Patent Publication Number: US-2022228121-A1

Title: Cultured meat product with genetically modified cells

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 62/855,698, filed May 31, 2019, and U.S. Provisional Application No. 62/861,606, filed Jun. 14, 2019, each of which is incorporated herein by reference in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     This invention was made with government support under grant EB002520 awarded by the National Institutes of Health. The government has certain rights in the invention. 
    
    
     REFERENCE TO A SEQUENCE LISTING SUBMITTED VIA EFS-WEB 
     The content of the ASCII text file of the sequence listing named “166118_00970_ST25.txt” which is 114 kb in size was created on Jun. 1, 2020 and electronically submitted via EFS-Web herewith the application is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Synthetic biology and metabolic engineering have become major tools across numerous disciplines (Keasling, 2010). However, broad use in mammalian systems has been slow to develop, and progress within these systems has been largely isolated to applications such as therapeutic protein production (e.g., monoclonal antibodies) or the study and treatment of disease (e.g., metabolic reprogramming) (Davy et al., 2017; Schukur and Fussenegger, 2016). In these efforts, apart from genetic tools such as viral or bacterial editing or regulatory systems, little attention has been given to heterologous engineering of mammalian cells using genes from other taxa (i.e., bacteria or plants) (Mojica and Montoliu, 2016; Zhang et al., 2006). In contrast, metabolic engineering efforts in bacteria, yeasts or plants have exploited diverse taxonomic transgenes for applications from medicine and cosmetics to energy and agriculture (Heider and Wendisch, 2015; Nielsen, 2015; Sack et al., 2015). Recent advances in tissue engineering have expanded our perspective about possible applications of animal cell culture to food and nutrition, robotics, and biosensors (Banerjee and Bhunia, 2009; Rubio et al., 2019). This shift provides the opportunity to revisit mammalian metabolic engineering and expand efforts to include cross-taxa engineering for broad applications. 
     One such application is the production of meat through cell culture (known by various terms—this paper will use “cultured meat”), which has been proposed as a means of addressing the environmental, ethical, and public-health concerns of animal agriculture (Mattick et al., 2015; Post, 2012). 
     SUMMARY OF THE INVENTION 
     In a first aspect, provided herein is an engineered cell that endogenously synthesizes phytoene and comprises a heterologous polynucleotide encoding phytoene synthase. In some embodiments, the phytoene synthase has a sequence at least 90% identical to SEQ ID NO:1 or SEQ ID NO:_. In some embodiments, the cell endogenously synthesizes lycopene and comprises a heterologous polynucleotide encoding phytoene desaturase. In some embodiments, the phytoene desaturase has a sequence at least 90% identical to SEQ ID NO:3. In some embodiments, the cell endogenously synthesizes β-carotene and comprises a heterologous polynucleotide encoding lycopene cyclase. In some embodiments, the lycopene cyclase has a sequence at least 90% identical to SEQ ID NO:5 or SEQ ID NO:_. In some embodiments, the cell is a mammalian cell. In some embodiments, cell is a Pax7 +  mammalian muscle precursor cell. In some embodiments, the cell is an Actin +  myosin heavy chain (MHC) +  mammalian multinucleated myotube. In some embodiments, total carotenoid production in the engineered cell is at least 5 times greater than total carotenoid production in said cell without the heterologous polynucleotides encoding phytoene synthase, phytoene desaturase, and lycopene cyclase. 
     In a second aspect, provided herein is a method of making an engineered cell as described herein, comprising introducing in a cell that natively synthesizes geranylgeranyl pyrophosphate (i) a heterologous polynucleotide encoding phytoene synthase; (ii) a heterologous polynucleotide encoding phytoene desaturase; (iii) a heterologous polynucleotide encoding lycopene cyclase; or (iv) a combination thereof. In some embodiments, the cell is a Pax7+ mammalian muscle precursor cell. 
     In a third aspect, provided herein is an engineered cell that endogenously synthesizes Vitamin C and comprises one or more exogenous polynucleotides encoding UDP-glucose 6-dehydrogenase (UGDH), UDP glucuronosyltransferase 1 (UGT1A1), aldo-keto reductase family 1 (AKR1A1), regucalcin (RGN), and L-gulono-gamma-lactone oxidase (GULO). 
     In a forth aspect, provided herein is an engineered cell that endogenously synthesizes curcumin and comprises one or more heterologous polynucleotides encoding tyrosine ammonia-lyase (PTAL), 4-coumarate-CoA ligase (4CL), phenylpropanoyl-diketide-CoA synthase (DCS) and curcumin synthase (CURS3). 
     In a fifth aspect, provided herein is an engineered cell that endogenously synthesizes cannabidiol (CBD) and comprises one or more heterologous polynucleotides encoding 3,5,7-trioxododecanoyl-CoA synthase (OLS), olivetolic acid cyclase (OAC), cannabigerolic acid synthase (CBGAS), and cannabidiolic acid synthase (CBDAS). 
     In a sixth aspect, provided herein is an engineered cell comprising a heterologous polynucleotide that encodes nanobody V565 having a sequence at least 95% identical to SEQ ID NO:7. In some embodiments, the polynucleotide encodes the V565 nanobody that is covalently linked to tumor necrosis factor α (TNFα) by a cleavable polypeptide linker. In some embodiments, the cleavable polypeptide linker comprises SEQ ID NO:9. 
     In a seventh aspect, provided herein is an engineered cell comprising a heterologous polynucleotide encoding antimicrobial peptide 16 (AMP16) having a sequence at least 95% identical to SEQ ID NO:8. In some embodiments, the polynucleotide encodes at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, or at least 10 repeats of AMP16 each separated by a linker polypeptide comprising Asn-Pro-Val repeats. 
     In an eight aspect, provided herein is a cultured meat product comprising a confluent serum-free culture comprising the an engineered cell as described herein seeded on a food safe substrate. In some embodiments, the substrate is a film. In some embodiments, the substrate is a sponge or three-dimensional matrix. In some embodiments, the substrate is a chitosan substrate. In some embodiments, the cell culture comprises multinucleated myotubes derived from Pax7+ mammalian satellite cells. In some embodiments, the multinucleated myotubes express myosin heavy chain (MHC) and actin. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The patent or patent application file contains at least one drawing in color. Copies of this patent or patent application publication with color drawings will be provided by the Office upon request and payment of the necessary fee. 
         FIG. 1  shows gene constructs and their corresponding terminal product in the carotenoid biosynthesis pathway. All gene constructs contain a puromycin resistance gene and genes of interest simultaneously promoted by a bi-direction synthetic RBPSA/CMV promoter. All gene of interest regions contain a green fluorescent protein (GFP) sequence produced in isolation or as part of a multi-cistronic mRNA transcript. The constructs are designated (from top to bottom) pGFP, pCrtB, pCrtB/I, and pCrtB/I/Y. 
         FIGS. 2A-2B  show bovine satellite cell characterization. ( FIG. 2A ) Immunofluorescent staining for Pax7 (green), a transcription factor and satellite cell marker, along with counter-stains for cellular actin (Phalloidin, re(D) and nuclei (DAPI, blue). ( FIG. 2B ) Immunofluorescent staining for myosin heavy chain (MF20, green), a contractile protein of skeletal muscle, along with counter-stains for cellular actin and nuclei. High-objective staining of differentiated cells reveals striated patterns in both actin and myosin heavy chain, indicating skeletal muscle sarcomere formation. Scale bars are 100 μm. 
         FIGS. 3A-3C  show engineered cell growth and development. ( FIG. 3A ) Fluorescence image of GFP expression in C2C12s and BSCs engineered with all four constructs (carotenoid-producing and control). GFP expression implies successful expression of other enzymes in gene constructs, due to the structure of the constructs. ( FIG. 3B ) Growth curves C2C12s and BSCs engineered with all four constructs over eight days n=3 distinct samples, * indicates significant difference from pGFP for the corresponding color, p&lt;0.05. ( FIG. 3C ) Immunofluorescent staining for Pax7 (re(D) and Myosin Heavy Chain (re(D) in pCrtB/I/Y BSCs before (top) and after (bottom) differentiation. Counterstains for DAPI (blue) show nuclei, and endogenous GFP (green) show cell morphology. Scale bars are 100 μm. 
         FIGS. 4A-4B  show carotenoid production in engineered cells. Carotenoid production in engineered cells. ( FIG. 4A ) Carotenoid production in C2C12s engineered with pCrtB, pCrtB/I, and pCrtB/I/Y. In pCrtB cells, only phytoene is produced. In pCrtB/I cells, most of the phytoene is converted to lycopene. In pCrtB/I/Y cells, carotenoids accumulate in β-carotene, though total carotenoid levels are notably reduced compared to pCrtB and pCrtB/I. n=3 distinct samples; different letters indicate statistical differences between bars, p&lt;0.05 ( FIG. 4B ) Carotenoid production in BSCs engineered with pCrtB, pCrtB/I, and pCrtB/I/Y. Trends follow those of C2C12s, with a ˜10-fold reduction in total carotenoid content in all cases compared with C2C12s. n=3 distinct samples; different letters indicate statistical differences between bars, p&lt;0.05. Carotenoid data is provided as μg/g protein. Individual values and data for comparing carotenoids to protein are given in  FIGS. 4C-4D . 
         FIGS. 4C-4D  show carotenoid and protein quantification data. Individual carotenoid and protein data points used for generating μg/g data. ( FIG. 4C ) C2C12 carotenoid and protein quantification per million cells for all cell types and treatments. Trends are the same as in  FIG. 4  and  FIG. 5 . ( FIG. 4D ) BSC carotenoid and protein quantification per million cells for all cell types and treatments. Trends are the same as in  FIG. 4A-4B  and  FIGS. 5A-5C . For all, n=3 distinct samples. Within plots, different letters indicate statistical differences between bars, p&lt;0.05). 
         FIGS. 5A-5C  show carotenoid optimization. ( FIG. 5A ) the carotenoid biosynthesis pathway in its context as a shared pathway for precursors in cholesterol synthesis. The possible mechanisms for optimization are shown. Puromycin (purple) acts by selecting cells that offer higher enzyme expression, and therefore increased flux in carotenoid synthesis. Ketoconazole (re(D) acts by inhibiting the conversion of lanosterol to zymosterol, increasing carotenoid precursor farnesyl pyrophosphate (FPP) levels by either causing the upstream accumulation of lanosterol, squalene, and FPP, or by reducing cholesterol&#39;s impact as a feedback inhibitor of upstream FPP synthesis reactions. ( FIG. 5B ) Cell pellet images of engineered BSCs. The color effect of carotenoids can be seen, with pGFP cells slightly green, pCrtB containing no pigment, and pCrtB/I and pCrtB/Y cells containing some orange pigment. Optimized pCrtB/I/Y cells are notably more orange, indicating an increase in carotenoid levels. ( FIG. 5C ) Quantitative HPLC of β-carotene in optimized cells. In BSCs, ketoconazole and puromycin conditioning offer an additive increase in β-carotene. In C2C12s, ketoconazole and puromycin together do not significantly increase β-carotene. n=3 distinct samples; * p&lt;0.05. Carotenoid data is provided as μg/g protein. Individual values and data for comparing carotenoids to protein are given in  FIGS. 4C-4D . 
         FIG. 6  shows thiobarbituric acid reactive substances (TBARS) assay for engineered BSCs with or without heating. All heated samples offer a significant increase in Malondialdehyde (MD(A) compared with raw samples, indicating significant oxidative challenge from this “cooking” process. In heated samples, pCrtB, pCrtB/I and pCrtB/I/Y cells offer significantly reduced malondialdehyde (MD(A) compared with controls. In unheated samples, pCrtB/I and pCrtB/I/Y samples offer a significant reduction in MDA, and pCrtB offers no significant change compared with control pGFP cells. n=3 distinct samples. Bars that do share a letter are statistically different (p&lt;0.05). 
         FIGS. 7A-7B  show carotenoid optimization treatments. ( FIG. 7A ) Flow cytometry measurements for mean fluorescent intensity in C2C12s and BSCs engineered with pCrtB/I/Y (full flow cytometry data in FIGS.  8 A_ 8 B). Cells were cultured with 2.5 ug/mL puromycin (1×), 5 ug/mL puromycin (2×) or 10 ug/mL puromycin (4×). Higher fluorescence intensity indicates higher average GFP expression, which corresponds to higher average enzyme expression. Errors given in standard error of the mean. n &gt;1,500 events for each condition. ( FIG. 7B ) 8-day cell growth for pCrtB/I/Y C2C12s and BSCs cultured in 0, 2.5, 5, 10, or 20 ug/mL ketoconazole. n=3 distinct samples. In both a &amp; b, * indicates p&lt;0.05. 
         FIGS. 8A-8B  show flow cytometry data. ( FIG. 8A ) BSC data for cells treated with different levels of puromycin. From left to right: non-engineered cells (GFP negative control), pGFP (GFP positive control), pCrtB/I/Y with 2.5 μg/mL puromycin (1× puro), pCrtB/I/Y with 5 μg/mL puromycin (2× puro), and pCrtB/I/Y with 10 μg/mL puromycin (4×). Top row is forward scattering (FSC) &amp; side scattering (SSC) data, showing gating for live cells (determined using non-engineered controls), where gate value is a percent of total counts (7,500). Bottom row is GFP data, showing gating for GFP-positive cells (determined using non-engineered controls), where gate value is a percent of live cells (gated in top row). ( FIG. 8B ) C2C12 data for cells treated with different levels of puromycin. From left to right: non-engineered cells (GFP negative control), pGFP (GFP positive control), pCrtB/I/Y with 2.5 μg/mL puromycin (1× puro), pCrtB/I/Y with 5 μg/mL puromycin (2× puro), and pCrtB/I/Y with 10 μg/mL puromycin (4×). Top row is FSC &amp; SSC data, showing gating for live cells (determined using non-engineered controls), where gate value is a percent of total counts (7,500). Bottom row is GFP data, showing gating for GFP-positive cells (determined using non-engineered controls), where gate value is a percent of live cells (gated in top row). 
         FIGS. 9A-9B  show carotenoid profiles of optimized cells. ( FIG. 9A ) phytoene, lycopene, and β-carotene content of pCrtB/I/Y C2C12s without optimization (top) or with puromycin conditioning and ketoconazole treatment (bottom). n=3 distinct samples. ( FIG. 9B ) phytoene, lycopene, and β-carotene content of pCrtB/I/Y BSCs without optimization (top left), without puromycin conditioning but with ketoconazole (top right), with puromycin conditioning by without ketoconazole (bottom left), or with puromycin conditioning and ketoconazole treatment (bottom left). n=3 distinct samples. Within plots, different letters indicate statistical differences between bars, p&lt;0.05). 
         FIG. 10  shows synthesis pathways for vitamin C, curcumin, and cannabidiol from precursors in BSCs. 
         FIG. 11  shows an overview of Example 2. In 1, cell composition will be analyzed pre- and post-differentiation. In 2, cells will be engineered to synthesize various compounds, which will be analyzed pre- and post-differentiation. In 3, cell growth and development, nutrient bioavailability, and nutrient function will be analyzed. 
         FIG. 12  shows an overview of Example 3. Drug expression vectors (A) and excipients (B) are engineered into bovine muscle and fat cells to explore drug synthesis in vitro. Simultaneous expression of green fluorescent protein (GFP) with therapeutic components serves as a simple marker of gene expression. Drug expression vectors (V565 and AMP16, each with GFP markers included) are further engineered to incorporate various disease-responsive mechanisms for drug activity, including trypsin-cleavable lysine-rich linkers, elastase-cleavable NPV-linkers, or a combination of the two. Disease-responsive edible therapeutics in bovine muscle cells (proliferative or differentiated) are tested in a 3D model of IBD and  Salmonella enterica  infection following in vitro digestion and both with and without heat treatment (i.e., cooking). 
         FIGS. 13A-13E  show bovine satellite cell (BSC) culture results. ( FIG. 13A ) Characterization of primary BSCs. Proliferative cells show ubiquitous expression of Pax7, a muscle stem cell marker (scalebar: 100 μm). ( FIG. 13B ) Differentiated cells show myotube formation and expression of Myosin Heavy Chain (MF20), indicating myogenic differentiation (scale bars are 100 um). ( FIG. 13C ) Four-day growth of BSCs cultured in dilutions of serum-containing growth media (GM) and serum-free media (B8). Dilutions containing B8 show significantly improved growth over four days compared to GM alone (far left column) in all cases, including B8 alone (i.e., serum-free, far right column). Different letters indicate statistical significance between groups (p&lt;0.05). ( FIG. 13D ) Adipogenic transdifferentiation of BSCs with free fatty acids (FFAs). Oil Red O staining of BSCs treated with 0 to 150 uM of linoleic acid and a combination of linoleic, erucic, and elaidid acid. Sparse lipid accumulation was observed in BSCs treated with 100 uM to 150 uM of linoleic acid. Robust lipid accumulation was observed in BSC treated with 75 uM to 125 uM of the combined FFAs. At 150 uM the FFA cocktail is detrimental to cell health (scalebar: 250 μm). ( FIG. 13E ) AdipoRed assay results for quantitative analysis of FFA-induced lipid accumulation in the BSCs. 
         FIGS. 14A-14D  show BSC compositional engineering. ( FIG. 14A ) Carotenoid production in BSCs engineered with pCrtB, pCrtB/I, and pCrtB/I/Y. In pCrtB cells, only phytoene is produced. In pCrtB/I cells, most of the phytoene is converted to lycopene. In pCrtB/I/Y cells, carotenoids accumulate in β-carotene, though total carotenoid levels are notably reduced compared to pCrtB and pCrtB/I. Different letters indicate statistical differences between bars, p&lt;0.05. ( FIG. 14B ) In BSCs, ketoconazole and puromycin conditioning offer an additive increase in β-carotene by increasing enzyme. * indicates significance (p&lt;0.05). ( FIG. 14C ) Thiobarbituric acid reactive substances (TBARS) assay for engineered BSCs with or without heating. All heated samples offer a significant increase in Malondialdehyde (MDA) compared with raw samples, indicating significant oxidative challenge from this “cooking” process. In heated samples, pCrtB, pCrtB/I and pCrtB/I/Y cells offer significantly reduced MDA compared with controls. In unheated samples, pCrtB/I and pCrtB/I/Y samples offer a significant reduction in MDA, and pCrtB offers no significant change compared with control pGFP cells. Bars that do share a letter are statistically different (p&lt;0.05). ( FIG. 14D ) Fluorescence and light microscopy images of BSCs engineered to express GFP alone (pGFP) or GFP along with CBD synthesis enzymes (pCBD). Green fluorescence indicates gene expression. Following selection in puromycin, all cells express GFP and enzymes (data not shown) (scalebar: 250 um). 
         FIGS. 15A-15H  show a 3D intestine model.  FIGS. 15A-15D  show an intestinal scaffold. 57 . ( FIGS. 15A-15B ) Schematics for generating 3D porous silk-based scaffolds for building patterned and non-patterned model intestines. Scaffolds were prepared by casting silk solutions in PDMS molds and inserting Teflon-coated wires or nylon screws across the cylinder, lyophilization and inducing β-sheet formation (scalebar: 4 mm). ( FIG. 15C ) Fluorescent staining for intestinal cell markers (ZO-1 and MUC2) in scaffolds and in 2D culture show increased expression in 3D scaffolds (scalebar: 200 μm).  FIG. 15D  Light microscopy of toluidine blue staining for mucus deposition in scaffolds and in 2D culture show increased mucus thickness in 3D scaffolds compared to 2D, and in patterned scaffolds compared to non-patterned (scalebar: 200 μm). Quantification (data not shown) reveal 2-fold and 3-fold increases in mucus deposition for non-patterned and patterned scaffolds, respectively, compared with 2D cultures.  FIGS. 15E-15  H show IBD modeling 55 .  FIG. 15E  Inflammation was induced by treatment with  E. coli O 111:B4 LPS and IFNγ. Staining for e-cadherin in inflammation models show differences in epithelial coverages between inflamed versus uninflamed groups at day 7 (scalebar: 100 μm). F) MUC2 staining shows positive staining on all groups indicating presence of goblet cells (scalebar: 100 μm).  FIG. 15G  Transverse sections of models at day 7 show variable epithelial coverages as seen by the e-cadherin (scalebar 1 mm).  FIG. 15H  A closer look at the epithelia shows monolayers for uninflamed groups and ball like structures in inflamed groups (scalebar: 100 μm). 
         FIGS. 15I-15L  show a 3D intestine model of infection with  Cryptosporidium parvum   56 .  FIG. 15I  Uninfected cells showing organized microvilli (scalebar: 2 μm).  FIG. 15J   C. parvum  type I meronts (thick arrows) and empty parasitophorous vacuoles (thin arrows) on day 3 (scalebar: 2 μm).  FIG. 15K  type I meronts containing eight merozoites on day 3 (enlargement of J; scalebar: 1 μm)).  FIG. 15L  a type I meront excysting on day 2 (scalebar: 1 μm). Figure adapted from the following references: A-D 57 , E-H 55 , I-L 56 . 
         FIGS. 16A-16B  show bovine satellite cell (BSC) culture results. ( FIG. 16A ) Characterization of primary BSCs. Proliferative cells (left image) show ubiquitous expression of Pax7, a muscle stem cell marker. Differentiated cells (right image) show myotube formation and expression of Myosin Heavy Chain (MF20), indicating myogenic differentiation. ( FIG. 16B ) BSCs cultured in dilutions of serum-containing growth media (GM) and serum-free media (B8) (left plot). Dilutions containing B8 show significantly improved growth over four days compared to GM alone (far left column) in all cases, including B8 alone (i.e., serum-free, far right column). FGF-2 dilutions within B8 media (right plot) reveal that FGF-2 concentrations greater than or equal to 1.25 ng/mL show significantly improved growth over four days compared to B8 media that is free of FGF-2. In the left plot, different letters indicate statistical significance between groups (p&lt;0.05). In the right plot, * indicates significant difference (p&lt;0.05). 
         FIGS. 17A-17B  show adipogenic transdifferentiation of bovine satellite cells (BSCs) with free fatty acids (FFAs). ( FIG. 17A ) Oil Red O staining of BSCs treated with 0 to 150 uM of linoleic acid and a combination of linoleic, erucic, and elaidid acid. Sparse lipid accumulation was observed in BSCs treated with 100 uM to 150 uM of linoleic acid. Robust lipid accumulation was observed in BSC treated with 75 uM to 125 uM of the combined FFAs. At 150 uM the FFA cocktail is detrimental to cell health. ( FIG. 17B ) AdipoRed assay results for quantitative analysis of FFA-induced lipid accumulation in the BSCs. 
         FIG. 18  shows an overview of Example 4. Media will be formulated to explore various diverse approaches to serum- and antibiotic-free culture of bovine muscle and adipose tissue. Cell proliferation and differentiation will be analyzed, as will nutrition and meat quality features. 
     
