               
               
                   
                   
                 Glutamyltransferase, 
                   
               
               
                   
                   
                 Globulin, Glucose, 
                   
               
               
                   
                   
                 Inorganic Phosphorus, Potassium, 
                   
               
               
                   
                   
                 Sodium, Total Bilirubin, 
                   
               
               
                   
                   
                 Total Cholesterol, 
                   
               
               
                   
                   
                 Total Protein, and Triglyceride 
               
               
                   
               
               
                   a Residual samples were discarded prior to study finalization 
               
            
           
         
       
     
     No test article-related effects in hematology, coagulation, and serum chemistry parameters were identified in this study. 
     Plasma Samples: Animals were fasted for 4 hours prior to removal of the sample. Approximately 1 mL of blood were collected from the femoral vein and transferred into 2 mL lithium heparin tubes on Days −1 and 30, and prior to dose administration on Days 2, 7, 14, and 28. After collection of the target volume of blood in the tube, approximately 0.05 (on Days −1 and 2) or 0.1 mL (on Days 7, 14, 28, and 30) of mineral oil was added to cover the surface of blood in the tubes. Tubes were not inverted and were placed on wet ice. 
     The samples were centrifuged within 15 minutes of collection at 2 to 8° C. to obtain plasma and the plasma was maintained on dry ice prior to storage at −60 to −86° C. 
     Analysis of specimens is conducted using a blood ammonia analyzer instrument. 
     Fecal Sample Collection: Two fecal samples per animal were collected at the target time points listed in Table 29. Sample collection dates and times were recorded. 50 mL falcon tube with approximately 5 mL PBS were used as the container (If feces is liquid, no PBS is added). To get the fecal sample weight, pre- and post-sampling weight of container was taken. Samples were collected from the bottom of the cage from each animal. To get fresh and un-contaminated samples, remaining food was removed and the cage pan was cleaned and squeegeed to remove debris and/or water before the collection. On Days −5, 2, 4, 7, and 14, food removals and pan cleanings were performed after the first feeding and/or dose administration. On Days 18, 20, 24, 28, 30, 35, 40, 46, and 50, the food removals and pan cleanings were performed the night before each collection. Visually fresh fecal samples were also collected in the morning before any procedures, except clinical observations, occurred. 
     Fecal Swab Collection: When fecal samples were not collected by the end of the scheduled day, fecal swab samples were collected with a cotton tip applicator from the rectum of animals restrained in a procedure cage. 
     Samples were put on wet ice immediately after the collection. Samples were stored at −20 to −15° C. until analysis. Analysis of specimens was conducted using a PCR analytical method as described in Example 31. 
     Two fecal samples per animal were collected on Day −5 and after dose administration on Days 2, 4, 7, and 14, and three fecal samples per animal were collected on Days 29, 30, 35, 40, 46, and 50, and prior to dose administration on Days 18 through 28. Fifty milliliter falcon tubes with approximately 5 mL PBS were used for the collections on Days −5 through 14, and 50 mL falcon tubes with approximately 5 mL PBS for Tube 1, 20 mL of 50% glycerol and 10 mM thymidine for Tube 2, and 20 mL of 50% glycerol/PBS for Tube 3, were used for the collections on Days 18 through 50. Specimens were put on wet ice immediately after the collection and the contents of each tube collected on Days 18 through 50 were broken-up and mixed using a sterile tongue depressor. 
     Since no fecal samples were collected from the animals listed in Table 29 by the end of the collection day, two fecal swab samples were collected per animal. After sample collection, the cotton part of the swab was transferred to a 5 mL cryovial with 1 mL of PBS and immediately put on wet ice. 
     Results are shown in  FIG. 37 , and show that the amount of bacteria quantified from fecal samples follows a similar pattern for Kanamycin resistant control Nissle (SYN-UCD107) and SYN-UCD303. Bacteria in the fecal samples reach a level of less than 1000 bacteria/per ml of feces by day 35. Results indicate that under these dosing conditions, similar amounts of bacteria were recovered with the auxotroph SYN-UCD303 as control kanamycin resistant Nissle in the feces. Similar results have been observed in mice. In conclusion, SYN-UCD303 appeared to be present in the NHP feces at nearly the same concentration as Nissle (SYN-UCD107). 
     In overall conclusion, the test article, SYN-UCD303, was well tolerated by female cynomolgus monkeys after 28 days of daily NG dose administration at doses up to 1×10 12  CFU/animal. No test article-related mortality occurred and no test article-related effects were identified upon clinical observation, body weight, and clinical pathology assessment. 
     Example 28. Repeat-Dose Pharmacokinetic and Pharmacodynamic Study of SYN-UCD-303 Following Daily Nasogastric Gavage Dose Administration for 28-Days in Cynomolgus Monkeys (Non-GLP) 
     Pharmacokinetics and pharmacodynamics of SYN-UCD303, SYN-UCD304, SYN-UCD305, and SYN-UCD306 and are studied following daily nasogastric gavage (NG) dose administration for 28-days to female cynomolgus monkeys essentially as described in Example 27. Cynomolgus monkeys are selected because this species is closely related, both phylogenetically and physiologically, to humans and is a species commonly used for nonclinical toxicity evaluations. The genetically engineered bacteria are administered by nasal gastric gavage, consistent with the proposed route of administration in humans. Animals overall well-being (clinical observations), weight clinical pathology (serum chemistry, hematology, and coagulation) are tracked. Plasma is analyzed for ammonia levels, and fecal samples are examined for bacterial load. 
     Example 29. 4-Week Toxicity Study in Cynomolgus Monkeys with a 4-Week Recovery (GLP) 
     To evaluate any potential toxicities arising from administration of the genetically engineered bacteria, the pharmacokinetics and pharmacodynamics of SYN-UCD303 is studied following daily nasogastric gavage (NG) dose administration for 28-days to female cynomolgus monkeys under GLP conditions. 
     In other embodiments, the study is conducted SYN-UCD304, SYN-UCD305, and/or SYN-UCD306. 
     The study is conducted in compliance with nonclinical Laboratory Studies Good Laboratory Practice Regulations issued by the U.S. Food and Drug Administration (Title 21 of the Code of Federal Regulations, Part 58; effective Jun. 20, 1979) and the OECD Principles on Good Laboratory Practice (C[97]186/Final; effective 1997). The animals are individually housed based on the recommendations set forth in the Guide for the Care and Use of Laboratory Animals (National Research Council 2011). 
     Animals are administered SYN-UCD303 or control vehicle essentially as described in the Example 27, except that all materials are manufactured under GMP standards. Dosing is tabulated in Table 31. Additionally, animals are acclimated for 14 days and the dosing period is daily for 28 days followed by a recovery period of 28 days. Additionally, animals are euthanized at the end of the study to conduct histological analysis. 
     
       
         
           
               
             
               
                 TABLE 31 
               
               
                   
               
               
                 Dosing Period and Regimen 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 ACCLIMATION 
                 14 days 
               
               
                 TEST ARTICLE PREP 
                 Daily 
               
               
                 DOSING PERIOD 
                 Daily for 28 days 
               
               
                 RECOVERY PERIOD 
                 28 days 
               
               
                 REGULATIONS 
                 FDA GLP 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 TEST 
                 DOSE 
                 DOSE 
                 NUMBER OF ANIMALS 
               
            
           
           
               
               
               
               
               
               
            
               
                 GROUP 
                 ARTICLE 
                 LEVEL 
                 ROUTE 
                 MALES (♂) 
                 FEMALES (♀) 
               
               
                   
               
               
                 1 
                 Vehicle 
                 0 
                 NG 
                 3 a  + 2 b   
                 3 a  + 2 b   
               
               
                 2 
                 SYN- 
                 1 × 10 ∧ 9  
                 NG 
                 3 a   
                 3 a   
               
               
                   
                 UCD303 
                   
                   
                   
                   
               
               
                 3 
                 SYN- 
                 1 × 10 ∧ 10 
                 NG 
                 3 a   
                 3 a   
               
               
                   
                 UCD303 
                   
                   
                   
                   
               
               
                 4 
                 SYN- 
                 1 × 10 ∧ 11 
                 NG 
                 3 a  + 2 b   
                 3 a  + 2 b   
               
               
                   
                 UCD303 
               
               
                   
               
               
                   a Terminal Necropsy, Day 29 
               
               
                   b Recovery Necropsy, Day 56 
               
            
           
         
       
     
     Study Analysis is conducted as described in Table 32. Hematology, Coagulation, Serum Chemistry and Plasma Samples parameters are essentially as described in Example 27, and are analyzed using the methods described in Example 27. Collection and analysis of fecal samples is essentially conducted as described in Example 27. 
     
       
         
           
               
             
               
                 TABLE 32 
               
             
            
               
                   
               
               
                 Study Analysis 
               
            
           
           
               
               
            
               
                 PROCEDURE 
                 TIME POINTS 
               
               
                   
               
               
                 DOSE CONCENTRATION 
                 Day 1 and Day 28 
               
               
                 ANALYSIS 
                   
               
               
                 CLINICAL OBSERVATIONS 
                 Twice Daily (cageside observations) 
               
               
                 FOOD CONSUMPTION 
                 Daily (qualitative) 
               
               
                 BODY WEIGHTS 
                 Weekly 
               
               
                 OPHTHALMOLOGY 
                 Once during acclimation, 
               
               
                   
                 Week 4, and Week 8 
               
               
                 ECGs/HR/BP 
                 Once during acclimation, 
               
               
                   
                 Week 4, and Week 8 
               
               
                 HEMATOLOGY 
                 Twice during acclimation, Day 2 
               
               
                   
                 (pre-dose), Day 15 (pre-dose), 
               
               
                   
                 Day 29, Day 42, and Day 56 
               
               
                 COAGULATION 
                 Twice during acclimation, Day 2 
               
               
                   
                 (pre-dose), Day 15 (pre-dose), 
               
               
                   
                 Day 29, Day 42, and Day 56 
               
               
                 SERUM CHEMISTRY 
                 Twice during acclimation, Day 2 
               
               
                   
                 (pre-dose), Day 15 (pre-dose), 
               
               
                   
                 Day 29, Day 42, and Day 56 
               
               
                 BODY 
                 Twice during acclimation 
               
               
                 (RECTAL) 
                 (with at least 7 
               
               
                 TEMPERATURE 
                 days between measurements); 
               
               
                   
                 once weekly during 
               
               
                   
                 dosing (~6 hrs post-dose), 
               
               
                   
                 and Weeks 5 and 8 
               
               
                 STOOL SAMPLE 
                 Once during acclimation, prior 
               
               
                 COLLECTION 
                 to dosing on Days 2, 7, and 14,  
               
               
                 (BACTERIAL CULTURE) 
                 Day 29, Day 33, and Week 8 
               
               
                   
                 Rectal/Fecal swabs are collected via 
               
               
                   
                 cotton tip applicator; the cotton  
               
               
                   
                 part of the swab is transferred to a 
               
               
                   
                 tube with an appropriate broth/ 
               
               
                   
                 media and immediately put on wet 
               
               
                   
                 ice. Fecal samples are stored 
               
               
                   
                 at 2 to 8° C. until time of analysis. 
               
               
                 CYTOKINE BLOOD 
                 Once during acclimation, Days 1, 
               
               
                 COLLECTIONS 
                 3, 7, 14 and 28 (6 hrs post- 
               
               
                   
                 dose), and Day 56 
               
               
                 ARCHIVE BLOOD SAMPLE 
                 Once during acclimation, Days 1, 
               
               
                 COLLECTION (SAMPLE 
                 3, 7, 14 and 28 (6 hrs post- 
               
               
                   
                 dose), and Day 56; 
               
               
                 TO BE HELD FOR 
                 Blood samples are processed to 
               
               
                 POSSIBLE ANALYSIS) 
                 serum; samples are stored frozen. 
               
               
                 NECROPSY &amp; TISSUE 
                 All animals (e.g., colon, intestine, 
               
               
                 COLLECTION 
                 cecum, liver, spleen) 
               
               
                 ORGAN WEIGHTS 
                 All animals 
               
               
                 TISSUE COLLECTION FOR 
                 All animals 
               
               
                 PK/PD ASSESSMENT 
                   
               
               
                 HISTOPATHOLOGY 
                 All animals 
               
               
                 STATISTICAL ANALYSIS 
                 Comparative (Anova/Bartletts) 
               
               
                   
               
            
           
         
       
     
     Example 30. 4-Week Repeat Dose Toxicity Study in Mice with a 2-Week Recovery (GLP) 
     To evaluate any potential toxicities arising from administration of the genetically engineered bacteria, the pharmacokinetics and pharmacodynamics of SYN-UCD303 is studied following daily gavage dose administration for 4 weeks followed by a two week recovery under GLP conditions. 
     All materials are manufactured under GLP conditions. CD-1 Mice, 6-8 weeks of age at initiation of study are acclimated for 7 days. Groups of males and female mice are studied separately. SYN-UCD303 or vehicle control are administered as described in Table 33. 
     In certain embodiments, the study is conducted SYN-UCD304, SYN-UCD305, and/or SYN-UCD306. 
     
       
         
           
               
             
               
                 TABLE 33 
               
             
            
               
                   
               
               
                 Study Design 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 DOSE 
                   
                   
               
               
                   
                 TEST 
                 LEVEL 
                 DOSE 
                 NUMBER OF ANIMALS 
               
            
           
           
               
               
               
               
               
               
            
               
                 GROUP 
                 ARTICLE 
                 (MG/KG) 
                 ROUTE 
                 MALES (♂) 
                 FEMALES (♀) 
               
               
                   
               
               
                 1 
                 Vehicle 
                 0 
                 NG 
                 10 a  + 6 b   
                 10 a  + 6 b   
               
               
                 2 
                 SYN-UCD303 
                 1 × 10 ∧ 9  
                 NG 
                 10 a  + 6 b   
                 10 a  + 6 b   
               
               
                 3 
                 SYN-UCD303 
                 1 × 10 ∧ 10 
                 NG 
                 10 a  + 6 b   
                 10 a  + 6 b   
               
               
                 4 
                 SYN-UCD303 
                 1 × 10 ∧ 11 
                 NG 
                 10 a  + 6 b   
                 10 a  + 6 b   
               
               
                   
               
               
                   a Toxicity (Tox) Animals, Terminal Necropsy Day 29; 
               
               
                   b Toxicity (Tox) Animals, Recovery Necropsy Day 42 
               
            
           
         
       
     
     The study analysis is described in Table 34. Hematology, Coagulation, Serum Chemistry and Plasma Samples parameters are essentially as described in Example 27, and are analyzed using the methods described in Example 27. Collection and analysis of fecal samples is essentially conducted as described in Example 27. Histology is conducted as in Example 29. 
     
       
         
           
               
             
               
                 TABLE 34 
               
             
            
               
                   
               
               
                 Study Analysis 
               
            
           
           
               
               
            
               
                 PROCEDURE 
                 TIME POINTS 
               
               
                   
               
               
                 DOSE CONCENTRATION 
                 Day 1 and Day 28 
               
               
                 ANALYSIS 
                   
               
               
                 CLINICAL OBSERVATIONS 
                 Daily (Cageside Observations) 
               
               
                 FOOD CONSUMPTION 
                 Weekly (Quantitative) 
               
               
                 BODY WEIGHTS 
                 Twice during acclimation, weekly 
               
               
                   
                 during study and recovery 
               
               
                 OPHTHALMOLOGY 
                 Once during acclimation, 
               
               
                   
                 Week 4, and Week 8 
               
               
                 HEMATOLOGY 
                 At each necropsy; Day 29: 5 
               
               
                   
                 animals/sex/group; Day 42: 3 
               
               
                   
                 animals/sex/group; Standard 
               
               
                   
                 panel as in Example 27 
               
               
                 COAGULATION 
                 At each necropsy; Day 29: 5 
               
               
                   
                 animals/sex/group; Day 42: 3 
               
               
                   
                 animals/sex/group; Standard 
               
               
                   
                 panel as in Example 27 
               
               
                 SERUM CHEMISTRY 
                 At each necropsy; Day 29: 5 
               
               
                   
                 animals/sex/group; Day 56: 3 
               
               
                   
                 animals/sex/group; Standard 
               
               
                   
                 panel as in Example 27 
               
               
                 FECAL SAMPLE 
                 Once during acclimation, Days 2, 7, 
               
               
                 COLLECTION 
                 14, 29, 33, and 42. Samples will 
               
               
                 (BACTERIAL 
                 be collected for up to a 2 hour period. 
               
               
                 CULTURE) 
                 For sample collection, animals, 
               
               
                   
                 as a group of 6, are placed in or 
               
               
                   
                 above a sterile surface. Fecal 
               
               
                   
                 pellets (for each sex and group) 
               
               
                   
                 are transferred to a tube with an 
               
               
                   
                 appropriate broth/media and 
               
               
                   
                 immediately put on wet ice. 
               
               
                 NECROPSY AND TISSUE 
                 At each necropsy Standard 
               
               
                 COLLECTION 
                 panel as in Example 29 
               
               
                 ORGAN WEIGHTS 
                 At each necropsy Standard 
               
               
                   
                 panel as in Example 29. 
               
               
                 HISTOPATHOLOGY 
                 Tox animals: Control &amp; High 
               
               
                   
                 dose groups only Example 29. 
               
               
                 STATISTICAL ANALYSIS 
                 Comparative (Anova/Bartletts) 
               
               
                   
               
            
           
         
       
     
     Example 31. Determination of Presence of Nissle in Fecal Samples of Non-human Primates 
     To analyze fecal samples from non-human primates (NHPs) for the presence of Nissle, the number of bacteria from NHP samples was quantified based on the quantity of DNA in the sample using qPCR. In some embodiments, this protocol is used for the analysis of fecal samples from other mammals, including, but not limited to, mice and humans. 
     Sample Homogenization: Fecal samples (stored at −20° C.) were thawed at room temperature for 90 minutes. For solid fecal samples, the approximate solid volume was estimated, and phosphate buffered saline (PBS) was added to double the volume. For liquid fecal samples, no additional PBS was added. Samples were then vortexed for 30 seconds per tube. Fecal samples were homogenized using a disposable Pestle (Fisher 12-141-363) in PBS in Eppendorf tubes and kept on ice for subsequent procedures. 
     DNA purification: The homogenized samples (250 μL) were removed using sterilized filter tips (Racked Gilson Expert Sterilized Filter Tips) cut at the first gradation line and transferred to Eppendorf tubes. DNA was purified from the homogenized samples (250 μl) using the MoBio PowerLyzer PowerSoil DNA Isolation Kit (12855-100) following manufacturer&#39;s protocol. The amount of purified DNA recovered from each sample was quantified by measuring the OD260 of the sample on a Eppendorf BioSpectrometer Basic. 
     PCR reaction: Two reactions (Reaction 1 and Reaction 2) were assembled and run in triplicate. The first reaction served to quantify the amount of Nissle, and the second to quantify the total amount of bacteria present in the fecal samples. For the first qPCR reaction, purified DNA (5 ng), 0.4 μL of Primer 1 (10 μM), 0.4 μL of Primer 2 (10 μM), and 10 μL of SYBR Green PCR Master Mix (Thermo Fisher Scientific: 4368577) were brought up to 20 μL with water. For the second qPCR reaction, purified DNA (5 ng), 0.4 μL of Primer 3 (10 μM), 0.4 μL of Primer 4 (10 μM), and 10 μL of SYBR Green PCR Master Mix (Thermo Fisher Scientific: 4368577) were brought up to 20 μL with water. 
     The sequences of primers used in the reactions at a concentration of 10 μM are found in Table 35. 
     
       
         
           
               
             
               
                 TABLE 35 
               
             
            
               
                   
               
               
                 Primer Sequences 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                   
                 SEQ 
               
               
                 Primer 
                   
                 Size of 
                 Identi- 
                 ID 
               
               
                 Name 
                 Primer Sequence 
                 Product 
                 fies 
                 NO 
               
               
                   
               
               
                 1 
                 GCAACTGGCCCGTAATTATCC 
                 191 bp 
                 Nissle 
                 74 
               
               
                   
               
               
                 2 
                 ACGCATCGCACGTAGGTTT 
                   
                   
                 75 
               
               
                   
               
               
                 3 
                 ggcaggcctaacacatgcaag 
                 240 bp 
                 Total 
                 76 
               
               
                   
               
               
                 4 
                 gtcgcctaggtgagcctttacc 
                   
                 Bacteria 
                 77 
               
               
                   
               
            
           
         
       
     
     For quantification of the amount of bacterial DNA amplified, a standard curve was run for each reaction. To generate the standard curve, Fragment #1 (synthesized at a set concentration) (Table 36) was diluted in 10-fold serial dilutions, resulting in the following amounts: no DNA, 1 copy of Fragment #1, 10 copies of Fragment #1, 100 copies of Fragment #1, and so on, until the eighth well has 106 copies of fragment #1. Standard DNAs were then added to the qPCR reaction mix for Reaction #1. 
     
       
         
           
               
             
               
                 TABLE 36 
               
             
            
               
                   
               
               
                 Standard DNA Sequence (Fragment #1) 
               
            
           
           
               
               
               
            
               
                   
                   
                 SEQ 
               
               
                 Descrip- 
                   
                 ID 
               
               
                 tion 
                 Sequence 
                 NO 
               
               
                   
               
               
                 Fragment 
                 gcaactggcccgtaattatccatagctgtagtgat 
                 78 
               
               
                 1 
                 cactcggtccgaattaaacgcaatgatggcgagct 
                   
               
               
                   
                 gagaacgattagcatcaaacgctttaacgaagatt 
                   
               
               
                   
                 ttgaacgagtggagcatgatgagtatcgcaaaata 
                   
               
               
                   
                 tgtgccgaaatagagcaggaaacaaacctgaaaaa 
                   
               
               
                   
                 cctacgtgcgatgcgt 
               
               
                   
               
            
           
         
       
     
     PCR reaction conditions for standard curve, and Reactions 1 and 2 are shown in Table 37. 
     
       
         
           
               
             
               
                 TABLE 37 
               
             
            
               
                   
               
               
                 PCR Reaction Conditions 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 Transition 
                   
               
               
                   
                 Temperature 
                 Time 
                 Speed 
                   
               
               
                   
                 (° C.) 
                 (seconds) 
                 (° C./second) 
                 Repeats 
               
               
                   
                   
               
               
                   
                 95 
                 15 
                 N/A 
                 40 
               
               
                   
                 60 
                 60 
                 N/A 
                   
               
            
           
           
               
            
               
                 Melt Curve 
               
            
           
           
               
               
               
               
               
            
               
                   
                 95 
                 15 
                 N/A 
                  1 
               
               
                   
                 60 
                 60 
                 0.3 
                   
               
               
                   
                 95 
                 15 
               
               
                   
                   
               
            
           
         
       
     
     As a quality control measure, the melt-curves of the test qPCR reactions were compared to the positive control for each primer set, to ensure that the melt-curve of the positive controls matched the melt-curve of the test samples. The presence and quantity of Nissle and total bacteria was determined by analyzing CT values (Cycle threshold values) against the standard curve. 
     Example 32. Construction of Vectors for Overproducing Butyrate 
     In addition to the ammonia conversion circuit, GABA transport circuit, GABA metabolic circuit, and/or manganese transport circuit described above, the  E. coli  Nissle bacteria further comprise one or more circuits for producing a gut barrier enhancer molecule. 
     To facilitate inducible production of butyrate in  E. coli  Nissle, the eight genes of the butyrate production pathway from  Peptoclostridium difficile  630 (bcd2, etfB3, etfA3, thiA1, hbd, crt2, bpt, and buk; NCBI), as well as transcriptional and translational elements, were synthesized (Gen9, Cambridge, Mass.) and cloned into vector pBR322. The butyrate gene cassette is placed under the control of a FNR regulatory region selected from SEQ ID NOs: 18-29 (Table 6). In certain constructs, the FNR-responsive promoter is further fused to a strong ribosome binding site sequence. For efficient translation of butyrate genes, each synthetic gene in the operon was separated by a 15 base pair ribosome binding site derived from the T7 promoter/translational start site. 
     In certain constructs, the butyrate gene cassette is placed under the control of an RNS-responsive regulatory region, e.g., norB, and the bacteria further comprises a gene encoding a corresponding RNS-responsive transcription factor, e.g., nsrR (see, e.g., Tables 38 and 39). In certain constructs, the butyrate gene cassette is placed under the control of an ROS-responsive regulatory region, e.g., oxyS, and the bacteria further comprises a gene encoding a corresponding ROS-responsive transcription factor, e.g., oxyR (see, e.g., Tables 14-17). In certain constructs, the butyrate gene cassette is placed under the control of a tetracycline-inducible or constitutive promoter. 
     
       
         
           
               
             
               
                 TABLE 38 
               
             
            
               
                   
               
               
                 pLogic031-nsrR-norB-butyrate construct (SEQ ID NO: 79) 
               
            
           
           
               
               
            
               
                   
                 Nucleotide sequences of pLogic031-nsrR-norB-butyrate 
               
               
                 Description 
                 construct (SEQ ID NO: 79) 
               
               
                   
               
               
                 Nucleic acid 
                 ttatta   tcgcaccgcaatcgggattttcgattcataaagcaggt     
               
               
                 sequence of an 
                 
                   
                     cgtaggtcggcttgttgagcaggtcttgcagcgtgaaaccgtcc 
                   
                 
               
               
                 exemplary RNS- 
                 
                   
                     agatacgtgaaaaacgacttcattgcaccgccgagtatgcccgt 
                   
                 
               
               
                 regulated construct 
                 
                   
                     cagccggcaggacggcgtaatcaggcattcgttgttcgggccca 
                   
                 
               
               
                 comprising a gene 
                 
                   
                     tacactcgaccagctgcatcggttcgaggtggcggacgaccgcg 
                   
                 
               
               
                 encoding nsrR, a 
                 
                   
                     ccgatattgatgcgttcgggcggcgcggccagcctcagcccgcc 
                   
                 
               
               
                 regulatory region of 
                 
                   
                     gcctttcccgcgtacgctgtgcaagaacccgcctttgaccagcg 
                   
                 
               
               
                 norB, and a 
                 
                   
                     cggtaaccactttcatcaaatggcttttggaaatgccgtaggtc 
                   
                 
               
               
                 butyrogenic gene 
                 
                   
                     gaggcgatggtggcgatattgaccagcgcgtcgtcgttgacggc 
                   
                 
               
               
                 cassette (pLogic031- 
                 
                   
                     ggtgtagatgaggacgcgcagcccgtagtcggtatgttgggtca 
                   
                 
               
               
                 nsrR-norB-butyrate 
                     gatacat   acaacctccttagtacatgcaaaattatttctagagc 
               
               
                 construct; SEQ ID 
                 aacatacgagccggaagcataaagtgtaaagcctggggtgccta 
               
               
                 NO: 79). The 
                 atgagttgagttgaggaattataacaggaagaaatattcctcat 
               
               
                 sequence encoding 
                 acgcttgtaattcctctatggttgttgacaattaatcatcggct 
               
               
                 NsrR is    underlined     
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                     and bolded   , and the 
                 gaaataattttgtttaactttaagaaggagatatacatatggat 
               
               
                 NsrR binding site, 
                 ttaaattctaaaaaatatcagatgcttaaagagctatatgtaag 
               
               
                 i.e., a regulatory 
                 cttcgctgaaaatgaagttaaacctttagcaacagaacttgatg 
               
               
                 region of norB is 
                 aagaagaaagatttccttatgaaacagtggaaaaaatggcaaaa 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 gcaggaatgatgggtataccatatccaaaagaatatggtggaga 
               
               
                   
                 aggtggagacactgtaggatatataatggcagttgaagaattgt 
               
               
                   
                 ctagagtttgtggtactacaggagttatattatcagctcataca 
               
               
                   
                 tctcttggctcatggcctatatatcaatatggtaatgaagaaca 
               
               
                   
                 aaaacaaaaattcttaagaccactagcaagtggagaaaaattag 
               
               
                   
                 gagcatttggtcttactgagcctaatgctggtacagatgcgtct 
               
               
                   
                 ggccaacaaacaactgctgttttagacggggatgaatacatact 
               
               
                   
                 taatggctcaaaaatatttataacaaacgcaatagctggtgaca 
               
               
                   
                 tatatgtagtaatggcaatgactgataaatctaaggggaacaaa 
               
               
                   
                 ggaatatcagcatttatagttgaaaaaggaactcctgggtttag 
               
               
                   
                 ctttggagttaaagaaaagaaaatgggtataagaggttcagcta 
               
               
                   
                 cgagtgaattaatatttgaggattgcagaatacctaaagaaaat 
               
               
                   
                 ttacttggaaaagaaggtcaaggatttaagatagcaatgtctac 
               
               
                   
                 tcttgatggtggtagaattggtatagctgcacaagctttaggtt 
               
               
                   
                 tagcacaaggtgctcttgatgaaactgttaaatatgtaaaagaa 
               
               
                   
                 agagtacaatttggtagaccattatcaaaattccaaaatacaca 
               
               
                   
                 attccaattagctgatatggaagttaaggtacaagcggctagac 
               
               
                   
                 accttgtatatcaagcagctataaataaagacttaggaaaacct 
               
               
                   
                 tatggagtagaagcagcaatggcaaaattatttgcagctgaaac 
               
               
                   
                 agctatggaagttactacaaaagctgtacaacttcatggaggat 
               
               
                   
                 atggatacactcgtgactatccagtagaaagaatgatgagagat 
               
               
                   
                 gctaagataactgaaatatatgaaggaactagtgaagttcaaag 
               
               
                   
                 aatggttatttcaggaaaactattaaaatagtaagaaggagata 
               
               
                   
                 tacatatggaggaaggatttatgaatatagtcgtttgtataaaa 
               
               
                   
                 caagttccagatacaacagaagttaaactagatcctaatacagg 
               
               
                   
                 tactttaattagagatggagtaccaagtataataaaccctgatg 
               
               
                   
                 ataaagcaggtttagaagaagctataaaattaaaagaagaaatg 
               
               
                   
                 ggtgctcatgtaactgttataacaatgggacctcctcaagcaga 
               
               
                   
                 tatggctttaaaagaagctttagcaatgggtgcagatagaggta 
               
               
                   
                 tattattaacagatagagcatttgcgggtgctgatacttgggca 
               
               
                   
                 acttcatcagcattagcaggagcattaaaaaatatagattttga 
               
               
                   
                 tattataatagctggaagacaggcgatagatggagatactgcac 
               
               
                   
                 aagttggacctcaaatagctgaacatttaaatcttccatcaata 
               
               
                   
                 acatatgctgaagaaataaaaactgaaggtgaatatgtattagt 
               
               
                   
                 aaaaagacaatttgaagattgttgccatgacttaaaagttaaaa 
               
               
                   
                 tgccatgccttataacaactcttaaagatatgaacacaccaaga 
               
               
                   
                 tacatgaaagttggaagaatatatgatgctttcgaaaatgatgt 
               
               
                   
                 agtagaaacatggactgtaaaagatatagaagttgacccttcta 
               
               
                   
                 atttaggtcttaaaggttctccaactagtgtatttaaatcattt 
               
               
                   
                 acaaaatcagttaaaccagctggtacaatatacaatgaagatgc 
               
               
                   
                 gaaaacatcagctggaattatcatagataaattaaaagagaagt 
               
               
                   
                 atatcatataataagaaggagatatacatatgggtaacgtttta 
               
               
                   
                 gtagtaatagaacaaagagaaaatgtaattcaaactgtttcttt 
               
               
                   
                 agaattactaggaaaggctacagaaatagcaaaagattatgata 
               
               
                   
                 caaaagtttctgcattacttttaggtagtaaggtagaaggttta 
               
               
                   
                 atagatacattagcacactatggtgcagatgaggtaatagtagt 
               
               
                   
                 agatgatgaagctttagcagtgtatacaactgaaccatatacaa 
               
               
                   
                 aagcagcttatgaagcaataaaagcagctgaccctatagttgta 
               
               
                   
                 ttatttggtgcaacttcaataggtagagatttagcgcctagagt 
               
               
                   
                 ttctgctagaatacatacaggtcttactgctgactgtacaggtc 
               
               
                   
                 ttgcagtagctgaagatacaaaattattattaatgacaagacct 
               
               
                   
                 gcctttggtggaaatataatggcaacaatagtttgtaaagattt 
               
               
                   
                 cagacctcaaatgtctacagttagaccaggggttatgaagaaaa 
               
               
                   
                 atgaacctgatgaaactaaagaagctgtaattaaccgtttcaag 
               
               
                   
                 gtagaatttaatgatgctgataaattagttcaagttgtacaagt 
               
               
                   
                 aataaaagaagctaaaaaacaagttaaaatagaagatgctaaga 
               
               
                   
                 tattagtttctgctggacgtggaatgggtggaaaagaaaactta 
               
               
                   
                 gacatactttatgaattagctgaaattataggtggagaagtttc 
               
               
                   
                 tggttctcgtgccactatagatgcaggttggttagataaagcaa 
               
               
                   
                 gacaagttggtcaaactggtaaaactgtaagaccagacctttat 
               
               
                   
                 atagcatgtggtatatctggagcaatacaacatatagctggtat 
               
               
                   
                 ggaagatgctgagtttatagttgctataaataaaaatccagaag 
               
               
                   
                 ctccaatatttaaatatgctgatgttggtatagttggagatgtt 
               
               
                   
                 cataaagtgcttccagaacttatcagtcagttaagtgttgcaaa 
               
               
                   
                 agaaaaaggtgaagttttagctaactaataagaaggagatatac 
               
               
                   
                 atatgagagaagtagtaattgccagtgcagctagaacagcagta 
               
               
                   
                 ggaagttttggaggagcatttaaatcagtttcagcggtagagtt 
               
               
                   
                 aggggtaacagcagctaaagaagctataaaaagagctaacataa 
               
               
                   
                 ctccagatatgatagatgaatctcttttagggggagtacttaca 
               
               
                   
                 gcaggtcttggacaaaatatagcaagacaaatagcattaggagc 
               
               
                   
                 aggaataccagtagaaaaaccagctatgactataaatatagttt 
               
               
                   
                 gtggttctggattaagatctgtttcaatggcatctcaacttata 
               
               
                   
                 gcattaggtgatgctgatataatgttagttggtggagctgaaaa 
               
               
                   
                 catgagtatgtctccttatttagtaccaagtgcgagatatggtg 
               
               
                   
                 caagaatgggtgatgctgcttttgttgattcaatgataaaagat 
               
               
                   
                 ggattatcagacatatttaataactatcacatgggtattactgc 
               
               
                   
                 tgaaaacatagcagagcaatggaatataactagagaagaacaag 
               
               
                   