    
    
     INCORPORATION BY REFERENCE 
     All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, and patent application was specifically and individually indicated to be incorporated by reference. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The present disclosure describes engineered cells and the use thereof in a cultured meat product. Cells may be engineered to endogenously produce one or more metabolites by expressing in the cell one or more exogenous biosynthetic pathway enzymes. Cells may also be engineered to increase or decrease one or more endogenously produced metabolites by increasing or decreasing biosynthetic pathway enzymes native to the cell or by introducing non-native biosynthetic pathway enzymes into the cell to increase endogenous production of native metabolites. 
     As used herein, “metabolite” refers to a chemical compound that is an intermediate or end product of primary or secondary metabolism in a cell through one or more biosynthetic pathways. Cellular metabolites have various functions in fuel, structure, signaling, stimulatory and inhibitory effects on proteins and enzymes, enzymatic co-factors or co-substrates, defense, and interactions with other organisms or cells (e.g., pigments, odorants, pheromones, quorum sensing, etc.). Metabolites may include, but are not limited to, alcohols, amino acids, nucleotides, antioxidants, organic acids, polyols, and vitamins. Cells described herein may be engineered to endogenously produce one or more metabolites including, but not limited to, phytochemicals, phytonutrients, vitamins, and therapeutic molecules. 
     As used herein, “phytochemical” refers to a biologically active compound found in and produced by plants that generally play a role in plant growth or defense against competitors, pathogens, or predators. Phytochemical biosynthetic pathways may be primary or secondary metabolic pathways. While phytochemicals can be extracted and isolated from the origin plant, biosynthetic pathways for phytochemical production may be genetically engineered into bacterial, fungal, or other eukaryotic cells or the phytochemical maybe produced synthetically. 
     “Phytonutrient” refers to phytochemicals that are essential nutrients in a mammalian diet or that have specific biological activities that support mammalian health and wellness. Phytonutrients may include, but are not limited to, polyphenols, terpenoids, resveratrol, flavonoids, isoflavonoids, carotenoids, limonoids, glucosinolates, phytoestrogens, phytosterols, anthocyanins, ω-3 fatty acids, and probiotics. Phytonutrients have specific pharmacological effects such as anti-microbial, anti-oxidant, anti-inflammatory, non-tolorigenic, anti-spasmodic, anti-cancer, anti-aging, hepatoprotective, hypolipidemic, neuroprotective, hypotensive, CNS stimulant, analgesic, UVB-induced carcinogenesis protective, immuno-modulary, and carminative properties. Phytonutrients and they functions in mammalian and human health and wellness are described in the art. See, for example, Gupta et al. (“Phytonutrients as therapeutic agents,” J. Complement Integr. Med., 2014, 11(3):151-169), which is incorporated herein by reference. 
     In general, one or more heterologous and/or exogenous polynucleotides, encoding one or more biosynthetic pathway enzymes necessary to produce the metabolite(s) of interest, are introduced into the mammalian cell to produce a genetically engineered cell that endogenously produces the metabolite(s) of interest. The cell may be engineered to transiently express the required biosynthetic pathway enzymes of interest or the cell may be engineered to stably express the required biosynthetic pathways enzymes of interest. The heterologous polynucleotide encoding the biosynthetic pathway enzyme may be introduced into the cell using any transfection or transduction method known in the art. 
     As used herein, “polypeptide,” “protein,” and “peptide” are used interchangeably and refer to the collective primary, secondary, tertiary, quaternary amino acid sequence and structure necessary to give the recited macromolecule it function and properties. As used herein, “enzyme” or “biosynthetic pathway enzyme” are used interchangeably and refer to a protein that catalysis a chemical reaction. The recitation of any particular enzyme either independently or as part of a biosynthetic pathway is understood to include the necessary co-factors, co-enzymes, and metals necessary for the enzyme to properly function. 
     As used herein, the terms “polynucleotide,” “polynucleotide sequence,” “nucleic acid” and “nucleic acid sequence” refer to a nucleotide, oligonucleotide, polynucleotide (which terms may be used interchangeably), or any fragment thereof. These phrases also refer to DNA or RNA of natural or synthetic origin (which may be single-stranded or double-stranded and may represent the sense or the antisense strand). The polynucleotides may be cDNA or genomic DNA. 
     Polynucleotides homologous to the polynucleotides described herein are also provided. Those of skill in the art understand the degeneracy of the genetic code and that a variety of polynucleotides can encode the same polypeptide. In some embodiments, the polynucleotides (i.e., polynucleotides encoding the biosynthetic pathway enzymes to synthesize a metabolite of interest) may be codon-optimized for expression in a particular cell including, without limitation, a mammalian cell, a plant cell, bacterial cell, or fungal cell. In some embodiments, the polynucleotide is codon-optimized for genus or species specific expression, for example, expression in a bovine cell. While examples of particular polynucleotide sequences are disclosed herein any polynucleotide sequences may be used which encode a desired form of the polypeptides described herein. Thus non-naturally occurring sequences may be used. These may be desirable, for example, to enhance expression in heterologous expression systems of polypeptides or proteins. Computer programs for generating degenerate coding sequences are available and can be used for this purpose. Pencil, paper, the genetic code, and a human hand can also be used to generate degenerate coding sequences. 
     In another aspect of the present invention, constructs are provided. As used herein, the term “construct” refers to recombinant polynucleotides including, without limitation, DNA and RNA, which may be single-stranded or double-stranded and may represent the sense or the antisense strand. Recombinant polynucleotides are polynucleotides formed by laboratory methods that include polynucleotide sequences derived from at least two different natural sources or they may be synthetic. Constructs thus may include new modifications to endogenous genes introduced by, for example, genome editing technologies. Constructs may also include recombinant polynucleotides created using, for example, recombinant DNA methodologies. 
     The constructs provided herein may be prepared by methods available to those of skill in the art. Notably each of the constructs described herein are recombinant molecules and as such do not occur in nature. Generally, the nomenclature used herein and the laboratory procedures utilized in the present invention include molecular, biochemical, and recombinant DNA techniques that are well known and commonly employed in the art. Standard techniques available to those skilled in the art may be used for cloning, DNA and RNA isolation, amplification and purification. Such techniques are thoroughly explained in the literature. 
     The constructs provided herein may include a promoter operably linked to any one of the polynucleotides described herein. The promoter may be a heterologous promoter or an endogenous promoter associated with the biosynthetic pathways described herein. 
     As used herein, the terms “heterologous promoter,” “promoter,” “promoter region,” or “promoter sequence” refer generally to transcriptional regulatory regions of a gene, which may be found at the 5′ or 3′ side of the polynucleotides described herein, or within the coding region of the polynucleotides, or within introns in the polynucleotides. Typically, a promoter is a DNA regulatory region capable of binding RNA polymerase in a cell and initiating transcription of a downstream (3′ direction) coding sequence. The typical 5′ promoter sequence is bounded at its 3′ terminus by the transcription initiation site and extends upstream (5′ direction) to include the minimum number of bases or elements necessary to initiate transcription at levels detectable above background. Within the promoter sequence is a transcription initiation site (conveniently defined by mapping with nuclease Si), as well as protein binding domains (consensus sequences) responsible for the binding of RNA polymerase. 
     In some embodiments, polynucleotides encoding the biosynthetic pathway enzymes described herein are operably connected to the promoter. As used herein, a polynucleotide is “operably connected” or “operably linked” when it is placed into a functional relationship with a second polynucleotide sequence. For instance, a promoter is operably linked to a polynucleotide if the promoter is connected to the polynucleotide such that it may affect transcription of the polynucleotides. In various embodiments, the polynucleotides may be operably linked to at least 1, at least 2, at least 3, at least 4, at least 5, or at least 10 promoters. 
     Heterologous promoters useful in the practice of the present invention include, but are not limited to, constitutive, inducible, temporally-regulated, developmentally regulated, chemically regulated, tissue-preferred and tissue-specific promoters. The heterologous promoter may be a plant, animal, bacterial, fungal, or synthetic promoter. Suitable promoters for expression in plants include, without limitation, the 35S promoter of the cauliflower mosaic virus, ubiquitin, tCUP cryptic constitutive promoter, the Rsyn7 promoter, pathogen-inducible promoters, the maize In2-2 promoter, the tobacco PR-1a promoter, glucocorticoid-inducible promoters, estrogen-inducible promoters and tetracycline-inducible and tetracycline-repressible promoters. Other promoters include the T3, T7 and SP6 promoter sequences, which are often used for in vitro transcription of RNA. In mammalian cells, typical promoters include, without limitation, promoters for Rous sarcoma virus (RSV), human immunodeficiency virus (HIV-1), cytomegalovirus (CMV), Dox-inducible promoter (e.g., Tet Response Element (TRE)), ubiquitin C (Ubc), CMV early enhancer/chicken beta actin (CAG), human beta actin, phosphoglycerate kinase 1 (PGK1), SV40 virus, and the like as well as the translational elongation factor EF-1a promoter or ubiquitin promoter. In insect cells, typical promoters include, without limitation, upstream activating sequence (UAS), actin 5c (Ac5), and polyhedrin. In fish cells, typical promoter include, without limitation,  Xenopus laevis  elongation factor 1α promoter (XlEef1a1) and ocean pout antifreeze protein promoter (OP5a) Those of skill in the art are familiar with a wide variety of additional promoters for use in various cell types. In some embodiments, the heterologous promoter includes a plant promoter, either endogenous to the plant host or heterologous. 
     Vectors including any of the constructs or polynucleotides described herein are provided. The term “vector” is intended to refer to a polynucleotide capable of transporting another polynucleotide to which it has been linked. In some embodiments, the vector may be a “plasmid,” which refers to a circular double-stranded DNA loop into which additional DNA segments may be ligated. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors can be integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome, such as some viral vectors or transposons. By way of example, appropriate vectors for the compositions and methods of this disclosure include episomal vectors, viral vectors (e.g., retrovirus, adenovirus, baculovirus), plasmids, RNA vectors, or linear or circular DNA or RNA molecules which may comprise or consist of a chromosomal, non-chromosomal, semi-synthetic, or synthetic nucleic acid. Large numbers of suitable vectors are known to those of skill in the art and commercially available. In some embodiments, vectors are episomal vectors, which are capable of autonomous replication due to the presence of an origin of replication. Plant mini-chromosomes are also included as vectors. In some embodiments, the vector is a multicistrinic vector including one or more internal ribosomal entry sites (IRES) and/or one or more 2A peptide sequences that allow for coexpression of multiple polynucleotides from a single construct or vector. Vectors may carry genetic elements, such as those that confer resistance to certain drugs or chemicals. 
     In some embodiments, a construct or vector described herein may include a selectable marker. As used herein, “selectable marker” refers to a genetic element that allows identification and selection of a cell that contains the construct or vector with said genetic element by expression of said genetic element in the cell. In some embodiments, the selectable marker is a polynucleotide encoding fluorescent protein such that cells expressing the fluorescent protein can be identified visually or by a suitable cell sorting method (e.g., fluorescent activated cell sorting (FACS)). In some embodiments, the selectable marker is a polynucleotide that confer antibiotic resistance to a cell expressing the selectable marker (e.g., puromycin, penicillin, streptomycin, or hygromycin resistance genes). Cells transduced with the vector incorporating the selectable marker can be exposed to a selection chemical specific to the selectable marker to select for cells containing the vector. The selectable marker confer resistance to the selection chemical such that cell containing the vector and the selectable marker survive whereas cells that do not contain the vector and the selectable marker are killed. 
     As used herein, “introducing” describes a process by which exogenous polynucleotides (e.g., DNA or RNA) are introduced into a recipient cell. Methods of introducing polynucleotides into a cell are known in the art and may include, without limitation, microinjection, transformation, and transfection methods. Transformation or transfection may occur under natural or artificial conditions according to various methods well known in the art, and may rely on any known method for the insertion of foreign nucleic acid sequences into a host cell. The method for transformation or transfection is selected based on the type of host cell being transformed and may include, but is not limited to 
     In some embodiments, the exogenous polyneucleotides, constructs, or vectors described herein are transfected into a cell using a suitable carrier. Suitable carriers are known and used in the art, including, but not limited to, lipid carriers (e.g., Lipofectamine), polymeric nanocarriers, 
     A cell is “genome edited” or “genetically modified” if the cell includes a modification to its genome compared to a non-genome edited cell of the same type. In some cases, a non-genome edited cell is a wild-type cell. As used herein, the terms “genetically modified” and “genetically engineered” are used interchangeably and refer to a prokaryotic or eukaryotic cell that includes an exogenous polynucleotide, regardless of the method used for insertion. In some cases, a cell has been modified to comprise a non-naturally occurring nucleic acid molecule that has been created or modified by the hand of man (e.g., using recombinant DNA technology) or is derived from such a molecule (e.g., by transcription, translation, etc.). A cell that contains an exogenous, recombinant, synthetic, and/or otherwise modified polynucleotide is considered to be an engineered or “genome edited” cell. Genetically editing or modifying a cell refers to modifying cellular nucleic acid within a cell, including genetic modifications to endogenous and/or exogenous nucleic acids within the cell. Genetic modifications can comprise deletions, insertions, integrations of exogenous DNA, gene correction and/or gene mutation. For example, gene editing can be performed using a nuclease (e.g., a natural-existing nuclease or an artificially engineered nuclease) or a transposase. Other methods of making genetic modifications suitable for use according to the methods provided herein include but are not limited to somatic cell nuclear transfer (SCNT) and introduction of a transgene. Procedures for obtaining recombinant or genetically modified cells are generally known in the art, and are described in Sambrook et al,  Molecular Cloning, A Laboratory Manual , Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989), incorporated herein by reference. 
     In some embodiments, polynucleotides encoding biosynthetic pathway enzymes required for production of the metabolite of interest are integrated into the genome of the cell using CRISPR/Cas mediated gene editing (e.g., a type II CRISPR/cas system). In some cases, the protein expression of one or more endogenous genes is reduced using a CRISPR/cas system. In some embodiments, a CRISPR/Cas system can be used to perform site specific insertion. For example, a nick on an insertion site in the genome can be made by CRISPR/cas to facilitate the insertion of a transgene at the insertion site. Suitable techniques for CRISPR/Cas mediated gene editing of a host cell are known and described in the art. 
     In some embodiments, polynucleotides encoding biosynthetic pathway enzymes required for production of the metabolite of interest are integrated into the genome of the cell using a transposon. Suitable transposons are known and described in the art including, but not limited to,  Sleeping Beauty , PiggyBac, Tol1, Tol2, Minos, Frog Prince, Passport, Hsmar1, and Harbinger3_DR. See, for example, Ivics et al. (“The expanding universe of transposon technologies for gene and cell engineering,” Mobile DNA, 1(25), 2010) which describes transposon systems and the use there of in the art. 
     In some embodiments, polynucleotides encoding biosynthetic pathway enzymes required for production of the metabolite of interest are integrated into the genome of the cell using a transgene. As used herein, the term “transgene” refers to a gene or genetic material that can be transferred into an organism or a cell thereof. 
     In some embodiments, the cell is engineered to endogenously produce the carotenoid phytoene. Phytoene is synthesized from two geranylgeranyl pyrophosphate molecules by the enzyme phytoene synthase. A polynucleotide encoding the phytoene synthase enzyme is introduced into a cell that natively produces geranylgeranyl pyrophosphate to produce a cell expressing phytoene synthase and endogenously synthesizing phytoene. In some embodiments the phytoene synthase is from the bacteria  Pantoea ananatis  and has the polypeptide sequence of SEQ ID NO:1 or SEQ ID NO:10. In some embodiments, the phytoene synthase has a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NO:1 or SEQ ID NO:10. In  Pantoea ananatis , phytoene synthase is encoded by the gene crtB having the sequence of SEQ ID NO:2. In some embodiments, the crtB sequence can be codon optimized for expression in a particular cell of interest. In some embodiments, the crtB sequence is codon optimized for expression in a bovine cell (e.g., SEQ ID NO:38). 
     
       
         
           
               
            
               
                 phytoene synthase (Uniprot P21683): 
               
               
                 SEQ ID NO: 1 
               
               
                 MNNPSLLNHAVETMAVGSKSFATASKLFDAKTRRSVLMLYAWCRHCDDVI 
               
               
                   
               
               
                 DDQTLGEQARQPALQTPEQRLMQLEMKTRQAYAGSQMHEPAFAAFQEVAM 
               
               
                   
               
               
                 AHDIAPAYAFDHLEGEAMDVREAQYSQLDDTLRYCYHVAGVVGLMMAQIM 
               
               
                   
               
               
                 GVRDKATLDRACDLGLAFQLTNIARDIVDDAHAGRCYLPASWLEHEGLNK 
               
               
                   
               
               
                 ENYAAPENRQALSRIARRLVQEAEPYYLSATAGLAGLPLRSAWAIATAKQ 
               
               
                   
               
               
                 VYRKIGVKVEQAGQQAWDQRQSTTTPEKLTLLLAASGQALTSRMRAHPPR 
               
               
                   
               
               
                 PAHLWQRPL 
               
               
                   
               
               
                 phytoene synthase: 
               
               
                 SEQ ID NO: 10 
               
               
                 MVNNPSLLNHAVETMAVGSKSFATASKLFDAKTRRSVLMLYAWCRHCDDV 
               
               
                   
               
               
                 IDDQTLGFQARQPALQTPEQRLMQLEMKTRQAYAGSQMHEPAFAAFQEVA 
               
               
                   
               
               
                 MAHDIAPAYAFDHLEGFAMDVREAQYSQLDDTLRYCYHVAGVVGLMMAQI 
               
               
                   
               
               
                 MGVRDNATLDRACDLGLAFQLTNIARDIVDDAHAGRCYLPASWLEHEGLN 
               
               
                   
               
               
                 KENYAAPENRQALSRIARRLVQEAEPYYLSATAGLAGLPLRSAWAIATAK 
               
               
                   
               
               
                 QVYRKIGVKVEQAGQQAWDQRQSTTTPEKLTLLLAASGQALTSRMRAHPP 
               
               
                   
               
               
                 RPAHLWQRPL 
               
               
                   
               
               
                 crtB: 
               
               
                 SEQ ID NO: 2 
               
               
                 ATGAATAATCCGTCGTTACTCAATCATGCGGTCGAAACGATGGCAGTTGG 
               
               
                   
               
               
                 CTCGAAAAGTTTTGCGACAGCCTCAAAGTTATTTGATGCAAAAACCCGGC 
               
               
                   
               
               
                 GCAGCGTACTGATGCTCTACGCCTGGTGCCGCCATTGTGACGATGTTATT 
               
               
                   
               
               
                 GACGATCAGACGCTGGGCTTTCAGGCCCGGCAGCCTGCCTTACAAACGCC 
               
               
                   
               
               
                 CGAACAACGTCTGATGCAACTTGAGATGAAAACGCGCCAGGCCTATGCAG 
               
               
                   
               
               
                 GATCGCAGATGCACGAACCGGCGTTTGCGGCTTTTCAGGAAGTGGCTATG 
               
               
                   
               
               
                 GCTCATGATATCGCCCCGGCTTACGCGTTTGATCATCTGGAAGGCTTCGC 
               
               
                   
               
               
                 CATGGATGTACGCGAAGCGCAATACAGCCAACTGGATGATACGCTGCGCT 
               
               
                   
               
               
                 ATTGCTATCACGTTGCAGGCGTTGTCGGCTTGATGATGGCGCAAATCATG 
               
               
                   
               
               
                 GGCGTGCGGGATAACGCCACGCTGGACCGCGCCTGTGACCTTGGGCTGGC 
               
               
                   
               
               
                 ATTTCAGTTGACCAATATTGCTCGCGATATTGTGGACGATGCGCATGCGG 
               
               
                   
               
               
                 GCCGCTGTTATCTGCCGGCAAGCTGGCTGGAGCATGAAGGTCTGAACAAA 
               
               
                   
               
               
                 GAGAATTATGCGGCACCTGAAAACCGTCAGGCGCTGAGCCGTATCGCCCG 
               
               
                   
               
               
                 TCGTTTGGTGCAGGAAGCAGAACCTTACTATTTGTCTGCCACAGCCGGCC 
               
               
                   
               
               
                 TGGCAGGGTTGCCCCTGCGTTCCGCCTGGGCAATCGCTACGGCGAAGCAG 
               
               
                   
               
               
                 GTTTACCGGAAAATAGGTGTCAAAGTTGAACAGGCCGGTCAGCAAGCCTG 
               
               
                   
               
               
                 GGATCAGCGGCAGTCAACGACCACGCCCGAAAAATTAACGCTGCTGCTGG 
               
               
                   
               
               
                 CCGCCTCTGGTCAGGCCCTTACTTCCCGGATGCGGGCTCATCCTCCCCGC 
               
               
                   
               
               
                 CCTGCGCATCTCTGGCAGCGCCCGCTCTAG 
               
            
           
         
       
     
     In some embodiments, the cell endogenously produces phytoene at an amount between about 1 μg/g protein and about 800 μg/g protein, between about 5 μg/g protein and about 600 μg/g protein, between about 10 μg/g protein and about 500 μg/g protein, between about 25 μg/g protein an about 300 μg/g protein, between about 30 μg/g protein and about 250 μg/g protein, or between about 30 μg/g protein and 100 μg/g protein. In some embodiments, the cell endogenously produces at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13 or at least 14 times more phytoene than the cell that does not contain a polynucleotide encoding phytoene synthase. 
     In some embodiments, the cell is engineered to endogenously produce the carotenoid lycopene. Lycopene is synthesized from phytoene by the enzyme phytoene desaturase. A polynucleotide encoding the phytoene desaturase enzyme is introduced into a cell that produces phytoene to produce a cell expressing phytoene desaturase and endogenously synthesizing lycopene. In some embodiments, the phytoene desaturase is from the bacteria  Pantoea ananatis  and has the polypeptide sequence of SEQ ID NO:3. In some embodiments, the phytoene desaturase has a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NO:3. In  Pantoea ananatis , phytoene desaturase is encoded by the gene crtI having the sequence of SEQ ID NO:4. In some embodiments, the crtI sequence can be codon optimized for expression in a particular cell of interest. In some embodiments, the crtI sequence is codon optimized for expression in a bovine cell (e.g., SEQ ID NO:39). 
     
       
         
           
               
            
               
                 phytoene desaturase (Uniprot P21685): 
               
               
                 SEQ ID NO: 3 
               
               
                 MKPTTVIGAGFGGLALAIRLQAAGIPVLLLEQRDKPGGRAYVYEDQGFTF 
               
               
                   
               
               
                 DAGPTVITDPSAIEELFALAGKQLKEYVELLPVTPFYRLCWESGKVFNYD 
               
               
                   
               
               
                 NDQTRLEAQIQQFNPRDVEGYRQFLDYSRAVFKEGYLKLGTVPFLSFRDM 
               
               
                   
               
               
                 LRAAPQLAKLQAWRSVYSKVASYIEDEHLRQAFSFHSLLVGGNPFATSSI 
               
               
                   
               
               
                 YTLIHALEREWGVWFPRGGTGALVQGMIKLFQDLGGEVVLNARVSHMETT 
               
               
                   
               
               
                 GNKIEAVHLEDGRRFLTQAVASNADVVHTYRDLLSQHPAAVKQSNKLQTK 
               
               
                   
               
               
                 RMSNSLFVLYFGLNHHHDQLAHHTVCFGPRYRELIDEIFNHDGLAEDFSL 
               
               
                   
               
               
                 YLHAPCVTDSSLAPEGCGSYYVLAPVPHLGTANLDWTVEGPKLRDRIFAY 
               
               
                   
               
               
                 LEQHYMPGLRSQLVTHRMFTPFDFRDQLNAYHGSAFSVEPVLTQSAWFRP 
               
               
                   
               
               
                 HNRDKTITNLYLVGAGTHPGAGIPGVIGSAKATAGLMLEDLI 
               
               
                   
               
               
                 ctrI: 
               
               
                 SEQ ID NO: 4 
               
               
                 ATGAAACCAACTACGGTAATTGGTGCAGGCTTCGGTGGCCTGGCACTGGC 
               
               
                   
               
               
                 AATTCGTCTACAGGCTGCGGGGATCCCCGTCTTACTGCTTGAACAACGTG 
               
               
                   
               
               
                 ATAAACCCGGCGGTCGGGCTTATGTCTACGAGGATCAGGGGTTTACCTTT 
               
               
                   
               
               
                 GATGCAGGCCCGACGGTTATCACCGATCCCAGTGCCATTGAAGAACTGTT 
               
               
                   
               
               
                 TGCACTGGCAGGAAAACAGTTAAAAGAGTATGTCGAACTGCTGCCGGTTA 
               
               
                   
               
               
                 CGCCGTTTTACCGCCTGTGTTGGGAGTCAGGGAAGGTCTTTAATTACGAT 
               
               
                   
               
               
                 AACGATCAGGCCCGGCTCGAAGCGCAGATTCAGCAGTTTAATCCCCGCGA 
               
               
                   