                 atgaattagctcttgcaagtcaaaataaagctgaaaaagctcaa 
               
               
                   
                 gctgaaggaaaatttgatgaagaaatagttcctgttgttataaa 
               
               
                   
                 aggaagaaaaggtgacactgtagtagataaagatgaatatatta 
               
               
                   
                 agcctggcactacaatggagaaacttgctaagttaagacctgca 
               
               
                   
                 tttaaaaaagatggaacagttactgctggtaatgcatcaggaat 
               
               
                   
                 aaatgatggtgctgctatgttagtagtaatggctaaagaaaaag 
               
               
                   
                 ctgaagaactaggaatagagcctcttgcaactatagtttcttat 
               
               
                   
                 ggaacagctggtgttgaccctaaaataatgggatatggaccagt 
               
               
                   
                 tccagcaactaaaaaagctttagaagctgctaatatgactattg 
               
               
                   
                 aagatatagatttagttgaagctaatgaggcatttgctgcccaa 
               
               
                   
                 tctgtagctgtaataagagacttaaatatagatatgaataaagt 
               
               
                   
                 taatgttaatggtggagcaatagctataggacatccaataggat 
               
               
                   
                 gctcaggagcaagaatacttactacacttttatatgaaatgaag 
               
               
                   
                 agaagagatgctaaaactggtcttgctacactttgtataggcgg 
               
               
                   
                 tggaatgggaactactttaatagttaagagatagtaagaaggag 
               
               
                   
                 atatacatatgaaattagctgtaataggtagtggaactatggga 
               
               
                   
                 agtggtattgtacaaacttttgcaagttgtggacatgatgtatg 
               
               
                   
                 tttaaagagtagaactcaaggtgctatagataaatgtttagctt 
               
               
                   
                 tattagataaaaatttaactaagttagttactaagggaaaaatg 
               
               
                   
                 gatgaagctacaaaagcagaaatattaagtcatgttagttcaac 
               
               
                   
                 tactaattatgaagatttaaaagatatggatttaataatagaag 
               
               
                   
                 catctgtagaagacatgaatataaagaaagatgttttcaagtta 
               
               
                   
                 ctagatgaattatgtaaagaagatactatcttggcaacaaatac 
               
               
                   
                 ttcatcattatctataacagaaatagcttcttctactaagcgcc 
               
               
                   
                 cagataaagttataggaatgcatttctttaatccagttcctatg 
               
               
                   
                 atgaaattagttgaagttataagtggtcagttaacatcaaaagt 
               
               
                   
                 tacttttgatacagtatttgaattatctaagagtatcaataaag 
               
               
                   
                 taccagtagatgtatctgaatctcctggatttgtagtaaataga 
               
               
                   
                 atacttatacctatgataaatgaagctgttggtatatatgcaga 
               
               
                   
                 tggtgttgcaagtaaagaagaaatagatgaagctatgaaattag 
               
               
                   
                 gagcaaaccatccaatgggaccactagcattaggtgatttaatc 
               
               
                   
                 ggattagatgttgttttagctataatgaacgttttatatactga 
               
               
                   
                 atttggagatactaaatatagacctcatccacttttagctaaaa 
               
               
                   
                 tggttagagctaatcaattaggaagaaaaactaagataggattc 
               
               
                   
                 tatgattataataaataataagaaggagatatacatatgagtac 
               
               
                   
                 aagtgatgttaaagtttatgagaatgtagctgttgaagtagatg 
               
               
                   
                 gaaatatatgtacagtgaaaatgaatagacctaaagcccttaat 
               
               
                   
                 gcaataaattcaaagactttagaagaactttatgaagtatttgt 
               
               
                   
                 agatattaataatgatgaaactattgatgttgtaatattgacag 
               
               
                   
                 gggaaggaaaggcatttgtagctggagcagatattgcatacatg 
               
               
                   
                 aaagatttagatgctgtagctgctaaagattttagtatcttagg 
               
               
                   
                 agcaaaagcttttggagaaatagaaaatagtaaaaaagtagtga 
               
               
                   
                 tagctgctgtaaacggatttgctttaggtggaggatgtgaactt 
               
               
                   
                 gcaatggcatgtgatataagaattgcatctgctaaagctaaatt 
               
               
                   
                 tggtcagccagaagtaactcttggaataactccaggatatggag 
               
               
                   
                 gaactcaaaggcttacaagattggttggaatggcaaaagcaaaa 
               
               
                   
                 gaattaatctttacaggtcaagttataaaagctgatgaagctga 
               
               
                   
                 aaaaatagggctagtaaatagagtcgttgagccagacattttaa 
               
               
                   
                 tagaagaagttgagaaattagctaagataatagctaaaaatgct 
               
               
                   
                 cagcttgcagttagatactctaaagaagcaatacaacttggtgc 
               
               
                   
                 tcaaactgatataaatactggaatagatatagaatctaatttat 
               
               
                   
                 ttggtctttgtttttcaactaaagaccaaaaagaaggaatgtca 
               
               
                   
                 gctttcgttgaaaagagagaagctaactttataaaagggtaata 
               
               
                   
                 agaaggagatatacatatgagaagttttgaagaagtaattaagt 
               
               
                   
                 ttgcaaaagaaagaggacctaaaactatatcagtagcatgttgc 
               
               
                   
                 caagataaagaagttttaatggcagttgaaatggctagaaaaga 
               
               
                   
                 aaaaatagcaaatgccattttagtaggagatatagaaaagacta 
               
               
                   
                 aagaaattgcaaaaagcatagacatggatatcgaaaattatgaa 
               
               
                   
                 ctgatagatataaaagatttagcagaagcatctctaaaatctgt 
               
               
                   
                 tgaattagtttcacaaggaaaagccgacatggtaatgaaaggct 
               
               
                   
                 tagtagacacatcaataatactaaaagcagttttaaataaagaa 
               
               
                   
                 gtaggtcttagaactggaaatgtattaagtcacgtagcagtatt 
               
               
                   
                 tgatgtagagggatatgatagattatttttcgtaactgacgcag 
               
               
                   
                 ctatgaacttagctcctgatacaaatactaaaaagcaaatcata 
               
               
                   
                 gaaaatgcttgcacagtagcacattcattagatataagtgaacc 
               
               
                   
                 aaaagttgctgcaatatgcgcaaaagaaaaagtaaatccaaaaa 
               
               
                   
                 tgaaagatacagttgaagctaaagaactagaagaaatgtatgaa 
               
               
                   
                 agaggagaaatcaaaggttgtatggttggtgggccttttgcaat 
               
               
                   
                 tgataatgcagtatctttagaagcagctaaacataaaggtataa 
               
               
                   
                 atcatcctgtagcaggacgagctgatatattattagccccagat 
               
               
                   
                 attgaaggtggtaacatattatataaagctttggtattcttctc 
               
               
                   
                 aaaatcaaaaaatgcaggagttatagttggggctaaagcaccaa 
               
               
                   
                 taatattaacttctagagcagacagtgaagaaactaaactaaac 
               
               
                   
                 tcaatagctttaggtgttttaatggcagcaaaggcataataaga 
               
               
                   
                 aggagatatacatatgagcaaaatatttaaaatcttaacaataa 
               
               
                   
                 atcctggttcgacatcaactaaaatagctgtatttgataatgag 
               
               
                   
                 gatttagtatttgaaaaaactttaagacattcttcagaagaaat 
               
               
                   
                 aggaaaatatgagaaggtgtctgaccaatttgaatttcgtaaac 
               
               
                   
                 aagtaatagaagaagctctaaaagaaggtggagtaaaaacatct 
               
               
                   
                 gaattagatgctgtagtaggtagaggaggacttcttaaacctat 
               
               
                   
                 aaaaggtggtacttattcagtaagtgctgctatgattgaagatt 
               
               
                   
                 taaaagtgggagttttaggagaacacgcttcaaacctaggtgga 
               
               
                   
                 ataatagcaaaacaaataggtgaagaagtaaatgttccttcata 
               
               
                   
                 catagtagaccctgttgttgtagatgaattagaagatgttgcta 
               
               
                   
                 gaatttctggtatgcctgaaataagtagagcaagtgtagtacat 
               
               
                   
                 gctttaaatcaaaaggcaatagcaagaagatatgctagagaaat 
               
               
                   
                 aaacaagaaatatgaagatataaatcttatagttgcacacatgg 
               
               
                   
                 gtggaggagtttctgttggagctcataaaaatggtaaaatagta 
               
               
                   
                 gatgttgcaaacgcattagatggagaaggacctttctctccaga 
               
               
                   
                 aagaagtggtggactaccagtaggtgcattagtaaaaatgtgct 
               
               
                   
                 ttagtggaaaatatactcaagatgaaattaaaaagaaaataaaa 
               
               
                   
                 ggtaatggcggactagttgcatacttaaacactaatgatgctag 
               
               
                   
                 agaagttgaagaaagaattgaagctggtgatgaaaaagctaaat 
               
               
                   
                 tagtatatgaagctatggcatatcaaatctctaaagaaatagga 
               
               
                   
                 gctagtgctgcagttcttaagggagatgtaaaagcaatattatt 
               
               
                   
                 aactggtggaatcgcatattcaaaaatgtttacagaaatgattg 
               
               
                   
                 cagatagagttaaatttatagcagatgtaaaagtttatccaggt 
               
               
                   
                 gaagatgaaatgattgcattagctcaaggtggacttagagtttt 
               
               
                   
                 aactggtgaagaagaggctcaagtttatgataactaataa 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 39 
               
             
            
               
                   
               
               
                 Nucleotide sequences of pLogic046-nsrR-norB-butyrate construct 
               
            
           
           
               
               
            
               
                   
                 Nucleotide sequences of pLogic046-nsrR-norB-butyrate construct 
               
               
                 Description 
                 (SEQ ID NO: 80) 
               
               
                   
               
               
                 Nucleic acid 
                 ttatta   tcgcaccgcaatcgggattttcgattcataaagcaggtcgta     
               
               
                 sequence of an 
                 
                   
                     ggtcggcttgttgagcaggtcttgcagcgtgaaaccgtccagatacgt 
                   
                 
               
               
                 exemplary RNS- 
                 
                   
                     gaaaaacgacttcattgcaccgccgagtatgcccgtcagccggcagga 
                   
                 
               
               
                 regulated 
                 
                   
                     cggcgtaatcaggcattcgttgttcgggcccatacactcgaccagctg 
                   
                 
               
               
                 construct 
                 
                   
                     catcggttcgaggtggcggacgaccgcgccgatattgatgcgttcggg 
                   
                 
               
               
                 comprising a 
                 
                   
                     cggcgcggccagcctcagcccgccgcctttcccgcgtacgctgtgcaa 
                   
                 
               
               
                 gene encoding 
                 
                   
                     gaacccgcctttgaccagcgcggtaaccactttcatcaaatggctttt 
                   
                 
               
               
                 nsrR, a 
                 
                   
                     ggaaatgccgtaggtcgaggcgatggtggcgatattgaccagcgcgtc 
                   
                 
               
               
                 regulatory 
                 
                   gtcgttgacggcggtgtagatgaggacgcgcagcccgtagtcggtatg 
                 
               
               
                 region of norB, 
                     ttgggtcagatacat   acaacctccttagtacatgcaaaattatttcta 
               
               
                 and a 
                 gagcaacatacgagccggaagcataaagtgtaaagcctggggtgccta 
               
               
                 butyrogenic 
                 atgagttgagttgaggaattataacaggaagaaatattcctcatacgc 
               
               
                 gene cassette 
                 ttgtaattcctctatggttgttgacaattaatcatcggctcgtataat 
               
               
                 (pLogic046-nsrR- 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 norB-butyrate 
                 ttaactttaagaaggagatatacatatgatcgtaaaacctatggtacg 
               
               
                 construct; SEQ 
                 caacaatatctgcctgaacgcccatcctcagggctgcaagaagggagt 
               
               
                 ID NO: 80). 
                 ggaagatcagattgaatataccaagaaacgcattaccgcagaagtcaa 
               
               
                   
                 agctggcgcaaaagctccaaaaaacgttctggtgcttggctgctcaaa 
               
               
                   
                 tggttacggcctggcgagccgcattactgctgcgttcggatacggggc 
               
               
                   
                 tgcgaccatcggcgtgtcctttgaaaaagcgggttcagaaaccaaata 
               
               
                   
                 tggtacaccgggatggtacaataatttggcatttgatgaagcggcaaa 
               
               
                   
                 acgcgagggtctttatagcgtgacgatcgacggcgatgcgttttcaga 
               
               
                   
                 cgagatcaaggcccaggtaattgaggaagccaaaaaaaaaggtatcaa 
               
               
                   
                 atttgatctgatcgtatacagcttggccagcccagtacgtactgatcc 
               
               
                   
                 tgatacaggtatcatgcacaaaagcgttttgaaaccctttggaaaaac 
               
               
                   
                 gttcacaggcaaaacagtagatccgtttactggcgagctgaaggaaat 
               
               
                   
                 ctccgcggaaccagcaaatgacgaggaagcagccgccactgttaaagt 
               
               
                   
                 tatggggggtgaagattgggaacgttggattaagcagctgtcgaagga 
               
               
                   
                 aggcctcttagaagaaggctgtattaccttggcctatagttatattgg 
               
               
                   
                 ccctgaagctacccaagctttgtaccgtaaaggcacaatcggcaaggc 
               
               
                   
                 caaagaacacctggaggccacagcacaccgtctcaacaaagagaaccc 
               
               
                   
                 gtcaatccgtgccttcgtgagcgtgaataaaggcctggtaacccgcgc 
               
               
                   
                 aagcgccgtaatcccggtaatccctctgtatctcgccagcttgttcaa 
               
               
                   
                 agtaatgaaagagaagggcaatcatgaaggttgtattgaacagatcac 
               
               
                   
                 gcgtctgtacgccgagcgcctgtaccgtaaagatggtacaattccagt 
               
               
                   
                 tgatgaggaaaatcgcattcgcattgatgattgggagttagaagaaga 
               
               
                   
                 cgtccagaaagcggtatccgcgttgatggagaaagtcacgggtgaaaa 
               
               
                   
                 cgcagaatctctcactgacttagcggggtaccgccatgatttcttagc 
               
               
                   
                 tagtaacggctttgatgtagaaggtattaattatgaagcggaagttga 
               
               
                   
                 acgcttcgaccgtatctgataagaaggagatatacatatgagagaagt 
               
               
                   
                 agtaattgccagtgcagctagaacagcagtaggaagttttggaggagc 
               
               
                   
                 atttaaatcagtttcagcggtagagttaggggtaacagcagctaaaga 
               
               
                   
                 agctataaaaagagctaacataactccagatatgatagatgaatctct 
               
               
                   
                 tttagggggagtacttacagcaggtcttggacaaaatatagcaagaca 
               
               
                   
                 aatagcattaggagcaggaataccagtagaaaaaccagctatgactat 
               
               
                   
                 aaatatagtttgtggttctggattaagatctgtttcaatggcatctca 
               
               
                   
                 acttatagcattaggtgatgctgatataatgttagttggtggagctga 
               
               
                   
                 aaacatgagtatgtctccttatttagtaccaagtgcgagatatggtgc 
               
               
                   
                 aagaatgggtgatgctgcttttgttgattcaatgataaaagatggatt 
               
               
                   
                 atcagacatatttaataactatcacatgggtattactgctgaaaacat 
               
               
                   
                 agcagagcaatggaatataactagagaagaacaagatgaattagctct 
               
               
                   
                 tgcaagtcaaaataaagctgaaaaagctcaagctgaaggaaaatttga 
               
               
                   
                 tgaagaaatagttcctgttgttataaaaggaagaaaaggtgacactgt 
               
               
                   
                 agtagataaagatgaatatattaagcctggcactacaatggagaaact 
               
               
                   
                 tgctaagttaagacctgcatttaaaaaagatggaacagttactgctgg 
               
               
                   
                 taatgcatcaggaataaatgatggtgctgctatgttagtagtaatggc 
               
               
                   
                 taaagaaaaagctgaagaactaggaatagagcctcttgcaactatagt 
               
               
                   
                 ttcttatggaacagctggtgttgaccctaaaataatgggatatggacc 
               
               
                   
                 agttccagcaactaaaaaagctttagaagctgctaatatgactattga 
               
               
                   
                 agatatagatttagttgaagctaatgaggcatttgctgcccaatctgt 
               
               
                   
                 agctgtaataagagacttaaatatagatatgaataaagttaatgttaa 
               
               
                   
                 tggtggagcaatagctataggacatccaataggatgctcaggagcaag 
               
               
                   
                 aatacttactacacttttatatgaaatgaagagaagagatgctaaaac 
               
               
                   
                 tggtcttgctacactttgtataggcggtggaatgggaactactttaat 
               
               
                   
                 agttaagagatagtaagaaggagatatacatatgaaattagctgtaat 
               
               
                   
                 aggtagtggaactatgggaagtggtattgtacaaacttttgcaagttg 
               
               
                   
                 tggacatgatgtatgtttaaagagtagaactcaaggtgctatagataa 
               
               
                   
                 atgtttagctttattagataaaaatttaactaagttagttactaaggg 
               
               
                   
                 aaaaatggatgaagctacaaaagcagaaatattaagtcatgttagttc 
               
               
                   
                 aactactaattatgaagatttaaaagatatggatttaataatagaagc 
               
               
                   
                 atctgtagaagacatgaatataaagaaagatgttttcaagttactaga 
               
               
                   
                 tgaattatgtaaagaagatactatcttggcaacaaatacttcatcatt 
               
               
                   
                 atctataacagaaatagcttcttctactaagcgcccagataaagttat 
               
               
                   
                 aggaatgcatttctttaatccagttcctatgatgaaattagttgaagt 
               
               
                   
                 tataagtggtcagttaacatcaaaagttacttttgatacagtatttga 
               
               
                   
                 attatctaagagtatcaataaagtaccagtagatgtatctgaatctcc 
               
               
                   
                 tggatttgtagtaaatagaatacttatacctatgataaatgaagctgt 
               
               
                   
                 tggtatatatgcagatggtgttgcaagtaaagaagaaatagatgaagc 
               
               
                   
                 tatgaaattaggagcaaaccatccaatgggaccactagcattaggtga 
               
               
                   
                 tttaatcggattagatgttgttttagctataatgaacgttttatatac 
               
               
                   
                 tgaatttggagatactaaatatagacctcatccacttttagctaaaat 
               
               
                   
                 ggttagagctaatcaattaggaagaaaaactaagataggattctatga 
               
               
                   
                 ttataataaataataagaaggagatatacatatgagtacaagtgatgt 
               
               
                   
                 taaagtttatgagaatgtagctgttgaagtagatggaaatatatgtac 
               
               
                   
                 agtgaaaatgaatagacctaaagcccttaatgcaataaattcaaagac 
               
               
                   
                 tttagaagaactttatgaagtatttgtagatattaataatgatgaaac 
               
               
                   
                 tattgatgttgtaatattgacaggggaaggaaaggcatttgtagctgg 
               
               
                   
                 agcagatattgcatacatgaaagatttagatgctgtagctgctaaaga 
               
               
                   
                 ttttagtatcttaggagcaaaagcttttggagaaatagaaaatagtaa 
               
               
                   
                 aaaagtagtgatagctgctgtaaacggatttgctttaggtggaggatg 
               
               
                   
                 tgaacttgcaatggcatgtgatataagaattgcatctgctaaagctaa 
               
               
                   
                 atttggtcagccagaagtaactcttggaataactccaggatatggagg 
               
               
                   
                 aactcaaaggcttacaagattggttggaatggcaaaagcaaaagaatt 
               
               
                   
                 aatctttacaggtcaagttataaaagctgatgaagctgaaaaaatagg 
               
               
                   
                 gctagtaaatagagtcgttgagccagacattttaatagaagaagttga 
               
               
                   
                 gaaattagctaagataatagctaaaaatgctcagcttgcagttagata 
               
               
                   
                 ctctaaagaagcaatacaacttggtgctcaaactgatataaatactgg 
               
               
                   
                 aatagatatagaatctaatttatttggtctttgtttttcaactaaaga 
               
               
                   
                 ccaaaaagaaggaatgtcagctttcgttgaaaagagagaagctaactt 
               
               
                   
                 tataaaagggtaataagaaggagatatacatatgagaagttttgaaga 
               
               
                   
                 agtaattaagtttgcaaaagaaagaggacctaaaactatatcagtagc 
               
               
                   
                 atgttgccaagataaagaagttttaatggcagttgaaatggctagaaa 
               
               
                   
                 agaaaaaatagcaaatgccattttagtaggagatatagaaaagactaa 
               
               
                   
                 agaaattgcaaaaagcatagacatggatatcgaaaattatgaactgat 
               
               
                   
                 agatataaaagatttagcagaagcatctctaaaatctgttgaattagt 
               
               
                   
                 ttcacaaggaaaagccgacatggtaatgaaaggcttagtagacacatc 
               
               
                   
                 aataatactaaaagcagttttaaataaagaagtaggtcttagaactgg 
               
               
                   
                 aaatgtattaagtcacgtagcagtatttgatgtagagggatatgatag 
               
               
                   
                 attatttttcgtaactgacgcagctatgaacttagctcctgatacaaa 
               
               
                   
                 tactaaaaagcaaatcatagaaaatgcttgcacagtagcacattcatt 
               
               
                   
                 agatataagtgaaccaaaagttgctgcaatatgcgcaaaagaaaaagt 
               
               
                   
                 aaatccaaaaatgaaagatacagttgaagctaaagaactagaagaaat 
               
               
                   
                 gtatgaaagaggagaaatcaaaggttgtatggttggtgggccttttgc 
               
               
                   
                 aattgataatgcagtatctttagaagcagctaaacataaaggtataaa 
               
               
                   
                 tcatcctgtagcaggacgagctgatatattattagccccagatattga 
               
               
                   
                 aggtggtaacatattatataaagctttggtattcttctcaaaatcaaa 
               
               
                   
                 aaatgcaggagttatagttggggctaaagcaccaataatattaacttc 
               
               
                   
                 tagagcagacagtgaagaaactaaactaaactcaatagctttaggtgt 
               
               
                   
                 tttaatggcagcaaaggcataataagaaggagatatacatatgagcaa 
               
               
                   
                 aatatttaaaatcttaacaataaatcctggttcgacatcaactaaaat 
               
               
                   
                 agctgtatttgataatgaggatttagtatttgaaaaaactttaagaca 
               
               
                   
                 ttcttcagaagaaataggaaaatatgagaaggtgtctgaccaatttga 
               
               
                   
                 atttcgtaaacaagtaatagaagaagctctaaaagaaggtggagtaaa 
               
               
                   
                 aacatctgaattagatgctgtagtaggtagaggaggacttcttaaacc 
               
               
                   
                 tataaaaggtggtacttattcagtaagtgctgctatgattgaagattt 
               
               
                   
                 aaaagtgggagttttaggagaacacgcttcaaacctaggtggaataat 
               
               
                   
                 agcaaaacaaataggtgaagaagtaaatgttccttcatacatagtaga 
               
               
                   
                 ccctgttgttgtagatgaattagaagatgttgctagaatttctggtat 
               
               
                   
                 gcctgaaataagtagagcaagtgtagtacatgctttaaatcaaaaggc 
               
               
                   
                 aatagcaagaagatatgctagagaaataaacaagaaatatgaagatat 
               
               
                   
                 aaatcttatagttgcacacatgggtggaggagtttctgttggagctca 
               
               
                   
                 taaaaatggtaaaatagtagatgttgcaaacgcattagatggagaagg 
               
               
                   
                 acctttctctccagaaagaagtggtggactaccagtaggtgcattagt 
               
               
                   
                 aaaaatgtgctttagtggaaaatatactcaagatgaaattaaaaagaa 
               
               
                   
                 aataaaaggtaatggcggactagttgcatacttaaacactaatgatgc 
               
               
                   
                 tagagaagttgaagaaagaattgaagctggtgatgaaaaagctaaatt 
               
               
                   
                 agtatatgaagctatggcatatcaaatctctaaagaaataggagctag 
               
               
                   
                 tgctgcagttcttaagggagatgtaaaagcaatattattaactggtgg 
               
               
                   
                 aatcgcatattcaaaaatgtttacagaaatgattgcagatagagttaa 
               
               
                   
                 atttatagcagatgtaaaagtttatccaggtgaagatgaaatgattgc 
               
               
                   
                 attagctcaaggtggacttagagttttaactggtgaagaagaggctca 
               
               
                   
                 agtttatgataactaataa 
               
               
                   
               
            
           
         
       
     
     The gene products of the bcd2-etfA3-etfB3 genes form a complex that converts crotonyl-CoA to butyryl-CoA and may exhibit dependence on oxygen as a co-oxidant. Because the recombinant bacteria of the invention are designed to produce butyrate in an oxygen-limited environment (e.g. the mammalian gut), that dependence on oxygen could have a negative effect of butyrate production in the gut. It has been shown that a single gene from  Treponema denticola , trans-2-enoynl-CoA reductase (ter), can functionally replace this three gene complex in an oxygen-independent manner. Therefore, a second butyrate gene cassette in which the ter gene replaces the bcd2-etfA3-etfB3 genes of the first butyrate cassette is synthesized (Genewiz, Cambridge, Mass.). The ter gene is codon-optimized for  E. coli  codon usage using Integrated DNA Technologies online codon optimization tool (https://www.idtdna.com/CodonOpt). The second butyrate gene cassette, as well as transcriptional and translational elements, is synthesized (Gen9, Cambridge, Mass.) and cloned into vector pBR322. The second butyrate gene cassette is placed under control of a FNR regulatory region as described above. In certain constructs, the butyrate gene cassette is placed under the control of an RNS-responsive regulatory region, e.g., norB, and the bacteria further comprises a gene encoding a corresponding RNS-responsive transcription factor, e.g., nsrR (see, e.g., Table 38 and Table 39). In certain constructs, the butyrate gene cassette is placed under the control of an ROS-responsive regulatory region, e.g., oxyS, and the bacteria further comprises a gene encoding a corresponding ROS-responsive transcription factor, e.g., oxyR (see, e.g., Table C and Table 40). 
     
       
         
           
               
             
               
                 TABLE 40 
               
             
            
               
                   
               
               
                 ROS regulated constructs, OxyR construct, Tet-regulated constructs 
               
            
           
           
               
               
            
               
                 Description 
                 Sequence 
               
               
                   
               
               
                 Nucleotide 
                 ctcgagttcattatccatcctccatcgccacgatagttcatggcgataggtagaatagc 
               
               
                 sequences of 
                 aatgaacgattatccctatcaagcattctgactgataattgctcacacgaattcattaa 
               
               
                 pLogic031- 
                 agaggagaaaggtaccatggatttaaattctaaaaaatatcagatgcttaaagagctat 
               
               
                 oxyS- 
                 atgtaagcttcgctgaaaatgaagttaaacctttagcaacagaacttgatgaagaagaa 
               
               
                 butyrate 
                 agatttccttatgaaacagtggaaaaaatggcaaaagcaggaatgatgggtataccata 
               
               
                 construct 
                 tccaaaagaatatggtggagaaggtggagacactgtaggatatataatggcagttgaag 
               
               
                 (SEQ ID NO: 
                 aattgtctagagtttgtggtactacaggagttatattatcagctcatacatctcttggc 
               
               
                 81) 
                 tcatggcctatatatcaatatggtaatgaagaacaaaaacaaaaattcttaagaccact 
               
               
                   
                 agcaagtggagaaaaattaggagcatttggtcttactgagcctaatgctggtacagatg 
               
               
                   
                 cgtctggccaacaaacaactgctgttttagacggggatgaatacatacttaatggctca 
               
               
                   
                 aaaatatttataacaaacgcaatagctggtgacatatatgtagtaatggcaatgactga 
               
               
                   
                 taaatctaaggggaacaaaggaatatcagcatttatagttgaaaaaggaactcctgggt 
               
               
                   
                 ttagctttggagttaaagaaaagaaaatgggtataagaggttcagctacgagtgaatta 
               
               
                   
                 atatttgaggattgcagaatacctaaagaaaatttacttggaaaagaaggtcaaggatt 
               
               
                   
                 taagatagcaatgtctactcttgatggtggtagaattggtatagctgcacaagctttag 
               
               
                   
                 gtttagcacaaggtgctcttgatgaaactgttaaatatgtaaaagaaagagtacaattt 
               
               
                   
                 ggtagaccattatcaaaattccaaaatacacaattccaattagctgatatggaagttaa 
               
               
                   
                 ggtacaagcggctagacaccttgtatatcaagcagctataaataaagacttaggaaaac 
               
               
                   
                 cttatggagtagaagcagcaatggcaaaattatttgcagctgaaacagctatggaagtt 
               
               
                   
                 actacaaaagctgtacaacttcatggaggatatggatacactcgtgactatccagtaga 
               
               
                   
                 aagaatgatgagagatgctaagataactgaaatatatgaaggaactagtgaagttcaaa 
               
               
                   
                 gaatggttatttcaggaaaactattaaaatagtaagaaggagatatacatatggaggaa 
               
               
                   
                 ggatttatgaatatagtcgtttgtataaaacaagttccagatacaacagaagttaaact 
               
               
                   
                 agatcctaatacaggtactttaattagagatggagtaccaagtataataaaccctgatg 
               
               
                   
                 ataaagcaggtttagaagaagctataaaattaaaagaagaaatgggtgctcatgtaact 
               
               
                   
                 gttataacaatgggacctcctcaagcagatatggctttaaaagaagctttagcaatggg 
               
               
                   
                 tgcagatagaggtatattattaacagatagagcatttgcgggtgctgatacttgggcaa 
               
               
                   
                 cttcatcagcattagcaggagcattaaaaaatatagattttgatattataatagctgga 
               
               
                   
                 agacaggcgatagatggagatactgcacaagttggacctcaaatagctgaacatttaaa 
               
               
                   
                 tcttccatcaataacatatgctgaagaaataaaaactgaaggtgaatatgtattagtaa 
               
               
                   
                 aaagacaatttgaagattgttgccatgacttaaaagttaaaatgccatgccttataaca 
               
               
                   
                 actcttaaagatatgaacacaccaagatacatgaaagttggaagaatatatgatgcttt 
               
               
                   
                 cgaaaatgatgtagtagaaacatggactgtaaaagatatagaagttgacccttctaatt 
               
               
                   
                 taggtcttaaaggttctccaactagtgtatttaaatcatttacaaaatcagttaaacca 
               
               
                   
                 gctggtacaatatacaatgaagatgcgaaaacatcagctggaattatcatagataaatt 
               
               
                   
                 aaaagagaagtatatcatataataagaaggagatatacatatgggtaacgttttagtag 
               
               
                   
                 taatagaacaaagagaaaatgtaattcaaactgtttctttagaattactaggaaaggct 
               
               
                   
                 acagaaatagcaaaagattatgatacaaaagtttctgcattacttttaggtagtaaggt 
               
               
                   
                 agaaggtttaatagatacattagcacactatggtgcagatgaggtaatagtagtagatg 
               
               
                   
                 atgaagctttagcagtgtatacaactgaaccatatacaaaagcagcttatgaagcaata 
               
               
                   
                 aaagcagctgaccctatagttgtattatttggtgcaacttcaataggtagagatttagc 
               
               
                   
                 gcctagagtttctgctagaatacatacaggtcttactgctgactgtacaggtcttgcag 
               
               
                   
                 tagctgaagatacaaaattattattaatgacaagacctgcctttggtggaaatataatg 
               
               
                   
                 gcaacaatagtttgtaaagatttcagacctcaaatgtctacagttagaccaggggttat 
               
               
                   
                 gaagaaaaatgaacctgatgaaactaaagaagctgtaattaaccgtttcaaggtagaat 
               
               
                   
                 ttaatgatgctgataaattagttcaagttgtacaagtaataaaagaagctaaaaaacaa 
               
               
                   
                 gttaaaatagaagatgctaagatattagtttctgctggacgtggaatgggtggaaaaga 
               
               
                   
                 aaacttagacatactttatgaattagctgaaattataggtggagaagtttctggttctc 
               
               
                   
                 gtgccactatagatgcaggttggttagataaagcaagacaagttggtcaaactggtaaa 
               
               
                   
                 actgtaagaccagacctttatatagcatgtggtatatctggagcaatacaacatatagc 
               
               
                   
                 tggtatggaagatgctgagtttatagttgctataaataaaaatccagaagctccaatat 
               
               
                   
                 ttaaatatgctgatgttggtatagttggagatgttcataaagtgcttccagaacttatc 
               
               
                   
                 agtcagttaagtgttgcaaaagaaaaaggtgaagttttagctaactaataagaaggaga 
               
               
                   
                 tatacatatgagagaagtagtaattgccagtgcagctagaacagcagtaggaagttttg 
               
               
                   
                 gaggagcatttaaatcagtttcagcggtagagttaggggtaacagcagctaaagaagct 
               
               
                   
                 ataaaaagagctaacataactccagatatgatagatgaatctcttttagggggagtact 
               
               
                   
                 tacagcaggtcttggacaaaatatagcaagacaaatagcattaggagcaggaataccag 
               
               
                   
                 tagaaaaaccagctatgactataaatatagtttgtggttctggattaagatctgtttca 
               
               
                   
                 atggcatctcaacttatagcattaggtgatgctgatataatgttagttggtggagctga 
               
               
                   
                 aaacatgagtatgtctccttatttagtaccaagtgcgagatatggtgcaagaatgggtg 
               
               
                   
                 atgctgcttttgttgattcaatgataaaagatggattatcagacatatttaataactat 
               
               
                   
                 cacatgggtattactgctgaaaacatagcagagcaatggaatataactagagaagaaca 
               
               
                   
                 agatgaattagctcttgcaagtcaaaataaagctgaaaaagctcaagctgaaggaaaat 
               
               
                   
                 ttgatgaagaaatagttcctgttgttataaaaggaagaaaaggtgacactgtagtagat 
               
               
                   
                 aaagatgaatatattaagcctggcactacaatggagaaacttgctaagttaagacctgc 
               
               
                   
                 atttaaaaaagatggaacagttactgctggtaatgcatcaggaataaatgatggtgctg 
               
               
                   
                 ctatgttagtagtaatggctaaagaaaaagctgaagaactaggaatagagcctcttgca 
               
               
                   
                 actatagtttcttatggaacagctggtgttgaccctaaaataatgggatatggaccagt 
               
               
                   
                 tccagcaactaaaaaagctttagaagctgctaatatgactattgaagatatagatttag 
               
               
                   
                 ttgaagctaatgaggcatttgctgcccaatctgtagctgtaataagagacttaaatata 
               
               
                   
                 gatatgaataaagttaatgttaatggtggagcaatagctataggacatccaataggatg 
               
               
                   
                 ctcaggagcaagaatacttactacacttttatatgaaatgaagagaagagatgctaaaa 
               
               
                   
                 ctggtcttgctacactttgtataggcggtggaatgggaactactttaatagttaagaga 
               
               
                   
                 tagtaagaaggagatatacatatgaaattagctgtaataggtagtggaactatgggaag 
               
               
                   
                 tggtattgtacaaacttttgcaagttgtggacatgatgtatgtttaaagagtagaactc 
               
               
                   
                 aaggtgctatagataaatgtttagctttattagataaaaatttaactaagttagttact 
               
               
                   
                 aagggaaaaatggatgaagctacaaaagcagaaatattaagtcatgttagttcaactac 
               
               
                   
                 taattatgaagatttaaaagatatggatttaataatagaagcatctgtagaagacatga 
               
               
                   
                 atataaagaaagatgttttcaagttactagatgaattatgtaaagaagatactatcttg 
               
               
                   
                 gcaacaaatacttcatcattatctataacagaaatagcttcttctactaagcgcccaga 
               
               
                   
                 taaagttataggaatgcatttctttaatccagttcctatgatgaaattagttgaagtta 
               
               
                   
                 taagtggtcagttaacatcaaaagttacttttgatacagtatttgaattatctaagagt 
               
               
                   
                 atcaataaagtaccagtagatgtatctgaatctcctggatttgtagtaaatagaatact 
               
               
                   
                 tatacctatgataaatgaagctgttggtatatatgcagatggtgttgcaagtaaagaag 
               
               
                   
                 aaatagatgaagctatgaaattaggagcaaaccatccaatgggaccactagcattaggt 
               
               
                   
                 gatttaatcggattagatgttgttttagctataatgaacgttttatatactgaatttgg 
               
               
                   
                 agatactaaatatagacctcatccacttttagctaaaatggttagagctaatcaattag 
               
               
                   
                 gaagaaaaactaagataggattctatgattataataaataataagaaggagatatacat 
               
               
                   
                 atgagtacaagtgatgttaaagtttatgagaatgtagctgttgaagtagatggaaatat 
               
               
                   
                 atgtacagtgaaaatgaatagacctaaagcccttaatgcaataaattcaaagactttag 
               
               
                   
                 aagaactttatgaagtatttgtagatattaataatgatgaaactattgatgttgtaata 
               
               
                   
                 ttgacaggggaaggaaaggcatttgtagctggagcagatattgcatacatgaaagattt 
               
               
                   
                 agatgctgtagctgctaaagattttagtatcttaggagcaaaagcttttggagaaatag 
               
               
                   
                 aaaatagtaaaaaagtagtgatagctgctgtaaacggatttgctttaggtggaggatgt 
               
               
                   
                 gaacttgcaatggcatgtgatataagaattgcatctgctaaagctaaatttggtcagcc 
               
               
                   
                 agaagtaactcttggaataactccaggatatggaggaactcaaaggcttacaagattgg 
               
               
                   
                 ttggaatggcaaaagcaaaagaattaatctttacaggtcaagttataaaagctgatgaa 
               
               
                   
                 gctgaaaaaatagggctagtaaatagagtcgttgagccagacattttaatagaagaagt 
               
               
                   
                 tgagaaattagctaagataatagctaaaaatgctcagcttgcagttagatactctaaag 
               
               
                   
                 aagcaatacaacttggtgctcaaactgatataaatactggaatagatatagaatctaat 
               
               
                   
                 ttatttggtctttgtttttcaactaaagaccaaaaagaaggaatgtcagctttcgttga 
               
               
                   
                 aaagagagaagctaactttataaaagggtaataagaaggagatatacatatgagaagtt 
               
               
                   
                 ttgaagaagtaattaagtttgcaaaagaaagaggacctaaaactatatcagtagcatgt 
               
               
                   
                 tgccaagataaagaagttttaatggcagttgaaatggctagaaaagaaaaaatagcaaa 
               
               
                   
                 tgccattttagtaggagatatagaaaagactaaagaaattgcaaaaagcatagacatgg 
               
               
                   
                 atatcgaaaattatgaactgatagatataaaagatttagcagaagcatctctaaaatct 
               
               
                   
                 gttgaattagtttcacaaggaaaagccgacatggtaatgaaaggcttagtagacacatc 
               
               
                   
                 aataatactaaaagcagttttaaataaagaagtaggtcttagaactggaaatgtattaa 
               
               
                   
                 gtcacgtagcagtatttgatgtagagggatatgatagattatttttcgtaactgacgca 
               
               
                   
                 gctatgaacttagctcctgatacaaatactaaaaagcaaatcatagaaaatgcttgcac 
               
               
                   
                 agtagcacattcattagatataagtgaaccaaaagttgctgcaatatgcgcaaaagaaa 
               
               
                   
                 aagtaaatccaaaaatgaaagatacagttgaagctaaagaactagaagaaatgtatgaa 
               
               
                   
                 agaggagaaatcaaaggttgtatggttggtgggccttttgcaattgataatgcagtatc 
               
               
                   
                 tttagaagcagctaaacataaaggtataaatcatcctgtagcaggacgagctgatatat 
               
               
                   
                 tattagccccagatattgaaggtggtaacatattatataaagctttggtattcttctca 
               
               
                   
                 aaatcaaaaaatgcaggagttatagttggggctaaagcaccaataatattaacttctag 
               
               
                   
                 agcagacagtgaagaaactaaactaaactcaatagctttaggtgttttaatggcagcaa 
               
               
                   
                 aggcataataagaaggagatatacatatgagcaaaatatttaaaatcttaacaataaat 
               
               
                   
                 cctggttcgacatcaactaaaatagctgtatttgataatgaggatttagtatttgaaaa 
               
               
                   
                 aactttaagacattcttcagaagaaataggaaaatatgagaaggtgtctgaccaatttg 
               
               
                   
                 aatttcgtaaacaagtaatagaagaagctctaaaagaaggtggagtaaaaacatctgaa 
               
               
                   
                 ttagatgctgtagtaggtagaggaggacttcttaaacctataaaaggtggtacttattc 
               
               
                   
                 agtaagtgctgctatgattgaagatttaaaagtgggagttttaggagaacacgcttcaa 
               
               
                   
                 acctaggtggaataatagcaaaacaaataggtgaagaagtaaatgttccttcatacata 
               
               
                   
                 gtagaccctgttgttgtagatgaattagaagatgttgctagaatttctggtatgcctga 
               
               
                   
                 aataagtagagcaagtgtagtacatgctttaaatcaaaaggcaatagcaagaagatatg 
               
               
                   
                 ctagagaaataaacaagaaatatgaagatataaatcttatagttgcacacatgggtgga 
               
               
                   
                 ggagtttctgttggagctcataaaaatggtaaaatagtagatgttgcaaacgcattaga 
               
               
                   
                 tggagaaggacctttctctccagaaagaagtggtggactaccagtaggtgcattagtaa 
               
               
                   
                 aaatgtgctttagtggaaaatatactcaagatgaaattaaaaagaaaataaaaggtaat 
               
               
                   
                 ggcggactagttgcatacttaaacactaatgatgctagagaagttgaagaaagaattga 
               
               
                   
                 agctggtgatgaaaaagctaaattagtatatgaagctatggcatatcaaatctctaaag 
               
               
                   
                 aaataggagctagtgctgcagttcttaagggagatgtaaaagcaatattattaactggt 
               
               
                   
                 ggaatcgcatattcaaaaatgtttacagaaatgattgcagatagagttaaatttatagc 
               
               
                   
                 agatgtaaaagtttatccaggtgaagatgaaatgattgcattagctcaaggtggactta 
               
               
                   
                 gagttttaactggtgaagaagaggctcaagtttatgataactaataa 
               
               
                   
               
               
                 Nucleotide 
                 ctcgagttcattatccatcctccatcgccacgatagttcatggcgataggtagaatagc 
               
               
                 sequences of 
                 aatgaacgattatccctatcaagcattctgactgataattgctcacacgaattcattaa 
               
               
                 pLogic046- 
                 agaggagaaaggtaccatgatcgtaaaacctatggtacgcaacaatatctgcctgaacg 
               
               
                 oxyS- 
                 cccatcctcagggctgcaagaagggagtggaagatcagattgaatataccaagaaacgc 
               
               
                 butyrate 
                 attaccgcagaagtcaaagctggcgcaaaagctccaaaaaacgttctggtgcttggctg 
               
               
                 construct 
                 ctcaaatggttacggcctggcgagccgcattactgctgcgttcggatacggggctgcga 
               
               
                 (SEQ ID NO: 
                 ccatcggcgtgtcctttgaaaaagcgggttcagaaaccaaatatggtacaccgggatgg 
               
               
                 82) 
                 tacaataatttggcatttgatgaagcggcaaaacgcgagggtctttatagcgtgacgat 
               
               
                   
                 cgacggcgatgcgttttcagacgagatcaaggcccaggtaattgaggaagccaaaaaaa 
               
               
                   
                 aaggtatcaaatttgatctgatcgtatacagcttggccagcccagtacgtactgatcct 
               
               
                   
                 gatacaggtatcatgcacaaaagcgttttgaaaccctttggaaaaacgttcacaggcaa 
               
               
                   
                 aacagtagatccgtttactggcgagctgaaggaaatctccgcggaaccagcaaatgacg 
               
               
                   
                 aggaagcagccgccactgttaaagttatggggggtgaagattgggaacgttggattaag 
               
               
                   
                 cagctgtcgaaggaaggcctcttagaagaaggctgtattaccttggcctatagttatat 
               
               
                   
                 tggccctgaagctacccaagctttgtaccgtaaaggcacaatcggcaaggccaaagaac 
               
               
                   
                 acctggaggccacagcacaccgtctcaacaaagagaacccgtcaatccgtgccttcgtg 
               
               
                   
                 agcgtgaataaaggcctggtaacccgcgcaagcgccgtaatcccggtaatccctctgta 
               
               
                   
                 tctcgccagcttgttcaaagtaatgaaagagaagggcaatcatgaaggttgtattgaac 
               
               
                   
                 agatcacgcgtctgtacgccgagcgcctgtaccgtaaagatggtacaattccagttgat 
               
               
                   
                 gaggaaaatcgcattcgcattgatgattgggagttagaagaagacgtccagaaagcggt 
               
               
                   
                 atccgcgttgatggagaaagtcacgggtgaaaacgcagaatctctcactgacttagcgg 
               
               
                   
                 ggtaccgccatgatttcttagctagtaacggctttgatgtagaaggtattaattatgaa 
               
               
                   
                 gcggaagttgaacgcttcgaccgtatctgataagaaggagatatacatatgagagaagt 
               
               
                   
                 agtaattgccagtgcagctagaacagcagtaggaagttttggaggagcatttaaatcag 
               
               
                   
                 tttcagcggtagagttaggggtaacagcagctaaagaagctataaaaagagctaacata 
               
               
                   
                 actccagatatgatagatgaatctcttttagggggagtacttacagcaggtcttggaca 
               
               
                   
                 aaatatagcaagacaaatagcattaggagcaggaataccagtagaaaaaccagctatga 
               
               
                   
                 ctataaatatagtttgtggttctggattaagatctgtttcaatggcatctcaacttata 
               
               
                   
                 gcattaggtgatgctgatataatgttagttggtggagctgaaaacatgagtatgtctcc 
               
               
                   
                 ttatttagtaccaagtgcgagatatggtgcaagaatgggtgatgctgcttttgttgatt 
               
               
                   
                 caatgataaaagatggattatcagacatatttaataactatcacatgggtattactgct 
               
               
                   
                 gaaaacatagcagagcaatggaatataactagagaagaacaagatgaattagctcttgc 
               
               
                   
                 aagtcaaaataaagctgaaaaagctcaagctgaaggaaaatttgatgaagaaatagttc 
               
               
                   
                 ctgttgttataaaaggaagaaaaggtgacactgtagtagataaagatgaatatattaag 
               
               
                   
                 cctggcactacaatggagaaacttgctaagttaagacctgcatttaaaaaagatggaac 
               
               
                   
                 agttactgctggtaatgcatcaggaataaatgatggtgctgctatgttagtagtaatgg 
               
               
                   
                 ctaaagaaaaagctgaagaactaggaatagagcctcttgcaactatagtttcttatgga 
               
               
                   
                 acagctggtgttgaccctaaaataatgggatatggaccagttccagcaactaaaaaagc 
               
               
                   
                 tttagaagctgctaatatgactattgaagatatagatttagttgaagctaatgaggcat 
               
               
                   
                 ttgctgcccaatctgtagctgtaataagagacttaaatatagatatgaataaagttaat 
               
               
                   
                 gttaatggtggagcaatagctataggacatccaataggatgctcaggagcaagaatact 
               
               
                   
                 tactacacttttatatgaaatgaagagaagagatgctaaaactggtcttgctacacttt 
               
               
                   
                 gtataggcggtggaatgggaactactttaatagttaagagatagtaagaaggagatata 
               
               
                   
                 catatgaaattagctgtaataggtagtggaactatgggaagtggtattgtacaaacttt 
               
               
                   
                 tgcaagttgtggacatgatgtatgtttaaagagtagaactcaaggtgctatagataaat 
               
               
                   
                 gtttagctttattagataaaaatttaactaagttagttactaagggaaaaatggatgaa 
               
               
                   
                 gctacaaaagcagaaatattaagtcatgttagttcaactactaattatgaagatttaaa 
               
               
                   
                 agatatggatttaataatagaagcatctgtagaagacatgaatataaagaaagatgttt 
               
               
                   
                 tcaagttactagatgaattatgtaaagaagatactatcttggcaacaaatacttcatca 
               
               
                   
                 ttatctataacagaaatagcttcttctactaagcgcccagataaagttataggaatgca 
               
               
                   
                 tttctttaatccagttcctatgatgaaattagttgaagttataagtggtcagttaacat 
               
               
                   
                 caaaagttacttttgatacagtatttgaattatctaagagtatcaataaagtaccagta 
               
               
                   
                 gatgtatctgaatctcctggatttgtagtaaatagaatacttatacctatgataaatga 
               
               
                   
                 agctgttggtatatatgcagatggtgttgcaagtaaagaagaaatagatgaagctatga 
               
               
                   
                 aattaggagcaaaccatccaatgggaccactagcattaggtgatttaatcggattagat 
               
               
                   
                 gttgttttagctataatgaacgttttatatactgaatttggagatactaaatatagacc 
               
               
                   
                 tcatccacttttagctaaaatggttagagctaatcaattaggaagaaaaactaagatag 
               
               
                   
                 gattctatgattataataaataataagaaggagatatacatatgagtacaagtgatgtt 
               
               
                   
                 aaagtttatgagaatgtagctgttgaagtagatggaaatatatgtacagtgaaaatgaa 
               
               
                   
                 tagacctaaagcccttaatgcaataaattcaaagactttagaagaactttatgaagtat 
               
               
                   
                 ttgtagatattaataatgatgaaactattgatgttgtaatattgacaggggaaggaaag 
               
               
                   
                 gcatttgtagctggagcagatattgcatacatgaaagatttagatgctgtagctgctaa 
               
               
                   
                 agattttagtatcttaggagcaaaagcttttggagaaatagaaaatagtaaaaaagtag 
               
               
                   
                 tgatagctgctgtaaacggatttgctttaggtggaggatgtgaacttgcaatggcatgt 
               
               
                   
                 gatataagaattgcatctgctaaagctaaatttggtcagccagaagtaactcttggaat 
               
               
                   
                 aactccaggatatggaggaactcaaaggcttacaagattggttggaatggcaaaagcaa 
               
               
                   
                 aagaattaatctttacaggtcaagttataaaagctgatgaagctgaaaaaatagggcta 
               
               
                   
                 gtaaatagagtcgttgagccagacattttaatagaagaagttgagaaattagctaagat 
               
               
                   
                 aatagctaaaaatgctcagcttgcagttagatactctaaagaagcaatacaacttggtg 
               
               
                   
                 ctcaaactgatataaatactggaatagatatagaatctaatttatttggtctttgtttt 
               
               
                   
                 tcaactaaagaccaaaaagaaggaatgtcagctttcgttgaaaagagagaagctaactt 
               
               
                   
                 tataaaagggtaataagaaggagatatacatatgagaagttttgaagaagtaattaagt 
               
               
                   
                 ttgcaaaagaaagaggacctaaaactatatcagtagcatgttgccaagataaagaagtt 
               
               
                   
                 ttaatggcagttgaaatggctagaaaagaaaaaatagcaaatgccattttagtaggaga 
               
               
                   
                 tatagaaaagactaaagaaattgcaaaaagcatagacatggatatcgaaaattatgaac 
               
               
                   
                 tgatagatataaaagatttagcagaagcatctctaaaatctgttgaattagtttcacaa 
               
               
                   
                 ggaaaagccgacatggtaatgaaaggcttagtagacacatcaataatactaaaagcagt 
               
               
                   
                 tttaaataaagaagtaggtcttagaactggaaatgtattaagtcacgtagcagtatttg 
               
               
                   
                 atgtagagggatatgatagattatttttcgtaactgacgcagctatgaacttagctcct 
               
               
                   
                 gatacaaatactaaaaagcaaatcatagaaaatgcttgcacagtagcacattcattaga 
               
               
                   
                 tataagtgaaccaaaagttgctgcaatatgcgcaaaagaaaaagtaaatccaaaaatga 
               
               
                   
                 aagatacagttgaagctaaagaactagaagaaatgtatgaaagaggagaaatcaaaggt 
               
               
                   
                 tgtatggttggtgggccttttgcaattgataatgcagtatctttagaagcagctaaaca 
               
               
                   
                 taaaggtataaatcatcctgtagcaggacgagctgatatattattagccccagatattg 
               
               
                   
                 aaggtggtaacatattatataaagctttggtattcttctcaaaatcaaaaaatgcagga 
               
               
                   
                 gttatagttggggctaaagcaccaataatattaacttctagagcagacagtgaagaaac 
               
               
                   
                 taaactaaactcaatagctttaggtgttttaatggcagcaaaggcataataagaaggag 
               
               
                   
                 atatacatatgagcaaaatatttaaaatcttaacaataaatcctggttcgacatcaact 
               
               
                   
                 aaaatagctgtatttgataatgaggatttagtatttgaaaaaactttaagacattcttc 
               
               
                   
                 agaagaaataggaaaatatgagaaggtgtctgaccaatttgaatttcgtaaacaagtaa 
               
               
                   
                 tagaagaagctctaaaagaaggtggagtaaaaacatctgaattagatgctgtagtaggt 
               
               
                   
                 agaggaggacttcttaaacctataaaaggtggtacttattcagtaagtgctgctatgat 
               
               
                   
                 tgaagatttaaaagtgggagttttaggagaacacgcttcaaacctaggtggaataatag 
               
               
                   
                 caaaacaaataggtgaagaagtaaatgttccttcatacatagtagaccctgttgttgta 
               
               
                   
                 gatgaattagaagatgttgctagaatttctggtatgcctgaaataagtagagcaagtgt 
               
               
                   
                 agtacatgctttaaatcaaaaggcaatagcaagaagatatgctagagaaataaacaaga 
               
               
                   
                 aatatgaagatataaatcttatagttgcacacatgggtggaggagtttctgttggagct 
               
               
                   
                 cataaaaatggtaaaatagtagatgttgcaaacgcattagatggagaaggacctttctc 
               
               
                   
                 tccagaaagaagtggtggactaccagtaggtgcattagtaaaaatgtgctttagtggaa 
               
               
                   
                 aatatactcaagatgaaattaaaaagaaaataaaaggtaatggcggactagttgcatac 
               
               
                   
                 ttaaacactaatgatgctagagaagttgaagaaagaattgaagctggtgatgaaaaagc 
               
               
                   
                 taaattagtatatgaagctatggcatatcaaatctctaaagaaataggagctagtgctg 
               
               
                   
                 cagttcttaagggagatgtaaaagcaatattattaactggtggaatcgcatattcaaaa 
               
               
                   
                 atgtttacagaaatgattgcagatagagttaaatttatagcagatgtaaaagtttatcc 
               
               
                   
                 aggtgaagatgaaatgattgcattagctcaaggtggacttagagttttaactggtgaag 
               
               
                   
                 aagaggctcaagtttatgataactaataa 
               
               
                   
               
               
                 Nucleotide 
                 ctcgagatgctagcaattgtgagcggataacaattgacattgtgagcggataacaagat 
               
               
                 sequences of 
                 actgagcacatcagcaggacgcactgaccttaattaaaagaattcattaaagaggagaa 
               
               
                 pZA22-oxyR 
                 aggtaccatgaatattcgtgatcttgagtacctggtggcattggctgaacaccgccatt 
               
               
                 construct 
                 ttcggcgtgcggcagattcctgccacgttagccagccgacgcttagcgggcaaattcgt 
               
               
                 (SEQ ID NO: 
                 aagctggaagatgagctgggcgtgatgttgctggagcggaccagccgtaaagtgttgtt 
               
               
                 83) 
                 cacccaggcgggaatgctgctggtggatcaggcgcgtaccgtgctgcgtgaggtgaaag 
               
               
                   
                 tccttaaagagatggcaagccagcagggcgagacgatgtccggaccgctgcacattggt 
               
               
                   
                 ttgattcccacagttggaccgtacctgctaccgcatattatccctatgctgcaccagac 
               
               
                   
                 ctttccaaagctggaaatgtatctgcatgaagcacagacccaccagttactggcgcaac 
               
               
                   
                 tggacagcggcaaactcgattgcgtgatcctcgcgctggtgaaagagagcgaagcattc 
               
               
                   
                 attgaagtgccgttgtttgatgagccaatgttgctggctatctatgaagatcacccgtg 
               
               
                   
                 ggcgaaccgcgaatgcgtaccgatggccgatctggcaggggaaaaactgctgatgctgg 
               
               
                   
                 aagatggtcactgtttgcgcgatcaggcaatgggtttctgttttgaagccggggcggat 
               
               
                   
                 gaagatacacacttccgcgcgaccagcctggaaactctgcgcaacatggtggcggcagg 
               
               
                   
                 tagcgggatcactttactgccagcgctggctgtgccgccggagcgcaaacgcgatgggg 
               
               
                   
                 ttgtttatctgccgtgcattaagccggaaccacgccgcactattggcctggtttatcgt 
               
               
                   
                 cctggctcaccgctgcgcagccgctatgagcagctggcagaggccatccgcgcaagaat 
               
               
                   
                 ggatggccatttcgataaagttttaaaacaggcggtttaaggatcccatggtacgcgtg 
               
               
                   
                 ctagaggcatcaaataaaacgaaaggctcagtcgaaagactgggcctttcgttttatct 
               
               
                   
                 gttgtttgtcggtgaacgctctcctgagtaggacaaatccgccgccctagacctagggg 
               
               
                   
                 atatattccgcttcctcgctcactgactcgctacgctcggtcgttcgactgcggcgagc 
               
               
                   
                 ggaaatggcttacgaacggggcggagatttcctggaagatgccaggaagatacttaaca 
               
               
                   
                 gggaagtgagagggccgcggcaaagccgtttttccataggctccgcccccctgacaagc 
               
               
                   
                 atcacgaaatctgacgctcaaatcagtggtggcgaaacccgacaggactataaagatac 
               
               
                   
                 caggcgtttccccctggcggctccctcgtgcgctctcctgttcctgcctttcggtttac 
               
               
                   
                 cggtgtcattccgctgttatggccgcgtttgtctcattccacgcctgacactcagttcc 
               
               
                   
                 gggtaggcagttcgctccaagctggactgtatgcacgaaccccccgttcagtccgaccg 
               
               
                   
                 ctgcgccttatccggtaactatcgtcttgagtccaacccggaaagacatgcaaaagcac 
               
               
                   
                 cactggcagcagccactggtaattgatttagaggagttagtcttgaagtcatgcgccgg 
               
               
                   
                 ttaaggctaaactgaaaggacaagttttggtgactgcgctcctccaagccagttacctc 
               
               
                   
                 ggttcaaagagttggtagctcagagaaccttcgaaaaaccgccctgcaaggcggttttt 
               
               
                   
                 tcgttttcagagcaagagattacgcgcagaccaaaacgatctcaagaagatcatcttat 
               
               
                   
                 taatcagataaaatatttctagatttcagtgcaatttatctcttcaaatgtagcacctg 
               
               
                   
                 aagtcagccccatacgatataagttgttactagtgcttggattctcaccaataaaaaac 
               
               
                   
                 gcccggcggcaaccgagcgttctgaacaaatccagatggagttctgaggtcattactgg 
               
               
                   
                 atctatcaacaggagtccaagcgagctctcgaaccccagagtcccgctcagaagaactc 
               
               
                   
                 gtcaagaaggcgatagaaggcgatgcgctgcgaatcgggagcggcgataccgtaaagca 
               
               
                   
                 cgaggaagcggtcagcccattcgccgccaagctcttcagcaatatcacgggtagccaac 
               
               
                   
                 gctatgtcctgatagcggtccgccacacccagccggccacagtcgatgaatccagaaaa 
               
               
                   
                 gcggccattttccaccatgatattcggcaagcaggcatcgccatgggtcacgacgagat 
               
               
                   
                 cctcgccgtcgggcatgcgcgccttgagcctggcgaacagttcggctggcgcgagcccc 
               
               
                   
                 tgatgctcttcgtccagatcatcctgatcgacaagaccggcttccatccgagtacgtgc 
               
               
                   
                 tcgctcgatgcgatgtttcgcttggtggtcgaatgggcaggtagccggatcaagcgtat 
               
               
                   
                 gcagccgccgcattgcatcagccatgatggatactttctcggcaggagcaaggtgagat 
               
               
                   
                 gacaggagatcctgccccggcacttcgcccaatagcagccagtcccttcccgcttcagt 
               
               
                   
                 gacaacgtcgagcacagctgcgcaaggaacgcccgtcgtggccagccacgatagccgcg 
               
               
                   
                 ctgcctcgtcctgcagttcattcagggcaccggacaggtcggtcttgacaaaaagaacc 
               
               
                   
                 gggcgcccctgcgctgacagccggaacacggcggcatcagagcagccgattgtctgttg 
               
               
                   
                 tgcccagtcatagccgaatagcctctccacccaagcggccggagaacctgcgtgcaatc 
               
               
                   
                 catcttgttcaatcatgcgaaacgatcctcatcctgtctcttgatcagatcttgatccc 
               
               
                   
                 ctgcgccatcagatccttggcggcaagaaagccatccagtttactttgcagggcttccc 
               
               
                   
                 aaccttaccagagggcgccccagctggcaattccgacgtctaagaaaccattattatca 
               
               
                   
                 tgacattaacctataaaaataggcgtatcacgaggccctttcgtcttcac 
               
               
                   
               
               
                 Nucleotide 
                 gtaaaacgacggccagtgaattcg ttaagacccactttcacatttaagttgtttttcta   
               
               
                 sequences 
                 
                   atccgcatatgatcaattcaaggccgaataagaaggctggctctgcaccttggtgatca 
                 
               
               
                 pLogic031- 
                 
                   aataattcgatagcttgtcgtaataatggcggcatactatcagtagtaggtgtttccct 
                 
               
               
                 tet-butyrate 
                 
                   ttcttctttagcgacttgatgctcttgatcttccaatacgcaacctaaagtaaaatgcc 
                 
               
               
                 construct 
                 
                   ccacagcgctgagtgcatataatgcattctctagtgaaaaaccttgttggcataaaaag 
                 
               
               
                 (SEQ ID NO: 
                 
                   gctaattgattttcgagagtttcatactgtttttctgtaggccgtgtacctaaatgtac 
                 
               
               
                 84) The 
                 
                   ttttgctccatcgcgatgacttagtaaagcacatctaaaacttttagcgttattacgta 
                 
               
               
                 sequence 
                 
                   aaaaatcttgccagctttccccttctaaagggcaaaagtgagtatggtgcctatctaac 
                 
               
               
                 encoding 
                 
                   atctcaatggctaaggcgtcgagcaaagcccgcttattttttacatgccaatacaatgt 
                 
               
               
                 TetR is 
                 
                   aggctgctctacacctagcttctgggcgagtttacgggttgttaaaccttcgattccga 
                 
               
               
                   underlined , 
                 
                   cctcattaagcagctctaatgcgctgttaatcactttacttttatctaatctagacatc 
                 
               
               
                 and the 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 overlapping 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 tetR/tetA 
                 tacatatggatttaaattctaaaaaatatcagatgcttaaagagctatatgtaagcttc 
               
               
                 promoters 
                 gctgaaaatgaagttaaacctttagcaacagaacttgatgaagaagaaagatttcctta 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 tgaaacagtggaaaaaatggcaaaagcaggaatgatgggtataccatatccaaaagaat 
               
               
                   
                 atggtggagaaggtggagacactgtaggatatataatggcagttgaagaattgtctaga 
               
               
                   
                 gtttgtggtactacaggagttatattatcagctcatacatctcttggctcatggcctat 
               
               
                   
                 atatcaatatggtaatgaagaacaaaaacaaaaattcttaagaccactagcaagtggag 
               
               
                   
                 aaaaattaggagcatttggtcttactgagcctaatgctggtacagatgcgtctggccaa 
               
               
                   
                 caaacaactgctgttttagacggggatgaatacatacttaatggctcaaaaatatttat 
               
               
                   
                 aacaaacgcaatagctggtgacatatatgtagtaatggcaatgactgataaatctaagg 
               
               
                   
                 ggaacaaaggaatatcagcatttatagttgaaaaaggaactcctgggtttagctttgga 
               
               
                   
                 gttaaagaaaagaaaatgggtataagaggttcagctacgagtgaattaatatttgagga 
               
               
                   
                 ttgcagaatacctaaagaaaatttacttggaaaagaaggtcaaggatttaagatagcaa 
               
               
                   
                 tgtctactcttgatggtggtagaattggtatagctgcacaagctttaggtttagcacaa 
               
               
                   
                 ggtgctcttgatgaaactgttaaatatgtaaaagaaagagtacaatttggtagaccatt 
               
               
                   
                 atcaaaattccaaaatacacaattccaattagctgatatggaagttaaggtacaagcgg 
               
               
                   
                 ctagacaccttgtatatcaagcagctataaataaagacttaggaaaaccttatggagta 
               
               
                   
                 gaagcagcaatggcaaaattatttgcagctgaaacagctatggaagttactacaaaagc 
               
               
                   
                 tgtacaacttcatggaggatatggatacactcgtgactatccagtagaaagaatgatga 
               
               
                   
                 gagatgctaagataactgaaatatatgaaggaactagtgaagttcaaagaatggttatt 
               
               
                   
                 tcaggaaaactattaaaatagtaagaaggagatatacatatggaggaaggatttatgaa 
               
               
                   
                 tatagtcgtttgtataaaacaagttccagatacaacagaagttaaactagatcctaata 
               
               
                   
                 caggtactttaattagagatggagtaccaagtataataaaccctgatgataaagcaggt 
               
               
                   
                 ttagaagaagctataaaattaaaagaagaaatgggtgctcatgtaactgttataacaat 
               
               
                   
                 gggacctcctcaagcagatatggctttaaaagaagctttagcaatgggtgcagatagag 
               
               
                   
                 gtatattattaacagatagagcatttgcgggtgctgatacttgggcaacttcatcagca 
               
               
                   
                 ttagcaggagcattaaaaaatatagattttgatattataatagctggaagacaggcgat 
               
               
                   
                 agatggagatactgcacaagttggacctcaaatagctgaacatttaaatcttccatcaa 
               
               
                   
                 taacatatgctgaagaaataaaaactgaaggtgaatatgtattagtaaaaagacaattt 
               
               
                   
                 gaagattgttgccatgacttaaaagttaaaatgccatgccttataacaactcttaaaga 
               
               
                   
                 tatgaacacaccaagatacatgaaagttggaagaatatatgatgctttcgaaaatgatg 
               
               
                   
                 tagtagaaacatggactgtaaaagatatagaagttgacccttctaatttaggtcttaaa 
               
               
                   
                 ggttctccaactagtgtatttaaatcatttacaaaatcagttaaaccagctggtacaat 
               
               
                   
                 atacaatgaagatgcgaaaacatcagctggaattatcatagataaattaaaagagaagt 
               
               
                   
                 atatcatataataagaaggagatatacatatgggtaacgttttagtagtaatagaacaa 
               
               
                   
                 agagaaaatgtaattcaaactgtttctttagaattactaggaaaggctacagaaatagc 
               
               
                   
                 aaaagattatgatacaaaagtttctgcattacttttaggtagtaaggtagaaggtttaa 
               
               
                   
                 tagatacattagcacactatggtgcagatgaggtaatagtagtagatgatgaagcttta 
               
               
                   
                 gcagtgtatacaactgaaccatatacaaaagcagcttatgaagcaataaaagcagctga 
               
               
                   
                 ccctatagttgtattatttggtgcaacttcaataggtagagatttagcgcctagagttt 
               
               
                   
                 ctgctagaatacatacaggtcttactgctgactgtacaggtcttgcagtagctgaagat 
               
               
                   
                 acaaaattattattaatgacaagacctgcctttggtggaaatataatggcaacaatagt 
               
               
                   
                 ttgtaaagatttcagacctcaaatgtctacagttagaccaggggttatgaagaaaaatg 
               
               
                   
                 aacctgatgaaactaaagaagctgtaattaaccgtttcaaggtagaatttaatgatgct 
               
               
                   
                 gataaattagttcaagttgtacaagtaataaaagaagctaaaaaacaagttaaaataga 
               
               
                   
                 agatgctaagatattagtttctgctggacgtggaatgggtggaaaagaaaacttagaca 
               
               
                   
                 tactttatgaattagctgaaattataggtggagaagtttctggttctcgtgccactata 
               
               
                   
                 gatgcaggttggttagataaagcaagacaagttggtcaaactggtaaaactgtaagacc 
               
               
                   
                 agacctttatatagcatgtggtatatctggagcaatacaacatatagctggtatggaag 
               
               
                   
                 atgctgagtttatagttgctataaataaaaatccagaagctccaatatttaaatatgct 
               
               
                   
                 gatgttggtatagttggagatgttcataaagtgcttccagaacttatcagtcagttaag 
               
               
                   
                 tgttgcaaaagaaaaaggtgaagttttagctaactaataagaaggagatatacatatga 
               
               
                   
                 gagaagtagtaattgccagtgcagctagaacagcagtaggaagttttggaggagcattt 
               
               
                   
                 aaatcagtttcagcggtagagttaggggtaacagcagctaaagaagctataaaaagagc 
               
               
                   