               
               
                 TGTCGAAGGTTATCGTCAGTTTCTGGACTATTCACGCGCGGTGTTTAAAG 
               
               
                   
               
               
                 AAGGGTATCTGAAGCTCGGTACTGTCCCTTTTTTATCGTTCAGAGACATG 
               
               
                   
               
               
                 CTTCGCGCCGCACCTCAACTGGCGAAACTGCAGGCATGGAGAAGCGTTTA 
               
               
                   
               
               
                 CAGTAAGGTTGCCAGTTACATCGAAGATGAACATCTGCGCCAGGCGTTTT 
               
               
                   
               
               
                 CTTTCCACTCGCTGTTGGTGGGCGGCAATCCCTTCGCCACCTCATCCATT 
               
               
                   
               
               
                 TATACGTTGATACACGCGCTGGAACGTGAGTGGGGCGTCTGGTTTCCGCG 
               
               
                   
               
               
                 TGGCGGCACCGGCGCATTAGTTCAGGGGATGATAAAGCTGTTTCAGGATC 
               
               
                   
               
               
                 TGGGTGGCGAAGTCGTGTTAAACGCCAGAGTCAGCCATATGGAAACGACA 
               
               
                   
               
               
                 GGAAACAAGATTGAAGCCGTGCATTTAGAGGACGGTCGCAGGTTCCTGAC 
               
               
                   
               
               
                 GCAAGCCGTCGCGTCAAATGCAGATGTGGTTCATACCTATCGCGACCTGT 
               
               
                   
               
               
                 TAAGCCAGCACCCTGCCGCGGTTAAGCAGTCCAACAAACTGCAGACTAAG 
               
               
                   
               
               
                 CGCATGAGTAACTCTCTGTTTGTGCTCTATTTTGGTTTGAATCACCATCA 
               
               
                   
               
               
                 TGATCAGCTCGCGCATCACACGGTTTGTTTCGGCCCGCGTTACCGCGAGC 
               
            
           
         
       
     
     In some embodiments, the cell endogenously produces lycopene at an amount between about 1 μg/g protein and about 800 μg/g protein, between about 5 μg/g protein and about 600 μg/g protein, between about 10 μg/g protein and about 500 μg/g protein, between about 25 μg/g protein an about 300 μg/g protein, between about 30 μg/g protein and about 250 μg/g protein, or between about 30 μg/g protein and 100 μg/g protein. In some embodiments, the cell endogenously produces at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13 or at least 14 times more lycopene than the cell that does not contain a polynucleotide encoding phytoene synthase and phytoene desaturase. 
     In some embodiments, the cell is engineered to endogenously produce the carotenoid β-carotene. B-carotene is synthesized from lycopene by the enzyme lycopene cyclase. A polynucleotide encoding the lycopene cyclase enzyme is introduced into a cell that produces lycopene to produce a cell expressing lycopene cyclase and endogenously synthesizing (3-carotene. In some embodiments, the lycopene cyclase is from the bacteria  Pantoea ananatis  and has the polypeptide sequence of SEQ ID NO:5 or SEQ ID NO:11. In some embodiments, the lycopene cyclase has a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NO:5 or SEQ ID NO:11. In  Pantoea ananatis , lycopene cyclase is encoded by the gene crtY having the sequence of SEQ ID NO:6. In some embodiments, the crtY sequence can be codon optimized for expression in a particular cell of interest. In some embodiments, the crtY sequence is codon optimized for expression in a bovine cell (e.g., SEQ ID NO:40). While the sequences listed below are from  Pantoea ananatis , a skilled artisan would recognize that homologous sequences can be identified from other species for use in the engineered cell and methods described herein. 
     
       
         
           
               
            
               
                 lycopene cyclase (Uniprot P21687): 
               
               
                 SEQ ID NO: 5 
               
               
                 MQPHYDLILVGAGLANGLIALRLQQQQPDMRILLIDAAPQAGGNHTWSFH 
               
               
                   
               
               
                 HDDLTESQHRWIAPLVVEIHWPDYQVRFPTRRRKLNSGYFCITSQRFAEV 
               
               
                   
               
               
                 LLRQFGPHLWMDTAVAEVNAESVRLKKGQVIGARAVIDGRGYAANSALSV 
               
               
                   
               
               
                 GFQAFIGQEWRLSRPHGLSSPIIMDATVDQQNGYRFVYSLPLSPTRLLIE 
               
               
                   
               
               
                 DTHYIDNATLDPERARQNICDYAAQQGWQLQTLLREEQGALPITLSGNAD 
               
               
                   
               
               
                 AFWQQRPLACSGLRAGLFHPTTGYSLPLAVAVADRLSALDVFTSASIHQA 
               
               
                   
               
               
                 ITHFARERWQQQRFFRMLNRMLFLAGPADLRWRVMQRFYGLPEDLIARFY 
               
               
                   
               
               
                 AGKLTLTDRLRILSGKPPVPVLAALQAIMTTHR 
               
               
                   
               
               
                 lycopene cyclase: 
               
               
                 SEQ ID NO: 11 
               
               
                 MQPHYDLILVGAGLANGLIALRLQQQQPDMRILLIDAAPQAGGNHTWSFH 
               
               
                   
               
               
                 HDDLTESQHRWIAPLVVEIHWPDYQVRFPTRRRKLNSGYFCITSQRFAEV 
               
               
                   
               
               
                 LQRQFGPHLWMDTAVAEVNAESVRLKKGQVIGARAVIDGRGYAANSALSV 
               
               
                   
               
               
                 GFQAFIGQEWRLSHPHGLSSPIIMDATVDQQNGYRFVYSLPLSPTRLLIE 
               
               
                   
               
               
                 DTHYIDNATLDPECARQNICDYAAQQGWQLQTLLREEQGALPITLSGNAD 
               
               
                   
               
               
                 AFWQQRPLACSGLRAGLFHPTTGYSLPLAVAVADRLSALDVFTSASIHHA 
               
               
                   
               
               
                 ITHFARERWQQQGFFRMLNRMLFLAGPADSRWRVMQRFYGLPEDLIARFY 
               
               
                   
               
               
                 AGKLTLTDRLRILSGKPPVPVLAALQAIMTTHR 
               
               
                   
               
               
                 ctrY: 
               
               
                 SEQ ID NO: 6 
               
               
                 ATGCAACCGCATTATGATCTGATTCTCGTGGGGGCTGGACTCGCGAATGG 
               
               
                   
               
               
                 CCTTATCGCCCTGCGTCTTCAGCAGCAGCAACCTGATATGCGTATTTTGC 
               
               
                   
               
               
                 TTATCGACGCCGCACCCCAGGCGGGCGGAAATCATACGTGGTCATTTCAC 
               
               
                   
               
               
                 CACGATGATTTGACTGAGAGCCAACATCGTTGGATAGCGCCGCTGGTGGT 
               
               
                   
               
               
                 TCATCACTGGCCCGACTATCAGGTGCGCTTTCCCACACGCCGTCGTAAGC 
               
               
                   
               
               
                 TGAACAGCGGCTACTTCTGTATTACTTCTCAGCGTTTCGCTGAGGTTTTA 
               
               
                   
               
               
                 CTGCGACAGTTTGGCCCGCACTTGTGGATGGATACCGCGGTCGCAGAGGT 
               
               
                   
               
               
                 TAATGCGGAATCTGTTCGGTTGAAAAAGGGTCAGGTTATCGGTGCCCGCG 
               
               
                   
               
               
                 CGGTGATTGACGGGCGGGGTTATGCGGCAAACTCAGCACTGAGCGTGGGC 
               
               
                   
               
               
                 TTCCAGGCGTTTATTGGCCAGGAATGGCGATTGAGCCGCCCGCATGGTTT 
               
               
                   
               
               
                 ATCGTCTCCCATTATCATGGATGCCACGGTCGATCAGCAAAATGGTTATC 
               
               
                   
               
               
                 GCTTCGTGTACAGCCTGCCGCTCTCGCCGACCAGATTGTTAATTGAAGAC 
               
               
                   
               
               
                 ACGCACTATATCGATAATGCGACATTAGATCCTGAACGCGCGCGGCAAAA 
               
               
                   
               
               
                 TATTTGCGACTATGCCGCGCAACAGGGTTGGCAGCTTCAGACTCTGCTGC 
               
               
                   
               
               
                 GTGAAGAACAGGGCGCCTTACCCATTACCCTGTCGGGCAATGCCGACGCA 
               
               
                   
               
               
                 TTCTGGCAGCAGCGCCCCCTGGCCTGTAGTGGATTACGTGCCGGTCTGTT 
               
               
                   
               
               
                 CCATCCTACCACCGGCTATTCACTGCCGCTGGCGGTTGCCGTGGCCGACC 
               
               
                   
               
               
                 GCCTGAGCGCACTTGATGTCTTTACGTCGGCCTCAATTCATCAGGCCATT 
               
               
                   
               
               
                 ACGCATTTTGCCCGCGAGCGCTGGCAGCAGCAGCGCTTTTTCCGCATGCT 
               
               
                   
               
               
                 GAATCGCATGCTGTTTTTAGCCGGGCCCGCCGATTTACGCTGGCGGGTTA 
               
            
           
         
       
     
     In some embodiments, the cell endogenously produces β-carotene at an amount between about 1 μg/g protein and about 800 μg/g protein, between about 5 μg/g protein and about 600 μg/g protein, between about 10 μg/g protein and about 500 μg/g protein, between about 25 μg/g protein an about 300 μg/g protein, between about 30 μg/g protein and about 250 μg/g protein, or between about 30 μg/g protein and 100 μg/g protein. In some embodiments, the cell endogenously produces at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13 or at least 14 times more β-carotene than the cell that does not contain a polynucleotide encoding phytoene synthase, phytoene desaturase, and lycopene cyclase. 
     In some embodiments, total carotenoid production in the engineered cell is between about 1 μg/g protein and about 800 μg/g protein, between about 5 μg/g protein and about 600 μg/g protein, between about 10 μg/g protein and about 500 μg/g protein, between about 25 μg/g protein an about 300 μg/g protein, between about 30 μg/g protein and about 250 μg/g protein, or between about 30 μg/g protein and 100 μg/g protein. In some embodiments, total carotenoid production in the engineered cell is at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13 or at least 14 times more than total carotenoid production in the cell that does not contain a polynucleotide encoding phytoene synthase, phytoene desaturase, and lycopene cyclase. 
     In some embodiments, the cell is engineered for endogenous production of Vitamin C. While mammalian cells, for example, natively produce the Vitamin C precursor UDP-glucose and have genes encoding Vitamin C biosynthetic pathway enzymes, the Vitamin C biosynthetic pathway in typically silent in mammalian cells. A schematic of Vitamin C biosynthesis, including intermediates, is shown in  FIG. 10 . Vitamin C biosynthetic pathway enzymes include UDP-glucose 6-dehydrogenase (UGDH), UDP glucuronosyltransferase 1 (UGT1A1), aldo-keto reductase family 1 (AKR1A1), regucalcin (RGN), and L-gulono-gamma-lactone oxidase (GULO). In some embodiments, a heterologous polynucleotide encoding UGT1A1 is introduced into a cell. In some embodiments, a heterologous polynucleotide encoding UGDH is introduced into a cell. In some embodiments, a heterologous polynucleotide encoding AKR1A1 is introduced into a cell. In some embodiments, a heterologous polynucleotide encoding RGN is introduced into a cell. In some embodiments, a heterologous polynucleotide encoding GULO is introduced into a cell. In some embodiments, one or more heterologous polynucleotides encoding one, two, three, four, or all five of UGT1A1, UGDH, AKR1A1, RGN, and GULO are introduced into a cell. In some embodiments, the amino acid sequence of UGT1A1, UGDH, AKR1A1, RGN, and GULO are endogenous to the cell into which the polynucleotide sequence is introduced. In some embodiments, the amino acid sequence of UGT1A1, UGDH, AKR1A1, RGN, and GULO are exogenous to the cell into which the polynucleotide sequence is introduced. In some embodiments, the UGDH, UGT1A1, AKR1A1, RGN, and GULO enzymes are from  Bos taurus , and have the polypeptide sequence of SEQ ID NOs:12-16, respectively, and the cell into which the polynucleotide sequences are introduced is a bovine cell. In some embodiments, the UGDH, UGT1A1, AKR1A1, RGN, and GULO enzymes have a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NOs:12-16, respectively. While the sequences listed below are from  Bos taurus , a skilled artisan would recognize that homologous sequences can be identified from other species for use in the engineered cell and methods described herein. 
     
       
         
           
               
            
               
                 UGDH (UniProt: P12378): 
               
               
                 SEQ ID NO: 12 
               
               
                 MFEIKKICCIGAGYVGGPTCSVIAHMCPEIRVTVVDINESRINAWNSPTL 
               
               
                   
               
               
                 PIYEPGLKEVVESCRGKNLFFSTNIDDAIKEADLVFISVNTPTKTYGMGK 
               
               
                   
               
               
                 GRAADLKYIEACARRIVQNSHGYKIVTEKSTVPVRAAESIRRIFDANTKP 
               
               
                   
               
               
                 NLNLQVLSNPEFLAEGTAIKDLKNPDRVLIGGDETPEGQRAVQALCAVYE 
               
               
                   
               
               
                 HWVPREKILTTNTWSSELSKLTANAFLAQRISSINSISALCEATGADVEE 
               
               
                   
               
               
                 VATAIGMDQRIGNKFLKASVGFGGSCFQKDVLNLVYLCEALNLPEVARYW 
               
               
                   
               
               
                 QQVIDMNDYQRRRFASRIIDSLFNTVTDKKIAILGFAFKKDTGDTRESSS 
               
               
                   
               
               
                 IYISKYLMDEGAHLHIYDPKVPREQIVVDLSHPGVSKDDQVARLVTISKD 
               
               
                   
               
               
                 PYEACDGAHAVVICTEWDMFKELDYERIHKKMLKPAFIFDGRRVLDGLHN 
               
               
                   
               
               
                 ELQTIGFQIETIGKKVSSKRIPYAPSGEIPKFSLQDMPNKKPRV 
               
               
                   
               
               
                 UGT1A1 (UniProt: E1BBB3): 
               
               
                 SEQ ID NO: 13 
               
               
                 MNMMAVKRLLLLLLLQLTCYFSSGSCGKVLVWPVEYSHWMNMKIILDELV 
               
               
                   
               
               
                 MRGHEVTVLTSSASILIDPNKPSAIKFENFSVSLTKDDFEDALKNFVGNW 
               
               
                   
               
               
                 TDLTNSFWTFPLLLQSLFDEYSDLTLKICKELISNKKLMTKLHESRFDVV 
               
               
                   
               
               
                 LADTVGPCGELLAEIFKVPLVYSVRFTPGYSIERKSGKLPYSPSYVPVIL 
               
               
                   
               
               
                 SELSDHMTFMERVKNMIYVLYFDFYFQMLNEKKWDQFYSEVLGRPTTLLE 
               
               
                   
               
               
                 TMGKAEFWLFRSYWDFEYPCPLLPNVEFIGGLHCKPAKPLPKEMEEFVQS 
               
               
                   
               
               
                 SGENGIVVFTLGSMVTNVTEERANMIASALAQIPQKVLWRYDGKKPDTLG 
               
               
                   
               
               
                 PNTRLYKWVPQNDLLGHPKTKAFITHGGTNGIYEAIYHGVPMVGLPLFAE 
               
               
                   
               
               
                 QPDNINRVKAKGAAVRLNLETMSKTDFLNALKQVINNPSYKRNAMWLSTI 
               
               
                   
               
               
                 QRDQPMKPLDRAVFWIEFVMRHKGAKYLRPAAHKLTWFQYHSLDVIGFLL 
               
               
                   
               
               
                 ACVATAVFVITKCFLFCCRKFAETGKKRKRE 
               
               
                   
               
               
                 AKR1A1 (UniProt: Q3ZCJ2): 
               
               
                 SEQ ID NO: 14 
               
               
                 MAASCILLHTGQKMPLIGLGTWKSDPGQVKAAIKYALSVGYRHIDCAAIY 
               
               
                   