                 taacataactccagatatgatagatgaatctcttttagggggagtacttacagcaggtc 
               
               
                   
                 ttggacaaaatatagcaagacaaatagcattaggagcaggaataccagtagaaaaacca 
               
               
                   
                 gctatgactataaatatagtttgtggttctggattaagatctgtttcaatggcatctca 
               
               
                   
                 acttatagcattaggtgatgctgatataatgttagttggtggagctgaaaacatgagta 
               
               
                   
                 tgtctccttatttagtaccaagtgcgagatatggtgcaagaatgggtgatgctgctttt 
               
               
                   
                 gttgattcaatgataaaagatggattatcagacatatttaataactatcacatgggtat 
               
               
                   
                 tactgctgaaaacatagcagagcaatggaatataactagagaagaacaagatgaattag 
               
               
                   
                 ctcttgcaagtcaaaataaagctgaaaaagctcaagctgaaggaaaatttgatgaagaa 
               
               
                   
                 atagttcctgttgttataaaaggaagaaaaggtgacactgtagtagataaagatgaata 
               
               
                   
                 tattaagcctggcactacaatggagaaacttgctaagttaagacctgcatttaaaaaag 
               
               
                   
                 atggaacagttactgctggtaatgcatcaggaataaatgatggtgctgctatgttagta 
               
               
                   
                 gtaatggctaaagaaaaagctgaagaactaggaatagagcctcttgcaactatagtttc 
               
               
                   
                 ttatggaacagctggtgttgaccctaaaataatgggatatggaccagttccagcaacta 
               
               
                   
                 aaaaagctttagaagctgctaatatgactattgaagatatagatttagttgaagctaat 
               
               
                   
                 gaggcatttgctgcccaatctgtagctgtaataagagacttaaatatagatatgaataa 
               
               
                   
                 agttaatgttaatggtggagcaatagctataggacatccaataggatgctcaggagcaa 
               
               
                   
                 gaatacttactacacttttatatgaaatgaagagaagagatgctaaaactggtcttgct 
               
               
                   
                 acactttgtataggcggtggaatgggaactactttaatagttaagagatagtaagaagg 
               
               
                   
                 agatatacatatgaaattagctgtaataggtagtggaactatgggaagtggtattgtac 
               
               
                   
                 aaacttttgcaagttgtggacatgatgtatgtttaaagagtagaactcaaggtgctata 
               
               
                   
                 gataaatgtttagctttattagataaaaatttaactaagttagttactaagggaaaaat 
               
               
                   
                 ggatgaagctacaaaagcagaaatattaagtcatgttagttcaactactaattatgaag 
               
               
                   
                 atttaaaagatatggatttaataatagaagcatctgtagaagacatgaatataaagaaa 
               
               
                   
                 gatgttttcaagttactagatgaattatgtaaagaagatactatcttggcaacaaatac 
               
               
                   
                 ttcatcattatctataacagaaatagcttcttctactaagcgcccagataaagttatag 
               
               
                   
                 gaatgcatttctttaatccagttcctatgatgaaattagttgaagttataagtggtcag 
               
               
                   
                 ttaacatcaaaagttacttttgatacagtatttgaattatctaagagtatcaataaagt 
               
               
                   
                 accagtagatgtatctgaatctcctggatttgtagtaaatagaatacttatacctatga 
               
               
                   
                 taaatgaagctgttggtatatatgcagatggtgttgcaagtaaagaagaaatagatgaa 
               
               
                   
                 gctatgaaattaggagcaaaccatccaatgggaccactagcattaggtgatttaatcgg 
               
               
                   
                 attagatgttgttttagctataatgaacgttttatatactgaatttggagatactaaat 
               
               
                   
                 atagacctcatccacttttagctaaaatggttagagctaatcaattaggaagaaaaact 
               
               
                   
                 aagataggattctatgattataataaataataagaaggagatatacatatgagtacaag 
               
               
                   
                 tgatgttaaagtttatgagaatgtagctgttgaagtagatggaaatatatgtacagtga 
               
               
                   
                 aaatgaatagacctaaagcccttaatgcaataaattcaaagactttagaagaactttat 
               
               
                   
                 gaagtatttgtagatattaataatgatgaaactattgatgttgtaatattgacagggga 
               
               
                   
                 aggaaaggcatttgtagctggagcagatattgcatacatgaaagatttagatgctgtag 
               
               
                   
                 ctgctaaagattttagtatcttaggagcaaaagcttttggagaaatagaaaatagtaaa 
               
               
                   
                 aaagtagtgatagctgctgtaaacggatttgctttaggtggaggatgtgaacttgcaat 
               
               
                   
                 ggcatgtgatataagaattgcatctgctaaagctaaatttggtcagccagaagtaactc 
               
               
                   
                 ttggaataactccaggatatggaggaactcaaaggcttacaagattggttggaatggca 
               
               
                   
                 aaagcaaaagaattaatctttacaggtcaagttataaaagctgatgaagctgaaaaaat 
               
               
                   
                 agggctagtaaatagagtcgttgagccagacattttaatagaagaagttgagaaattag 
               
               
                   
                 ctaagataatagctaaaaatgctcagcttgcagttagatactctaaagaagcaatacaa 
               
               
                   
                 cttggtgctcaaactgatataaatactggaatagatatagaatctaatttatttggtct 
               
               
                   
                 ttgtttttcaactaaagaccaaaaagaaggaatgtcagctttcgttgaaaagagagaag 
               
               
                   
                 ctaactttataaaagggtaataagaaggagatatacatatgagaagttttgaagaagta 
               
               
                   
                 attaagtttgcaaaagaaagaggacctaaaactatatcagtagcatgttgccaagataa 
               
               
                   
                 agaagttttaatggcagttgaaatggctagaaaagaaaaaatagcaaatgccattttag 
               
               
                   
                 taggagatatagaaaagactaaagaaattgcaaaaagcatagacatggatatcgaaaat 
               
               
                   
                 tatgaactgatagatataaaagatttagcagaagcatctctaaaatctgttgaattagt 
               
               
                   
                 ttcacaaggaaaagccgacatggtaatgaaaggcttagtagacacatcaataatactaa 
               
               
                   
                 aagcagttttaaataaagaagtaggtcttagaactggaaatgtattaagtcacgtagca 
               
               
                   
                 gtatttgatgtagagggatatgatagattatttttcgtaactgacgcagctatgaactt 
               
               
                   
                 agctcctgatacaaatactaaaaagcaaatcatagaaaatgcttgcacagtagcacatt 
               
               
                   
                 cattagatataagtgaaccaaaagttgctgcaatatgcgcaaaagaaaaagtaaatcca 
               
               
                   
                 aaaatgaaagatacagttgaagctaaagaactagaagaaatgtatgaaagaggagaaat 
               
               
                   
                 caaaggttgtatggttggtgggccttttgcaattgataatgcagtatctttagaagcag 
               
               
                   
                 ctaaacataaaggtataaatcatcctgtagcaggacgagctgatatattattagcccca 
               
               
                   
                 gatattgaaggtggtaacatattatataaagctttggtattcttctcaaaatcaaaaaa 
               
               
                   
                 tgcaggagttatagttggggctaaagcaccaataatattaacttctagagcagacagtg 
               
               
                   
                 aagaaactaaactaaactcaatagctttaggtgttttaatggcagcaaaggcataataa 
               
               
                   
                 gaaggagatatacatatgagcaaaatatttaaaatcttaacaataaatcctggttcgac 
               
               
                   
                 atcaactaaaatagctgtatttgataatgaggatttagtatttgaaaaaactttaagac 
               
               
                   
                 attcttcagaagaaataggaaaatatgagaaggtgtctgaccaatttgaatttcgtaaa 
               
               
                   
                 caagtaatagaagaagctctaaaagaaggtggagtaaaaacatctgaattagatgctgt 
               
               
                   
                 agtaggtagaggaggacttcttaaacctataaaaggtggtacttattcagtaagtgctg 
               
               
                   
                 ctatgattgaagatttaaaagtgggagttttaggagaacacgcttcaaacctaggtgga 
               
               
                   
                 ataatagcaaaacaaataggtgaagaagtaaatgttccttcatacatagtagaccctgt 
               
               
                   
                 tgttgtagatgaattagaagatgttgctagaatttctggtatgcctgaaataagtagag 
               
               
                   
                 caagtgtagtacatgctttaaatcaaaaggcaatagcaagaagatatgctagagaaata 
               
               
                   
                 aacaagaaatatgaagatataaatcttatagttgcacacatgggtggaggagtttctgt 
               
               
                   
                 tggagctcataaaaatggtaaaatagtagatgttgcaaacgcattagatggagaaggac 
               
               
                   
                 ctttctctccagaaagaagtggtggactaccagtaggtgcattagtaaaaatgtgcttt 
               
               
                   
                 agtggaaaatatactcaagatgaaattaaaaagaaaataaaaggtaatggcggactagt 
               
               
                   
                 tgcatacttaaacactaatgatgctagagaagttgaagaaagaattgaagctggtgatg 
               
               
                   
                 aaaaagctaaattagtatatgaagctatggcatatcaaatctctaaagaaataggagct 
               
               
                   
                 agtgctgcagttcttaagggagatgtaaaagcaatattattaactggtggaatcgcata 
               
               
                   
                 ttcaaaaatgtttacagaaatgattgcagatagagttaaatttatagcagatgtaaaag 
               
               
                   
                 tttatccaggtgaagatgaaatgattgcattagctcaaggtggacttagagttttaact 
               
               
                   
                 ggtgaagaagaggctcaagtttatgataactaataa 
               
               
                   
               
               
                 Nucleotide 
                 gtaaaacgacggccagtgaattcg ttaagacccactttcacatttaagttgtttttcta   
               
               
                 sequences of 
                 
                   atccgcatatgatcaattcaaggccgaataagaaggctggctctgcaccttggtgatca 
                 
               
               
                 pLogic046- 
                 
                   aataattcgatagcttgtcgtaataatggcggcatactatcagtagtaggtgtttccct 
                 
               
               
                 tet-butyrate 
                 
                   ttcttctttagcgacttgatgctcttgatcttccaatacgcaacctaaagtaaaatgcc 
                 
               
               
                 construct 
                 
                   ccacagcgctgagtgcatataatgcattctctagtgaaaaaccttgttggcataaaaag 
                 
               
               
                 (SEQ ID NO: 
                 
                   gctaattgattttcgagagtttcatactgtttttctgtaggccgtgtacctaaatgtac 
                 
               
               
                 85) The 
                 
                   ttttgctccatcgcgatgacttagtaaagcacatctaaaacttttagcgttattacgta 
                 
               
               
                 sequence 
                 
                   aaaaatcttgccagctttccccttctaaagggcaaaagtgagtatggtgcctatctaac 
                 
               
               
                 encoding 
                 
                   atctcaatggctaaggcgtcgagcaaagcccgcttattttttacatgccaatacaatgt 
                 
               
               
                 TetR is 
                 
                   aggctgctctacacctagcttctgggcgagtttacgggttgttaaaccttcgattccga 
                 
               
               
                   underlined , 
                 
                   cctcattaagcagctctaatgcgctgttaatcactttacttttatctaatctagacatc 
                 
               
               
                 and the 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 overlapping 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                 tetR/tetA 
                 tacatatgatcgtaaaacctatggtacgcaacaatatctgcctgaacgcccatcctcag 
               
               
                 promoters 
                 ggctgcaagaagggagtggaagatcagattgaatataccaagaaacgcattaccgcaga 
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 agtcaaagctggcgcaaaagctccaaaaaacgttctggtgcttggctgctcaaatggtt 
               
               
                   
                 acggcctggcgagccgcattactgctgcgttcggatacggggctgcgaccatcggcgtg 
               
               
                   
                 tcctttgaaaaagcgggttcagaaaccaaatatggtacaccgggatggtacaataattt 
               
               
                   
                 ggcatttgatgaagcggcaaaacgcgagggtctttatagcgtgacgatcgacggcgatg 
               
               
                   
                 cgttttcagacgagatcaaggcccaggtaattgaggaagccaaaaaaaaaggtatcaaa 
               
               
                   
                 tttgatctgatcgtatacagcttggccagcccagtacgtactgatcctgatacaggtat 
               
               
                   
                 catgcacaaaagcgttttgaaaccctttggaaaaacgttcacaggcaaaacagtagatc 
               
               
                   
                 cgtttactggcgagctgaaggaaatctccgcggaaccagcaaatgacgaggaagcagcc 
               
               
                   
                 gccactgttaaagttatggggggtgaagattgggaacgttggattaagcagctgtcgaa 
               
               
                   
                 ggaaggcctcttagaagaaggctgtattaccttggcctatagttatattggccctgaag 
               
               
                   
                 ctacccaagctttgtaccgtaaaggcacaatcggcaaggccaaagaacacctggaggcc 
               
               
                   
                 acagcacaccgtctcaacaaagagaacccgtcaatccgtgccttcgtgagcgtgaataa 
               
               
                   
                 aggcctggtaacccgcgcaagcgccgtaatcccggtaatccctctgtatctcgccagct 
               
               
                   
                 tgttcaaagtaatgaaagagaagggcaatcatgaaggttgtattgaacagatcacgcgt 
               
               
                   
                 ctgtacgccgagcgcctgtaccgtaaagatggtacaattccagttgatgaggaaaatcg 
               
               
                   
                 cattcgcattgatgattgggagttagaagaagacgtccagaaagcggtatccgcgttga 
               
               
                   
                 tggagaaagtcacgggtgaaaacgcagaatctctcactgacttagcggggtaccgccat 
               
               
                   
                 gatttcttagctagtaacggctttgatgtagaaggtattaattatgaagcggaagttga 
               
               
                   
                 acgcttcgaccgtatctgataagaaggagatatacatatgagagaagtagtaattgcca 
               
               
                   
                 gtgcagctagaacagcagtaggaagttttggaggagcatttaaatcagtttcagcggta 
               
               
                   
                 gagttaggggtaacagcagctaaagaagctataaaaagagctaacataactccagatat 
               
               
                   
                 gatagatgaatctcttttagggggagtacttacagcaggtcttggacaaaatatagcaa 
               
               
                   
                 gacaaatagcattaggagcaggaataccagtagaaaaaccagctatgactataaatata 
               
               
                   
                 gtttgtggttctggattaagatctgtttcaatggcatctcaacttatagcattaggtga 
               
               
                   
                 tgctgatataatgttagttggtggagctgaaaacatgagtatgtctccttatttagtac 
               
               
                   
                 caagtgcgagatatggtgcaagaatgggtgatgctgcttttgttgattcaatgataaaa 
               
               
                   
                 gatggattatcagacatatttaataactatcacatgggtattactgctgaaaacatagc 
               
               
                   
                 agagcaatggaatataactagagaagaacaagatgaattagctcttgcaagtcaaaata 
               
               
                   
                 aagctgaaaaagctcaagctgaaggaaaatttgatgaagaaatagttcctgttgttata 
               
               
                   
                 aaaggaagaaaaggtgacactgtagtagataaagatgaatatattaagcctggcactac 
               
               
                   
                 aatggagaaacttgctaagttaagacctgcatttaaaaaagatggaacagttactgctg 
               
               
                   
                 gtaatgcatcaggaataaatgatggtgctgctatgttagtagtaatggctaaagaaaaa 
               
               
                   
                 gctgaagaactaggaatagagcctcttgcaactatagtttcttatggaacagctggtgt 
               
               
                   
                 tgaccctaaaataatgggatatggaccagttccagcaactaaaaaagctttagaagctg 
               
               
                   
                 ctaatatgactattgaagatatagatttagttgaagctaatgaggcatttgctgcccaa 
               
               
                   
                 tctgtagctgtaataagagacttaaatatagatatgaataaagttaatgttaatggtgg 
               
               
                   
                 agcaatagctataggacatccaataggatgctcaggagcaagaatacttactacacttt 
               
               
                   
                 tatatgaaatgaagagaagagatgctaaaactggtcttgctacactttgtataggcggt 
               
               
                   
                 ggaatgggaactactttaatagttaagagatagtaagaaggagatatacatatgaaatt 
               
               
                   
                 agctgtaataggtagtggaactatgggaagtggtattgtacaaacttttgcaagttgtg 
               
               
                   
                 gacatgatgtatgtttaaagagtagaactcaaggtgctatagataaatgtttagcttta 
               
               
                   
                 ttagataaaaatttaactaagttagttactaagggaaaaatggatgaagctacaaaagc 
               
               
                   
                 agaaatattaagtcatgttagttcaactactaattatgaagatttaaaagatatggatt 
               
               
                   
                 taataatagaagcatctgtagaagacatgaatataaagaaagatgttttcaagttacta 
               
               
                   
                 gatgaattatgtaaagaagatactatcttggcaacaaatacttcatcattatctataac 
               
               
                   
                 agaaatagcttcttctactaagcgcccagataaagttataggaatgcatttctttaatc 
               
               
                   
                 cagttcctatgatgaaattagttgaagttataagtggtcagttaacatcaaaagttact 
               
               
                   
                 tttgatacagtatttgaattatctaagagtatcaataaagtaccagtagatgtatctga 
               
               
                   
                 atctcctggatttgtagtaaatagaatacttatacctatgataaatgaagctgttggta 
               
               
                   
                 tatatgcagatggtgttgcaagtaaagaagaaatagatgaagctatgaaattaggagca 
               
               
                   
                 aaccatccaatgggaccactagcattaggtgatttaatcggattagatgttgttttagc 
               
               
                   
                 tataatgaacgttttatatactgaatttggagatactaaatatagacctcatccacttt 
               
               
                   
                 tagctaaaatggttagagctaatcaattaggaagaaaaactaagataggattctatgat 
               
               
                   
                 tataataaataataagaaggagatatacatatgagtacaagtgatgttaaagtttatga 
               
               
                   
                 gaatgtagctgttgaagtagatggaaatatatgtacagtgaaaatgaatagacctaaag 
               
               
                   
                 cccttaatgcaataaattcaaagactttagaagaactttatgaagtatttgtagatatt 
               
               
                   
                 aataatgatgaaactattgatgttgtaatattgacaggggaaggaaaggcatttgtagc 
               
               
                   
                 tggagcagatattgcatacatgaaagatttagatgctgtagctgctaaagattttagta 
               
               
                   
                 tcttaggagcaaaagcttttggagaaatagaaaatagtaaaaaagtagtgatagctgct 
               
               
                   
                 gtaaacggatttgctttaggtggaggatgtgaacttgcaatggcatgtgatataagaat 
               
               
                   
                 tgcatctgctaaagctaaatttggtcagccagaagtaactcttggaataactccaggat 
               
               
                   
                 atggaggaactcaaaggcttacaagattggttggaatggcaaaagcaaaagaattaatc 
               
               
                   
                 tttacaggtcaagttataaaagctgatgaagctgaaaaaatagggctagtaaatagagt 
               
               
                   
                 cgttgagccagacattttaatagaagaagttgagaaattagctaagataatagctaaaa 
               
               
                   
                 atgctcagcttgcagttagatactctaaagaagcaatacaacttggtgctcaaactgat 
               
               
                   
                 ataaatactggaatagatatagaatctaatttatttggtctttgtttttcaactaaaga 
               
               
                   
                 ccaaaaagaaggaatgtcagctttcgttgaaaagagagaagctaactttataaaagggt 
               
               
                   
                 aataagaaggagatatacatatgagaagttttgaagaagtaattaagtttgcaaaagaa 
               
               
                   
                 agaggacctaaaactatatcagtagcatgttgccaagataaagaagttttaatggcagt 
               
               
                   
                 tgaaatggctagaaaagaaaaaatagcaaatgccattttagtaggagatatagaaaaga 
               
               
                   
                 ctaaagaaattgcaaaaagcatagacatggatatcgaaaattatgaactgatagatata 
               
               
                   
                 aaagatttagcagaagcatctctaaaatctgttgaattagtttcacaaggaaaagccga 
               
               
                   
                 catggtaatgaaaggcttagtagacacatcaataatactaaaagcagttttaaataaag 
               
               
                   
                 aagtaggtcttagaactggaaatgtattaagtcacgtagcagtatttgatgtagaggga 
               
               
                   
                 tatgatagattatttttcgtaactgacgcagctatgaacttagctcctgatacaaatac 
               
               
                   
                 taaaaagcaaatcatagaaaatgcttgcacagtagcacattcattagatataagtgaac 
               
               
                   
                 caaaagttgctgcaatatgcgcaaaagaaaaagtaaatccaaaaatgaaagatacagtt 
               
               
                   
                 gaagctaaagaactagaagaaatgtatgaaagaggagaaatcaaaggttgtatggttgg 
               
               
                   
                 tgggccttttgcaattgataatgcagtatctttagaagcagctaaacataaaggtataa 
               
               
                   
                 atcatcctgtagcaggacgagctgatatattattagccccagatattgaaggtggtaac 
               
               
                   
                 atattatataaagctttggtattcttctcaaaatcaaaaaatgcaggagttatagttgg 
               
               
                   
                 ggctaaagcaccaataatattaacttctagagcagacagtgaagaaactaaactaaact 
               
               
                   
                 caatagctttaggtgttttaatggcagcaaaggcataataagaaggagatatacatatg 
               
               
                   
                 agcaaaatatttaaaatcttaacaataaatcctggttcgacatcaactaaaatagctgt 
               
               
                   
                 atttgataatgaggatttagtatttgaaaaaactttaagacattcttcagaagaaatag 
               
               
                   
                 gaaaatatgagaaggtgtctgaccaatttgaatttcgtaaacaagtaatagaagaagct 
               
               
                   
                 ctaaaagaaggtggagtaaaaacatctgaattagatgctgtagtaggtagaggaggact 
               
               
                   
                 tcttaaacctataaaaggtggtacttattcagtaagtgctgctatgattgaagatttaa 
               
               
                   
                 aagtgggagttttaggagaacacgcttcaaacctaggtggaataatagcaaaacaaata 
               
               
                   
                 ggtgaagaagtaaatgttccttcatacatagtagaccctgttgttgtagatgaattaga 
               
               
                   
                 agatgttgctagaatttctggtatgcctgaaataagtagagcaagtgtagtacatgctt 
               
               
                   
                 taaatcaaaaggcaatagcaagaagatatgctagagaaataaacaagaaatatgaagat 
               
               
                   
                 ataaatcttatagttgcacacatgggtggaggagtttctgttggagctcataaaaatgg 
               
               
                   
                 taaaatagtagatgttgcaaacgcattagatggagaaggacctttctctccagaaagaa 
               
               
                   
                 gtggtggactaccagtaggtgcattagtaaaaatgtgctttagtggaaaatatactcaa 
               
               
                   
                 gatgaaattaaaaagaaaataaaaggtaatggcggactagttgcatacttaaacactaa 
               
               
                   
                 tgatgctagagaagttgaagaaagaattgaagctggtgatgaaaaagctaaattagtat 
               
               
                   
                 atgaagctatggcatatcaaatctctaaagaaataggagctagtgctgcagttcttaag 
               
               
                   
                 ggagatgtaaaagcaatattattaactggtggaatcgcatattcaaaaatgtttacaga 
               
               
                   
                 aatgattgcagatagagttaaatttatagcagatgtaaaagtttatccaggtgaagatg 
               
               
                   
                 aaatgattgcattagctcaaggtggacttagagttttaactggtgaagaagaggctcaa 
               
               
                   
                 gtttatgataactaataa 
               
               
                   
               
            
           
         
       
     
     In certain constructs, the butyrate gene cassette is placed under the control of a tetracycline-inducible or constitutive promoter. 
     In a third butyrate gene cassette, the pbt and buk genes are replaced with tesB. TesB is a thioesterase found in  E. Coli  that cleaves off the butyrate from butyryl-coA, thus obviating the need for pbt-buk. 
     In one embodiment, tesB is placed under the control of a FNR regulatory region selected from any of the sequences in Table 6. In an alternate embodiment, tesB is placed under the control of an RNS-responsive regulatory region, e.g., norB, and the bacteria further comprises a gene encoding a corresponding RNS-responsive transcription factor, e.g., nsrR. In yet another embodiment, tesB is placed under the control of an ROS-responsive regulatory region, e.g., oxyS, and the bacteria further comprises a gene encoding a corresponding ROS-responsive transcription factor, e.g., oxyR. In certain constructs, the different described butyrate gene cassettes are each placed under the control of a tetracycline-inducible or constitutive promoter. For example, genetically engineered Nissle are generated comprising a butyrate gene cassette in which the pbt and buk genes are replaced with tesB expressed under the control of a nitric oxide-responsive regulatory element. SEQ ID NO: 86 comprises a reverse complement of the nsrR repressor gene from  Neisseria gonorrhoeae  (underlined), intergenic region containing divergent promoters controlling nsrR and the butyrogenic gene cassette and their respective RBS (bold), and the butyrate genes (ter-thiA-hbd-crt-tesB) separated by RBS. 
     
       
         
           
               
             
               
                 TABLE 41 
               
               
                   
               
               
                 SEQ ID NO: 86 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 SEQ ID NO: 86 
               
               
                 ttatta tcgcaccgcaatcgggattttcgattcataaagcaggtcgtaggtcggcttgttgagc   
               
               
                   
               
               
                 
                   aggtcttgcagcgtgaaaccgtccagatacgtgaaaaacgacttcattgcaccgccgagtatgc 
                 
               
               
                   
               
               
                 
                   ccgtcagccggcaggacggcgtaatcaggcattcgttgttcgggcccatacactcgaccagctg 
                 
               
               
                   
               
               
                 
                   catcggttcgaggtggcggacgaccgcgccgatattgatgcgttcgggcggcgcggccagcctc 
                 
               
               
                   
               
               
                 
                   agcccgccgcctttcccgcgtacgctgtgcaagaacccgcctttgaccagcgcggtaaccactt 
                 
               
               
                   
               
               
                 
                   tcatcaaatggcttttggaaatgccgtaggtcgaggcgatggtggcgatattgaccagcgcgtc 
                 
               
               
                   
               
               
                 
                   gtcgttgacggcggtgtagatgaggacgcgcagcccgtagtcggtatgttgggtcagatacat 
                   a 
                 
               
               
                   
               
               
                 
                   caacctccttagtacatgcaaaattatttctagagcaacatacgagccggaagcataaagtgta 
                 
               
               
                   
               
               
                 
                   aagcctggggtgcctaatgagttgagttgaggaattataacaggaagaaatattcctcatacgc 
                 
               
               
                   
               
               
                 
                   ttgtaattcctctatggttgttgacaattaatcatcggctcgtataatgtataacattcatatt 
                 
               
               
                   
               
               
                   ttgtgaattttaaactctagaaataattttgtttaactttaagaaggagatatacat atgatcg 
               
               
                   
               
               
                 taaaacctatggtacgcaacaatatctgcctgaacgcccatcctcagggctgcaagaagggagt 
               
               
                   
               
               
                 ggaagatcagattgaatataccaagaaacgcattaccgcagaagtcaaagctggcgcaaaagct 
               
               
                   
               
               
                 ccaaaaaacgttctggtgcttggctgctcaaatggttacggcctggcgagccgcattactgctg 
               
               
                   
               
               
                 cgttcggatacggggctgcgaccatcggcgtgtcctttgaaaaagcgggttcagaaaccaaata 
               
               
                   
               
               
                 tggtacaccgggatggtacaataatttggcatttgatgaagcggcaaaacgcgagggtctttat 
               
               
                   
               
               
                 agcgtgacgatcgacggcgatgcgttttcagacgagatcaaggcccaggtaattgaggaagcca 
               
               
                   
               
               
                 aaaaaaaaggtatcaaatttgatctgatcgtatacagcttggccagcccagtacgtactgatcc 
               
               
                   
               
               
                 tgatacaggtatcatgcacaaaagcgttttgaaaccctttggaaaaacgttcacaggcaaaaca 
               
               
                   
               
               
                 gtagatccgtttactggcgagctgaaggaaatctccgcggaaccagcaaatgacgaggaagcag 
               
               
                   
               
               
                 ccgccactgttaaagttatggggggtgaagattgggaacgttggattaagcagctgtcgaagga 
               
               
                   
               
               
                 aggcctcttagaagaaggctgtattaccttggcctatagttatattggccctgaagctacccaa 
               
               
                   
               
               
                 gctttgtaccgtaaaggcacaatcggcaaggccaaagaacacctggaggccacagcacaccgtc 
               
               
                   
               
               
                 tcaacaaagagaacccgtcaatccgtgccttcgtgagcgtgaataaaggcctggtaacccgcgc 
               
               
                   
               
               
                 aagcgccgtaatcccggtaatccctctgtatctcgccagcttgttcaaagtaatgaaagagaag 
               
               
                   
               
               
                 ggcaatcatgaaggttgtattgaacagatcacgcgtctgtacgccgagcgcctgtaccgtaaag 
               
               
                   
               
               
                 atggtacaattccagttgatgaggaaaatcgcattcgcattgatgattgggagttagaagaaga 
               
               
                   
               
               
                 cgtccagaaagcggtatccgcgttgatggagaaagtcacgggtgaaaacgcagaatctctcact 
               
               
                   
               
               
                 gacttagcggggtaccgccatgatttcttagctagtaacggctttgatgtagaaggtattaatt 
               
               
                   
               
               
                 atgaagcggaagttgaacgcttcgaccgtatctgataagaaggagatatacatatgagagaagt 
               
               
                   
               
               
                 agtaattgccagtgcagctagaacagcagtaggaagttttggaggagcatttaaatcagtttca 
               
               
                   
               
               
                 gcggtagagttaggggtaacagcagctaaagaagctataaaaagagctaacataactccagata 
               
               
                   
               
               
                 tgatagatgaatctcttttagggggagtacttacagcaggtcttggacaaaatatagcaagaca 
               
               
                   
               
               
                 aatagcattaggagcaggaataccagtagaaaaaccagctatgactataaatatagtttgtggt 
               
               
                   
               
               
                 tctggattaagatctgtttcaatggcatctcaacttatagcattaggtgatgctgatataatgt 
               
               
                   
               
               
                 tagttggtggagctgaaaacatgagtatgtctccttatttagtaccaagtgcgagatatggtgc 
               
               
                   
               
               
                 aagaatgggtgatgctgcttttgttgattcaatgataaaagatggattatcagacatatttaat 
               
               
                   
               
               
                 aactatcacatgggtattactgctgaaaacatagcagagcaatggaatataactagagaagaac 
               
               
                   
               
               
                 aagatgaattagctcttgcaagtcaaaataaagctgaaaaagctcaagctgaaggaaaatttga 
               
               
                   
               
               
                 tgaagaaatagttcctgttgttataaaaggaagaaaaggtgacactgtagtagataaagatgaa 
               
               
                   
               
               
                 tatattaagcctggcactacaatggagaaacttgctaagttaagacctgcatttaaaaaagatg 
               
               
                   
               
               
                 gaacagttactgctggtaatgcatcaggaataaatgatggtgctgctatgttagtagtaatggc 
               
               
                   
               
               
                 taaagaaaaagctgaagaactaggaatagagcctcttgcaactatagtttcttatggaacagct 
               
               
                   
               
               
                 ggtgttgaccctaaaataatgggatatggaccagttccagcaactaaaaaagctttagaagctg 
               
               
                   
               
               
                 ctaatatgactattgaagatatagatttagttgaagctaatgaggcatttgctgcccaatctgt 
               
               
                   
               
               
                 agctgtaataagagacttaaatatagatatgaataaagttaatgttaatggtggagcaatagct 
               
               
                   
               
               
                 ataggacatccaataggatgctcaggagcaagaatacttactacacttttatatgaaatgaaga 
               
               
                   
               
               
                 gaagagatgctaaaactggtcttgctacactttgtataggcggtggaatgggaactactttaat 
               
               
                   
               
               
                 agttaagagatagtaagaaggagatatacatatgaaattagctgtaataggtagtggaactatg 
               
               
                   
               
               
                 ggaagtggtattgtacaaacttttgcaagttgtggacatgatgtatgtttaaagagtagaactc 
               
               
                   
               
               
                 aaggtgctatagataaatgtttagctttattagataaaaatttaactaagttagttactaaggg 
               
               
                   
               
               
                 aaaaatggatgaagctacaaaagcagaaatattaagtcatgttagttcaactactaattatgaa 
               
               
                   
               
               
                 gatttaaaagatatggatttaataatagaagcatctgtagaagacatgaatataaagaaagatg 
               
               
                   
               
               
                 ttttcaagttactagatgaattatgtaaagaagatactatcttggcaacaaatacttcatcatt 
               
               
                   
               
               
                 atctataacagaaatagcttcttctactaagcgcccagataaagttataggaatgcatttcttt 
               
               
                   
               
               
                 aatccagttcctatgatgaaattagttgaagttataagtggtcagttaacatcaaaagttactt 
               
               
                   
               
               
                 ttgatacagtatttgaattatctaagagtatcaataaagtaccagtagatgtatctgaatctcc 
               
               
                   
               
               
                 tggatttgtagtaaatagaatacttatacctatgataaatgaagctgttggtatatatgcagat 
               
               
                   
               
               
                 ggtgttgcaagtaaagaagaaatagatgaagctatgaaattaggagcaaaccatccaatgggac 
               
               
                   
               
               
                 cactagcattaggtgatttaatcggattagatgttgttttagctataatgaacgttttatatac 
               
               
                   
               
               
                 tgaatttggagatactaaatatagacctcatccacttttagctaaaatggttagagctaatcaa 
               
               
                   
               
               
                 ttaggaagaaaaactaagataggattctatgattataataaataataagaaggagatatacata 
               
               
                   
               
               
                 tgagtacaagtgatgttaaagtttatgagaatgtagctgttgaagtagatggaaatatatgtac 
               
               
                   
               
               
                 agtgaaaatgaatagacctaaagcccttaatgcaataaattcaaagactttagaagaactttat 
               
               
                   
               
               
                 gaagtatttgtagatattaataatgatgaaactattgatgttgtaatattgacaggggaaggaa 
               
               
                   
               
               
                 aggcatttgtagctggagcagatattgcatacatgaaagatttagatgctgtagctgctaaaga 
               
               
                   
               
               
                 ttttagtatcttaggagcaaaagcttttggagaaatagaaaatagtaaaaaagtagtgatagct 
               
               
                   
               
               
                 gctgtaaacggatttgctttaggtggaggatgtgaacttgcaatggcatgtgatataagaattg 
               
               
                   
               
               
                 catctgctaaagctaaatttggtcagccagaagtaactcttggaataactccaggatatggagg 
               
               
                   
               
               
                 aactcaaaggcttacaagattggttggaatggcaaaagcaaaagaattaatctttacaggtcaa 
               
               
                   
               
               
                 gttataaaagctgatgaagctgaaaaaatagggctagtaaatagagtcgttgagccagacattt 
               
               
                   
               
               
                 taatagaagaagttgagaaattagctaagataatagctaaaaatgctcagcttgcagttagata 
               
               
                   
               
               
                 ctctaaagaagcaatacaacttggtgctcaaactgatataaatactggaatagatatagaatct 
               
               
                   
               
               
                 aatttatttggtctttgtttttcaactaaagaccaaaaagaaggaatgtcagctttcgttgaaa 
               
               
                   
               
               
                 agagagaagctaactttataaaagggtaataagaaggagatatacatatgAGTCAGGCGCTAAA 
               
               
                   
               
               
                 AAATTTACTGACATTGTTAAATCTGGAAAAAATTGAGGAAGGACTCTTTCGCGGCCAGAGTGAA 
               
               
                   
               
               
                 GATTTAGGTTTACGCCAGGTGTTTGGCGGCCAGGTCGTGGGTCAGGCCTTGTATGCTGCAAAAG 
               
               
                   
               
               
                 AGACCGTCCCTGAAGAGCGGCTGGTACATTCGTTTCACAGCTACTTTCTTCGCCCTGGCGATAG 
               
               
                   
               
               
                 TAAGAAGCCGATTATTTATGATGTCGAAACGCTGCGTGACGGTAACAGCTTCAGCGCCCGCCGG 
               
               
                   
               
               
                 GTTGCTGCTATTCAAAACGGCAAACCGATTTTTTATATGACTGCCTCTTTCCAGGCACCAGAAG 
               
               
                   
               
               
                 CGGGTTTCGAACATCAAAAAACAATGCCGTCCGCGCCAGCGCCTGATGGCCTCCCTTCGGAAAC 
               
               
                   
               
               
                 GCAAATCGCCCAATCGCTGGCGCACCTGCTGCCGCCAGTGCTGAAAGATAAATTCATCTGCGAT 
               
               
                   
               
               
                 CGTCCGCTGGAAGTCCGTCCGGTGGAGTTTCATAACCCACTGAAAGGTCACGTCGCAGAACCAC 
               
               
                   
               
               
                 ATCGTCAGGTGTGGATCCGCGCAAATGGTAGCGTGCCGGATGACCTGCGCGTTCATCAGTATCT 
               
               
                   
               
               
                 GCTCGGTTACGCTTCTGATCTTAACTTCCTGCCGGTAGCTCTACAGCCGCACGGCATCGGTTTT 
               
               
                   
               
               
                 CTCGAACCGGGGATTCAGATTGCCACCATTGACCATTCCATGTGGTTCCATCGCCCGTTTAATT 
               
               
                   
               
               
                 TGAATGAATGGCTGCTGTATAGCGTGGAGAGCACCTCGGCGTCCAGCGCACGTGGCTTTGTGCG 
               
               
                   
               
               
                 CGGTGAGTTTTATACCCAAGACGGCGTACTGGTTGCCTCGACCGTTCAGGAAGGGGTGATGCGT 
               
               
                   
               
               
                 AATCACAATtaa 
               
               
                   
               
            
           
         
       
     
     Example 33. Construction of Vectors for Overproducing Butyrate Using a Tet-Inducible Promoter 
     To facilitate inducible production of butyrate in  Escherichia coli  Nissle, the eight genes of the butyrate production pathway from  Peptoclostridium difficile  (bcd, etfB, etfA, thiA, hbd, crt, bpt, and buk; NCBI), as well as transcriptional and translational elements, were synthesized (Gen, Cambridge, Mass.) and cloned into vector pBR to create pLogic. As synthesized, the genes were placed under control of a tetracycline-inducible promoter, with the tet repressor (tetR) expressed constitutively, divergent from the tet-inducible synthetic butyrate operon. For efficient translation of butyrate genes, each synthetic gene in the operon was separated by a base pair ribosome binding site derived from the T promoter. 
     The gene products of bcd-etfA-etfB form a complex that convert crotonyl-CoA to butyryl-CoA, and may show some dependence on oxygen as a co-oxidant. Because an effective probiotic should be able to function in an oxygen-limited environment (e.g. the mammalian gut), and because it has been shown that a single gene from  Treponema denticola  can functionally replace this three gene complex in an oxygen-independent manner (trans-enoynl-CoA reductase; ter), we created a second plasmid capable of butyrate production in  E. coli . Inverse PCR was used to amplify the entire sequence of pLogic outside of the bcd-etfA-etfB region. The ter gene was codon optimized for  E. coli  codon usage using Integrated DNA technologies online codon optimization tool (https://www.idtdna.com/CodonOpt), synthesized (Genewiz, Cambridge, Mass.), and cloned into this inverse PCR fragment using Gibson assembly to create pLogic. 
     Example 34. Transforming  E. coli    
     Each plasmid is transformed into  E. coli  Nissle or  E. coli  DH5a. All tubes, solutions, and cuvettes are pre-chilled to 4° C. An overnight culture of  E. coli  Nissle or  E. coli  DH5a is diluted 1:100 in 5 mL of lysogeny broth (LB) and grown until it reached an OD600 of 0.4-0.6. The cell culture medium contains a selection marker, e.g., ampicillin, that is suitable for the plasmid. The  E. coli  cells are then centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 1 mL of 4° C. water. The  E. coli  are again centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are resuspended in 0.5 mL of 4° C. water. The  E. coli  are again centrifuged at 2,000 rpm for 5 min. at 4° C., the supernatant is removed, and the cells are finally resuspended in 0.1 mL of 4° C. water. The electroporator is set to 2.5 kV. 0.5 μg of one of the above plasmids is added to the cells, mixed by pipetting, and pipetted into a sterile, chilled cuvette. The dry cuvette is placed into the sample chamber, and the electric pulse is applied. One mL of room-temperature SOC media is immediately added, and the mixture is transferred to a culture tube and incubated at 37° C. for 1 hr. The cells are spread out on an LB plate containing ampicillin and incubated overnight. 
     In alternate embodiments, the butyrate cassette can be inserted into the Nissle genome through homologous recombination (Genewiz, Cambridge, Mass.). Organization of the constructs and nucleotide sequences are provided herein. To create a vector capable of integrating the synthesized butyrate cassette construct into the chromosome, Gibson assembly was first used to add 1000 bp sequences of DNA homologous to the Nissle lacZ locus into the R6K origin plasmid pKD3. This targets DNA cloned between these homology arms to be integrated into the lacZ locus in the Nissle genome. Gibson assembly was used to clone the fragment between these arms. PCR was used to amplify the region from this plasmid containing the entire sequence of the homology arms, as well as the butyrate cassette between them. This PCR fragment was used to transform electrocompetent Nissle-pKD46, a strain that contains a temperature-sensitive plasmid encoding the lambda red recombinase genes. After transformation, cells were grown out for 2 hours before plating on chloramphenicol at 20 ug/mL at 37 degrees C. Growth at 37 degrees C. also cures the pKD46 plasmid. Transformants containing cassette were chloramphenicol resistant and lac-minus (lac-). 
     Example 35. Production of Butyrate in Recombinant  E. coli    
     Production of butyrate is assessed in  E. coli  Nissle strains containing the butyrate cassettes described above in order to determine the effect of oxygen on butyrate production. All incubations are performed at 37° C. Cultures of  E. coli  strains DH5a and Nissle transformed with the butyrate cassettes are grown overnight in LB and then diluted 1:200 into 4 mL of M9 minimal medium containing 0.5% glucose. The cells are grown with shaking (250 rpm) for 4-6 h and incubated aerobically or anaerobically in a Coy anaerobic chamber (supplying 90% N2, 5% CO2, 5% H2). One mL culture aliquots are prepared in 1.5 mL capped tubes and incubated in a stationary incubator to limit culture aeration. One tube is removed at each time point (0, 1, 2, 4, and 20 hrs) and analyzed for butyrate concentration by LC-MS to confirm that butyrate production in these recombinant strains can be achieved in a low-oxygen environment. 
     Example 36. Production of Butyrate in Recombinant  E. coli    
     Production of butyrate is assessed in  E. coli  Nissle strains containing the butyrate cassettes described above in order to determine the effect of oxygen on butyrate production. All incubations are performed at 37° C. Cultures of  E. coli  strains DH5a and Nissle transformed with the butyrate cassettes are grown overnight in LB and then diluted 1:200 into 4 mL of M9 minimal medium containing 0.5% glucose. The cells are grown with shaking (250 rpm) for 4-6 h and incubated aerobically or anaerobically in a Coy anaerobic chamber (supplying 90% N2, 5% CO2, 5% H2). One mL culture aliquots are prepared in 1.5 mL capped tubes and incubated in a stationary incubator to limit culture aeration. One tube is removed at each time point (0, 1, 2, 4, and 20 hrs) and analyzed for butyrate concentration by LC-MS to confirm that butyrate production in these recombinant strains can be achieved in a low-oxygen environment. 
     Example 37. Production of Butyrate in Recombinant  E. coli  Using Tet-Inducible Promoter 
       FIG. 48  shows butyrate cassettes described above under the control of a tet-inducible promoter. Production of butyrate is assessed using the methods described below in Example 40. The tet-inducible cassettes tested include (1) tet-butyrate cassette comprising all eight genes (pLOGIC031); (2) tet-butyrate cassette in which the ter is substituted (pLOGIC046) and (3) tet-butyarte cassette in which tesB is substituted in place of pbt and buk genes.  FIG. 51A  shows butyrate production in strains pLOGIC031 and pLOGIC046 in the presence and absence of oxygen, in which there is no significant difference in butyrate production. Enhanced butyrate production was shown in Nissle in low copy plasmid expressing pLOGIC046 which contain a deletion of the final two genes (ptb-buk) and their replacement with the endogenous  E. Coli  tesB gene (a thioesterase that cleaves off the butyrate portion from butyryl CoA). 
     Overnight cultures of cells were diluted 1:100 in Lb and grown for 1.5 hours until early log phase was reached at which point anhydrous tet was added at a final concentration of 100 ng/ml to induce plasmid expression. After 2 hours induction, cells were washed and resuspended in M9 minimal media containing 0.5% glucose at OD600=0.5. Samples were removed at indicated times and cells spun down. The supernatant was tested for butyrate production using LC-MS.  FIG. 51B  shows butyrate production in strains comprising a tet-butyrate cassette having ter substitution (pLOGIC046) or the tesB substitution (ptb-buk deletion), demonstrating that the tesB substituted strain has greater butyrate production. 
       FIG. 52  shows the BW25113 strain of  E. Coli , which is a common cloning strain and the background of the KEIO collection of  E. Coli  mutants. NuoB mutants having NuoB deletion were obtained. NuoB is a protein complex involved in the oxidation of NADH during respiratory growth (form of growth requiring electron transport). Preventing the coupling of NADH oxidation to electron transport allows an increase in the amount of NADH being used to support butyrate production.  FIG. 52  shows that compared with wild-type Nissle, deletion of NuoB results in grater production of butyrate. 
     
       
         
           
               
             
               
                 TABLE 42 
               
               
                   
               
               
                 pLOGIC046-tesB-butyrate 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 pLOGIC046-tesB-butyrate: SEQ ID NO: 87 
               
               
                 gtaaaacgacggccagtgaattcgttaagacccactttcacatttaagttgtttttctaatccg 
               
               
                   
               
               
                 catatgatcaattcaaggccgaataagaaggctggctctgcaccttggtgatcaaataattcga 
               
               
                   
               
               
                 tagcttgtcgtaataatggcggcatactatcagtagtaggtgtttccctttcttctttagcgac 
               
               
                   
               
               
                 ttgatgctcttgatcttccaatacgcaacctaaagtaaaatgccccacagcgctgagtgcatat 
               
               
                   
               
               
                 aatgcattctctagtgaaaaaccttgttggcataaaaaggctaattgattttcgagagtttcat 
               
               
                   
               
               
                 actgtttttctgtaggccgtgtacctaaatgtacttttgctccatcgcgatgacttagtaaagc 
               
               
                   
               
               
                 acatctaaaacttttagcgttattacgtaaaaaatcttgccagctttccccttctaaagggcaa 
               
               
                   
               
               
                 aagtgagtatggtgcctatctaacatctcaatggctaaggcgtcgagcaaagcccgcttatttt 
               
               
                   
               
               
                 ttacatgccaatacaatgtaggctgctctacacctagcttctgggcgagtttacgggttgttaa 
               
               
                   
               
               
                 accttcgattccgacctcattaagcagctctaatgcgctgttaatcactttacttttatctaat 
               
               
                   
               
               
                 ctagacatcattaattcctaatttttgttgacactctatcattgatagagttattttaccactc 
               
               
                   
               
               
                 cctatcagtgatagagaaaagtgaactctagaaataattttgtttaactttaagaaggagatat 
               
               
                   
               
               
                 acatatgatcgtaaaacctatggtacgcaacaatatctgcctgaacgcccatcctcagggctgc 
               
               
                   
               
               
                 aagaagggagtggaagatcagattgaatataccaagaaacgcattaccgcagaagtcaaagctg 
               
               
                   
               
               
                 gcgcaaaagctccaaaaaacgttctggtgcttggctgctcaaatggttacggcctggcgagccg 
               
               
                   
               
               
                 cattactgctgcgttcggatacggggctgcgaccatcggcgtgtcctttgaaaaagcgggttca 
               
               
                   
               
               
                 gaaaccaaatatggtacaccgggatggtacaataatttggcatttgatgaagcggcaaaacgcg 
               
               
                   
               
               
                 agggtctttatagcgtgacgatcgacggcgatgcgttttcagacgagatcaaggcccaggtaat 
               
               
                   
               
               
                 tgaggaagccaaaaaaaaaggtatcaaatttgatctgatcgtatacagcttggccagcccagta 
               
               
                   
               
               
                 cgtactgatcctgatacaggtatcatgcacaaaagcgttttgaaaccctttggaaaaacgttca 
               
               
                   
               
               
                 caggcaaaacagtagatccgtttactggcgagctgaaggaaatctccgcggaaccagcaaatga 
               
               
                   
               
               
                 cgaggaagcagccgccactgttaaagttatggggggtgaagattgggaacgttggattaagcag 
               
               
                   
               
               
                 ctgtcgaaggaaggcctcttagaagaaggctgtattaccttggcctatagttatattggccctg 
               
               
                   
               
               
                 aagctacccaagctttgtaccgtaaaggcacaatcggcaaggccaaagaacacctggaggccac 
               
               
                   
               
               
                 agcacaccgtctcaacaaagagaacccgtcaatccgtgccttcgtgagcgtgaataaaggcctg 
               
               
                   
               
               
                 gtaacccgcgcaagcgccgtaatcccggtaatccctctgtatctcgccagcttgttcaaagtaa 
               
               
                   
               
               
                 tgaaagagaagggcaatcatgaaggttgtattgaacagatcacgcgtctgtacgccgagcgcct 
               
               
                   
               
               
                 gtaccgtaaagatggtacaattccagttgatgaggaaaatcgcattcgcattgatgattgggag 
               
               
                   
               
               
                 ttagaagaagacgtccagaaagcggtatccgcgttgatggagaaagtcacgggtgaaaacgcag 
               
               
                   
               
               
                 aatctctcactgacttagcggggtaccgccatgatttcttagctagtaacggctttgatgtaga 
               
               
                   
               
               
                 aggtattaattatgaagcggaagttgaacgcttcgaccgtatctgataagaaggagatatacat 
               
               
                   
               
               
                 atgagagaagtagtaattgccagtgcagctagaacagcagtaggaagttttggaggagcattta 
               
               
                   
               
               
                 aatcagtttcagcggtagagttaggggtaacagcagctaaagaagctataaaaagagctaacat 
               
               
                   
               
               
                 aactccagatatgatagatgaatctcttttagggggagtacttacagcaggtcttggacaaaat 
               
               
                   
               
               
                 atagcaagacaaatagcattaggagcaggaataccagtagaaaaaccagctatgactataaata 
               
               
                   
               
               
                 tagtttgtggttctggattaagatctgtttcaatggcatctcaacttatagcattaggtgatgc 
               
               
                   
               
               
                 tgatataatgttagttggtggagctgaaaacatgagtatgtctccttatttagtaccaagtgcg 
               
               
                   
               
               
                 agatatggtgcaagaatgggtgatgctgcttttgttgattcaatgataaaagatggattatcag 
               
               
                   
               
               
                 acatatttaataactatcacatgggtattactgctgaaaacatagcagagcaatggaatataac 
               
               
                   
               
               
                 tagagaagaacaagatgaattagctcttgcaagtcaaaataaagctgaaaaagctcaagctgaa 
               
               
                   
               
               
                 ggaaaatttgatgaagaaatagttcctgttgttataaaaggaagaaaaggtgacactgtagtag 
               
               
                   
               
               
                 ataaagatgaatatattaagcctggcactacaatggagaaacttgctaagttaagacctgcatt 
               
               
                   
               
               
                 taaaaaagatggaacagttactgctggtaatgcatcaggaataaatgatggtgctgctatgtta 
               
               
                   
               
               
                 gtagtaatggctaaagaaaaagctgaagaactaggaatagagcctcttgcaactatagtttctt 
               
               
                   
               
               
                 atggaacagctggtgttgaccctaaaataatgggatatggaccagttccagcaactaaaaaagc 
               
               
                   
               
               
                 tttagaagctgctaatatgactattgaagatatagatttagttgaagctaatgaggcatttgct 
               
               
                   
               
               
                 gcccaatctgtagctgtaataagagacttaaatatagatatgaataaagttaatgttaatggtg 
               
               
                   
               
               
                 gagcaatagctataggacatccaataggatgctcaggagcaagaatacttactacacttttata 
               
               
                   
               
               
                 tgaaatgaagagaagagatgctaaaactggtcttgctacactttgtataggcggtggaatggga 
               
               
                   
               
               
                 actactttaatagttaagagatagtaagaaggagatatacatatgaaattagctgtaataggta 
               
               
                   
               
               
                 gtggaactatgggaagtggtattgtacaaacttttgcaagttgtggacatgatgtatgtttaaa 
               
               
                   
               
               
                 gagtagaactcaaggtgctatagataaatgtttagctttattagataaaaatttaactaagtta 
               
               
                   
               
               
                 gttactaagggaaaaatggatgaagctacaaaagcagaaatattaagtcatgttagttcaacta 
               
               
                   
               
               
                 ctaattatgaagatttaaaagatatggatttaataatagaagcatctgtagaagacatgaatat 
               
               
                   
               
               
                 aaagaaagatgttttcaagttactagatgaattatgtaaagaagatactatcttggcaacaaat 
               
               
                   
               
               
                 acttcatcattatctataacagaaatagcttcttctactaagcgcccagataaagttataggaa 
               
               
                   
               
               
                 tgcatttctttaatccagttcctatgatgaaattagttgaagttataagtggtcagttaacatc 
               
               
                   
               
               
                 aaaagttacttttgatacagtatttgaattatctaagagtatcaataaagtaccagtagatgta 
               
               
                   
               
               
                 tctgaatctcctggatttgtagtaaatagaatacttatacctatgataaatgaagctgttggta 
               
               
                   
               
               
                 tatatgcagatggtgttgcaagtaaagaagaaatagatgaagctatgaaattaggagcaaacca 
               
               
                   
               
               
                 tccaatgggaccactagcattaggtgatttaatcggattagatgttgttttagctataatgaac 
               
               
                   
               
               
                 gttttatatactgaatttggagatactaaatatagacctcatccacttttagctaaaatggtta 
               
               
                   
               
               
                 gagctaatcaattaggaagaaaaactaagataggattctatgattataataaataataagaagg 
               
               
                   
               
               
                 agatatacatatgagtacaagtgatgttaaagtttatgagaatgtagctgttgaagtagatgga 
               
               
                   
               
               
                 aatatatgtacagtgaaaatgaatagacctaaagcccttaatgcaataaattcaaagactttag 
               
               
                   
               
               
                 aagaactttatgaagtatttgtagatattaataatgatgaaactattgatgttgtaatattgac 
               
               
                   
               
               
                 aggggaaggaaaggcatttgtagctggagcagatattgcatacatgaaagatttagatgctgta 
               
               
                   
               
               
                 gctgctaaagattttagtatcttaggagcaaaagcttttggagaaatagaaaatagtaaaaaag 
               
               
                   
               
               
                 tagtgatagctgctgtaaacggatttgctttaggtggaggatgtgaacttgcaatggcatgtga 
               
               
                   
               
               
                 tataagaattgcatctgctaaagctaaatttggtcagccagaagtaactcttggaataactcca 
               
               
                   
               
               
                 ggatatggaggaactcaaaggcttacaagattggttggaatggcaaaagcaaaagaattaatct 
               
               
                   
               
               
                 ttacaggtcaagttataaaagctgatgaagctgaaaaaatagggctagtaaatagagtcgttga 
               
               
                   
               
               
                 gccagacattttaatagaagaagttgagaaattagctaagataatagctaaaaatgctcagctt 
               
               
                   
               
               
                 gcagttagatactctaaagaagcaatacaacttggtgctcaaactgatataaatactggaatag 
               
               
                   
               
               
                 atatagaatctaatttatttggtctttgtttttcaactaaagaccaaaaagaaggaatgtcagc 
               
               
                   
               
               
                 tttcgttgaaaagagagaagctaactttataaaagggtaataagaaggagatatacatatgAGT 
               
               
                   
               
               
                 CAGGCGCTAAAAAATTTACTGACATTGTTAAATCTGGAAAAAATTGAGGAAGGACTCTTTCGCG 
               
               
                   
               
               
                 GCCAGAGTGAAGATTTAGGTTTACGCCAGGTGTTTGGCGGCCAGGTCGTGGGTCAGGCCTTGTA 
               
               
                   
               
               
                 TGCTGCAAAAGAGACCGTCCCTGAAGAGCGGCTGGTACATTCGTTTCACAGCTACTTTCTTCGC 
               
               
                   
               
               
                 CCTGGCGATAGTAAGAAGCCGATTATTTATGATGTCGAAACGCTGCGTGACGGTAACAGCTTCA 
               
               
                   
               
               
                 GCGCCCGCCGGGTTGCTGCTATTCAAAACGGCAAACCGATTTTTTATATGACTGCCTCTTTCCA 
               
               
                   
               
               
                 GGCACCAGAAGCGGGTTTCGAACATCAAAAAACAATGCCGTCCGCGCCAGCGCCTGATGGCCTC 
               
               
                   
               
               
                 CCTTCGGAAACGCAAATCGCCCAATCGCTGGCGCACCTGCTGCCGCCAGTGCTGAAAGATAAAT 
               
               
                   
               
               
                 TCATCTGCGATCGTCCGCTGGAAGTCCGTCCGGTGGAGTTTCATAACCCACTGAAAGGTCACGT 
               
               
                   
               
               
                 CGCAGAACCACATCGTCAGGTGTGGATCCGCGCAAATGGTAGCGTGCCGGATGACCTGCGCGTT 
               
               
                   
               
               
                 CATCAGTATCTGCTCGGTTACGCTTCTGATCTTAACTTCCTGCCGGTAGCTCTACAGCCGCACG 
               
               
                   
               
               
                 GCATCGGTTTTCTCGAACCGGGGATTCAGATTGCCACCATTGACCATTCCATGTGGTTCCATCG 
               
               
                   
               
               
                 CCCGTTTAATTTGAATGAATGGCTGCTGTATAGCGTGGAGAGCACCTCGGCGTCCAGCGCACGT 
               
               
                   
               
               
                 GGCTTTGTGCGCGGTGAGTTTTATACCCAAGACGGCGTACTGGTTGCCTCGACCGTTCAGGAAG 
               
               
                   
               
               
                 GGGTGATGCGTAATCACAATtaa 
               
               
                   
               
            
           
         
       
     
     Example 38. Production of Butyrate in Recombinant  E. coli    
     Production of butyrate is assessed in  E. coli  Nissle strains containing the butyrate cassettes described above in order to determine the effect of oxygen on butyrate production. All incubations are performed at 37° C. Cultures of  E. coli  strains DH5a and Nissle transformed with the butyrate cassettes are grown overnight in LB and then diluted 1:200 into 4 mL of M9 minimal medium containing 0.5% glucose. The cells are grown with shaking (250 rpm) for 4-6 h and incubated aerobically or anaerobically in a Coy anaerobic chamber (supplying 90% N2, 5% CO2, 5% H2). One mL culture aliquots are prepared in 1.5 mL capped tubes and incubated in a stationary incubator to limit culture aeration. One tube is removed at each time point (0, 1, 2, 4, and 20 hours) and analyzed for butyrate concentration by LC-MS to confirm that butyrate production in these recombinant strains can be achieved in a low-oxygen environment. 
     In an alternate embodiment, overnight bacterial cultures were diluted 1:100 into fresh LB and grown for 1.5 hrs to allow entry into early log phase. At this point, long half-life nitric oxide donor (DETA-NO; diethylenetriamine-nitric oxide adduct) was added to cultures at a final concentration of 0.3 mM to induce expression from plasmid. After 2 hours of induction, cells were spun down, supernatant was discarded, and the cells were resuspended in M9 minimal media containing 0.5% glucose. Culture supernatant was then analyzed at indicated time points to assess levels of butyrate production. Genetically engineered Nissle comprising pLogic031-nsrR-norB-butyrate operon construct; SYN-UCD507) or (pLogic046-nsrR-norB-butyrate operon construct; SYN-UCD508) produce significantly more butyrate as compared to wild-type Nissle. 
     Genetically engineered Nissle were generated comprising a butyrate gene cassette in which the pbt and buk genes are replaced with tesB (SEQ ID NO: 48) expressed under the control of a tetracycline promoter (pLOGIC046-tesB-butyrate; SEQ ID NO: 88). SEQ ID NO: 88 comprises a reverse complement of the tetR repressor (underlined), an intergenic region containing divergent promoters controlling tetR and the butyrate operon and their respective RBS (bold), and the butyrate genes (ter-thiA1-hbd-crt2-tesB) separated by RBS. 
     
       
         
           
               
             
               
                 TABLE 43 
               
               
                   
               
               
                 pLOGIC046-tesB-butyrate sequence 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 SEQ ID NO: 88 
               
               
                 gtaaaacgacggccagtgaattcg ttaagacccactttcacatttaagttgtttttctaatccg   
               
               
                   
               
               
                 
                   catatgatcaattcaaggccgaataagaaggctggctctgcaccttggtgatcaaataattcga 
                 
               
               
                   
               
               
                 
                   tagcttgtcgtaataatggcggcatactatcagtagtaggtgtttccctttcttctttagcgac 
                 
               
               
                   
               
               
                 
                   ttgatgctcttgatcttccaatacgcaacctaaagtaaaatgccccacagcgctgagtgcatat 
                 
               
               
                   
               
               
                 
                   aatgcattctctagtgaaaaaccttgttggcataaaaaggctaattgattttcgagagtttcat 
                 
               
               
                   
               
               
                 
                   actgtttttctgtaggccgtgtacctaaatgtacttttgctccatcgcgatgacttagtaaagc 
                 
               
               
                   
               
               
                 
                   acatctaaaacttttagcgttattacgtaaaaaatcttgccagctttccccttctaaagggcaa 
                 
               
               
                   
               
               
                 
                   aagtgagtatggtgcctatctaacatctcaatggctaaggcgtcgagcaaagcccgcttatttt 
                 
               
               
                   
               
               
                 
                   ttacatgccaatacaatgtaggctgctctacacctagcttctgggcgagtttacgggttgttaa 
                 
               
               
                   
               
               
                 
                   accttcgattccgacctcattaagcagctctaatgcgctgttaatcactttacttttatctaat 
                 
               
               
                   
               
               
                 
                   ctagacat 
                   cattaattcctaatttttgttgacactctatcattgatagagttattttaccactc 
                 
               
               
                   
               
               
                 
                   cctatcagtgatagagaaaagtgaactctagaaataattttgtttaactttaagaaggagatat 
                 
               
               
                   
               
               
                   acat atgatcgtaaaacctatggtacgcaacaatatctgcctgaacgcccatcctcagggctgc 
               
               
                   
               
               
                 aagaagggagtggaagatcagattgaatataccaagaaacgcattaccgcagaagtcaaagctg 
               
               
                   
               
               
                 gcgcaaaagctccaaaaaacgttctggtgcttggctgctcaaatggttacggcctggcgagccg 
               
               
                   
               
               
                 cattactgctgcgttcggatacggggctgcgaccatcggcgtgtcctttgaaaaagcgggttca 
               
               
                   
               
               
                 gaaaccaaatatggtacaccgggatggtacaataatttggcatttgatgaagcggcaaaacgcg 
               
               
                   
               
               
                 agggtctttatagcgtgacgatcgacggcgatgcgttttcagacgagatcaaggcccaggtaat 
               
               
                   
               
               
                 tgaggaagccaaaaaaaaaggtatcaaatttgatctgatcgtatacagcttggccagcccagta 
               
               
                   
               
               
                 cgtactgatcctgatacaggtatcatgcacaaaagcgttttgaaaccctttggaaaaacgttca 
               
               
                   
               
               
                 caggcaaaacagtagatccgtttactggcgagctgaaggaaatctccgcggaaccagcaaatga 
               
               
                   
               
               
                 cgaggaagcagccgccactgttaaagttatggggggtgaagattgggaacgttggattaagcag 
               
               
                   
               
               
                 ctgtcgaaggaaggcctcttagaagaaggctgtattaccttggcctatagttatattggccctg 
               
               
                   
               
               
                 aagctacccaagctttgtaccgtaaaggcacaatcggcaaggccaaagaacacctggaggccac 
               
               
                   
               
               
                 agcacaccgtctcaacaaagagaacccgtcaatccgtgccttcgtgagcgtgaataaaggcctg 
               
               
                   
               
               
                 gtaacccgcgcaagcgccgtaatcccggtaatccctctgtatctcgccagcttgttcaaagtaa 
               
               
                   
               
               
                 tgaaagagaagggcaatcatgaaggttgtattgaacagatcacgcgtctgtacgccgagcgcct 
               
               
                   
               
               
                 gtaccgtaaagatggtacaattccagttgatgaggaaaatcgcattcgcattgatgattgggag 
               
               
                   
               
               
                 ttagaagaagacgtccagaaagcggtatccgcgttgatggagaaagtcacgggtgaaaacgcag 
               
               
                   
               
               
                 aatctctcactgacttagcggggtaccgccatgatttcttagctagtaacggctttgatgtaga 
               
               
                   
               
               
                 aggtattaattatgaagcggaagttgaacgcttcgaccgtatctgataagaaggagatatacat 
               
               
                   
               
               
                 atgagagaagtagtaattgccagtgcagctagaacagcagtaggaagttttggaggagcattta 
               
               
                   
               
               
                 aatcagtttcagcggtagagttaggggtaacagcagctaaagaagctataaaaagagctaacat 
               
               
                   
               
               
                 aactccagatatgatagatgaatctcttttagggggagtacttacagcaggtcttggacaaaat 
               
               
                   
               
               
                 atagcaagacaaatagcattaggagcaggaataccagtagaaaaaccagctatgactataaata 
               
               
                   
               
               
                 tagtttgtggttctggattaagatctgtttcaatggcatctcaacttatagcattaggtgatgc 
               
               
                   
               
               
                 tgatataatgttagttggtggagctgaaaacatgagtatgtctccttatttagtaccaagtgcg 
               
               
                   
               
               
                 agatatggtgcaagaatgggtgatgctgcttttgttgattcaatgataaaagatggattatcag 
               
               
                   
               
               
                 acatatttaataactatcacatgggtattactgctgaaaacatagcagagcaatggaatataac 
               
               
                   
               
               
                 tagagaagaacaagatgaattagctcttgcaagtcaaaataaagctgaaaaagctcaagctgaa 
               
               
                   
               
               
                 ggaaaatttgatgaagaaatagttcctgttgttataaaaggaagaaaaggtgacactgtagtag 
               
               
                   
               
               
                 ataaagatgaatatattaagcctggcactacaatggagaaacttgctaagttaagacctgcatt 
               
               
                   
               
               
                 taaaaaagatggaacagttactgctggtaatgcatcaggaataaatgatggtgctgctatgtta 
               
               
                   
               
               
                 gtagtaatggctaaagaaaaagctgaagaactaggaatagagcctcttgcaactatagtttctt 
               
               
                   
               
               
                 atggaacagctggtgttgaccctaaaataatgggatatggaccagttccagcaactaaaaaagc 
               
               
                   
               
               
                 tttagaagctgctaatatgactattgaagatatagatttagttgaagctaatgaggcatttgct 
               
               
                   
               
               
                 gcccaatctgtagctgtaataagagacttaaatatagatatgaataaagttaatgttaatggtg 
               
               
                   
               
               
                 gagcaatagctataggacatccaataggatgctcaggagcaagaatacttactacacttttata 
               
               
                   
               
               
                 tgaaatgaagagaagagatgctaaaactggtcttgctacactttgtataggcggtggaatggga 
               
               
                   
               
               
                 actactttaatagttaagagatagtaagaaggagatatacatatgaaattagctgtaataggta 
               
               
                   
               
               
                 gtggaactatgggaagtggtattgtacaaacttttgcaagttgtggacatgatgtatgtttaaa 
               
               
                   
               
               
                 gagtagaactcaaggtgctatagataaatgtttagctttattagataaaaatttaactaagtta 
               
               
                   
               
               
                 gttactaagggaaaaatggatgaagctacaaaagcagaaatattaagtcatgttagttcaacta 
               
               
                   
               
               
                 ctaattatgaagatttaaaagatatggatttaataatagaagcatctgtagaagacatgaatat 
               
               
                   
               
               
                 aaagaaagatgttttcaagttactagatgaattatgtaaagaagatactatcttggcaacaaat 
               
               
                   
               
               
                 acttcatcattatctataacagaaatagcttcttctactaagcgcccagataaagttataggaa 
               
               
                   
               
               
                 tgcatttctttaatccagttcctatgatgaaattagttgaagttataagtggtcagttaacatc 
               
               
                   
               
               
                 aaaagttacttttgatacagtatttgaattatctaagagtatcaataaagtaccagtagatgta 
               
               
                   
               
               
                 tctgaatctcctggatttgtagtaaatagaatacttatacctatgataaatgaagctgttggta 
               
               
                   
               
               
                 tatatgcagatggtgttgcaagtaaagaagaaatagatgaagctatgaaattaggagcaaacca 
               
               
                   
               
               
                 tccaatgggaccactagcattaggtgatttaatcggattagatgttgttttagctataatgaac 
               
               
                   
               
               
                 gttttatatactgaatttggagatactaaatatagacctcatccacttttagctaaaatggtta 
               
               
                   