               
               
                 GNETEIGEALKENVGPGKLVPREELFVTSKLWNTKHHPEDVEPALRKTLA 
               
               
                   
               
               
                 DLQLEYLDLYLMHWPYAFERGDSPFPKNADGTIRYDSTHYKETWRALEAL 
               
               
                   
               
               
                 VAKGLVRALGLSNFNSRQIDDVLSVASVRPAVLQVECHPYLAQNELIAHC 
               
               
                   
               
               
                 QARNLEVTAYSPLGSSDRAWRDPEEPVLLKEPVVLALAEKHGRSPAQILL 
               
               
                   
               
               
                 RWQVQRKVSCIPKSVTPSRILENIQVFDFTFSPEEMKQLDALNKNLRFIV 
               
               
                   
               
               
                 PMLTVDGKRVPRDAGHPLYPFNDPY 
               
               
                   
               
               
                 RGN (UniProt: Q9TTJ5): 
               
               
                 SEQ ID NO: 15 
               
               
                 MSSIKIECVLRENCHCGESPVWEEASNSLLFVDIPAKKVCRWDSLSKQVQ 
               
               
                   
               
               
                 RVTVDAPVSSVALRQSGGYVATVGTKFCALNWEDQSAVVLATVDKEKKNN 
               
               
                   
               
               
                 RFNDGKVDPAGRYFAGTMAEETAPAVLERRQGSLYSLFPDHHVEKYFDQV 
               
               
                   
               
               
                 DISNGLDWSMDHKIFYYIDSLSYSVDAFDYDLQTGKISNRRSVYKLEKEE 
               
               
                   
               
               
                 QIPDGMCIDVEGKLWVACYNGGRVIRLDPETGKRLQTVKLPVDKTTSCCF 
               
               
                   
               
               
                 GGKDYSEMYVTCARDGLDSKGLLQQPEAGGIFKITGLGVKGIPPYPYTG 
               
               
                   
               
               
                 GULO (UniProt: Q3ZC33): 
               
               
                 SEQ ID NO: 16 
               
               
                 MVHGYKGVKFQNWARTYGCCPEMYFQPTSVEEVREVLALARQQNKRVKVV 
               
               
                   
               
               
                 GGGHSPSDIACTDGFMIHMGKMNRVLKVDTEKKQVTVEAGILLADLHPQL 
               
               
                   
               
               
                 DKHGLALSNLGAVSDVTAGGVIGSGTHNTGIKHGILATQVVALTLLTANG 
               
               
                   
               
               
                 TILECSESSNAEVFQAARVHLGCLGVILTVTLQCVPQFHLQETTFPSTLK 
               
               
                   
               
               
                 EVLDNLDSHLKKSEYFRFLWFPHSENVSVIYQDHTNKPPSSSANWFWDYA 
               
               
                   
               
               
                 IGFYLLEFLLWISTFLPGLVGWINRFFFWLLFNGKKENCNLSHKIFTYEC 
               
               
                   
               
               
                 RFKQHVQDWAIPREKTKEALLELKAMLEANPKVVAHYPVEVRFTRGDDIL 
               
               
                   
               
               
                 LSPCFQRDSCYMNIIMYRPYGKDVPRLDYWLAYETIMKKVGGRPHWAKAH 
               
               
                   
               
               
                 NCTRKDFEKMYPAFQRFCAIREKLDPTGMFLNAYLEKVFY 
               
            
           
         
       
     
     In some embodiments, the cell is engineered to endogenously produce curcumin. Tyrosine, which is natively produced in mammalian cells, is the precursor for curcumin biosynthesis using the biosynthetic pathway enzymes tyrosine ammonia-lyase (PTAL), 4-coumarate-CoA ligase (4CL), phenylpropanoyl-diketide-CoA synthase (DCS) and curcumin synthase (CURS3). A schematic of the biosynthetic pathway, including intermediates, is shown in  FIG. 10 . One or more polynucleotides encoding PTAL, 4CL, DCS, and CURS3 are introduced into a cell that natively produces tyrosine to produce a cell expressing PTAL, 4CL, DCS, and CURS3 and endogenously synthesizing curcumin. In some embodiments, the PTAL, 4CL, DCS, and CURS3 biosynthetic enzymes are from  Oryza sativa  and  Curcuma longa  and have the polypeptide sequence of SEQ ID NOs:17-20, respectively. In some embodiments, PTAL, 4CL, DCS, and CURS3 have a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NOs:17-20 respectively. In some embodiments, only one, two, or three of the biosynthetic pathway enzymes are engineered into the cell such that pathway intermediates are produced. While the sequences listed below are from  Oryza sativa  and  Curcuma longa , a skilled artisan would recognize that homologous sequences can be identified from other species for use in the engineered cell and methods described herein. 
     
       
         
           
               
            
               
                 PTAL  Oryza sativa japonica  (Uniprot: P14717): 
               
               
                 SEQ ID NO: 17 
               
               
                 MAGNGPINKEDPLNWGAAAAEMAGSHLDEVKRMVAQFREPLVKIQGATLR 
               
               
                   
               
               
                 VGQVAAVAQAKDAAGVAVELDEEARPRVKASSEWILNCIAHGGDIYGVTT 
               
               
                   
               
               
                 GFGGTSHRRTKDGPALQVELLRHLNAGIFGTGSDGHTLPSETVRAAMLVR 
               
               
                   
               
               
                 INTLLQGYSGIRFEILEAITKLLNTGVTPCLPLRGTITASGDLVPLSYIA 
               
               
                   
               
               
                 GLITGRPNAQAISPDGRKVDAAEAFKLAGIEGGFFTLNPKEGLAIVNGTS 
               
               
                   
               
               
                 VGSALAATVMFDANILAVLSEVLSAVFCEVIVINGKPEYTDHLTHKLKHH 
               
               
                   
               
               
                 PGSIEAAAIMEHILAGSSFMSHAKKVNEMDPLLKPKQDRYALRTSPQWLG 
               
               
                   
               
               
                 PQIEVIRAATKSIEREVNSVNDNPVIDVHRGKALHGGNFQGTPIGVSMDN 
               
               
                   
               
               
                 ARLAIANIGKLMFAQFSELVNEFYNNGLTSNLAGSRNPSLDYGFKGTEIA 
               
               
                   
               
               
                 MASYCSELQYLANPITNHVQSAEQHNQDVNSLGLVSARKTLEAVDILKLM 
               
               
                   
               
               
                 TSTYIVALCQAVDLRHLEENIKSSVKNCVTQVAKKVLTMNPTGDLSSARF 
               
               
                   
               
               
                 SEKNLLTAIDREAVFSYADDPCSANYPLMQKLRAVLVEHALTSGDAEPEA 
               
               
                   
               
               
                 SVFSKITKFEEELRSALPREIEAARVAVANGTAPVANRIVESRSFPLYRF 
               
               
                   
               
               
                 VREELGCVFLTGEKLKSPGEECNKVFLGISQGKLIDPMLDCLKEWNGEPL 
               
               
                   
               
               
                 PIN 
               
               
                   
               
               
                 4CL  Oryza sativa japonica  (UniProt: Q6ETN3): 
               
               
                 SEQ ID NO: 18 
               
               
                 MGSVAAEEVVVFRSKLPDIEIDNSMTLQEYCFARMAEVGARPCLIDGQTG 
               
               
                   
               
               
                 ESYTYAEVESASRRAAAGLRRMGVGKGDVVMSLLRNCPEFAFSFLGAARL 
               
               
                   
               
               
                 GAATTTANPFYTPHEVHRQAEAAGARVIVTEACAVEKVREFAAERGVPVV 
               
               
                   
               
               
                 TVDGAFDGCVEFREVLAAEELDADADVHPDDVVALPYSSGTTGLPKGVML 
               
               
                   
               
               
                 THRSLITSVAQQVDGENPNLYFSKDDVILCLLPLFHIYSLNSVLLAGLRA 
               
               
                   
               
               
                 GSTIVIMRKFDLGALVDLVRKHNITIAPFVPPIVVEIAKSPRVTAEDLAS 
               
               
                   
               
               
                 IRMVMSGAAPMGKDLQDAFMAKIPNAVLGQGYGMTEAGPVLAMCLAFAKE 
               
               
                   
               
               
                 PFKVKSGSCGTVVRNAELKIVDPDTGTSLGRNQSGEICIRGEQIMKGYLN 
               
               
                   
               
               
                 DPEATKNTIDEDGWLHTGDIGFVDDDDEIFIVDRLKEIIKYKGFQVPPAE 
               
               
                   
               
               
                 LEALLITHPEIKDAAVVSMKDDLAGEVPVAFIVRTEGSEITEDEIKKFVA 
               
               
                   
               
               
                 KEVVFYKRINKVFFTDSIPKNPSGKILRKDLRARLAAGIPDAVAAAAADA 
               
               
                   
               
               
                 PKSS 
               
               
                   
               
               
                 DCS  Curcuma longa  (UniProt: C0SVZ5): 
               
               
                 SEQ ID NO: 19 
               
               
                 MEANGYRITHSADGPATILAIGTANPTNVVDQNAYPDFYFRVTNSEYLQE 
               
               
                   
               
               
                 LKAKFRRICEKAAIRKRHLYLTEEILRENPSLLAPMAPSFDARQAIVVEA 
               
               
                   
               
               
                 VPKLAKEAAEKAIKEWGRPKSDITHLVFCSASGIDMPGSDLQLLKLLGLP 
               
               
                   
               
               
                 PSVNRVMLYNVGCHAGGTALRVAKDLAENNRGARVLAVCSEVTVLSYRGP 
               
               
                   
               
               
                 HPAHIESLFVQALFGDGAAALVVGSDPVDGVERPIFEIASASQVMLPESA 
               
               
                   
               
               
                 EAVGGHLREIGLTFHLKSQLPSIIASNIEQSLTTACSPLGLSDWNQLFWA 
               
               
                   
               
               
                 VHPGGRAILDQVEARLGLEKDRLAATRHVLSEYGNMQSATVLFILDEMRN 
               
               
                   
               
               
                 RSAAEGHATTGEGLDWGVLLGFGPGLSIETVVLHSCRLN 
               
               
                   
               
               
                 CURS3  Curcuma longa  (UniProt: C6L7V9): 
               
               
                 SEQ ID NO: 20 
               
               
                 MGSLQAMRRAQRAQGPATIMAVGTSNPPNLYEQTSYPDFYFRVTNSDHKH 
               
               
                   
               
               
                 ALKNKFRVICEKTKVKRRYLHLTEEILKQRPKLCSYMEPSFDDRQDIVVE 
               
               
                   
               
               
                 EIPKLAKEAAEKAIKEWGRPKSEITHLVFCSISGIDMPGADYRLATLLGL 
               
               
                   
               
               
                 PLSVNRLMLYSQACHMGAQMLRIAKDLAENNRGARVLAVSCEITVLSFRG 
               
               
                   
               
               
                 PDAGDFEALACQAGFGDGAAAVVVGADPLPGVERPIYEIAAAMQETVPES 
               
               
                   
               
               
                 ERAVGGHLREIGWTFHFFNQLPKLIAENIEGSLARAFKPLGISEWNDVFW 
               
               
                   
               
               
                 VAHPGNWGIMDAIETKLGLEQGKLATARHVFSEYGNMQSATVYFVMDEVR 
               
               
                   
               
               
                 KRSAAEGRATTGEGLEWGVLFGFGPGLTIETVVLRSVPLP 
               
            
           
         
       
     
     In some embodiments, the cell is engineered to endogenously produce curcumin using the biosynthetic pathway enzymes PTAL, 4CL, and bisdemethoxycurcumin synthase. One or more polynucleotides encoding PTAL, 4CL and bisdemethoxycurcumin synthase are introduced into a cell that natively produces tyrosine to produce a cell expressing PTAL, 4CL and bisdemethoxycurcumin synthase and endogenously synthesizing curcumin. In some embodiments, the PTAL, 4CL and bisdemethoxycurcumin synthase have the amino acid sequences of SEQ ID NOs:17, 18, and 21, respectively. In some embodiments, the PTAL, 4CL and bisdemethoxycurcumin synthase have an amino acid sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NOs:17, 18, and 21, respectively. While the sequence listed below are from  Oryza sativa , a skilled artisan would recognize that homologous sequences can be identified from other species for use in the engineered cell and methods described herein. 
     
       
         
           
               
            
               
                 bisdemethoxycurcumin synthase 
               
               
                   Oryza sativa japonica  (UniProt: Q8LIL0): 
               
               
                 SEQ ID NO: 21 
               
               
                 MAPTTTMGSALYPLGEMRRSQRADGLAAVLAIGTANPPNCVTQEEFPDFY 
               
               
                   
               
               
                 FRVTNSDHLTALKDKFKRICQEMGVQRRYLHHTEEMLSAHPEFVDRDAPS 
               
               
                   
               
               
                 LDARLDIAADAVPELAAEAAKKAIAEWGRPAADITHLVVTTNSGAHVPGV 
               
               
                   
               
               
                 DFRLVPLLGLRPSVRRTMLHLNGCFAGCAALRLAKDLAENSRGARVLVVA 
               
               
                   
               
               
                 AELTLMYFTGPDEGCFRTLLVQGLFGDGAAAVIVGADADDVERPLFEIVS 
               
               
                   
               
               
                 AAQTIIPESDHALNMRFTERRLDGVLGRQVPGLIGDNVERCLLDMFGPLL 
               
               
                   
               
               
                 GGDGGGGWNDLFWAVHPGSSTIMDQVDAALGLEPGKLAASRRVLSDYGNM 
               
               
                   
               
               
                 SGATVIFALDELRRQRKEAAAAGEWPELGVMMAFGPGMTVDAMLLHATSH 
               
               
                   
               
               
                 VN 
               
            
           
         
       
     
     In some embodiments, the cell is engineered to endogenously produce cannabidiol. Malonyl-CoA, which is natively produced in mammalian cells, is the precursor for cannabidiol (CBD) biosynthesis using the biosynthetic pathway enzymes 3,5,7-trioxododecanoyl-CoA synthase (OLS), olivetolic acid cyclase (OAC), cannabigerolic acid synthase (CBGAS, also known as prenyltransferase 1 or PT1), and cannabidiolic acid synthase (CBDAS). A schematic of the biosynthetic pathway, including intermediates, is shown in  FIG. 10 . One or more polynucleotides encoding OLS, OAC, CPGAS, and CBDAS are introduced into a cell that natively produces malonyl-CoA to produce a cell expressing OLS, OAC, CPGAS, and CBDAS and endogenously synthesizing CBD. In some embodiments, prenyltransferase NphB can be used in place of CPGAS in the CBD biosynthetic pathway. In some embodiments, the OLS, OAC, CPGAS, CBDAS, and NphB biosynthetic enzymes are from  Cannabis sativa  and have the polypeptide sequence of SEQ ID NOs:22-26, respectively. In some embodiments, OLS, OAC, CPGAS, CBDAS, and NphB have a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NOs:22-26 respectively. In some embodiments, only one, two, or three of the biosynthetic pathway enzymes are engineered into the cell such that pathway intermediates are produced. While the sequences listed below are from  Cannabis sativa , a skilled artisan would recognize that homologous sequences can be identified from other species for use in the engineered cell and methods described herein. 
     