               
               
                 gagctaatcaattaggaagaaaaactaagataggattctatgattataataaataataagaagg 
               
               
                   
               
               
                 agatatacatatgagtacaagtgatgttaaagtttatgagaatgtagctgttgaagtagatgga 
               
               
                   
               
               
                 aatatatgtacagtgaaaatgaatagacctaaagcccttaatgcaataaattcaaagactttag 
               
               
                   
               
               
                 aagaactttatgaagtatttgtagatattaataatgatgaaactattgatgttgtaatattgac 
               
               
                   
               
               
                 aggggaaggaaaggcatttgtagctggagcagatattgcatacatgaaagatttagatgctgta 
               
               
                   
               
               
                 gctgctaaagattttagtatcttaggagcaaaagcttttggagaaatagaaaatagtaaaaaag 
               
               
                   
               
               
                 tagtgatagctgctgtaaacggatttgctttaggtggaggatgtgaacttgcaatggcatgtga 
               
               
                   
               
               
                 tataagaattgcatctgctaaagctaaatttggtcagccagaagtaactcttggaataactcca 
               
               
                   
               
               
                 ggatatggaggaactcaaaggcttacaagattggttggaatggcaaaagcaaaagaattaatct 
               
               
                   
               
               
                 ttacaggtcaagttataaaagctgatgaagctgaaaaaatagggctagtaaatagagtcgttga 
               
               
                   
               
               
                 gccagacattttaatagaagaagttgagaaattagctaagataatagctaaaaatgctcagctt 
               
               
                   
               
               
                 gcagttagatactctaaagaagcaatacaacttggtgctcaaactgatataaatactggaatag 
               
               
                   
               
               
                 atatagaatctaatttatttggtctttgtttttcaactaaagaccaaaaagaaggaatgtcagc 
               
               
                   
               
               
                 tttcgttgaaaagagagaagctaactttataaaagggtaataagaaggagatatacatatgAGT 
               
               
                   
               
               
                 CAGGCGCTAAAAAATTTACTGACATTGTTAAATCTGGAAAAAATTGAGGAAGGACTCTTTCGCG 
               
               
                   
               
               
                 GCCAGAGTGAAGATTTAGGTTTACGCCAGGTGTTTGGCGGCCAGGTCGTGGGTCAGGCCTTGTA 
               
               
                   
               
               
                 TGCTGCAAAAGAGACCGTCCCTGAAGAGCGGCTGGTACATTCGTTTCACAGCTACTTTCTTCGC 
               
               
                   
               
               
                 CCTGGCGATAGTAAGAAGCCGATTATTTATGATGTCGAAACGCTGCGTGACGGTAACAGCTTCA 
               
               
                   
               
               
                 GCGCCCGCCGGGTTGCTGCTATTCAAAACGGCAAACCGATTTTTTATATGACTGCCTCTTTCCA 
               
               
                   
               
               
                 GGCACCAGAAGCGGGTTTCGAACATCAAAAAACAATGCCGTCCGCGCCAGCGCCTGATGGCCTC 
               
               
                   
               
               
                 CCTTCGGAAACGCAAATCGCCCAATCGCTGGCGCACCTGCTGCCGCCAGTGCTGAAAGATAAAT 
               
               
                   
               
               
                 TCATCTGCGATCGTCCGCTGGAAGTCCGTCCGGTGGAGTTTCATAACCCACTGAAAGGTCACGT 
               
               
                   
               
               
                 CGCAGAACCACATCGTCAGGTGTGGATCCGCGCAAATGGTAGCGTGCCGGATGACCTGCGCGTT 
               
               
                   
               
               
                 CATCAGTATCTGCTCGGTTACGCTTCTGATCTTAACTTCCTGCCGGTAGCTCTACAGCCGCACG 
               
               
                   
               
               
                 GCATCGGTTTTCTCGAACCGGGGATTCAGATTGCCACCATTGACCATTCCATGTGGTTCCATCG 
               
               
                   
               
               
                 CCCGTTTAATTTGAATGAATGGCTGCTGTATAGCGTGGAGAGCACCTCGGCGTCCAGCGCACGT 
               
               
                   
               
               
                 GGCTTTGTGCGCGGTGAGTTTTATACCCAAGACGGCGTACTGGTTGCCTCGACCGTTCAGGAAG 
               
               
                   
               
               
                 GGGTGATGCGTAATCACAATtaa 
               
               
                   
               
            
           
         
       
     
     Overnight bacterial cultures were diluted 1:100 into fresh LB and grown for 1.5 hrs to allow entry into early log phase. At this point, anhydrous tetracycline (ATC) was added to cultures at a final concentration of 100 ng/mL to induce expression of butyrate genes from plasmid. After 2 hours of induction, cells were spun down, supernatant was discarded, and the cells were resuspended in M9 minimal media containing 0.5% glucose. Culture supernatant was then analyzed at indicated time points to assess levels of butyrate production. Replacement of pbt and buk with tesB leads to greater levels of butyrate production. 
       FIG. 53C  shows butyrate production in strains comprising an FNR-butyrate cassette syn 363 (having the ter substitution) in the presence/absence of glucose and oxygen.  FIG. 53C  shows that bacteria need both glucose and anaerobic conditions for butyrate production from the FNR promoter. Cells were grown aerobically or anaerobically in media containing no glucose (LB) or in media containing glucose at 0.5% (RMC). Culture samples were taken at indicated time pints and supernatant fractions were assessed for butyrate concentration using LC-MS. These data show that SYN 363 requires glucose for butyrate production and that in the presence of glucose butyrate production can be enhanced under anaerobic conditions when under the control of the anaerobic FNR-regulated ydfZ promoter. 
     Example 39. In vitro Activity of Bacterial Strain Comprising Ammonia-Metabolizing and Butyrate Producing Circuits 
     Do determine whether ammonia uptake and conversion to arginine and production of butyrate could be accomplished in one strain, a plasmid (Logic156) comprising a butyrate production cassette construct, was used for initial proof-of-concept experiments. The following strains were generated using the plasmid: SYN-UCD501 (comprising Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance); and SYN-UCD601, which is SYN-UCD-305, additionally comprising Logic156 (i.e., SYN-UCD601 comprises ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance)). Arginine and butyrate production was the compared between the butyrate only producer SYN-UCD501, the arginine only producer SYN-UCD305, and the combined butyrate/arginine producer SYN-UCD-601. Sequences for the butyrate cassette used are shown in Table 38. 
     Briefly, 3 ml LB (containing selective antibiotics (Amp for SYN-UCD501 and SYN-UCD601) and 3 mM thymidine for SYN-UCD-305 and SYN-UCD601) with bacteria from frozen glycerol stocks. Bacteria were grown overnight at 37 C with shaking. Overnight cultures were diluted 1:100 dilution into 10 ml LB (containing antibiotics and thymidine where necessary as above) in a 125 ml baffled flask. Cultures were grown aerobically at 37 C with shaking for about 1.5 h, and then transferred to the anaerobic chamber at 37 C for 4 h. Bacteria (2×108 CFU) were added to 1 ml M9 media containing 50 mM MOPS with 0.5% glucose in microcentrifuge tubes. Cells were plated to determine cell counts. The assay tubes were placed in the anaerobic chamber at 37 C. At indicated times (1, 2, 24 h), 120 ul cells were removed and pelleted at 14,000 rpm for 1 min, and 100 ul of the supernatant was transferred to a 96-well assay plate and sealed with aluminum foil, and stored at −80 C until analysis by LC-MS for arginine and butyrate concentrations (as described in Example 13 and Example 40). 
     Results are depicted in  FIG. 53A  and  FIG. 53B , and show that SYN-UCD601 is able to produce similar levels of arginine as SYN-UCD305 and similar levels of butyrate as SYN-UCD501 in vitro. 
     
       
         
           
               
             
               
                 TABLE 44 
               
             
            
               
                   
               
               
                 Butyrate cassette sequences 
               
            
           
           
               
               
               
            
               
                   
                   
                 SEQ 
               
               
                 Description 
                 Sequence 
                 ID NO 
               
               
                   
               
               
                 ydfZ + RBS 
                 CATTTCCTCTCATCCCATCCGGGGTGAGAGTCTTTTC 
                 SEQ 
               
               
                 (RBS is bolded) 
                 CCCCGACTTATGGCTCATGCATGCATCAAAAAAGATG 
                 ID NO: 
               
               
                   
                 TGAGCTTGATCAAAAACAAAAAATATTTCACTCGACA 
                 89 
               
               
                   
                 GGAGTATTTATATTGCGCCCGGATCCCTCTAGAAATA 
                   
               
               
                   
                 A TTTTGTTTAACTTTAAGAAGGAGATATACAT   
                   
               
               
                   
               
               
                 Ter 
                 atgatcgtaaaacctatggtacgcaacaatatctgcctgaacgcccatcctca 
                 SEQ 
               
               
                 (polynucleotide 
                 gggctgcaagaagggagtggaagatcagattgaatataccaagaaacgca 
                 ID NO: 
               
               
                 sequence) 
                 ttaccgcagaagtcaaagctggcgcaaaagctccaaaaaacgttctggtgctt 
                 90 
               
               
                   
                 ggctgctcaaatggttacggcctggcgagccgcattactgctgcgttcggatac 
                   
               
               
                   
                 ggggctgcgaccatcggcgtgtcctttgaaaaagcgggttcagaaaccaaat 
                   
               
               
                   
                 atggtacaccgggatggtacaataatttggcatttgatgaagcggcaaaacgc 
                   
               
               
                   
                 gagggtctttatagcgtgacgatcgacggcgatgcgttttcagacgagatcaa 
                   
               
               
                   
                 ggcccaggtaattgaggaagccaaaaaaaaaggtatcaaatttgatctgatc 
                   
               
               
                   
                 gtatacagcttggccagcccagtacgtactgatcctgatacaggtatcatgcac 
                   
               
               
                   
                 aaaagcgttttgaaaccctttggaaaaacgttcacaggcaaaacagtagatc 
                   
               
               
                   
                 cgtttactggcgagctgaaggaaatctccgcggaaccagcaaatgacgagg 
                   
               
               
                   
                 aagcagccgccactgttaaagttatggggggtgaagattgggaacgttggatt 
                   
               
               
                   
                 aagcagctgtcgaaggaaggcctcttagaagaaggctgtattaccttggccta 
                   
               
               
                   
                 tagttatattggccctgaagctacccaagctttgtaccgtaaaggcacaatcgg 
                   
               
               
                   
                 caaggccaaagaacacctggaggccacagcacaccgtctcaacaaagag 
                   
               
               
                   
                 aacccgtcaatccgtgccttcgtgagcgtgaataaaggcctggtaacccgcg 
                   
               
               
                   
                 caagcgccgtaatcccggtaatccctctgtatctcgccagcttgttcaaagtaat 
                   
               
               
                   
                 gaaagagaagggcaatcatgaaggttgtattgaacagatcacgcgtctgtac 
                   
               
               
                   
                 gccgagcgcctgtaccgtaaagatggtacaattccagttgatgaggaaaatc 
                   
               
               
                   
                 gcattcgcattgatgattgggagttagaagaagacgtccagaaagcggtatcc 
                   
               
               
                   
                 gcgttgatggagaaagtcacgggtgaaaacgcagaatctctcactgacttag 
                   
               
               
                   
                 cggggtaccgccatgatttcttagctagtaacggctttgatgtagaaggtattaat 
                   
               
               
                   
                 tatgaagcggaagttgaacgcttcgaccgtatctga 
                   
               
               
                   
               
               
                 Ter (polypeptide 
                 MIVKPMVRNNICLNAHPQGCKKGVEDQIEYTKKRITAEV 
                 SEQ 
               
               
                 sequence) 
                 KAGAKAPKNVLVLGCSNGYGLASRITAAFGYGAATIGV 
                 ID NO: 
               
               
                   
                 SFEKAGSETKYGTPGWYNNLAFDEAAKREGLYSVTIDG 
                 91 
               
               
                   
                 DAFSDEIKAQVIEEAKKKGIKFDLIVYSLASPVRTDPDTGI 
                   
               
               
                   
                 MHKSVLKPFGKTFTGKTVDPFTGELKEISAEPANDEEA 
                   
               
               
                   
                 AATVKVMGGEDWERWIKQLSKEGLLEEGCITLAYSYIG 
                   
               
               
                   
                 PEATQALYRKGTIGKAKEHLEATAHRLNKENPSIRAFVS 
                   
               
               
                   
                 VNKGLVTRASAVIPVIPLYLASLFKVMKEKGNHEGCIEQI 
                   
               
               
                   
                 TRLYAERLYRKDGTIPVDEENRIRIDDWELEEDVQKAVS 
                   
               
               
                   
                 ALMEKVTGENAESLTDLAGYRHDFLASNGFDVEGINYE 
                   
               
               
                   
                 AEVERFDRI 
                   
               
               
                   
               
               
                 ThiA 
                 atgagagaagtagtaattgccagtgcagctagaacagcagtaggaagttttg 
                 SEQ 
               
               
                 (polynucleotide 
                 gaggagcatttaaatcagtttcagcggtagagttaggggtaacagcagctaa 
                 ID NO: 
               
               
                 sequence) 
                 agaagctataaaaagagctaacataactccagatatgatagatgaatctctttt 
                 92 
               
               
                   
                 agggggagtacttacagcaggtcttggacaaaatatagcaagacaaatagc 
                   
               
               
                   
                 attaggagcaggaataccagtagaaaaaccagctatgactataaatatagttt 
                   
               
               
                   
                 gtggttctggattaagatctgtttcaatggcatctcaacttatagcattaggtgatg 
                   
               
               
                   
                 ctgatataatgttagttggtggagctgaaaacatgagtatgtctccttatttagtac 
                   
               
               
                   
                 caagtgcgagatatggtgcaagaatgggtgatgctgcttttgttgattcaatgat 
                   
               
               
                   
                 aaaagatggattatcagacatatttaataactatcacatgggtattactgctgaa 
                   
               
               
                   
                 aacatagcagagcaatggaatataactagagaagaacaagatgaattagct 
                   
               
               
                   
                 cttgcaagtcaaaataaagctgaaaaagctcaagctgaaggaaaatttgatg 
                   
               
               
                   
                 aagaaatagttcctgttgttataaaaggaagaaaaggtgacactgtagtagat 
                   
               
               
                   
                 aaagatgaatatattaagcctggcactacaatggagaaacttgctaagttaag 
                   
               
               
                   
                 acctgcatttaaaaaagatggaacagttactgctggtaatgcatcaggaataa 
                   
               
               
                   
                 atgatggtgctgctatgttagtagtaatggctaaagaaaaagctgaagaacta 
                   
               
               
                   
                 ggaatagagcctcttgcaactatagtttcttatggaacagctggtgttgacccta 
                   
               
               
                   
                 aaataatgggatatggaccagttccagcaactaaaaaagctttagaagctgct 
                   
               
               
                   
                 aatatgactattgaagatatagatttagttgaagctaatgaggcatttgctgccc 
                   
               
               
                   
                 aatctgtagctgtaataagagacttaaatatagatatgaataaagttaatgttaat 
                   
               
               
                   
                 ggtggagcaatagctataggacatccaataggatgctcaggagcaagaata 
                   
               
               
                   
                 cttactacacttttatatgaaatgaagagaagagatgctaaaactggtcttgcta 
                   
               
               
                   
                 cactttgtataggcggtggaatgggaactactttaatagttaagagatag 
                   
               
               
                   
               
               
                 ThiA 
                 MREVVIASAARTAVGSFGGAFKSVSAVELGVTAAKEAIK 
                 SEQ 
               
               
                 (polypeptide 
                 RANITPDMIDESLLGGVLTAGLGQNIARQIALGAGIPVEK 
                 ID NO: 
               
               
                 sequence) 
                 PAMTINIVCGSGLRSVSMASQLIALGDADIMLVGGAENM 
                 93 
               
               
                   
                 SMSPYLVPSARYGARMGDAAFVDSMIKDGLSDIFNNYH 
                   
               
               
                   
                 MGITAENIAEQWNITREEQDELALASQNKAEKAQAEGK 
                   
               
               
                   
                 FDEEIVPVVIKGRKGDTVVDKDEYIKPGTTMEKLAKLRP 
                   
               
               
                   
                 AFKKDGTVTAGNASGINDGAAMLVVMAKEKAEELGIEP 
                   
               
               
                   
                 LATIVSYGTAGVDPKIMGYGPVPATKKALEAANMTIEDID 
                   
               
               
                   
                 LVEANEAFAAQSVAVIRDLNIDMNKVNVNGGAIAIGHPIG 
                   
               
               
                   
                 CSGARILTTLLYEMKRRDAKTGLATLCIGGGMGTTLIVK 
                   
               
               
                   
                 R 
                   
               
               
                   
               
               
                 Hbd 
                 atgaaattagctgtaataggtagtggaactatgggaagtggtattgtacaaactt 
                 SEQ 
               
               
                 (polynucleotide 
                 ttgcaagttgtggacatgatgtatgtttaaagagtagaactcaaggtgctataga 
                 ID NO: 
               
               
                 sequence) 
                 taaatgtttagctttattagataaaaatttaactaagttagttactaagggaaaaat 
                 94 
               
               
                   
                 ggatgaagctacaaaagcagaaatattaagtcatgttagttcaactactaatta 
                   
               
               
                   
                 tgaagatttaaaagatatggatttaataatagaagcatctgtagaagacatgaa 
                   
               
               
                   
                 tataaagaaagatgttttcaagttactagatgaattatgtaaagaagatactatct 
                   
               
               
                   
                 tggcaacaaatacttcatcattatctataacagaaatagcttcttctactaagcgc 
                   
               
               
                   
                 ccagataaagttataggaatgcatttctttaatccagttcctatgatgaaattagtt 
                   
               
               
                   
                 gaagttataagtggtcagttaacatcaaaagttacttttgatacagtatttgaatta 
                   
               
               
                   
                 tctaagagtatcaataaagtaccagtagatgtatctgaatctcctggatttgtagt 
                   
               
               
                   
                 aaatagaatacttatacctatgataaatgaagctgttggtatatatgcagatggt 
                   
               
               
                   
                 gttgcaagtaaagaagaaatagatgaagctatgaaattaggagcaaaccat 
                   
               
               
                   
                 ccaatgggaccactagcattaggtgatttaatcggattagatgttgttttagctata 
                   
               
               
                   
                 atgaacgttttatatactgaatttggagatactaaatatagacctcatccactttta 
                   
               
               
                   
                 gctaaaatggttagagctaatcaattaggaagaaaaactaagataggattcta 
                   
               
               
                   
                 tgattataataaataa 
                   
               
               
                   
               
               
                 Hbd 
                 MKLAVIGSGTMGSGIVQTFASCGHDVCLKSRTQGAIDK 
                 SEQ 
               
               
                 (polypeptide 
                 CLALLDKNLTKLVTKGKMDEATKAEILSHVSSTTNYEDL 
                 ID NO: 
               
               
                 sequence) 
                 KDMDLIIEASVEDMNIKKDVFKLLDELCKEDTILATNTSS 
                 95 
               
               
                   
                 LSITEIASSTKRPDKVIGMHFFNPVPMMKLVEVISGQLTS 
                   
               
               
                   
                 KVTFDTVFELSKSINKVPVDVSESPGFVVNRILIPMINEA 
                   
               
               
                   
                 VGIYADGVASKEEIDEAMKLGANHPMGPLALGDLIGLDV 
                   
               
               
                   
                 VLAIMNVLYTEFGDTKYRPHPLLAKMVRANQLGRKTKIG 
                   
               
               
                   
                 FYDYNK 
                   
               
               
                   
               
               
                 Crt2 
                 atgagtacaagtgatgttaaagtttatgagaatgtagctgttgaagtagatgga 
                 SEQ 
               
               
                 (polynucleotide 
                 aatatatgtacagtgaaaatgaatagacctaaagcccttaatgcaataaattca 
                 ID NO: 
               
               
                 sequence) 
                 aagactttagaagaactttatgaagtatttgtagatattaataatgatgaaactatt 
                 96 
               
               
                   
                 gatgttgtaatattgacaggggaaggaaaggcatttgtagctggagcagatatt 
                   
               
               
                   
                 gcatacatgaaagatttagatgctgtagctgctaaagattttagtatcttaggag 
                   
               
               
                   
                 caaaagcttttggagaaatagaaaatagtaaaaaagtagtgatagctgctgta 
                   
               
               
                   
                 aacggatttgctttaggtggaggatgtgaacttgcaatggcatgtgatataaga 
                   
               
               
                   
                 attgcatctgctaaagctaaatttggtcagccagaagtaactcttggaataactc 
                   
               
               
                   
                 caggatatggaggaactcaaaggcttacaagattggttggaatggcaaaag 
                   
               
               
                   
                 caaaagaattaatctttacaggtcaagttataaaagctgatgaagctgaaaaa 
                   
               
               
                   
                 atagggctagtaaatagagtcgttgagccagacattttaatagaagaagttga 
                   
               
               
                   
                 gaaattagctaagataatagctaaaaatgctcagcttgcagttagatactctaa 
                   
               
               
                   
                 agaagcaatacaacttggtgctcaaactgatataaatactggaatagatatag 
                   
               
               
                   
                 aatctaatttatttggtctttgtttttcaactaaagaccaaaaagaaggaatgtca 
                   
               
               
                   
                 gctttcgttgaaaagagagaagctaactttataaaagggtaa 
                   
               
               
                   
               
               
                 Crt2 
                 MSTSDVKVYENVAVEVDGNICTVKMNRPKALNAINSKT 
                 SEQ 
               
               
                 (polypeptide 
                 LEELYEVFVDINNDETIDVVILTGEGKAFVAGADIAYMKD 
                 ID NO: 
               
               
                 sequence) 
                 LDAVAAKDFSILGAKAFGEIENSKKVVIAAVNGFALGGG 
                 97 
               
               
                   
                 CELAMACDIRIASAKAKFGQPEVTLGITPGYGGTQRLTR 
                   
               
               
                   
                 LVGMAKAKELIFTGQVIKADEAEKIGLVNRVVEPDILIEEV 
                   
               
               
                   
                 EKLAKIIAKNAQLAVRYSKEAIQLGAQTDINTGIDIESNLF 
                   
               
               
                   
                 GLCFSTKDQKEGMSAFVEKREANFIKG 
                   
               
               
                   
               
               
                 Pbt 
                 atgagaagttttgaagaagtaattaagtttgcaaaagaaagaggacctaaaa 
                 SEQ 
               
               
                 (polynucleotide 
                 ctatatcagtagcatgttgccaagataaagaagttttaatggcagttgaaatgg 
                 ID NO: 
               
               
                 sequence) 
                 ctagaaaagaaaaaatagcaaatgccattttagtaggagatatagaaaaga 
                 98 
               
               
                   
                 ctaaagaaattgcaaaaagcatagacatggatatcgaaaattatgaactgat 
                   
               
               
                   
                 agatataaaagatttagcagaagcatctctaaaatctgttgaattagtttcacaa 
                   
               
               
                   
                 ggaaaagccgacatggtaatgaaaggcttagtagacacatcaataatactaa 
                   
               
               
                   
                 aagcagttttaaataaagaagtaggtcttagaactggaaatgtattaagtcacg 
                   
               
               
                   
                 tagcagtatttgatgtagagggatatgatagattatttttcgtaactgacgcagct 
                   
               
               
                   
                 atgaacttagctcctgatacaaatactaaaaagcaaatcatagaaaatgcttg 
                   
               
               
                   
                 cacagtagcacattcattagatataagtgaaccaaaagttgctgcaatatgcg 
                   
               
               
                   
                 caaaagaaaaagtaaatccaaaaatgaaagatacagttgaagctaaagaa 
                   
               
               
                   
                 ctagaagaaatgtatgaaagaggagaaatcaaaggttgtatggttggtgggc 
                   
               
               
                   
                 cttttgcaattgataatgcagtatctttagaagcagctaaacataaaggtataaa 
                   
               
               
                   
                 tcatcctgtagcaggacgagctgatatattattagccccagatattgaaggtggt 
                   
               
               
                   
                 aacatattatataaagctttggtattcttctcaaaatcaaaaaatgcaggagttat 
                   
               
               
                   
                 agttggggctaaagcaccaataatattaacttctagagcagacagtgaagaa 
                   
               
               
                   
                 actaaactaaactcaatagctttaggtgttttaatggcagcaaaggcataa 
                   
               
               
                   
               
               
                 Pbt (polypeptide 
                 MRSFEEVIKFAKERGPKTISVACCQDKEVLMAVEMARK 
                 SEQ 
               
               
                 sequence) 
                 EKIANAILVGDIEKTKEIAKSIDMDIENYELIDIKDLAEASL 
                 ID NO: 
               
               
                   
                 KSVELVSQGKADMVMKGLVDTSIILKAVLNKEVGLRTG 
                 99 
               
               
                   
                 NVLSHVAVFDVEGYDRLFFVTDAAMNLAPDTNTKKQIIE 
                   
               
               
                   
                 NACTVAHSLDISEPKVAAICAKEKVNPKMKDTVEAKELE 
                   
               
               
                   
                 EMYERGEIKGCMVGGPFAIDNAVSLEAAKHKGINHPVA 
                   
               
               
                   
                 GRADILLAPDIEGGNILYKALVFFSKSKNAGVIVGAKAPII 
                   
               
               
                   
                 LTSRADSEETKLNSIALGVLMAAKA 
                   
               
               
                   
               
               
                 Buk 
                 atgagcaaaatatttaaaatcttaacaataaatcctggttcgacatcaactaaa 
                 SEQ 
               
               
                 (polynucleotide 
                 atagctgtatttgataatgaggatttagtatttgaaaaaactttaagacattcttca 
                 ID NO: 
               
               
                 sequence) 
                 gaagaaataggaaaatatgagaaggtgtctgaccaatttgaatttcgtaaaca 
                 100 
               
               
                   
                 agtaatagaagaagctctaaaagaaggtggagtaaaaacatctgaattagat 
                   
               
               
                   
                 gctgtagtaggtagaggaggacttcttaaacctataaaaggtggtacttattca 
                   
               
               
                   
                 gtaagtgctgctatgattgaagatttaaaagtgggagttttaggagaacacgctt 
                   
               
               
                   
                 caaacctaggtggaataatagcaaaacaaataggtgaagaagtaaatgttc 
                   
               
               
                   
                 cttcatacatagtagaccctgttgttgtagatgaattagaagatgttgctagaattt 
                   
               
               
                   
                 ctggtatgcctgaaataagtagagcaagtgtagtacatgctttaaatcaaaag 
                   
               
               
                   
                 gcaatagcaagaagatatgctagagaaataaacaagaaatatgaagatata 
                   
               
               
                   
                 aatcttatagttgcacacatgggtggaggagtttctgttggagctcataaaaatg 
                   
               
               
                   
                 gtaaaatagtagatgttgcaaacgcattagatggagaaggacctttctctccag 
                   
               
               
                   
                 aaagaagtggtggactaccagtaggtgcattagtaaaaatgtgctttagtgga 
                   
               
               
                   
                 aaatatactcaagatgaaattaaaaagaaaataaaaggtaatggcggacta 
                   
               
               
                   
                 gttgcatacttaaacactaatgatgctagagaagttgaagaaagaattgaagc 
                   
               
               
                   
                 tggtgatgaaaaagctaaattagtatatgaagctatggcatatcaaatctctaa 
                   
               
               
                   
                 agaaataggagctagtgctgcagttcttaagggagatgtaaaagcaatattatt 
                   
               
               
                   
                 aactggtggaatcgcatattcaaaaatgtttacagaaatgattgcagatagagt 
                   
               
               
                   
                 taaatttatagcagatgtaaaagtttatccaggtgaagatgaaatgattgcatta 
                   
               
               
                   
                 gctcaaggtggacttagagttttaactggtgaagaagaggctcaagtttatgat 
                   
               
               
                   
                 aactaa 
                   
               
               
                   
               
               
                 Buk 
                 MSKIFKILTINPGSTSTKIAVFDNEDLVFEKTLRHSSEEIG 
                 SEQ 
               
               
                 (polypeptide 
                 KYEKVSDQFEFRKQVIEEALKEGGVKTSELDAVVGRGG 
                 ID NO: 
               
               
                 sequence) 
                 LLKPIKGGTYSVSAAMIEDLKVGVLGEHASNLGGIIAKQI 
                 101 
               
               
                   
                 GEEVNVPSYIVDPVVVDELEDVARISGMPEISRASVVHA 
                   
               
               
                   
                 LNQKAIARRYAREINKKYEDINLIVAHMGGGVSVGAHKN 
                   
               
               
                   
                 GKIVDVANALDGEGPFSPERSGGLPVGALVKMCFSGK 
                   
               
               
                   
                 YTQDEIKKKIKGNGGLVAYLNTNDAREVEERIEAGDEKA 
                   
               
               
                   
                 KLVYEAMAYQISKEIGASAAVLKGDVKAILLTGGIAYSKM 
                   
               
               
                   
                 FTEMIADRVKFIADVKVYPGEDEMIALAQGGLRVLTGEE 
                   
               
               
                   
                 EAQVYDN 
                   
               
               
                   
               
               
                 First RBS (in 
                 TTTGTTTAACTTTAAGAAGGAGA 
                 SEQ 
               
               
                 ydfZ = 2RBS) 
                   
                 ID NO: 
               
               
                   
                   
                 102 
               
               
                   
               
               
                 Internal RBS 
                 taagaaggagatatacat 
                 SEQ 
               
               
                 between genes 
                   
                 ID NO: 
               
               
                   
                   
                 103 
               
               
                   
               
               
                 Butryate 
                 CATTTCCTCTCATCCCATCCGGGGTGAGAGTCTTTTC 
                 SEQ 
               
               
                 cassette under 
                 CCCCGACTTATGGCTCATGCATGCATCAAAAAAGATG 
                 ID NO: 
               
               
                 the control of 
                 TGAGCTTGATCAAAAACAAAAAATATTTCACTCGACA 
                 104 
               
               
                 the ydfZ 
                 GGAGTATTTATATTGCGCCCGGATCCCTCTAGAAATA 
                   
               
               
                 promoter 
                 A TTTTGTTTAACTTTAAGAAGGAGATATACAT atgatcgt 
                   
               
               
                 (uppercase: 
                 aaaacctatggtacgcaacaatatctgcctgaacgcccatcctcagggctgc 
                   
               
               
                 ydfZ promoter, 
                 aagaagggagtggaagatcagattgaatataccaagaaacgcattaccgca 
                   
               
               
                 with RBS in 
                 gaagtcaaagctggcgcaaaagctccaaaaaacgttctggtgcttggctgctc 
                   
               
               
                 bold; lower 
                 aaatggttacggcctggcgagccgcattactgctgcgttcggatacggggctg 
                   
               
               
                 case: coding 
                 cgaccatcggcgtgtcctttgaaaaagcgggttcagaaaccaaatatggtac 
                   
               
               
                 regions in the 
                 accgggatggtacaataatttggcatttgatgaagcggcaaaacgcgagggt 
                   
               
               
                 following order: 
                 ctttatagcgtgacgatcgacggcgatgcgttttcagacgagatcaaggccca 
                   
               
               
                 ter, thiA, hbd, 
                 ggtaattgaggaagccaaaaaaaaaggtatcaaatttgatctgatcgtataca 
                   
               
               
                 crt2, pbt, buk, 
                 gcttggccagcccagtacgtactgatcctgatacaggtatcatgcacaaaagc 
                   
               
               
                 separated by 
                 gttttgaaaccctttggaaaaacgttcacaggcaaaacagtagatccgtttact 
                   
               
               
                 internal RBS 
                 ggcgagctgaaggaaatctccgcggaaccagcaaatgacgaggaagcag 
                   
               
               
                 (uppercase and 
                 ccgccactgttaaagttatggggggtgaagattgggaacgttggattaagcag 
                   
               
               
                 underlined) 
                 ctgtcgaaggaaggcctcttagaagaaggctgtattaccttggcctatagttata 
                   
               
               
                   
                 ttggccctgaagctacccaagctttgtaccgtaaaggcacaatcggcaaggc 
                   
               
               
                   
                 caaagaacacctggaggccacagcacaccgtctcaacaaagagaacccg 
                   
               
               
                   
                 tcaatccgtgccttcgtgagcgtgaataaaggcctggtaacccgcgcaagcg 
                   
               
               
                   
                 ccgtaatcccggtaatccctctgtatctcgccagcttgttcaaagtaatgaaaga 
                   
               
               
                   
                 gaagggcaatcatgaaggttgtattgaacagatcacgcgtctgtacgccgag 
                   
               
               
                   
                 cgcctgtaccgtaaagatggtacaattccagttgatgaggaaaatcgcattcg 
                   
               
               
                   
                 cattgatgattgggagttagaagaagacgtccagaaagcggtatccgcgttga 
                   
               
               
                   
                 tggagaaagtcacgggtgaaaacgcagaatctctcactgacttagcggggta 
                   
               
               
                   
                 ccgccatgatttcttagctagtaacggctttgatgtagaaggtattaattatgaag 
                   
               
               
                   
                 cggaagttgaacgcttcgaccgtatctga TAAGAAGGAGATATACA   
                   
               
               
                   
                   T atgagagaagtagtaattgccagtgcagctagaacagcagtaggaagtttt 
                   
               
               
                   
                 ggaggagcatttaaatcagtttcagcggtagagttaggggtaacagcagcta 
                   
               
               
                   
                 aagaagctataaaaagagctaacataactccagatatgatagatgaatctcttt 
                   
               
               
                   
                 tagggggagtacttacagcaggtcttggacaaaatatagcaagacaaatagc 
                   
               
               
                   
                 attaggagcaggaataccagtagaaaaaccagctatgactataaatatagttt 
                   
               
               
                   
                 gtggttctggattaagatctgtttcaatggcatctcaacttatagcattaggtgatg 
                   
               
               
                   
                 ctgatataatgttagttggtggagctgaaaacatgagtatgtctccttatttagtac 
                   
               
               
                   
                 caagtgcgagatatggtgcaagaatgggtgatgctgcttttgttgattcaatgat 
                   
               
               
                   
                 aaaagatggattatcagacatatttaataactatcacatgggtattactgctgaa 
                   
               
               
                   
                 aacatagcagagcaatggaatataactagagaagaacaagatgaattagct 
                   
               
               
                   
                 cttgcaagtcaaaataaagctgaaaaagctcaagctgaaggaaaatttgatg 
                   
               
               
                   
                 aagaaatagttcctgttgttataaaaggaagaaaaggtgacactgtagtagat 
                   
               
               
                   
                 aaagatgaatatattaagcctggcactacaatggagaaacttgctaagttaag 
                   
               
               
                   
                 acctgcatttaaaaaagatggaacagttactgctggtaatgcatcaggaataa 
                   
               
               
                   
                 atgatggtgctgctatgttagtagtaatggctaaagaaaaagctgaagaacta 
                   
               
               
                   
                 ggaatagagcctcttgcaactatagtttcttatggaacagctggtgttgacccta 
                   
               
               
                   
                 aaataatgggatatggaccagttccagcaactaaaaaagctttagaagctgct 
                   
               
               
                   
                 aatatgactattgaagatatagatttagttgaagctaatgaggcatttgctgccc 
                   
               
               
                   
                 aatctgtagctgtaataagagacttaaatatagatatgaataaagttaatgttaat 
                   
               
               
                   
                 ggtggagcaatagctataggacatccaataggatgctcaggagcaagaata 
                   
               
               
                   
                 cttactacacttttatatgaaatgaagagaagagatgctaaaactggtcttgcta 
                   
               
               
                   
                 cactttgtataggcggtggaatgggaactactttaatagttaagagatag TAA   
                   
               
               
                   
                   GAAGGAGATATACAT atgaaattagctgtaataggtagtggaactat 
                   
               
               
                   
                 gggaagtggtattgtacaaacttttgcaagttgtggacatgatgtatgtttaaaga 
                   
               
               
                   
                 gtagaactcaaggtgctatagataaatgtttagctttattagataaaaatttaact 
                   
               
               
                   
                 aagttagttactaagggaaaaatggatgaagctacaaaagcagaaatattaa 
                   
               
               
                   
                 gtcatgttagttcaactactaattatgaagatttaaaagatatggatttaataatag 
                   
               
               
                   
                 aagcatctgtagaagacatgaatataaagaaagatgttttcaagttactagatg 
                   
               
               
                   
                 aattatgtaaagaagatactatcttggcaacaaatacttcatcattatctataaca 
                   
               
               
                   
                 gaaatagcttcttctactaagcgcccagataaagttataggaatgcatttctttaa 
                   
               
               
                   
                 tccagttcctatgatgaaattagttgaagttataagtggtcagttaacatcaaaa 
                   
               
               
                   
                 gttacttttgatacagtatttgaattatctaagagtatcaataaagtaccagtagat 
                   
               
               
                   
                 gtatctgaatctcctggatttgtagtaaatagaatacttatacctatgataaatga 
                   
               
               
                   
                 agctgttggtatatatgcagatggtgttgcaagtaaagaagaaatagatgaag 
                   
               
               
                   
                 ctatgaaattaggagcaaaccatccaatgggaccactagcattaggtgattta 
                   
               
               
                   
                 atcggattagatgttgttttagctataatgaacgttttatatactgaatttggagata 
                   
               
               
                   
                 ctaaatatagacctcatccacttttagctaaaatggttagagctaatcaattagg 
                   
               
               
                   
                 aagaaaaactaagataggattctatgattataataaataa TAAGAAGGA   
                   
               
               
                   
                   GATATACAT atgagtacaagtgatgttaaagtttatgagaatgtagctgttg 
                   
               
               
                   
                 aagtagatggaaatatatgtacagtgaaaatgaatagacctaaagcccttaat 
                   
               
               
                   
                 gcaataaattcaaagactttagaagaactttatgaagtatttgtagatattaataa 
                   
               
               
                   
                 tgatgaaactattgatgttgtaatattgacaggggaaggaaaggcatttgtagct 
                   
               
               
                   
                 ggagcagatattgcatacatgaaagatttagatgctgtagctgctaaagatttta 
                   
               
               
                   
                 gtatcttaggagcaaaagcttttggagaaatagaaaatagtaaaaaagtagtg 
                   
               
               
                   
                 atagctgctgtaaacggatttgctttaggtggaggatgtgaacttgcaatggcat 
                   
               
               
                   
                 gtgatataagaattgcatctgctaaagctaaatttggtcagccagaagtaactct 
                   
               
               
                   
                 tggaataactccaggatatggaggaactcaaaggcttacaagattggttgga 
                   
               
               
                   
                 atggcaaaagcaaaagaattaatctttacaggtcaagttataaaagctgatga 
                   
               
               
                   
                 agctgaaaaaatagggctagtaaatagagtcgttgagccagacattttaatag 
                   
               
               
                   
                 aagaagttgagaaattagctaagataatagctaaaaatgctcagcttgcagtt 
                   
               
               
                   
                 agatactctaaagaagcaatacaacttggtgctcaaactgatataaatactgg 
                   
               
               
                   
                 aatagatatagaatctaatttatttggtctttgtttttcaactaaagaccaaaaaga 
                   
               
               
                   
                 aggaatgtcagctttcgttgaaaagagagaagctaactttataaaagggtaa T   
                   
               
               
                   
                   AAGAAGGAGATATACAT atgagaagttttgaagaagtaattaagttt 
                   
               
               
                   
                 gcaaaagaaagaggacctaaaactatatcagtagcatgttgccaagataaa 
                   
               
               
                   
                 gaagttttaatggcagttgaaatggctagaaaagaaaaaatagcaaatgcca 
                   
               
               
                   
                 ttttagtaggagatatagaaaagactaaagaaattgcaaaaagcatagacat 
                   
               
               
                   
                 ggatatcgaaaattatgaactgatagatataaaagatttagcagaagcatctct 
                   
               
               
                   
                 aaaatctgttgaattagtttcacaaggaaaagccgacatggtaatgaaaggct 
                   
               
               
                   
                 tagtagacacatcaataatactaaaagcagttttaaataaagaagtaggtctta 
                   
               
               
                   
                 gaactggaaatgtattaagtcacgtagcagtatttgatgtagagggatatgata 
                   
               
               
                   
                 gattatttttcgtaactgacgcagctatgaacttagctcctgatacaaatactaaa 
                   
               
               
                   
                 aagcaaatcatagaaaatgcttgcacagtagcacattcattagatataagtga 
                   
               
               
                   
                 accaaaagttgctgcaatatgcgcaaaagaaaaagtaaatccaaaaatgaa 
                   
               
               
                   
                 agatacagttgaagctaaagaactagaagaaatgtatgaaagaggagaaat 
                   
               
               
                   
                 caaaggttgtatggttggtgggccttttgcaattgataatgcagtatctttagaag 
                   
               
               
                   
                 cagctaaacataaaggtataaatcatcctgtagcaggacgagctgatatattat 
                   
               
               
                   
                 tagccccagatattgaaggtggtaacatattatataaagctttggtattcttctcaa 
                   
               
               
                   
                 aatcaaaaaatgcaggagttatagttggggctaaagcaccaataatattaact 
                   
               
               
                   
                 tctagagcagacagtgaagaaactaaactaaactcaatagctttaggtgtttta 
                   
               
               
                   
                 atggcagcaaaggcataa TAAGAAGGAGATATACAT atgagcaa 
                   
               
               
                   
                 aatatttaaaatcttaacaataaatcctggttcgacatcaactaaaatagctgtat 
                   
               
               
                   
                 ttgataatgaggatttagtatttgaaaaaactttaagacattcttcagaagaaata 
                   
               
               
                   
                 ggaaaatatgagaaggtgtctgaccaatttgaatttcgtaaacaagtaataga 
                   
               
               
                   
                 agaagctctaaaagaaggtggagtaaaaacatctgaattagatgctgtagta 
                   
               
               
                   
                 ggtagaggaggacttcttaaacctataaaaggtggtacttattcagtaagtgct 
                   
               
               
                   
                 gctatgattgaagatttaaaagtgggagttttaggagaacacgcttcaaaccta 
                   
               
               
                   
                 ggtggaataatagcaaaacaaataggtgaagaagtaaatgttccttcatacat 
                   
               
               
                   
                 agtagaccctgttgttgtagatgaattagaagatgttgctagaatttctggtatgc 
                   
               
               
                   
                 ctgaaataagtagagcaagtgtagtacatgctttaaatcaaaaggcaatagc 
                   
               
               
                   
                 aagaagatatgctagagaaataaacaagaaatatgaagatataaatcttata 
                   
               
               
                   
                 gttgcacacatgggtggaggagtttctgttggagctcataaaaatggtaaaata 
                   
               
               
                   
                 gtagatgttgcaaacgcattagatggagaaggacctttctctccagaaagaag 
                   
               
               
                   
                 tggtggactaccagtaggtgcattagtaaaaatgtgctttagtggaaaatatact 
                   
               
               
                   
                 caagatgaaattaaaaagaaaataaaaggtaatggcggactagttgcatact 
                   
               
               
                   
                 taaacactaatgatgctagagaagttgaagaaagaattgaagctggtgatga 
                   
               
               
                   
                 aaaagctaaattagtatatgaagctatggcatatcaaatctctaaagaaatag 
                   
               
               
                   
                 gagctagtgctgcagttcttaagggagatgtaaaagcaatattattaactggtg 
                   
               
               
                   
                 gaatcgcatattcaaaaatgtttacagaaatgattgcagatagagttaaatttat 
                   
               
               
                   
                 agcagatgtaaaagtttatccaggtgaagatgaaatgattgcattagctcaag 
                   
               
               
                   
                 gtggacttagagttttaactggtgaagaagaggctcaagtttatgataactaata 
                   
               
               
                   
                 a 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 90 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 90 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 90 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 90 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 92 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 92 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 92 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 92 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 94 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 94 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 94 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 94 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 96 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 96 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 96 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 96 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 98 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 98 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 98 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 98 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 100 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 100 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 100 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 100 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 104 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 104 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 104 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 104 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 48 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 48 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 48 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 48 or a functional fragment thereof. 
     In alternate embodiments, pbt and buk are replaced with TesB (SEQ ID NO: 48) 
     In some embodiments, the butyrate cassette is driven by an inducible promoter. For example, other FNR promotors can be used in lieu of ydfZ, e.g., in SEQ ID NO:. 
     Non-limiting FNR promoter sequences are provided herein. In some embodiments, the genetically engineered bacteria of the invention comprise a butyrate cassette under the control of one or more of promoter sequences found in Table 6, e.g., nirB promoter, ydfZ promoter, nirB promoter fused to a strong ribosome binding site, ydfZ promoter fused to a strong ribosome binding site, fnrS, an anaerobically induced small RNA gene (fnrS promoter), nirB promoter fused to a crp binding site, and fnrS fused to a crp binding site. 
     In some embodiments, the butyrate cassetted is under the control of a promoter which is inducible by metabolites present in the gut. In some embodiments the butyrate cassette is induced by HE-specific molecules or metabolites indicative of liver damage, e.g., bilirubin. In some embodiments, the butyrate cassette is placed under the control of promoter, which is inducible by inflammation or an inflammatory response (e.g., RNS or ROS promoter). 
     In some embodiments, the genetically engineered bacteria comprise a butyrate cassette driven by a promoter induced by a molecule or metabolite, e.g., bilirubin, aspartate aminotransferase, alanine aminotransferase, blood coagulation factors II, VII, IX, and X, alkaline phosphatase, gamma glutamyl transferase, hepatitis antigens and antibodies, alpha fetoprotein, anti-mitochondrial, smooth muscle, and anti-nuclear antibodies, iron, transferrin, ferritin, copper, ceruloplasmin, ammonia, and manganese in their blood and intestines. Promoters that respond to one of these molecules or their metabolites may be used in the genetically engineered bacteria provided herein. 
     In some embodiments, the butyrate cassette is inducible by arabinose and is driven by the AraBAD promoter. 
     Example 40. Quantification of Butyrate by LC-MS/MS 
     To obtain the butyrate measurements in Example 37 a LC-MS/MS protocol for butyrate quantification was used. 
     Sample Preparation 
     First, fresh sodium butyrate stock solution (10 mg/m), and 1000, 500, 250, 100, 20, 4 and 0.8 μg/mL of sodium butyrate standards were prepared in water. Then, 10 μL of sample (bacterial supernatants and standards) were pipetted into a V-bottom polypropylene 96-well plate, and 90 μL of 67% ACN (60 uL ACN+30 uL water per reaction) with 4 ug/mL of butyrate-d7 (CDN isotope) internal standard in final solution were added to each sample. The plate was heat-sealed, mixed well, and centrifuged at 4000 rpm for 5 minutes. In a round-bottom 96-well polypropylene plate, 20 μL of diluted samples were added to 180 μL of a buffer containing 10 mM MES pH4.5, 20 mM EDC (N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide), and 20 mM TFEA (2,2,2-trifluroethylamine). The plate was again heat-sealed and mixed well, and samples were incubated at room temperature for 1 hour. 
     LC-MS/MS Method 
     Butyrate was measured by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using a Thermo TSQ Quantum Max triple quadrupole mass spectrometer. HPLC Details are listed in Table 45 and Table 46. Tandem Mass Spectrometry details are found in Table 47. 
     
       
         
           
               
             
               
                 TABLE 45 
               
             
            
               
                   
               
               
                 HPLC Details 
               
            
           
           
               
               
               
            
               
                   
                   
                 Thermo Aquasil C18 column, 
               
               
                   
                 Column 
                 5 μm (50 × 2.1 mm) 
               
               
                   
                   
               
               
                   
                 Mobile 
                 100% H2O, 0.1% 
               
               
                   
                 Phase A 
                 Formic Acid 
               
               
                   
                 Mobile 
                 100% ACN, 0.1% 
               
               
                   
                 Phase B 
                 Formic Acid 
               
               
                   
                 Injection 
                 10 uL 
               
               
                   
                 volume 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 46 
               
             
            
               
                   
               
               
                 HPLC Method 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Total 
                 Flow 
                   
                   
               
               
                   
                 Time 
                 Rate 
                   
                   
               
               
                   
                 (min) 
                 (μL/min) 
                 A % 
                 B % 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 0 
                 0.5 
                 100 
                  0 
               
               
                   
                 1 
                 0.5 
                 100 
                  0 
               
               
                   
                 2 
                 0.5 
                  10 
                 90 
               
               
                   
                 4 
                 0.5 
                  10 
                 90 
               
               
                   
                 4.01 
                 0.5 
                 100 
                  0 
               
               
                   
                 4.25 
                 0.5 
                 100 
                  0 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 47 
               
             
            
               
                   
               
               
                 Tandem Mass Spectrometry Details 
               
            
           
           
               
               
               
            
               
                   
                 Ion Source 
                 HESI-II 
               
               
                   
                   
               
               
                   
                 Polarity 
                 Positive 
               
               
                   
                 SRM 
                 Butyrate 170.0/71.1, 
               
               
                   
                 transitions 
                 Butyrate d7 
               
               
                   
                   
                 177.1/78.3 
               
               
                   
                   
               
            
           
         
       
     
     Example 41. Efficacy of Genetically Engineered Bacteria Producing Arginine and/or Butyrate in a Bile Duct Ligation Model 
     Ligation of the common bile duct in rodents has used as an experimental procedure in research for many years to induce liver cholestasis and fibrosis (see e.g., Tag et a., Bile Duct Ligation in Mice: Induction of Inflammatory Liver Injury and Fibrosis by Obstructive Cholestasis, Journal of Visualized Experiments, February 2015; 96; e52438, and references therein). 
     To determine the efficacy of a strain comprising an arginine and butyrate producing circuit in reducing symptoms of liver inflammation and fibrosis, a bile duct ligation model is used. A Nissle control (SYN-UCD107, kanamycin resistant Nissle), an arginine producing strain (SYN-UCD305), a butyrate producing strain (SYN-UCD502), and a strain producing both butyrate and arginine (SYN-UCD605) are compared in the study. ALT/AST levels, fibrosis (portal, perisinusoidal and total) and hepatic inflammation are the primary endpoints of the study; overall animal health is the secondary endpoint of the study. 
     Animals (C57BL6, 8 weeks) are treated by oral gavage with either H2O control (n=12), or SYN-UCD107 (n=12; kanamycin resistant Nissle), or arginine producing SYN-UCD305 (n=12; comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and no antibiotic resistance), or butyrate producing SYN-UCD502 (n=12; comprising a PydfZ-ter butyrate cassette integrated on the chromosome) or SYN-UCD605 (n=12; comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and PydfZ-ter butyrate cassette integrated on the chromosome, and no antibiotic resistance). Bacteria are administered at a dose of &gt;10e10 cells/ml. 
     In some embodiments, SYN-UCD501 (comprising wild type ArgR, no FNR-ArgAfbr, wild type ThyA, and Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance) and SYN-UCD602 (comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance)) are used instead of SYN-UCD502 and SYN-UCD605. 
     On Day 0, bile duct ligation surgery is performed as described in Example 40. On day 1, mice are weighed and randomized. Mice are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502 or SYN-UCD605 in the AM and PM. On day two, mice are gavaged with 100 ul H2O, SYN798 and SYN993—in the AM and PM. On day three, mice are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502 or SYN-UCD605 in the AM and PM. At 4 h post AM dose, blood is collected for ALT/AST analysis. On days 4-6, mice are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502 or SYN-UCD605 in the AM and PM. On day 7, mice are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502 or SYN-UCD605 in the AM and PM. At 4 h post AM dose, blood is collected for ALT/AST analysis. On days 8-9, mice are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502 or SYN-UCD605 in the AM and PM. On day 10, mice are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502 or SYN-UCD605 in the AM and PM. At 4 h post AM dose, blood is collected for ALT/AST analysis. On days 11-13, mice are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502 or SYN-UCD605 in the AM and PM. On day 14, animals are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502 or SYN-UCD605 in the AM. Then, 4 h post dose animals are euthanized, and blood is collected by cardiac bleed for ALT/AST analysis. The liver tissue is harvested for fibrosis analysis by histological assessment. 
     Example 42. Bile Duct Ligation Procedure 
     Bile Duct Ligation 
     Pre-Surgical Preparation: 
     During the complete experimentation, the animal is kept on a warming plate at a temperature of 37° C., permanently connected to an anesthesia system, and the operational area is covered overall with fluid-impermeable, self-adhesive drapes. 
     The mouse is anaesthetized with inhalation of 4 vol % isoflurane in 100% oxygen at a flow rate of 4 L/min for the induction of the anesthesia. The depth of anesthetization is sufficient when the following vital criteria are reached: regular spontaneous breathing, no reflex after setting of pain stimuli between toes, and no response to pain. The abdominal fur of the mouse is shaved with an electric fur shaver and the eyes are protected from drying out by usage of eye and nose ointment. The mouse is placed on a 37° C. heated hot plate, the mouse snout is inserted in the Fluovac mask of a Fluovac anesthesia system, and the legs of the animal are fixed with stripes of silk tape. Anesthesia of the mouse is maintained by inhalation of 1.5-3 vol % isoflurane in 100% oxygen at a flow rate of 1 L/min and induct perioperative analgesia via intraperitoneal injection of buprenorphine solution (0.1 mg/kg BW dissolved in 0.9% NaCl solution). 
     The shaved abdominal skin is sterilized with a gauze swab that is moistened with a standard antiseptic, ready to use alcoholic solution for preoperative treatment of the skin. 
     Surgical Procedures: 
     The abdomen is opened with a midline laparotomy of a length of approximately 2 cm by cutting the cutis plus fascia at the same time with an 11.5 cm surgical scissor. The connective tissue on top of the peritoneum is dissected by using the scissor as a spreader. The peritoneum is cut along the linea alba to open the peritoneal cavity. The cavity is enlarged by inserting a holding suture in the sternum, raising the filament of the suture, and fixing it on top of the Fluovac mask. The operation area is spread by inserting a Colibri retractor in the peritoneal cavity. The liver is lifted with a moisturized (0.9% NaCl solution) cotton swab so that the ventral side of it sticks to the diaphragm and the hilum is clearly visible. The bile duct is exposed by caudal movement of the gut. The bile duct is separated carefully from the flanking portal vein and hepatic artery using a micro-serrations forceps. The 5-0 suture is placed around the bile duct and secured with two surgical knots. When tying the knots the tractive force is increased continuously to ensure effective obstruction without severing the bile duct. A second cranial ligation is added in the same manner without dissecting the bile duct in between. The ends of the sutures are cut, the sternum lowered, and the retractor removed. The peritoneal cavity is rinsed with 0.9% NaCl solution and the abdominal organs replaced to the physiological positions. Both abdominal layers (peritoneum and cutis plus facia) are closed with separate running sutures with 6-0 Mersilk. The ends of the sutures are cut and the operation area is sterilized with a gauze swab moistened with antiseptic solution. 
     Postoperative Treatment and Follow-Up: 
     The mouse is allowed to recover in a cage warmed up by an infrared lamp until the mouse is fully awake and active. Afterwards, the mouse is moved to a normal cage and provided ad libitum access to water and food. After the surgery, the animals are monitored at regular intervals and follow-up postoperative treatments are carried out with suitable analgesia (e.g., buprenorphine solution) following the local recommendation of the internal animal care and use committees. Animals are kept with free access to food and water ad libitum until the end of the experiment. 
     Example 43. TAA model of Hepatic Encephalopathy 
     TAA treatment of mice has previously been employed in the literature to model increased blood ammonia levels associated with UCDs, acute and chronic liver disease and HE (Wallace M C, et al., Lab Anim. 2015 April; 49(1 Suppl):21-9. Standard operating procedures in experimental liver research: thioacetamide model in mice and rat)s. In some embodiments, a TAA-induced mouse model of hyperammonemia is employed to investigate the duration of activity of the genetically engineered bacteria and to generate additional data to support this approach to the treatment of hepatic encephalopathy. 
     To determine the efficacy of a strain comprising an arginine and butyrate producing circuit in alleviating symptoms of liver inflammation and fibrosis, Nissle control (SYN-UCD107, kanamycin resistant Nissle), an arginine producing strain (SYN-UCD305), a butyrate producing strain (SYN-UCD502), and a strain producing both butyrate and arginine (SYN-UCD605) are compared in a TAA model study. ALT/AST levels, fibrosis (portal, perisinusoidal and total) and hepatic inflammation are the primary endpoints of the study. Overall animal health is the secondary endpoint of the study. 
     To investigate the effects of engineered bacteria on prolonged elevations of blood ammonia, the bacteria are administered to C57BL6 mice that are also administered a dose of 300 mpk thioacetamide (TAA). 
     C57BL6 (10 weeks old) are administered one daily dose of SYN-UCD107, or SYN-UCD305 (n=12), SYN-UCD502 (n=12), or SYN-UCD605 (n=12) (100 ul of &gt;1×10 10  cells/ml) or vehicle control. Alternatively, mice are administered 2 daily doses of bacteria (100 ul of &gt;1×10 10  cells/ml) (n=5 for each treatment group), once in the AM and once in the PM. After three days of pre-dosing with the bacteria, the mice are treated intraperitoneally with thioacetamide (TAA) at 300 mpk or with H2O as control. Alternatively, the mice are treated twice daily, once in the AM and once in the PM with 250 mpk. The duration of the study is five days. Ammonium levels are measured and overall health survival, body weight change is monitored. 
     In brief, animals are acclimated for 7 days. On day 1 of the time course, animals are weighed, bled to measure baseline ALT/AST and collect fecal pellets (per cage), and are randomized based on ALT/AST levels. Animals are dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605 (100 ul/dose/animal). Water is changed to H2O(+)20 mg/ml ATC. On day 2, animals are dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605 (100 ul/dose/animal). On day 3, animals are weighed and dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605 (100 ul/dose/animal). Additionally, animals are dosed intraperitoneally with 300 mpk TAA (or saline control). Alternatively, animals are dosed with 250 mpk TAA (or saline control) once in the AM and once in the PM. On day 4, animals are weighed and blood is collected for ALT/AST analysis. Fecal pellets are collected per cage. Animals are dosed per oral gavage either once or twice (AM and PM) with H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605 (100 ul/dose/animal). Animals may also be dosed with 250 mpk TAA (or saline control). On day 5, animals are weighed and blood is collected for ALT/AST analysis. Fecal pellets are collected (per cage). Animals are dosed by oral gavage either once or twice (AM and PM) with H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605 (100 ul/dose/animal). ALT/AST levels, bacterial load in the fecal pellets, and overall health survival, and body weight changes are monitored. The liver tissue is harvested for fibrosis analysis by histological assessment. 
     Example 44. Carbontetrachloride (CCl4) Model of Hepatic Encephalopathy 
     CCl4 is often used to induce hepaticfibrosis and cirrhosis in animals because the underlying iochemical mechanisms and histological characteristics are similar to those observed in human liver cirrhosis (Nhung et al., Establishment of a standardized mouse model of hepatic fibrosis for biomedical research; Biomedical Research and Therapy 2014, 1(2):43-49). 
     CYP2E1 is an enzyme which is expressed in perivenular hepatocytes, and which converts CCl4 into a CCl3+ radical. The accumulation of the CCl3+ radical causes centrilobular necrosis and changes the permeability of the hepatocyte plasma and mitochondrial membranes. As a result, an increase in inflammation and fibrogenesis, and extracellular matrix deposition is observed. Chronic CCl4 exposure causes the formation of nodules and fibrosis, products of the wound healing process. CCl4 treatment has been shown to cause fibrosis after 2-4 weeks, significant bridging fibrosis after 5-7 weeks, cirrhosis after 9-11 weeks, and micronodular cirrhosis after 10-20 weeks (Nhung et al., Establishment of a standardized mouse model of hepatic fibrosis for biomedical research; Biomedical Research and Therapy 2014, 1(2):43-49, and references therein). 
     To determine the efficacy of a strain comprising an arginine and butyrate producing circuit in alleviating symptoms of liver inflammation and fibrosis, a CCl4 mouse model of liver cirrhosis is used. A Nissle control (SYN-UCD107, kanamycin resistant Nissle), an arginine producing strain (SYN-UCD305), a butyrate producing strain (SYN-UCD502), and a strain producing both butyrate and arginine (SYN-UCD605) are compared in the study. ALT/AST levels, fibrosis (portal, perisinusoidal and total) and hepatic inflammation are the primary endpoints of the study. Overall animal health is the secondary endpoint of the study. Study duration is 8 weeks. 
     Animals (C57BL6, 8 weeks) are treated by oral gavage with either H2O control (n=12), or SYN-UCD107 (n=12; kanamycin resistant Nissle), or arginine producing SYN-UCD305 (n=12; comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and no antibiotic resistance), or butyrate producing SYN-UCD502 (n=12; comprising wild type ArgR, no FNR-ArgAfbr, wild type ThyA, and a PydfZ-ter butyrate cassette integrated on the chromosome) or SYN-UCD605 (n=12; comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, PydfZ-ter butyrate cassette integrated on the chromosome, and no antibiotic resistance. Bacteria are administered at a dose of &gt;10e10 cells/ml in 100 ul. 
     In some embodiments, SYN-UCD501 (comprising Wild type ArgR, no FNR-ArgAfbr, wild type ThyA, and Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance) and SYN-UCD602 (comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance)) are used instead of SYN-UCD502 and SYN-UCD605. 
     On Day 1, mice are weighed and randomized. Animals are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605 in the AM. Additionally animals are gavaged with olive oil (sham control) or 1 ml/kg CCL4 in olive oil (all other treatment groups). Animals are gavaged with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605 in the PM. 
     Through Week 1-8, animals are gavaged BID with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605. Additionally, animals are gavaged 3×/week with olive oil (sham control) or 1 ml/kg CCL4 in olive oil (all other treatment groups). Animals are weighed 3×/week, and blood for ALT/AST analysis is collected 1×/week. 
     At the end of Week 8 animals are gavaged with 100 ul with 100 ul H2O, SYN-UCD107, SYN-UCD305, SYN-UCD502, or SYN-UCD605 in the AM. At 4 h post dose, animals are weighed, euthanized and blood is collected by cardiac bleed for ALT/AST analysis. The liver is harvested for fibrosis analysis by histological assessment. 
     Example 45. Efficacy of Butyrate-Expressing Bacteria in a DSS Mouse Model 
     Bacteria harboring the butyrate cassettes described above are grown overnight in LB. Bacteria are then diluted 1:100 into LB containing a suitable selection marker, e.g., ampicillin, and grown to an optical density of 0.4-0.5 and then pelleted by centrifugation. Bacteria are resuspended in phosphate buffered saline and 100 microliters is administered by oral gavage to mice. Damage to the gut is induced in mice by supplementing drinking water with 3% dextran sodium sulfate for 7 days prior to bacterial gavage. Mice are treated daily for 1 week and bacteria in stool samples are detected by plating stool homogenate on agar plates supplemented with a suitable selection marker, e.g., ampicillin. After 5 days of bacterial treatment, gut damage is scored in live mice using endoscopy. Endoscopic damage score is determined by assessing colon translucency, fibrin attachment, mucosal and vascular pathology, and/or stool characteristics. Mice are sacrificed and colonic tissues are isolated. Distal colonic sections are fixed and scored for inflammation and ulceration. Colonic tissue is homogenized and measurements are made for myeloperoxidase activity using an enzymatic assay kit and for cytokine levels (IL-1β, TNF-α, IL-6, IFN-γ and IL-10). 
     Example 46. Generating a DSS-Induced Mouse Model of HE 
     The genetically engineered bacteria described can be tested in the dextran sodium sulfate (DSS)-induced mouse model. The administration of DSS to animals results in chemical injury to the intestinal epithelium, allowing proinflammatory intestinal contents (e.g., luminal antigens, enteric bacteria, bacterial products) to disseminate and trigger inflammation (Low et al., 2013). To prepare mice for DSS treatment, mice are labeled using ear punch, or any other suitable labeling method. Labeling individual mice allows the investigator to track disease progression in each mouse, since mice show differential susceptibilities and responsiveness to DSS induction. Mice are then weighed, and if required, the average group weight is equilibrated to eliminate any significant weight differences between groups. Stool is also collected prior to DSS administration, as a control for subsequent assays. Exemplary assays for fecal markers of inflammation (e.g., cytokine levels or myeloperoxidase activity) are described below. 
     For DSS administration, a 3% solution of DSS (MP Biomedicals, Santa Ana, Calif.; Cat. No. 160110) in autoclaved water is prepared. Cage water bottles are then filled with 100 mL of DSS water, and control mice are given the same amount of water without DSS supplementation. This amount is generally sufficient for 5 mice for 2-3 days. Although DSS is stable at room temperature, both types of water are changed every 2 days, or when turbidity in the bottles is observed. 
     Acute, chronic, and resolving models of intestinal inflammation are achieved by modifying the dosage of DSS (usually 1-5%) and the duration of DSS administration (Chassaing et al., 2014). For example, acute and resolving gut damage may be achieved after a single continuous exposure to DSS over one week or less, whereas chronic gut damage is typically induced by cyclical administration of DSS punctuated with recovery periods (e.g., four cycles of DSS treatment for 7 days, followed by 7-10 days of water). 
       FIG. 53D  shows that butyrate produced in vivo in DSS mouse models under the control of an FNR promoter can be gut protective. LCN2 and calprotectin are both a measure of gut barrier disruption (measure by ELISA in this assay).  FIG. 53D  shows that Syn 363 (ter substitution) reduces inflammation and/or protects gut barrier as compared to Syn 94 (wildtype Nissle). 
     Example 47. Monitoring Disease Progression in Vivo 
     Following initial administration of DSS, stool is collected from each animal daily, by placing a single mouse in an empty cage (without bedding material) for 15-30 min. However, as DSS administration progresses and inflammation becomes more robust, the time period required for collection increases. Stool samples are collected using sterile forceps, and placed in a microfuge tube. A single pellet is used to monitor occult blood according to the following scoring system: 0, normal stool consistency with negative hemoccult; 1, soft stools with positive hemoccult; 2, very soft stools with traces of blood; and 3, watery stools with visible rectal bleeding. This scale is used for comparative analysis of intestinal bleeding. All remaining stool is reserved for the measurement of inflammatory markers, and frozen at −20° C. 
     The body weight of each animal is also measured daily. Body weights may increase slightly during the first three days following initial DSS administration, and then begin to decrease gradually upon initiation of bleeding. For mouse models of acute colitis, DSS is typically administered for 7 days. However, this length of time may be modified at the discretion of the investigator. 
     Example 48. In Vivo Efficacy of Genetically Engineered Bacteria Following DSS Induction 
     The genetically engineered bacteria described herein can be tested in DSS-induced animal models of HE. Bacteria are grown overnight in LB supplemented with the appropriate antibiotic. Bacteria are then diluted 1:100 in fresh LB containing selective antibiotic, grown to an optical density of 0.4-0.5, and pelleted by centrifugation. Bacteria are then resuspended in phosphate buffered saline (PBS). Gut damage is induced in mice by supplementing drinking water with 3% DSS for 7 days prior to bacterial gavage. On day 7 of DSS treatment, 100 μL of bacteria (or vehicle) is administered to mice by oral gavage. Bacterial treatment is repeated once daily for 1 week, and bacteria in stool samples are detected by plating stool homogenate on selective agar plates. 
     After 5 days of bacterial treatment, gut damage is scored in live mice using the Coloview system (Karl Storz Veterinary Endoscopy, Goleta, Calif.). In mice under 1.5-2.0% isoflurane anesthesia, colons are inflated with air and approximately 3 cm of the proximal colon can be visualized (Chassaing et al., 2014). Endoscopic damage is scored by assessing colon translucency (score 0-3), fibrin attachment to the bowel wall (score 0-3), mucosal granularity (score 0-3), vascular pathology (score 0-3), stool characteristics (normal to diarrhea; score 0-3), and the presence of blood in the lumen (score 0-3), to generate a maximum score of 18. Mice are sacrificed and colonic tissues are isolated using protocols described in Examples 8 and 9. Distal colonic sections are fixed and scored for inflammation and ulceration. Remaining colonic tissue is homogenized and cytokine levels (e.g., IL-1β, TNF-α, IL-6, IFN-γ, and IL-10), as well as myeloperoxidase activity, are measured using methods described below. 
     Example 49. Euthanasia Procedures for Rodent Models of HE 
     Four and 24 hours prior to sacrifice, 5-bromo-2′-deooxyuridine (BrdU) (Invitrogen, Waltham, Mass.; Cat. No. B23151) may be intraperitoneally administered to mice, as recommended by the supplier. BrdU is used to monitor intestinal epithelial cell proliferation and/or migration via immunohistochemistry with standard anti-BrdU antibodies (Abcam, Cambridge, Mass.). 
     On the day of sacrifice, mice are deprived of food for 4 hours, and then gavaged with FITC-dextran tracer (4 kDa, 0.6 mg/g body weight). Fecal pellets are collected, and mice are euthanized 3 hours following FITC-dextran administration. Animals are then cardiac bled to collect hemolysis-free serum. Intestinal permeability correlates with fluorescence intensity of appropriately diluted serum (excitation, 488 nm; emission, 520 nm), and is measured using spectrophotometry. Serial dilutions of a known amount of FITC-dextran in mouse serum are used to prepare a standard curve. 
     Alternatively, intestinal inflammation is quantified according to levels of serum keratinocyte-derived chemokine (KC), lipocalin 2, calprotectin, and/or CRP-1. These proteins are reliable biomarkers of inflammatory disease activity, and are measured using DuoSet ELISA kits (R&amp;D Systems, Minneapolis, Minn.) according to manufacturer&#39;s instructions. For these assays, control serum samples are diluted 1:2 or 1:4 for KC, and 1:200 for lipocalin 2. Samples from DSS-treated mice require a significantly higher dilution. 
     Example 42. Non-obese Diabetes (NOD) Model of Hepatic Encephalopathy 
     NOD mice can be used as an in vivo model for testing the efficacy of bacteria comprising a gut-barrier enhancing circuit, e.g., a butyrate biosynthetic cassette, as these mice exhibit a pronounced “leaky gut” phenotype, which is evidenced by a decrease in the level of tight junction proteins (e.g., occludin, zonula occludin, mucin, E-cadherin). 
     To determine the efficacy of a strain comprising an arginine and butyrate producing circuit in alleviating symptoms associated with “leaky gut”, a NOD mouse model is used. NOD mice result from the autoimmune destruction of pancreatic islet β cells. A Nissle control (SYN-UCD107, kanamycin resistant Nissle), an arginine producing strain (SYN-UCD305), a butyrate producing strain (SYN-UCD502), and a strain producing both butyrate and arginine (SYN-UCD605) are compared in the study. Epithelial gut integrity (occludin and other tight junction markers) and gut inflammation (inflammatory biomarkers, e.g., IL-1A, IL-6, TNFa, IL-21) are the primary endpoints of the study. Overall animal health is the secondary endpoint of the study. Study duration is 8 weeks. 
     Animals (C57BL6, 8 weeks) are treated by oral gavage with either H2O control (n=12), or 100 mM butyrate (n=12), or arginine producing SYN-UCD305 (n=12; comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and no antibiotic resistance), or butyrate producing SYN-UCD502 (n=12; comprising wild type ArgR, no FNR-ArgAfbr, wild type ThyA, and a PydfZ-ter butyrate cassette integrated on the chromosome) or SYN-UCD605 (n=12; comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, PydfZ-ter butyrate cassette integrated on the chromosome, and no antibiotic resistance. Bacteria are administered at a dose of &gt;10e10 cells/ml in 100 ul. 
     In some embodiments, SYN-UCD501 (comprising Wild type ArgR, no FNR-ArgAfbr, wild type ThyA, and Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance) and SYN-UCD602 (comprising ΔArgR, PfnrS-ArgAfbr integrated into the chromosome at the malEK locus, ΔThyA, and Logic156 (pSC101 PydfZ-ter butyrate plasmid; amp resistance)) are used instead of SYN-UCD502 and SYN-UCD605. 
     On Day 1, mice are weighed and randomized. Animals are gavaged with 100 ul H2O, 100 mM butyrate, SYN-UCD305, SYN-UCD502, or SYN-UCD605 in the AM. Animals are gavaged with 100 ul H2O, 100 mM butyrate, SYN-UCD305, SYN-UCD502, or SYN-UCD605 in the PM. Animals are gavaged BID with 100 ul H2O, 100 mM butyrate, SYN-UCD305, SYN-UCD502, or SYN-UCD605. Animals are weighed daily. 
     On day 5, mice are fasted for 4 h and then gavaged with 0.6 mg/g FITC-dextran (40 kD). 3 h post FITC-dex administration mice are weighed, and blood is collected by cardiac bleed and colons and fecal pellets are harvested. 
     Haptoglobin/zonulin and Lcn2 are measured. RNA levels of TJP1, OCLN, CLDN25, and EPCAM are measured in colon samples (increased levels of these markers indicate therapeutic effect). RNA levels of inflammatory biomarkers are measured in the blood samples (decreased levels of these biomarkers indicate therapeutic effect). 
     Example 51. GABA Transport and Metabolic Circuits 
     In addition to the ammonia conversion circuit described above, the  E. coli  Nissle bacteria further comprise one or more GABA transport and/or one or more GABA metabolic circuits. Genetically engineered strains comprising at least one GABA transport circuit comprise a gene encoding an exemplary GABA transport protein, such as GabP (SEQ ID NO: 105, Table 48; SEQ ID NO: 106, Table 49), and are constructed using methods described above. Genetically engineered strains comprising at least one GABA metabolic circuit comprise genes encoding enzymes required for GABA catabolism, including, but not limited to GSST and SSDH, and are constructed using methods described above. 
     The genes encoding GabP, GSST, and SSDH are expressed under the control of a tetracycline-inducible promoter, a FNR promoter selected from SEQ ID NOs: 18-29, or a promoter induced by HE-related molecules or metabolites. The genes encoding GabP, GSST, and SSDH may be expressed under the control of the same or different promoters. As discussed herein, other promoters may be used. The genes encoding GabP, GSST, and SSDH are expressed on a high-copy plasmid, a low-copy plasmid, or a chromosome. The genes encoding GabP, GSST, and SSDH are inserted into the bacterial genome at one or more of the following insertion sites in  E. coli  Nissle: malE/K, araC/BAD, lacZ, thyA, malP/T. Any suitable insertion site may be used, see, e.g.,  FIG. 18 . 
     