       
         
           
               
            
               
                 OLS (UniProt: B1Q2B6): 
               
               
                 SEQ ID NO: 22 
               
               
                 MNHLRAEGPASVLAIGTANPENILLQDEFPDYYFRVTKSEHMTQLKEKFR 
               
               
                   
               
               
                 KICDKSMIRKRNCFLNEEHLKQNPRLVEHEMQTLDARQDMLVVEVPKLGK 
               
               
                   
               
               
                 DACAKAIKEWGQPKSKITHLIFTSASTTDMPGADYHCAKLLGLSPSVKRV 
               
               
                   
               
               
                 MMYQLGCYGGGTVLRIAKDIAENNKGARVLAVCCDIMACLFRGPSESDLE 
               
               
                   
               
               
                 LLVGQAIFGDGAAAVIVGAEPDESVGERPIFELVSTGQTILPNSEGTIGG 
               
               
                   
               
               
                 HIREAGLIFDLHKDVPMLISNNIEKCLIEAFTPIGISDWNSIFWITHPGG 
               
               
                   
               
               
                 KAILDKVEEKLHLKSDKFVDSRHVLSEHGNMSSSTVLFVMDELRKRSLEE 
               
               
                   
               
               
                 GKSTTGDGFEWGVLFGFGPGLTVERVVVRSVPIKY 
               
               
                   
               
               
                 OAC (UniProt: I6WU39): 
               
               
                 SEQ ID NO: 23 
               
               
                 MAVKHLIVLKFKDEITEAQKEEFFKTYVNLVNIIPAMKDVYWGKDVTQKN 
               
               
                   
               
               
                 KEEGYTHIVEVTFESVETIQDYIIHPAHVGFGDVYRSFWEKLLIFDYTPR 
               
               
                   
               
               
                 K 
               
               
                   
               
               
                 CBGAS or PT1 (UniProt: A0A455ZIK6): 
               
               
                 SEQ ID NO: 24 
               
               
                 MGLSSVCTFSFQTNYHTLLNPHNNNPKTSLLCYRHPKTPIKYSYNNFPSK 
               
               
                   
               
               
                 HCSTKSFHLQNKCSESLSIAKNSIRAATTNQTEPPESDNHSVATKILNFG 
               
               
                   
               
               
                 KACWKLQRPYTIIAFTSCACGLFGKELLHNTNLISWSLMFKAFFFLVAIL 
               
               
                   
               
               
                 CIASFTTTINQIYDLHIDRINKPDLPLASGEISVNTAWIMSIIVALFGLI 
               
               
                   
               
               
                 ITIKMKGGPLYIFGYCFGIFGGIVYSVPPFRWKQNPSTAFLLNFLAHIIT 
               
               
                   
               
               
                 NFTFYYASRAALGLPFELRPSFTFLLAFMKSMGSALALIKDASDVEGDTK 
               
               
                   
               
               
                 FGISTLASKYGSRNLTLFCSGIVLLSYVAAILAGIIWPQAFNSNVMLLSH 
               
               
                   
               
               
                 AILAFWLILQTRDFALTNYDPEAGRRFYEFMWKLYYAEYLVYVFI 
               
               
                   
               
               
                 CBDAS (UniProt: A6P6V9): 
               
               
                 SEQ ID NO: 25 
               
               
                 MKCSTFSFWFVCKIIFFFFSFNIQTSIANPRENFLKCFSQYIPNNATNLK 
               
               
                   
               
               
                 LVYTQNNPLYMSVLNSTIHNLRFTSDTTPKPLVIVTPSHVSHIQGTILCS 
               
               
                   
               
               
                 KKVGLQIRTRSGGHDSEGMSYISQVPFVIVDLRNMRSIKIDVHSQTAWVE 
               
               
                   
               
               
                 AGATLGEVYYWVNEKNENLSLAAGYCPTVCAGGHFGGGGYGPLMRNYGLA 
               
               
                   
               
               
                 ADNIIDAHLVNVHGKVLDRKSMGEDLFWALRGGGAESFGIIVAWKIRLVA 
               
               
                   
               
               
                 VPKSTMFSVKKIMEIHELVKLVNKWQNIAYKYDKDLLLMTHFITRNITDN 
               
               
                   
               
               
                 QGKNKTAIHTYFSSVFLGGVDSLVDLMNKSFPELGIKKTDCRQLSWIDTI 
               
               
                   
               
               
                 IFYSGVVNYDTDNFNKEILLDRSAGQNGAFKIKLDYVKKPIPESVFVQIL 
               
               
                   
               
               
                 EKLYEEDIGAGMYALYPYGGIMDEISESAIPFPHRAGILYELWYICSWEK 
               
               
                   
               
               
                 QEDNEKHLNWIRNIYNFMTPYVSKNPRLAYLNYRDLDIGINDPKNPNNYT 
               
               
                   
               
               
                 QARIWGEKYFGKNFDRLVKVKTLVDPNNFFRNEQSIPPLPRHRH 
               
               
                   
               
               
                 NphB (UniProt: A0A2Z4JFA9): 
               
               
                 SEQ ID NO: 26 
               
               
                 MSGAADVERVYAAMEEAAGLLDVSCAREKIYPLLTVFQDTLTDGVVVFSM 
               
               
                   
               
               
                 ASGRRSTELDFSISVPVSQGDPYATVVKEGLFQATGSPVDELLADTVAHL 
               
               
                   
               
               
                 PVSMFAIDGEVTGGFKKTYAFFPTDDMPGVAQLAAIPSMPASVAENAELF 
               
               
                   
               
               
                 ARYGLDKVQMTSMDYKKRQVNLYFSDLKQEYLQPESVVALARELGLRVPG 
               
               
                   
               
               
                 ELGLEFCKRSFAVYPTLNWDTGKIDRLCFAAISTDPTLVPSEDERDIEMF 
               
               
                   
               
               
                 RNYATKAPYAYVGEKRTLVYGLTLSSTEEYYKLGAYYHITDIQRQLLKAF 
               
               
                   
               
               
                 DALED 
               
            
           
         
       
     
     The following gene sequences are codon optimized for expression in a bovine cell. One of skill in the art will recognize that the gene sequence may be optimized for expression in a cell from anther species or the wild-type sequence from  Cannabis sativa  may be used. 
     
       
         
           
               
               
            
               
                 OLS: 
                   
               
               
                 SEQ ID NO: 27 
                   
               
               
                 ATGAACCACCTGAGAGCCGAAGGACCTGCCTCTGTGCTGGCCATCGGAACCGCCAA 
                   
               
               
                   
               
               
                 TCCTGAGAACATCCTGCTGCAGGACGAGTTCCCCGACTACTACTTCAGAGTGACCAA 
               
               
                   
               
               
                 GAGCGAGCACATGACCCAGCTGAAAGAGAAGTTCCGCAAGATCTGCGACAAGAGC 
               
               
                   
               
               
                 ATGATCCGCAAGAGGAACTGCTTCCTGAACGAGGAACACCTGAAGCAGAACCCCAG 
               
               
                   
               
               
                 GCTGGTGGAACACGAGATGCAGACCCTGGACGCCAGACAGGATATGCTGGTGGTGG 
               
               
                   
               
               
                 AAGTGCCCAAGCTGGGCAAAGATGCCTGTGCCAAGGCCATCAAAGAGTGGGGCCAG 
               
               
                   
               
               
                 CCTAAGAGCAAGATCACCCACCTGATCTTCACCAGCGCCAGCACCACAGATATGCCT 
               
               
                   
               
               
                 GGCGCCGATTACCACTGCGCCAAACTGCTGGGACTGAGCCCTTCTGTGAAGCGCGTG 
               
               
                   
               
               
                 ATGATGTACCAGCTGGGCTGTTACGGCGGAGGCACCGTGCTGAGAATCGCCAAGGA 
               
               
                   
               
               
                 TATCGCCGAGAACAACAAGGGCGCCAGAGTGCTGGCCGTGTGCTGTGATATTATGG 
               
               
                   
               
               
                 CCTGCCTGTTCAGGGGCCCCAGCGAGTCTGATCTGGAACTGCTCGTTGGCCAGGCCA 
               
               
                   
               
               
                 TTTTTGGAGATGGCGCCGCTGCTGTGATCGTGGGAGCTGAGCCTGATGAGAGCGTGG 
               
               
                   
               
               
                 GCGAAAGACCCATCTTCGAGCTGGTGTCTACCGGCCAGACCATCCTGCCTAACTCTG 
               
               
                   
               
               
                 AGGGAACCATCGGCGGCCACATCAGAGAAGCCGGCCTGATCTTTGACCTGCACAAG 
               
               
                   
               
               
                 GACGTGCCCATGCTGATCTCCAACAACATCGAGAAGTGCCTGATCGAGGCCTTCACA 
               
               
                   
               
               
                 CCCATCGGCATCAGCGACTGGAACAGCATCTTCTGGATCACACACCCTGGCGGAAA 
               
               
                   
               
               
                 GGCCATCCTGGACAAGGTGGAAGAGAAGCTGCACCTGAAGTCCGACAAGTTCGTGG 
               
               
                   
               
               
                 ACAGCAGACACGTGCTGTCCGAGCACGGCAACATGAGCAGCTCTACCGTGCTGTTC 
               
               
                   
               
               
                 GTGATGGACGAGCTGAGGAAGCGCTCTCTGGAAGAGGGCAAGTCTACCACCGGCGA 
               
               
                   
               
               
                 CGGATTTGAATGGGGCGTGCTGTTTGGCTTCGGCCCTGGACTGACAGTGGAAAGAGT 
               
               
                   
               
               
                 GGTCGTCAGAAGCGTGCCCATCAAATAC 
               
               
                   
               
               
                 OAC 
               
               
                 SEQ ID NO: 28 
                   
               
               
                 ATGGCAGTTAAGCACCTGATCGTGCTGAAGTTCAAGGACGAGATCACAGAGGCCCA 
                   
               
               
                   
               
               
                 GAAAGAAGAGTTCTTCAAGACCTACGTGAACCTGGTCAACATCATCCCCGCCATGA 
               
               
                   
               
               
                 AGGACGTGTACTGGGGCAAAGACGTGACCCAGAAGAACAAAGAGGAAGGCTACAC 
               
               
                   
               
               
                 CCACATCGTGGAAGTGACCTTCGAGTCCGTGGAAACCATCCAGGACTACATCATTCA 
               
               
                   
               
               
                 CCCCGCTCACGTCGGATTCGGCGACGTGTACAGATCCTTCTGGGAAAAGCTGCTGAT 
               
               
                   
               
               
                 CTTCGACTACACACCTAGAAAG 
               
               
                   
               
               
                 CBGAS or PT1 
               
               
                 SEQ ID NO: 29 
                   
               
               
                 ATGGGATTGAGTAGCGTGTGCACCTTCAGCTTCCAAACGAACTACCACACACTGCTG 
                   
               
               
                   
               
               
                 AACCCGCACAACAACAACCCCAAGACCAGCCTGCTGTGCTACAGGCACCCTAAGAC 
               
               
                   
               
               
                 ACCCATCAAGTACAGCTACAACAACTTCCCCAGCAAGCACTGCAGCACCAAGAGCT 
               
               
                   
               
               
                 TCCATCTGCAAAACAAGTGCAGCGAGAGCCTGTCTATCGCCAAGAACTCCATCAGA 
               
               
                   
               
               
                 GCCGCCACCACCAATCAGACCGAGCCTCCAGAGTCTGACAACCACAGCGTGGCCAC 
               
               
                   
               
               
                 CAAGATCCTGAACTTCGGCAAGGCCTGCTGGAAGCTGCAGAGGCCCTACACCATCA 
               
               
                   
               
               
                 TTGCCTTCACCTCTTGCGCCTGCGGCCTGTTCGGAAAAGAGCTGCTGCACAACACCA 
               
               
                   
               
               
                 ATCTGATCAGCTGGTCCCTGATGTTCAAGGCCTTCTTCTTCCTGGTGGCCATTCTGTG 
               
               
                   
               
               
                 TATCGCCAGCTTCACCACCACCATCAACCAGATCTACGATCTGCACATCGACCGCAT 
               
               
                   
               
               
                 CAACAAGCCCGATCTGCCTCTGGCCTCTGGCGAGATCTCTGTGAATACCGCCTGGAT 
               
               
                   
               
               
                 CATGAGCATCATCGTGGCCCTGTTCGGGCTGATCATCACCATCAAGATGAAGGGCGG 
               
               
                   
               
               
                 ACCCCTGTACATCTTCGGCTACTGCTTCGGCATCTTCGGAGGCATCGTGTACTCCGTG 
               
               
                   
               
               
                 CCTCCATTCCGCTGGAAGCAGAATCCCTCTACCGCCTTCCTGCTGAACTTTCTGGCCC 
               
               
                   
               
               
                 ACATCATTACCAACTTCACCTTCTACTACGCCAGCAGGGCCGCTCTGGGACTGCCTT 
               
               
                   
               
               
                 TTGAACTGAGGCCCTCTTTCACCTTTCTGCTGGCCTTTATGAAGTCCATGGGCAGCGC 
               
               
                   
               
               
                 CCTGGCTCTGATCAAGGATGCCAGTGATGTGGAAGGCGACACCAAGTTCGGAATCA 
               
               
                   
               
               
                 GCACCCTGGCCTCTAAGTACGGCAGCAGAAATCTGACCCTGTTCTGCAGCGGCATCG 
               
               
                   
               
               
                 TGCTGCTGTCTTACGTGGCCGCTATCCTGGCCGGAATCATTTGGCCTCAGGCCTTCAA 
               
               
                   
               
               
                 CAGCAACGTGATGCTGCTGAGCCACGCCATTCTGGCCTTTTGGCTGATCCTGCAGAC 
               
               
                   
               
               
                 CAGGGATTTCGCCCTGACCAACTACGATCCTGAGGCCGGCAGACGCTTCTACGAGTT 
               
               
                   
               
               
                 CATGTGGAAGCTGTACTACGCCGAGTACCTGGTGTACGTCTTCATC 
               
               
                   
               
               
                 CBDAS 
               
               
                 SEQ ID NO: 30 
                   
               
               
                 ATGAAGTGCAGTACCTTCTCCTTTTGGTTCGTGTGCAAGATTATCTTCTTCTTTTTCTC 
                   
               
               
                   
               
               
                 ATTCAATATCCAGACCTCTATCGCTAACCCGCGCGAGAACTTCCTGAAGTGCTTCAG 
               
               
                   
               
               
                 CCAGTACATCCCCAACAATGCCACCAACCTGAAGCTGGTGTATACGCAAAACAACC 
               
               
                   
               
               
                 CGCTGTACATGAGCGTGCTGAACAGCACCATCCACAACCTGAGGTTCACCTCCGACA 
               
               
                   
               
               
                 CCACACCTAAGCCTCTGGTCATCGTGACCCCTAGCCACGTGTCACACATTCAGGGCA 
               
               
                   
               
               
                 CCATCCTGTGCAGCAAGAAAGTGGGACTGCAGATCAGGACCAGAAGCGGCGGACAC 
               
               
                   
               
               
                 GATAGCGAGGGCATGAGCTACATTTCTCAGGTGCCCTTCGTGATTGTGGACCTGAGG 
               
               
                   
               
               
                 AACATGCGCAGCATCAAGATCGACGTGCACAGCCAGACAGCCTGGGTTGAAGCAGG 
               
               
                   
               
               
                 CGCTACACTGGGCGAAGTGTACTACTGGGTCAACGAGAAGAACGAGAACCTGAGCC 
               
               
                   
               
               
                 TGGCCGCTGGCTACTGTCCTACAGTTTGTGCTGGCGGCCACTTTGGCGGCGGAGGAT 
               
               
                   
               
               
                 ATGGACCTCTGATGAGGAATTACGGCCTGGCTGCCGACAATATCATCGACGCCCACC 
               
               
                   
               
               
                 TCGTGAACGTGCACGGCAAGGTGCTGGACAGAAAGTCTATGGGCGAAGATCTGTTC 
               
               
                   
               
               
                 TGGGCCCTGAGAGGTGGCGGAGCCGAGTCTTTTGGAATTATCGTGGCCTGGAAGATC 
               
               
                   
               
               
                 CGCCTGGTGGCTGTGCCTAAGTCCACCATGTTCAGCGTGAAGAAAATCATGGAAATC 
               
               
                   
               
               
                 CACGAGCTGGTCAAGCTCGTGAACAAGTGGCAGAATATCGCCTACAAATACGACAA 
               
               
                   
               
               
                 GGACCTCCTGCTGATGACCCACTTCATCACCAGAAACATCACCGACAACCAGGGCA 
               
               
                   
               
               