       
         
           
               
             
               
                 TABLE 48 
               
               
                   
               
               
                 Amino acid sequence of GabP transporter (SEQ ID 
               
               
                 NO: 105) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 MGQSSQPHELGGGLKSRHVTMLSIAGVIGASLFVGSSVAIAEAGPAVLLA 
               
               
                   
               
               
                 YLFAGLLVVMIMRMLAEMAVATPDTGSFSTYADKAIGRWAGYTIGWLYWW 
               
               
                   
               
               
                 FWVLVIPLEANIAAMILHSWVPGIPIWLFSLVITLALTGSNLLSVKNYGE 
               
               
                   
               
               
                 FEFWLALCKVIAILAFIFLGAVAISGFYPYAEVSGISRLWDSGGFMPNGF 
               
               
                   
               
               
                 GAVLSAMLITMFSFMGAEIVTIAAAESDTPEKHIVRATNSVIWRISIFYL 
               
               
                   
               
               
                 CSIFVVVALIPWNMPGLKAVGSYRSVLELLNIPHAKLIMDCVILLSVTSC 
               
               
                   
               
               
                 LNSALYTASRMLYSLSRRGDAPAVMGKINRSKTPYVAVLLSTGAAFLTVV 
               
               
                   
               
               
                 VNYYAPAKVFKFLIDSSGAIALLVYLVIAVSQLRMRKILRAEGSEIRLRM 
               
               
                   
               
               
                 WLYPWLTWLVIGFITFVLVVMLFRPAQQLEVISTGLLAIGIICTVPIMAR 
               
               
                   
               
               
                 WKKLVLWQKTPVHNTR 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 49 
               
               
                   
               
               
                 Codon optimized polynucleotide sequence of GabP 
               
               
                 transporter (SEQ ID NO: 106) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 ATGGGACAGTCTTCACAACCACACGAACTTGGGGGTGGATTGAAATCGCG 
               
               
                   
               
               
                 CCATGTGACCATGTTAAGTATCGCAGGCGTGATTGGCGCCTCCTTATTTG 
               
               
                   
               
               
                 TGGGGTCCTCCGTGGCGATTGCAGAGGCGGGTCCGGCTGTACTTTTGGCA 
               
               
                   
               
               
                 TATCTTTTTGCGGGTTTACTGGTTGTGATGATCATGCGCATGCTTGCCGA 
               
               
                   
               
               
                 AATGGCTGTGGCCACGCCGGACACGGGGTCATTTTCCACTTATGCGGACA 
               
               
                   
               
               
                 AGGCGATTGGCCGCTGGGCCGGGTACACAATCGGGTGGCTGTATTGGTGG 
               
               
                   
               
               
                 TTCTGGGTGTTAGTTATCCCCTTGGAGGCCAACATCGCCGCAATGATTCT 
               
               
                   
               
               
                 GCACTCCTGGGTTCCGGGTATCCCGATCTGGCTGTTCAGCTTGGTGATCA 
               
               
                   
               
               
                 CCCTGGCACTGACGGGCAGCAACTTATTGAGTGTGAAAAACTATGGAGAG 
               
               
                   
               
               
                 TTTGAATTTTGGCTGGCCCTGTGTAAAGTCATTGCTATCTTGGCATTCAT 
               
               
                   
               
               
                 TTTTTTAGGAGCGGTAGCAATCAGTGGCTTCTACCCTTATGCAGAAGTTT 
               
               
                   
               
               
                 CGGGGATTTCCCGTCTTTGGGATAGTGGCGGATTCATGCCAAACGGGTTT 
               
               
                   
               
               
                 GGAGCTGTACTGTCAGCCATGTTGATTACCATGTTTAGCTTTATGGGTGC 
               
               
                   
               
               
                 CGAGATCGTGACAATCGCCGCAGCCGAGAGTGATACCCCGGAAAAGCACA 
               
               
                   
               
               
                 TTGTTCGTGCGACGAATTCGGTAATTTGGCGTATTTCGATTTTTTACTTA 
               
               
                   
               
               
                 TGCTCCATTTTCGTTGTGGTCGCCCTTATCCCCTGGAACATGCCAGGCTT 
               
               
                   
               
               
                 AAAAGCAGTAGGCAGCTACCGCTCAGTCCTGGAATTACTGAACATTCCTC 
               
               
                   
               
               
                 ACGCGAAGTTAATTATGGATTGCGTAATCCTGTTATCGGTAACGAGCTGC 
               
               
                   
               
               
                 CTTAACAGTGCTCTGTACACGGCTTCACGTATGCTGTACTCTTTAAGTCG 
               
               
                   
               
               
                 CCGTGGCGATGCACCTGCCGTTATGGGCAAGATTAACCGCAGTAAGACGC 
               
               
                   
               
               
                 CGTATGTAGCTGTTTTGCTGTCGACTGGAGCTGCGTTTCTTACAGTCGTA 
               
               
                   
               
               
                 GTAAACTATTACGCACCAGCTAAAGTTTTCAAATTCCTTATTGATTCGTC 
               
               
                   
               
               
                 TGGGGCAATCGCACTTCTGGTGTACCTGGTCATCGCGGTGTCACAACTTC 
               
               
                   
               
               
                 GCATGCGCAAGATCTTGCGTGCGGAGGGCAGTGAGATTCGTTTGCGTATG 
               
               
                   
               
               
                 TGGCTGTATCCGTGGCTGACGTGGCTTGTTATTGGTTTCATTACTTTTGT 
               
               
                   
               
               
                 GTTGGTAGTGATGCTGTTTCGTCCAGCGCAACAGCTGGAGGTGATTTCTA 
               
               
                   
               
               
                 CCGGACTGTTGGCAATCGGCATCATCTGTACCGTCCCAATCATGGCTCGC 
               
               
                   
               
               
                 TGGAAAAAGTTGGTCTTATGGCAGAAGACCCCTGTACACAACACCCGT 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria comprise the nucleic acid sequence of SEQ ID NO: 106 or a functional fragment thereof. In some embodiments, the genetically engineered bacteria comprise a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 106 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise a nucleic acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the DNA sequence of SEQ ID NO: 106 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 106 or a functional fragment thereof. 
     Example 52. Manganese Transport Circuit 
     In addition to the circuits described above, the  E. coli  Nissle bacteria further comprise one or more manganese transport circuits. Genetically engineered strains comprising at least one manganese transport circuit comprise a gene encoding an exemplary manganese transport protein, such as MntH (SEQ ID NO: 107, Table 50, SEQ ID NO: 108, Table 51), and are constructed using methods described above. 
     The gene encoding MntH is expressed under the control of a tetracycline-inducible promoter, a FNR promoter selected from SEQ ID NOs: 18-29, or a promoter induced by HE-related molecules or metabolites. As discussed herein, other promoters may be used. The gene encoding MntH is expressed on a high-copy plasmid, a low-copy plasmid, or a chromosome. The gene encoding MntH is inserted into the bacterial genome at one or more of the following insertion sites in  E. coli  Nissle: malE/K, araC/BAD, lacZ, thyA, malP/T. Any suitable insertion site may be used, see, e.g.,  FIG. 18 . 
     
       
         
           
               
             
               
                 TABLE 50 
               
               
                   
               
               
                 Amino acid sequence of MntH transporter (SEQ ID 
               
               
                 NO: 107) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 MTNYRVESSSGRAARKMRLALMGPAFIAAIGYIDPGNFATNIQAGASFGY 
               
               
                   
               
               
                 QLLWVVVWANLMAMLIQILSAKLGIATGKNLAEQIRDHYPRPVVWFYWVQ 
               
               
                   
               
               
                 AEIIAMATDLAEFIGAAIGFKLILGVSLLQGAVLTGIATFLILMLQRRGQ 
               
               
                   
               
               
                 KPLEKVIGGLLLFVAAAYIVELIFSQPNLAQLGKGMVIPSLPTSEAVFLA 
               
               
                   
               
               
                 AGVLGATIMPHVIYLHSSLTQHLHGGSRQQRYSATKWDVAIAMTIAGFVN 
               
               
                   
               
               
                 LAMMATAAAAFHFSGHTGVADLDEAYLTLQPLLSHAAATVFGLSLVAAGL 
               
               
                   
               
               
                 SSTVVGTLAGQVVMQGFIRFHIPLWVRRTVTMLPSFIVILMGLDPTRILV 
               
               
                   
               
               
                 MSQVLLSFGIALALVPLLIFTSDSKLMGDLVNSKRVKQTGWVIVVLVVAL 
               
               
                   
               
               
                 NIWLLVGTALGL 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 51 
               
               
                   
               
               
                 Polynucleotide sequence of MntH transporter (SEQ 
               
               
                 ID NO: 108) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
            
               
                 ATGACCAATTATCGTGTTGAAAGTAGTAGTGGCCGCGCGGCTCGTAAAAT 
               
               
                   
               
               
                 GCGTCTGGCCTTAATGGGCCCGGCGTTTATTGCTGCGATTGGATACATTG 
               
               
                   
               
               
                 ATCCGGGCAATTTCGCTACAAACATCCAAGCAGGTGCATCCTTCGGTTAC 
               
               
                   
               
               
                 CAGCTTCTGTGGGTAGTGGTATGGGCTAACCTGATGGCCATGCTTATTCA 
               
               
                   
               
               
                 AATTCTTTCAGCTAAGCTTGGTATTGCCACAGGAAAGAATTTAGCCGAGC 
               
               
                   
               
               
                 AGATTCGTGACCACTATCCCCGCCCCGTGGTCTGGTTCTATTGGGTCCAG 
               
               
                   
               
               
                 GCAGAGATTATCGCGATGGCGACTGATTTAGCCGAATTTATTGGGGCAGC 
               
               
                   
               
               
                 TATTGGATTTAAGCTGATCCTTGGCGTATCTCTGTTGCAAGGCGCGGTAT 
               
               
                   
               
               
                 TGACCGGAATTGCAACCTTTTTGATTCTTATGTTGCAACGTCGTGGGCAG 
               
               
                   
               
               
                 AAGCCTCTGGAAAAAGTCATCGGCGGGTTATTGCTTTTTGTTGCCGCGGC 
               
               
                   
               
               
                 CTACATTGTGGAACTGATCTTTTCTCAACCTAACCTGGCGCAGCTTGGTA 
               
               
                   
               
               
                 AAGGCATGGTAATCCCGTCACTTCCTACATCTGAGGCAGTATTCTTAGCA 
               
               
                   
               
               
                 GCCGGCGTCTTGGGCGCAACTATCATGCCCCATGTCATCTACTTACACAG 
               
               
                   
               
               
                 TTCTCTGACTCAGCACTTACACGGTGGGTCGCGCCAACAGCGTTACTCCG 
               
               
                   
               
               
                 CAACAAAGTGGGACGTTGCAATTGCCATGACCATTGCCGGTTTTGTTAAC 
               
               
                   
               
               
                 CTGGCGATGATGGCCACGGCTGCTGCCGCCTTTCATTTCAGTGGCCACAC 
               
               
                   
               
               
                 TGGTGTAGCCGATCTGGATGAGGCATACCTGACCTTGCAGCCTCTGTTGT 
               
               
                   
               
               
                 CTCATGCAGCCGCCACCGTTTTTGGTTTAAGCTTAGTAGCCGCCGGCTTG 
               
               
                   
               
               
                 AGTAGCACGGTGGTAGGCACATTGGCTGGACAGGTCGTGATGCAAGGTTT 
               
               
                   
               
               
                 CATTCGTTTCCATATTCCGTTATGGGTACGTCGCACGGTACGATGCTGCC 
               
               
                   
               
               
                 GTCATTTATCGTCATCCTGATGGGATTAGACCCGACGCGCATCCTGGTAA 
               
               
                   
               
               
                 TGTCGCAAGTTTTACTGAGCTTTGGAATCGCGTTGGCCCTGGTGCCATTA 
               
               
                   
               
               
                 CTTATCTTCACTAGCGATAGTAAGTTGATGGGTGATCTTGTCAATAGCAA 
               
               
                   
               
               
                 ACGTGTGAAGCAAACAGGCTGGGTCATTGTGGTACTGGTTGTGGCCTTAA 
               
               
                   
               
               
                 ACATTTGGTTGTTAGTGGGCACGGCCCTTGGCTTG 
               
               
                   
               
            
           
         
       
     
     Example 53. Circuit Comprising TesB 
     The nucleic acid sequence of TesB is translated as follows. 
     
       
         
           
               
             
               
                 TABLE 52 
               
               
                   
               
               
                 TesB sequences 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 tesB 
                 ATGAGTCAGGCGCTAAAAAATTTACTGACATTGTTAAATCTGGAAAAAAT 
               
               
                 SEQ ID NO 
                 TGAGGAAGGACTCTTTCGCGGCCAGAGTGAAGATTTAGGTTTACGCCAGG 
               
               
                 48 
                 TGTTTGGCGGCCAGGTCGTGGGTCAGGCCTTGTATGCTGCAAAAGAGACC 
               
               
                   
                 GTCCCTGAAGAGCGGCTGGTACATTCGTTTCACAGCTACTTTCTTCGCCC 
               
               
                   
                 TGGCGATAGTAAGAAGCCGATTATTTATGATGTCGAAACGCTGCGTGACG 
               
               
                   
                 GTAACAGCTTCAGCGCCCGCCGGGTTGCTGCTATTCAAAACGGCAAACCG 
               
               
                   
                 ATTTTTTATATGACTGCCTCTTTCCAGGCACCAGAAGCGGGTTTCGAACA 
               
               
                   
                 TCAAAAAACAATGCCGTCCGCGCCAGCGCCTGATGGCCTCCCTTCGGAAA 
               
               
                   
                 CGCAAATCGCCCAATCGCTGGCGCACCTGCTGCCGCCAGTGCTGAAAGAT 
               
               
                   
                 AAATTCATCTGCGATCGTCCGCTGGAAGTCCGTCCGGTGGAGTTTCATAA 
               
               
                   
                 CCCACTGAAAGGTCACGTCGCAGAACCACATCGTCAGGTGTGGATCCGCG 
               
               
                   
                 CAAATGGTAGCGTGCCGGATGACCTGCGCGTTCATCAGTATCTGCTCGGT 
               
               
                   
                 TACGCTTCTGATCTTAACTTCCTGCCGGTAGCTCTACAGCCGCACGGCAT 
               
               
                   
                 CGGTTTTCTCGAACCGGGGATTCAGATTGCCACCATTGACCATTCCATGT 
               
               
                   
                 GGTTCCATCGCCCGTTTAATTTGAATGAATGGCTGCTGTATAGCGTGGAG 
               
               
                   
                 AGCACCTCGGCGTCCAGCGCACGTGGCTTTGTGCGCGGTGAGTTTTATAC 
               
               
                   
                 CCAAGACGGCGTACTGGTTGCCTCGACCGTTCAGGAAGGGGTGATGCGTA 
               
               
                   
                 ATCACAATTAA 
               
               
                   
               
               
                 tesB: SEQ 
                 MSQALKNLLTLLNLEKIEEGLFRGQSEDLGLRQVFGGQVVGQALYAAKET 
               
               
                 ID NO: 109 
                 VPEERLVHSFHSYFLRPGDSKKPIIYDVETLRDGNSFSARRVAAIQNGKP 
               
               
                   
                 IFYMTASFQAPEAGFEHQKTMPSAPAPDGLPSETQIAQSLAHLLPPVLKD 
               
               
                   
                 KFICDRPLEVRPVEFHNPLKGHVAEPHRQVWIRANGSVPDDLRVHQYLLG 
               
               
                   
                 YASDLNFLPVALQPHGIGFLEPGIQIATIDHSMWFHRPFNLNEWLLYSVE 
               
               
                   
                 STSASSARGFVRGEFYTQDGVLVASTVQEGVMRNHN 
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 109 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 109 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 109 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 91 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 91 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 91 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 93 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 93 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 93 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 95 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 95 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 95 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 97 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 97 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 97 or a functional fragment thereof. 
     In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 99 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 99 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 99 or a functional fragment thereof. 
     
       
         
           
               
             
               
                 TABLE 53 
               
             
            
               
                   
               
               
                 FNRS-fbrArgA and no antibiotic resistance 
               
            
           
           
               
               
               
            
               
                 Description 
                 Sequence 
                 SEQ ID 
               
               
                   
               
               
                 Terminator 
                 
                   
                     CAAATAAAATGAAAGGCTCAGTCGAAAGACTGGGCC 
                   
                 
                 SEQ ID 
               
               
                 sequence 
                 
                   
                     TTTCGTTTTATCTGTTGTTTGTCGGTGAACGCTCTC 
                   
                 
                 NO: 110 
               
               
                   
                 
                   
                     CTGAGTAGGACAAAT 
                   
                 
                   
               
               
                   
               
               
                 Terminator 
                 
                   
                     AGAAGGCCATCCTGACGGATGGCCTTTT 
                   
                 
                 SEQ ID 
               
               
                   
                   
                 NO: 111 
               
               
                   
               
               
                 FRT site 
                 
                   
                   
                 
                 SEQ ID 
               
               
                   
                 
                   
                 
                 NO: 112 
               
               
                   
               
               
                 FNRS 
                 
                   GTACCAGTTGTTCTTATTGGTGGTGTTGCTTTATGG 
                 
                 SEQ ID 
               
               
                 promoter 
                 
                   TTGCATCGTAGTAAATGGTTGTAACAAAAGCAATTT 
                 
                 NO: 113 
               
               
                   
                 
                   TTCCGGCTGTCTGTATACAAAAACGCCGTAAAGTTT 
                 
                   
               
               
                   
                 
                   GAGCGAAGTCAATAAACTCTCTACCCATTCAGGGCA 
                 
                   
               
               
                   
                 
                   ATATCTCTCTTGGATCC 
                 
                   
               
               
                   
               
               
                 ArgAfbr 
                 
                   ATGGTAAAGGAACGTAAAACCGAGTTGGTCGAGGGA 
                 
                 SEQ ID 
               
               
                   
                 
                   TTCCGCCATTCGGTTCCCTGTATCAATACCCACCGG 
                 
                 NO: 114 
               
               
                   
                 
                   GGAAAAACGTTTGTCATCATGCTCGGCGGTGAAGCC 
                 
                   
               
               
                   
                 
                   ATTGAGCATGAGAATTTCTCCAGTATCGTTAATGAT 
                 
                   
               
               
                   
                 
                   ATCGGGTTGTTGCACAGCCTCGGCATCCGTCTGGTG 
                 
                   
               
               
                   
                 
                   GTGGTCTATGGCGCACGTCCGCAGATCGACGCAAAT 
                 
                   
               
               
                   
                 
                   CTGGCTGCGCATCACCACGAACCGCTGTATCACAAG 
                 
                   
               
               
                   
                 
                   AATATACGTGTGACCGACGCCAAAACACTGGAACTG 
                 
                   
               
               
                   
                 
                   GTGAAGCAGGCTGCGGGAACATTGCAACTGGATATT 
                 
                   
               
               
                   
                 
                   ACTGCTCGCCTGTCGATGAGTCTCAATAACACGCCG 
                 
                   
               
               
                   
                 
                   CTGCAGGGCGCGCATATCAACGTCGTCAGTGGCAAT 
                 
                   
               
               
                   
                 
                   TTTATTATTGCCCAGCCGCTGGGCGTCGATGACGGC 
                 
                   
               
               
                   
                 
                   GTGGATTACTGCCATAGCGGGCGTATCCGGCGGATT 
                 
                   
               
               
                   
                 
                   GATGAAGACGCGATCCATCGTCAACTGGACAGCGGT 
                 
                   
               
               
                   
                 
                   GCAATAGTGCTAATGGGGCCGGTCGCTGTTTCAGTC 
                 
                   
               
               
                   
                 
                   ACTGGCGAGAGCTTTAACCTGACCTCGGAAGAGATT 
                 
                   
               
               
                   
                 
                   GCCACTCAACTGGCCATCAAACTGAAAGCTGAAAAG 
                 
                   
               
               
                   
                 
                   ATGATTGGTTTTTGCTCTTCCCAGGGCGTCACTAAT 
                 
                   
               
               
                   
                 
                   GACGACGGTGATATTGTCTCCGAACTTTTCCCTAAC 
                 
                   
               
               
                   
                 
                   GAAGCGCAAGCGCGGGTAGAAGCCCAGGAAGAGAAA 
                 
                   
               
               
                   
                 
                   GGCGATTACAACTCCGGTACGGTGCGCTTTTTGCGT 
                 
                   
               
               
                   
                 
                   GGCGCAGTGAAAGCCTGCCGCAGCGGCGTGCGTCGC 
                 
                   
               
               
                   
                 
                   TGTCATTTAATCAGTTATCAGGAAGATGGCGCGCTG 
                 
                   
               
               
                   
                 
                   TTGCAAGAGTTGTTCTCACGCGACGGTATCGGTACG 
                 
                   
               
               
                   
                 
                   CAGATTGTGATGGAAAGCGCCGAGCAGATTCGTCGC 
                 
                   
               
               
                   
                 
                   GCAACAATCAACGATATTGGCGGTATTCTGGAGTTG 
                 
                   
               
               
                   
                 
                   ATTCGCCCACTGGAGCAGCAAGGTATTCTGGTACGC 
                 
                   
               
               
                   
                 
                   CGTTCTCGCGAGCAGCTGGAGATGGAAATCGACAAA 
                 
                   
               
               
                   
                 
                   TTCACCATTATTCAGCGCGATAACACGACTATTGCC 
                 
                   
               
               
                   
                 
                   TGCGCCGCGCTCTATCCGTTCCCGGAAGAGAAGATT 
                 
                   
               
               
                   
                 
                   GGGGAAATGGCCTGTGTGGCAGTTCACCCGGATTAC 
                 
                   
               
               
                   
                 
                   CGCAGTTCATCAAGGGGTGAAGTTCTGCTGGAACGC 
                 
                   
               
               
                   
                 
                   ATTGCCGCTCAGGCTAAGCAGAGCGGCTTAAGCAAA 
                 
                   
               
               
                   
                 
                   TTGTTTGTGCTGACCACGCGCAGTATTCACTGGTTC 
                 
                   
               
               
                   
                 
                   CAGGAACGTGGATTTACCCCAGTGGATATTGATTTA 
                 
                   
               
               
                   
                 
                   CTGCCCGAGAGCAAAAAGCAGTTGTACAACTACCAG 
                 
                   
               
               
                   
                 
                   CGTAAATCCAAAGTGTTGATGGCGGATTTAGGGTAA 
                 
                   
               
               
                   
               
               
                   
                 
                   
                   
                 
                 SEQ ID 
               
               
                   
                 
                   
                 
                 NO: 115 
               
               
                   
               
               
                 KanR gene 
                 
                   atgattgaacaagatggattgcacgcaggttctccg 
                 
                 SEQ ID 
               
               
                   
                 
                   gccgcttgggtggagaggctattcggctatgactgg 
                 
                 NO: 116 
               
               
                   
                 
                   gcacaacagacaatcggctgctctgatgccgccgtg 
                 
                   
               
               
                   
                 
                   ttccggctgtcagcgcaggggcgcccggttcttttt 
                 
                   
               
               
                   
                 
                   gtcaagaccgacctgtccggtgccctgaatgaactg 
                 
                   
               
               
                   
                 
                   caggacgaggcagcgcggctatcgtggctggccacg 
                 
                   
               
               
                   
                 
                   acgggcgttccttgcgcagctgtgctcgacgttgtc 
                 
                   
               
               
                   
                 
                   actgaagcgggaagggactggctgctattgggcgaa 
                 
                   
               
               
                   
                 
                   gtgccggggcaggatctcctgtcatctcaccttgct 
                 
                   
               
               
                   
                 
                   cctgccgagaaagtatccatcatggctgatgcaatg 
                 
                   
               
               
                   
                 
                   cggcggctgcatacgcttgatccggctacctgccca 
                 
                   
               
               
                   
                 
                   ttcgaccaccaagcgaaacatcgcatcgagcgagca 
                 
                   
               
               
                   
                 
                   cgtactcggatggaagccggtcttgtcgatcaggat 
                 
                   
               
               
                   
                 
                   gatctggacgaagagcatcaggggctcgcgccagcc 
                 
                   
               
               
                   
                 
                   gaactgttcgccaggctcaaggcgcgcatgcccgac 
                 
                   
               
               
                   
                 
                   ggcgaggatctcgtcgtgacccatggcgatgcctgc 
                 
                   
               
               
                   
                 
                   ttgccgaatatcatggtggaaaatggccgcttttct 
                 
                   
               
               
                   
                 
                   ggattcatcgactgtggccggctgggtgtggcggac 
                 
                   
               
               
                   
                 
                   cgctatcaggacatagcgttggctacccgtgatatt 
                 
                   
               
               
                   
                 
                   gctgaagagcttggcggcgaatgggctgaccgcttc 
                 
                   
               
               
                   
                 
                   ctcgtgctttacggtatcgccgctcccgattcgcag 
                 
                   
               
               
                   
                 
                   cgcatcgccttctatcgccttcttgacgagttcttc 
                 
                   
               
               
                   
                   tga gcgggactctggggttcgaaatgaccgaccaag 
                   
               
               
                   
                 cgacgcccaacctgccatcacgagatttcgattcca 
                   
               
               
                   
                 ccgccgccttctatgaaaggttgggcttcggaatcg 
                   
               
               
                   
                 ttttccgggacgccggctggatgatcctccagcgcg 
                   
               
               
                   
                 gggatctcatgctggagttcttcgcccaccccagct 
                   
               
               
                   
                 tcaaaagcgctct 
                   
               
               
                   
               
               
                 KanR 
                 
                   ggttgggaagccctgcaaagtaaactggatggcttt 
                 
                 SEQ ID 
               
               
                 promoter 
                 
                   cttgccgccaaggatctgatggcgcaggggatcaag 
                 
                 NO: 117 
               
               
                   
                 
                   atctgatcaagagacaggatgaggatcgtttcgc 
                 
                   
               
               
                   
               
               
                 CamR gene 
                 
                   TCATCGCAGTACTGTTGTATTCATTAAGCATCTGCC 
                 
                 SEQ ID 
               
               
                   
                 
                   GACATGGAAGCCATCACAAACGGCATGATGAACCTG 
                 
                 NO: 118 
               
               
                   
                 
                   AATCGCCAGCGGCATCAGCACCTTGTCGCCTTGCGT 
                 
                   
               
               
                   
                 
                   ATAATATTTGCCCATGGTGAAAACGGGGGCGAAGAA 
                 
                   
               
               
                   
                 
                   GTTGTCCATATTGGCCACGTTTAAATCAAAACTGGT 
                 
                   
               
               
                   
                 
                   GAAACTCACCCAGGGATTGGCTGAGACGAAAAACAT 
                 
                   
               
               
                   
                 
                   ATTCTCAATAAACCCTTTAGGGAAATAGGCCAGGTT 
                 
                   
               
               
                   
                 
                   TTCACCGTAACACGCCACATCTTGCGAATATATGTG 
                 
                   
               
               
                   
                 
                   TAGAAACTGCCGGAAATCGTCGTGGTATTCACTCCA 
                 
                   
               
               
                   
                 
                   GAGCGATGAAAACGTTTCAGTTTGCTCATGGAAAAC 
                 
                   
               
               
                   
                 
                   GGTGTAACAAGGGTGAACACTATCCCATATCACCAG 
                 
                   
               
               
                   
                 
                   CTCACCGTCTTTCATTGCCATACGTAATTCCGGATG 
                 
                   
               
               
                   
                 
                   AGCATTCATCAGGCGGGCAAGAATGTGAATAAAGGC 
                 
                   
               
               
                   
                 
                   CGGATAAAACTTGTGCTTATTTTTCTTTACGGTCTT 
                 
                   
               
               
                   
                 
                   TAAAAAGGCCGTAATATCCAGCTGAACGGTCTGGTT 
                 
                   
               
               
                   
                 
                   ATAGGTACATTGAGCAACTGACTGAAATGCCTCAAA 
                 
                   
               
               
                   
                 
                   ATGTTCTTTACGATGCCATTGGGATATATCAACGGT 
                 
                   
               
               
                   
                 
                   GGTATATCCAGTGATTTTTTTCTCCAT 
                 
                   
               
               
                   
               
               
                 CamR 
                 
                   TTTAGCTTCCTTAGCTCCTGAAAATCTCGACAACTC 
                 
                 SEQ ID 
               
               
                 promoter 
                 
                   AAAAAATACGCCCGGTAGTGATCTTATTTCATTATG 
                 
                 NO: 119 
               
               
                   
                 G TGAAAGTTGGAACCTCTTACGTGCCGATCA ACGTC 
                   
               
               
                   
                 TCATTTTCGCCAAAAGTTGGCCCAGGGCTTCCCGGT 
                   
               
               
                   
                 ATCAACAGGGACACCAGGATTTATTTATTCTGCGAA 
                   
               
               
                   
                 GTGATCTTCCGTCACAGGTAGGCGCGCC   
               
               
                   
               
            
           
         
       
     
     In some embodiments, the genetically engineered bacteria comprise the amino acid sequence of SEQ ID NO: 101 or a functional fragment thereof. In some embodiments, genetically engineered bacteria comprise an amino acid sequence that is at least about 80%, at least about 85%, at least about 90%, at least about 95%, or at least about 99% homologous to the amino acid sequence of SEQ ID NO: 101 or a functional fragment thereof, or a nucleic acid sequence that, but for the redundancy of the genetic code, encodes the same polypeptide as SEQ ID NO: 101 or a functional fragment thereof.