                 AGAACAAGACCGCCATCCACACCTACTTCAGCTCCGTGTTTCTCGGCGGCGTGGACT 
               
               
                   
               
               
                 CTCTGGTGGATCTGATGAACAAGAGCTTTCCCGAGCTGGGCATCAAGAAAACCGAC 
               
               
                   
               
               
                 TGCAGACAGCTGAGCTGGATCGATACCATCATCTTCTACAGCGGCGTGGTCAACTAC 
               
               
                   
               
               
                 GACACCGATAACTTCAACAAAGAGATCCTGCTGGACCGCAGCGCCGGACAGAATGG 
               
               
                   
               
               
                 GGCCTTTAAGATCAAGCTGGACTACGTGAAGAAGCCCATTCCTGAGTCCGTGTTCGT 
               
               
                   
               
               
                 GCAGATCCTGGAAAAACTGTACGAAGAGGACATCGGAGCCGGGATGTACGCTCTGT 
               
               
                   
               
               
                 ACCCTTACGGCGGCATCATGGATGAGATCTCCGAGAGCGCCATTCCATTTCCACACA 
               
               
                   
               
               
                 GAGCCGGCATCCTGTACGAGCTGTGGTACATCTGCAGCTGGGAGAAGCAAGAGGAT 
               
               
                   
               
               
                 AACGAGAAGCACCTCAACTGGATCCGCAACATCTACAACTTCATGACCCCTTACGTC 
               
               
                   
               
               
                 AGCAAGAACCCTAGACTGGCCTACCTGAACTACCGCGACCTGGACATCGGGATCAA 
               
               
                   
               
               
                 CGACCCAAAGAACCCCAACAACTACACCCAGGCCAGGATTTGGGGCGAGAAGTACT 
               
               
                   
               
               
                 TTGGCAAGAACTTCGACCGCCTGGTCAAAGTGAAAACCCTGGTGGACCCTAACAAC 
               
               
                   
               
               
                 TTCTTCAGAAACGAGCAGAGCATCCCTCCACTGCCTAGACATCGGCAT 
               
            
           
         
       
     
     In some embodiments, the cell is engineered to express anti-TNFα nanobody V565 (SEQ ID NO:7). The cell is transfected with a heterologous polynucleotide encoding nanobody V565 to produce a cell expressing nanobody V565. In some embodiments, the polynucleotide encodes a polypeptide at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NO:7. In some embodiments, the polynucleotide encoding V565 is codon optimized for expression in a particular cell of interest. In some embodiments, the polynucleotide encoding V565 is codon optimized for expression in a bovine cell. 
     
       
         
           
               
            
               
                 nanobody V565: 
               
               
                 SEQ ID NO: 7 
               
               
                 DVQLVESGGGLVQPGGSLKLSCAASGFDFSSHWMYWVRQAPGKELEWLSE 
               
               
                   
               
               
                 INTNGLITHYGDSVKGRFTVSRNNAANKMYLELTRLEPEDTALYYCARNQ 
               
               
                   
               
               
                 HGLNKGQGTQVTVSS 
               
            
           
         
       
     
     In some embodiments, V565 is linked to human TNFα by a flexible, cleavable linker and a polynucleotide expressing the V565 linked to human TNFα by a flexible, cleavable linker is introduced into a cell. Without wishing to be bound by any particular theory or mechanism, linking the V565 nanobody to TNFα will inhibit V565 from binding to target TNFα in the subject, and cleavage of the flexible, cleavable linker under specific conditions will release the V565 to bind target TNFα in the subject. In some embodiments, the flexible cleavage linker is a trypsin cleavable linker with at least one, two, three, four, or five lysine residues. In some embodiments, the linker is between about 10 and about 50 amino acids in length. In some embodiments, the linker is between about 15 and about 40 amino acids in length. In some embodiments, the linker have the sequence of SEQ ID NO:9 (GGG SGG GSG GGS GGK GGK GGK GGK GGG SGG GSG AQG). 
     In some embodiments, the cell is engineered to express antimicrobial peptide 16 (AMP16; SEQ ID NO:8). The cell is transfected with a heterologous polynucleotide encoding AMP16 to produce a cell expressing AMP16. In some embodiments, the polynucleotide encodes a polypeptide at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical to SEQ ID NO:8. In some embodiments, the polynucleotide encoding AMP16 is codon optimized for expression in a particular cell of interest. In some embodiments, the polynucleotide encoding AMP16 is codon optimized for expression in a bovine cell. 
     
       
         
           
               
               
            
               
                   
                 AMP16: 
               
               
                   
                 SEQ ID NO: 8 
               
               
                   
                 IRPI IRPI IRPI IRPI IRPI IRPI IRPI 
               
            
           
         
       
     
     In some embodiments, the AMP16 is attached to an elastase cleavable linker including Asn-Pro-Val (NPV) repeats. In some embodiments, at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, or at least 10 repeats of AMP16 will be assembled in a construct, each repeat separated by a NPV linker. 
     In some embodiments, the cell is engineered to express serine protease inhibitor (SPI) to inhibit pepsin digestion of V565 or AMP16. In some embodiments, the SPI is Tsp03044 having the amino acid sequence of SEQ ID NO:31 or a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical thereto. In some embodiments, the SPI is TspAd5 having the amino acid sequence of SEQ ID NO:33 or a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical thereto. 
     
       
         
           
               
               
            
               
                 Tsp03044 (NCBI Reference Sequence XM_003379333) 
                   
               
               
                 SEQ ID NO: 31 
                   
               
               
                 MANLYNSMMLISLIILCPLNEIWNSCGSSCEETCESIASGKDTPCTLQCVPGCFCVDGFVR 
                   
               
               
                   
               
               
                 DLRGRCIPMSLCPNKVNSSCPENEVFQECGSACPETCDTVSSGFERPCTGNCIAGCFCKN 
               
               
                   
               
               
                 GYVRGYDGKCIPPEDCGKPNNDKCGSNEVFMKCGSACPATCDSIRSENIIPCTKECVSGC 
               
               
                   
               
               
                 FCKSGYVRASTGECLAPEACGAHLGGCGPREEYRACGSACPESCESIKDLAPHACPAMC 
               
               
                   
               
               
                 VPGCFCKFPFVRGYDLRCIMPDDC 
               
               
                   
               
               
                 Tsp03044 
               
               
                 SEQ ID NO: 32 
                   
               
               
                 atggccaatc tctataatag tatgatgtta atatccttga tcattttgtg tccgttaaac 
                   
               
               
                   
               
               
                 gaaatttgga attcttgtgg aagttcatgt gaagaaactt gtgaaagcat tgctagtggc 
               
               
                   
               
               
                 aaagacacac cttgcactct gcagtgcgtt cctggttgct tttgtgtcga cggttttgta 
               
               
                   
               
               
                 cgagatttaa gaggtcgttg cattccaatg tcattatgtc caaataaagt caacagttca 
               
               
                   
               
               
                 tgtcctgaaa atgaagtctt tcaagaatgc ggttccgctt gtccagaaac atgcgataca 
               
               
                   
               
               
                 gtttcctcgg gatttgaaag accttgcacg gggaattgta ttgctggttg tttttgtaag 
               
               
                   
               
               
                 aatgggtatg tacgaggtta cgatggaaaa tgcattccac cagaagattg tggaaaacct 
               
               
                   
               
               
                 aataacgaca aatgtggatc aaatgaagtt ttcatgaagt gtggtagcgc ttgtcccgca 
               
               
                   
               
               
                 acctgcgatt cgatccgaag tgaaaatatt attccatgca ctaaagagtg tgtttcgggt 
               
               
                   
               
               
                 tgcttctgca aatctggcta cgtcagagca tctaccggtg aatgtttagc tccggaagct 
               
               
                   
               
               
                 tgtggtgcgc atttgggcgg ctgtggaccc cgagaagagt acagagcttg tggaagtgct 
               
               
                   
               
               
                 tgtccagaat cttgtgaatc tataaaagat cttgcgccac acgcgtgtcc tgctatgtgt 
               
               
                   
               
               
                 gtacctggat gtttctgcaa gtttccattc gttcgtgggt acgatctgcg ttgcataatg 
               
               
                   
               
               
                 cctgatgatt gctga 
               
               
                   
               
               
                 TspAd5 (GenBank: EU263307.1) 
               
               
                 SEQ ID NO: 33 
                   
               
               
                 METEIAKPLADFAYSLYQLEEAGNVFFSPVSIFLALAMVFFGSNGNTNTQLLNVMFKAG 
                   
               
               
                   
               
               
                 WKKNRTKKAMRSFVSSLTIDEYYDASLKLANRLYANDQYPILHPFLKDVKRYLSSDLVS 
               
               
                   
               
               
                 VNFADTEAARLQINKWVSDQTNHKINDLLQSGTVEANTRLIAVNAIYFKASWDEVEDE 
               
               
                   
               
               
                 AHTKRKKFYPTPHSSIKIPMMTQTNGYSYYETEDYQFLGMDYYPEYLKMFILLPKSGKT 
               
               
                   
               
               
                 LSELQQKENGETLLNLVSKVSGAEVKVTIPKMKFEKQMNLVEALKKLGIEDLFIPGKAD 
               
               
                   
               
               
                 LSGICVKEKLYVSDIVHKAYLEFNEEGTEAAAATADRIVPMSGVMYEDSFEFVADHPFL 
               
               
                   
               
               
                 FFIFDSRSKAILFIGRFSGN 
               
               
                   
               
               
                 SEQ ID NO: 34 
                   
               
               
                 agattattgg agaaaattgt ggaattgttg tgaacgaaat ggaaacagaa attgcaaaac 
                   
               
               
                   
               
               
                 cattagctga tttcgcttat tcgctttatc aattggaaga agcaggaaat gtattctttt 
               
               
                   
               
               
                 caccagtatc gatttttctg gcacttgcaa tggtattttt tggatccaac ggtaatacaa 
               
               
                   
               
               
                 atactcaact gctgaatgtg atgttcaaag ctggctggaa gaaaaatcgt acaaaaaagg 
               
               
                   
               
               
                 caatgcggtc gttcgtttca tcgctcacca tcgatgaata ctatgatgct tctttgaaat 
               
               
                   
               
               
                 tggccaatcg attgtatgct aatgatcaat atccaatatt gcatccattt cttaaagatg 
               
               
                   
               
               
                 tgaaaagata tctatcaagt gatttggtta gtgtaaattt tgccgacact gaagcagcac 
               
               
                   
               
               
                 gtttgcagat taataagtgg gtgagcgatc agacgaatca taaaatcaac gatttgcttc 
               
               
                   
               
               
                 aatctggaac agttgaggca aatactcgcc ttatcgccgt caacgcaatt tatttcaaag 
               
               
                   
               
               
                 cctcttggga tgaggttttc gacgaagcac atacaaagcg gaaaaaattt tatccaacac 
               
               
                   
               
               
                 cgcacagttc aattaaaata ccaatgatga cacagacaaa tggatattcg tattatgaaa 
               
               
                   
               
               
                 ctgaagatta tcaatttctt ggaatggatt attatccaga atatcttaaa atgttcattt 
               
               
                   
               
               
                 tattaccaaa gtcaggaaaa acactttctg aattacaaca aaagtttaat ggagaaactc 
               
               
                   
               
               
                 tgttaaattt ggtatccaaa gttagcggtg ctgaagtgaa agtgacaatt ccaaaaatga 
               
               
                   
               
               
                 agtttgagaa acagatgaat ttagttgaag cattgaagaa acttggtata gaagatcttt 
               
               
                   
               
               
                 tcattcctgg aaaagcagat ctttctggaa tttgtgttaa agaaaagctt tatgtatctg 
               
               
                   
               
               
                 atattgttca caaagcgtat ctagagttca atgaagaagg aactgaagca gcagcagcga 
               
               
                   
               
               
                 ccgccgatcg catagtaccc atgtccggcg ttatgtatga agacagtttt gaatttgttg 
               
               
                   
               
               
                 ctgatcatcc atttcttttc ttcatctttg acagcagatc aaaagcgatt ctttttattg 
               
               
                   
               
               
                 gacgtttttc tggtaattaa agataattag aaaatggata aatggagaaa aatgattttt 
               
               
                   
               
               
                 gctgggtgaa aatgcaagtt ttaaaagtat ttgaaaatat tttttaatga tgatttttat 
               
               
                   
               
               
                 tgtatgggaa aatagtaaag aatatttcat gcaaaaaaaa aaaaaaaaaa a 
               
            
           
         
       
     
     In some embodiments, the cell is engineered for increased expression of one or more growth factors selected from FGF-2, TGFβ-3, NRG-1 and IGF-1. In some embodiments, the cell is engineered for increased expression of insulin and transferrin. 
     In some embodiments the cell is engineered to endogenously produce cinnamaldehyde from the precursor phenylalanine by the introduction of one or more polynucleotides encoding phenylalanine ammonia-lyase, 4-coumarate-CoA ligase, and cinnamoyl-CoA reductase into the cell. 
     In some embodiments, the cell is engineered to endogenously produce (R)-limonene from the precursor geranyl pyrophosphate by introduction of a polynucleotide encoding (R)-limonene synthase into the cell. In some embodiments, (R)-limonene synthase has the amino acid sequence of SEQ ID NO:35 or a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical thereto. In some embodiments, the cell is engineered to endogenously produce (S)-limonene from the precursor geranyl pyrophosphate by introduction of a polynucleotide encoding (S)-limonene synthase. In some embodiments, (S)-limonene synthase has the amino acid sequence of SEQ ID NO:36 or a sequence at least 85%, 90%, 95%, 98%, 99%, or 99.9% identical thereto. 
     
       
         
           
               
            
               
                   Citrus limon  (UniProt: Q8L5K3): 
               
               
                 SEQ ID NO: 35 
               
               
                 MSSCINPSTLVTSVNAFKCLPLATNKAAIRIMAKYKPVQCLISAKYDNLT 
               
               
                   
               
               
                 VDRRSANYQPSIWDHDFLQSLNSNYTDEAYKRRAEELRGKVKIAIKDVIE 
               
               
                   
               
               
                 PLDQLELIDNLQRLGLAHRFETEIRNILNNIYNNNKDYNWRKENLYATSL 
               
               
                   
               
               
                 EFRLLRQHGYPVSQEVFNGFKDDQGGFICDDFKGILSLHEASYYSLEGES 
               
               
                   
               
               
                 IMEEAWQFTSKHLKEVMISKNMEEDVFVAEQAKRALELPLHWKVPMLEAR 
               
               
                   
               
               
                 WFIHIYERREDKNHLLLELAKMEFNTLQAIYQEELKEISGWWKDTGLGEK 
               
               
                   
               
               
                 LSFARNRLVASFLWSMGIAFEPQFAYCRRVLTISIALITVIDDIYDVYGT 
               
               
                   
               
               
                 LDELEIFTDAVERWDINYALKHLPGYMKMCFLALYNFVNEFAYYVLKQQD 
               
               
                   
               
               
                 FDLLLSIKNAWLGLIQAYLVEAKWYHSKYTPKLEEYLENGLVSITGPLII 
               
               
                   
               
               
                 TISYLSGTNPIIKKELEFLESNPDIVHWSSKIFRLQDDLGTSSDEIQRGD 
               
               
                   
               
               
                 VPKSIQCYMHETGASEEVARQHIKDMMRQMWKKVNAYTADKDSPLTGTTT 
               
               
                   
               
               
                 EFLLNLVRMSHFMYLHGDGHGVQNQETIDVGFTLLFQPIPLEDKHMAFTA 
               
               
                   
               
               
                 SPGTKG 
               
               
                   
               
               
                   Abies grandis  (UniProt: O22340) 
               
               
                 SEQ ID NO: 36 
               
               
                 MALLSIVSLQVPKSCGLKSLISSSNVQKALCISTAVPTLRMRRRQKALVI 
               
               
                   
               
               
                 NMKLTTVSHRDDNGGGVLQRRIADHHPNLWEDDFIQSLSSPYGGSSYSER 
               
               
                   
               
               
                 AETVVEEVKEMFNSIPNNRELFGSQNDLLTRLWMVDSIERLGIDRHFQNE 
               
               
                   
               
               
                 IRVALDYVYSYWKEKEGIGCGRDSTFPDLNSTALALRTLRLHGYNVSSDV 
               
               
                   
               
               
                 LEYFKDEKGHFACPAILTEGQITRSVLNLYRASLVAFPGEKVMEEAEIFS 
               
               
                   
               
               
                 ASYLKKVLQKIPVSNLSGEIEYVLEYGWHTNLPRLEARNYIEVYEQSGYE 
               
               
                   
               
               
                 SLNEMPYMNMKKLLQLAKLEFNIFHSLQLRELQSISRWWKESGSSQLTFT 
               
               
                   
               
               
                 RHRHVEYYTMASCISMLPKHSAFRMEFVKVCHLVTVLDDIYDTFGTMNEL 
               
               
                   
               
               
                 QLFTDAIKRWDLSTTRWLPEYMKGVYMDLYQCINEMVEEAEKTQGRDMLN 
               
               
                   
               
               
                 YIQNAWEALFDTFMQEAKWISSSYLPTFEEYLKNAKVSSGSRIATLQPIL 
               
               
                   
               
               
                 TLDVPLPDYILQEIDYPSRFNELASSILRLRGDTRCYKADRARGEEASAI 
               
               
                   
               
               
                 SCYMKDHPGSTEEDALNHINAMISDAIRELNWELLRPDSKSPISSKKHAF 
               
               
                   
               
               
                 DITRAFHHVYKYRDGYTVSNNETKNLVMKTVLEPLAL 
               
            
           
         
       
     
     Regarding the enzymes and polypeptides described herein, the phrases “% sequence identity,” “percent identity,” or “% identity,” are used interchangeably and refer to the percentage of residue matches between at least two amino acid sequences aligned using a standardized algorithm. Methods of amino acid sequence alignment are well-known. Some alignment methods take into account conservative amino acid substitutions. Such conservative substitutions, explained in more detail below, generally preserve the charge and hydrophobicity at the site of substitution, thus preserving the structure (and therefore function) of the polypeptide. Percent identity for amino acid sequences may be determined as understood in the art. (See, e.g., U.S. Pat. No. 7,396,664, which is incorporated herein by reference in its entirety). A suite of commonly used and freely available sequence comparison algorithms is provided by the National Center for Biotechnology Information (NCBI) Basic Local Alignment Search Tool (BLAST), which is available from several sources, including the NCBI, Bethesda, Md., at its website. The BLAST software suite includes various sequence analysis programs including “blastp,” that is used to align a known amino acid sequence with other amino acids sequences from a variety of databases. 
     Polypeptide sequence identity may be measured over the length of an entire defined polypeptide sequence, for example, as defined by a particular SEQ ID number, or may be measured over a shorter length, for example, over the length of a fragment taken from a larger, defined polypeptide sequence, for instance, a fragment of at least 15, at least 20, at least 30, at least 40, at least 50, at least 70 or at least 150 contiguous residues. Such lengths are exemplary only, and it is understood that any fragment length supported by the sequences shown herein, in the tables, figures or Sequence Listing, may be used to describe a length over which percentage identity may be measured. 
     A cell suitable for use in the methods described herein may include, but is not limited to, a primary cell, an immortalized cell, a pluripotent cell, or an embryonic cell. The genetically modified or engineered cell may be a plant cell or an animal cell that can be stably maintained, grown, and expanded in in vitro culture. An animal cell suitable for use in the composition and methods described herein may be a mammalian call, an insect cell, a fish cell, or an avian cell. Methods for the use of insect cells in a cultured meat product are described, for example, in publication No. ______ of International Application No. PCT/US2019/066452, which is incorporated herein by reference in its entirety. 
     The mammalian cell may be any mammalian cell that can be stably maintained, grown, and expanded in in vitro culture. The mammalian cell may be a porcine, bovine, cervine, hircine, leporine, or murine cell. The mammalian cell may be from a ruminant mammal (e.g., cattle, sheep, goats, buffalo, deer, elk, etc.). For use in a cultured meat product as outlined below, the mammalian cell is a non-human mammalian cell. 
     The mammalian cell may be a primary mammalian cell, an immortalized mammalian cell, or a mammalian cell differentiated from a pluripotent cell (e.g., embryonic stem cell, induced pluripotent cell, etc.). Primary mammalian cell may be grown and proliferated in culture for 1, 2, 3, 4, 5, 6, or more passages prior to transduction. In some embodiments, the mammalian cell is an immortalized cell that expresses TERT and CDK4. 
     In some embodiments, the animal cell is a muscle cell. The muscle cell is characterized by Actin, myogenin, and myosin heavy chain (MHC) and formation of multinucleated myotubes. 
     In some embodiments, the mammalian cell is a muscle cell. Mammalian muscle cells are characterized by expression of Actin, myogenin, and myosin heavy chain (MHC) and formation of multinucleated myotubes. In some embodiments, the mammalian cells are MHC +  Actin +  bovine muscle cells. 
     In some embodiments, the animal cell are muscle precursor cells that express paired box protein 7 (Pax7). In some embodiments, the mammalian cells are muscle precursor satellite cells that express paired box protein 7 (Pax7). In some embodiments, the mammalian cells are Pax7+ bovine satellite cells. In some embodiments, the mammalian cells are Pax7+ primary bovine satellite cells (BSCs). In some embodiments, the mammalian cells are from a cow of the species  Bos taurus.    
     In some embodiments, mammalian myotube cells are produced by myogenic differentiation of mammalian satellite cells. Mammalian satellite cells may be cultured to confluency in any culture medium that supports growth and expansion of the mammalian satellite cells. In some embodiments, the mammalian satellite cells are cultured to confluency in B8 medium, serum-contained growth medium (e.g., DMEM+20% fetal bovine serum), or other serum-free medium. Confluent mammalian satellite cells are then cultured in culture medium including a Neurobasal/L15 (1:1) basal media supplemented with epidermal growth factor (EGF; 0.01-5 ng/ml; preferably 0.5 ng/mL), insulin-like growth factor 1 (IGF-1; 0.01-5 ng/ml; preferably 0.05 ng/mL), and 1% Antibiotic-Antimycotic 61 . In some embodiments, the confluent mammalian satellite cells are cultured in DMEM supplemented with about 2% fetal bovine serum. Cells will be differentiated for about 1-2 weeks. 
     B8 medium includes DMEM:F12 (1:1) basal medium supplemented with L-ascorbic acid 2-phosphate (0.1 ug/ml to 500 ug/ml; preferably about 200 ug/mL), insulin (0.1 ug/ml to 100 up/ml; preferably about 20 ug/mL), transferrin (0.1 ug/ml to 100 ug/ml; preferably about 20 ug/mL), sodium selenite (0.1 ug/ml to 100 ug/ml; preferably 20 ng/mL), FGF-2 (0.01 ug/ml to 100 ug/ml; preferably 10 ng/mL), neuregulin 1 (NRG-1; 0.001 ng/ml to 50 ng/ml; preferably 0.1 ng/mL), and TGFβ-3 (0.001 ng/ml to 50 ng/ml; preferably 0.1 ng/uL). In some embodiments, B8 medium additionally includes insulin-like growth factor 1 (IGF-1; about 10 ng/mL). 
     In some embodiments, the culture medium includes, cinnamon, monolaurin (a derivative of coconut lauric acid), honey, or combinations thereof in addition to or instead of an antibiotic component. 
     In some embodiments, the culture medium may include a plant based or yeast based extract in place of serum. For example, yeast and plant based alternatives to serum include hydrolyzed proteins from soy, yeast, wheat gluten, cottonseed, or corn, as well as rapeseed peptide fractions, maitake mushroom extract, and silk derived sericin protein. 
     In some embodiments, the mammalian cell is an adipocyte. Mammalian adipose cells are characterized by expression of peroxisome proliferator-activated receptor gamma (PPARγ) and increase lipid production. 
     In some embodiments, the mammalian cells are produced by adipogenic differentiation from mammalian satellite cells. Lipid accumulation in mammalian satellite cells can be initiated using a differentiation media containing a combination of free fatty acids (FFAs). Specifically, a 3-FFA cocktail of linoleic acid, erucic acid, and elaidic acid at equal concentrations of 125 uM induces accumulation of intracellular lipids over about six days in culture. Additional details on adipogenic differentiation from mammalian satellite cell is described in Fish et al. (“Prospects and challenges for cell-cultured fat as a novel food ingredient,” Trends Food Sci Technol., 2020, 98:53-67) which is incorporated herein by reference. 
     In some embodiments, production of the metabolite of interest can be increased or decreased by altering enzyme expression levels or by altering availability of intermediate or precursor metabolites in the cell. 
     In some embodiments, the metabolite of interest is phytoene, lycopene, or β-carotene and production of these metabolites is increased by treatment of the cells with ketoconazole. Ketoconazole inhibits cellular cholesterol synthesis which competes for carotenoid precursor compounds. To increase carotenoid production, cells may be cultured with between about 0.5 μg/ml and about 50 μg/ml ketoconazole. In some embodiments, cells are cultured with between about 1 μg/ml and about 20 μg/ml ketoconazole. In some embodiments, cells are cultured with about 5 μg/ml ketoconazole. 
     In some embodiments, biosynthetic pathway enzyme expression is increased by increasing the selective pressure on the cells transduced with a vector comprising polynucleotides encoding the biosynthetic pathway enzyme and a selectable marker. For example, when the selectable marker is an antibiotic resistance gene, increasing the concentration of the antibiotic in the selection medium can place selective pressure on the cells to increase expression of the introduced vector whereby biosynthetic pathway enzyme expression is also increased. Likewise, biosynthetic pathway enzyme expression can be reduced by reducing the selective pressure on the cells, for example, by reducing the concentration of the selection chemical in culture. 
     As used herein, “cultured meat product” refers to an edible meat product produced from cell cultures, rather than whole organisms. In generally, the cultured meat product is visually identical to farmed meat, palatable to consumers and provides nutritional benefit. Cultured meat products described herein include mammalian satellite, muscle, and/or adipose cell cultures seeded on an edible, food safe substrate and cultured to confluence. The mammalian satellite, muscle, and/or adipose cell culture are seeded on the food safe substrate at a density between about 20,000 cell/cm 2  and about 400,000 cell/cm 2 , between about 30,000 cells/cm 2  and about 350,000 cells/cm 2 , or between about 35,000 cells/cm 2  and about 300,000 cells/cm 2 . In some embodiments, the cells are seeded at a density of about 50,000 cells/cm 2 . In some embodiments, the cells are seeded at a density of about 40,000 cells/cm 2 , about 50,000 cells/cm 2 , about 60,000 cells/cm 2 , about 70,000 cells/cm 2 , about 80,000 cells/cm 2 , about 100,000 cells/cm 2 , about 150,000 cells/cm 2 , about 200,000 cells/cm 2 , about 250,000 cells/cm 2 , about 300,000 cells/cm 2  or about 350,000 cells/cm 2 . In some embodiments, the cells become non-adherent on the food safe substrate once they reach confluence and lift off the food safe substrate without enzymatic dissociation. In some embodiments, the edible, food safe substrate is in the form of a two-dimensional film. In some embodiments, the edible, food safe substrate is in the form of a three-dimensional matrix or sponge, and the mammalian muscle cells form continuous muscle fibers when cultured in the matrix or sponge substrate. Suitable edible, food safe substrates are known in the art and include, but are not limited to, chitosan substrates, cellulosic substrates, silk substrates, alginate substrates, starch substrates, textured vegetable protein substrate, mycelium substrates, and whey substrates. 
     Additional methods for the production of cultured meat production are known and described in the art. See for example, Post (“Cultured meat from stem cells: Challenges and prospects,” Meat Science, 2012, 92, 297-301), Warner (“Review: analysis of the process and drivers for cellular meat production,” Animal, 2019, 13(12):3041-3058), U.S. Pat. Nos. 6,835,390, and 7,270,829. 
     In some embodiments, the cultured meat product is produced using a chitosan substrate. The chitosan substrate can be tuned to change the adherence and growth of the mammalian muscle cell culture. Generally, increasing chitosan concentration in the substrate decreased adhesion of the mammalian muscle cells. The concentration of chitosan in the food safe substrate of the cultured meat product can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, or 14%. In some embodiments, the concentration of chitosan is between about 1% and about 8%. In some embodiments, the concentration of chitosan is between about 2% and about 6%. In some embodiments, the concentration of chitosan is at least about 1%, at least about 2%, at least about 3%, at least about 4%, at least about 5%, at least about 6%, at least about 7%, or at least about 8%. Chitosan may be derived from any suitable source. Sources of chitosan include, but are not limited to, mushrooms, crustaceans, insects, green algae, and yeast. In some embodiments, the chitosan is mushroom derived chitosan. 
     Three-dimensional chitosan substrates or sponges suitable for use in the formation of muscle fibers and cultured meat products described herein can be formed using methods known in the art. In some embodiments, chitosan sponges are formed using directional freezing of chitosan. To form chitosan sponges by directional freezing, a chitosan is dissolved in a solvent, such as, but not limited to, acetic acid, and the chitosan solution is poured into tubes. One end of the tubes is exposed to liquid nitrogen or another suitable freezing agent, such as slurry of dry ice and ethanol, until the entire solution is frozen. The frozen chitosan is then lyophilized to form the chitosan sponge. The mechanical properties of the chitosan sponge can be tuned by altering the chitosan concentration. Sponges formed using low concentration chitosan (e.g., 1%, 2%, 3% chitosan solution) have a lower elastic moduli, while sponges formed using high concentration chitosan (e.g., 6%, 7%, 8% chitosan solution) have higher elastic moduli. Chitosan may be derived from any suitable source. Sources of chitosan include, but are not limited to, mushrooms, crustaceans, insects, green algae, and yeast. In some embodiments, the chitosan is mushroom derived chitosan. 
     As used herein, “food safe substrate” refers to substrates that are edible or are safe for human consumption if at least a portion of the substrate remains affixed or associated with the cultured meat product. In some embodiments, the food safe substrate is a chitosan substrate. Chitosan for use as a food safe substrate may be derived from the chitin of organisms including, but not limited to, mushrooms, crustaceans, insects, green algae, and yeast. In some embodiments, the food safe substrate is a mushroom-chitosan substrate. In some embodiments, the food safe substrate is a cellulose-based substrate such as a substrate formed from decellularized plants (e.g., decellularized spinach or apples). 
     In some embodiments, the cultured meat product includes the engineered cells described herein, plant based proteins, unmodified (i.e., wild-type) plant or animal cells, or combinations thereof. In some embodiments, the cultured meat product includes between about 1% to about 100% engineered cells described herein based on weight or based on cell count. 
     As used herein, “high density” refers to cells seeded at a density over 160,000 cells/mL to about 480,000 cells/ml for suspension culture or over 100,000 cells/cm 2  to about 300,000 cells/cm 2  for adherent culture. 
     As used herein, “medium density” refers to cells seeded at a density of over 64,000 cells/ml to about 160,000 cells/ml for suspension culture or over 40,000 cells/cm 2  to about 100,000 cells/cm 2  for adherent culture. 
     As used herein, “low density” refers to cells seeded at a density of about 16,000 cells/ml to about 64,000 cells/ml for suspension culture or between about 10,000 cells/cm 2  to about 40,000 cells/cm 2  for adherent culture. 
     As used herein, “serum-free” refers to culture conditions and culture medium that does not contain serum or serum replacement, or that it contains essentially no serum or serum replacement. For example, an essentially serum-free medium can contain less than about 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2% or 0.1% serum. As used herein, “serum-replacement,” refers to animal serum and animal cell product based replacements for serum traditionally used in culture medium. Any plant based or yeast based serum alternatives described herein do not fall under the definition of “serum-replacement” in a determination of a culture medium being serum free. In other words, a culture medium can be serum-free and include a plant based or yeast based serum alternative described herein. 
     The terms “defined culture medium,” “defined medium,” and the like, as used herein, indicate that the identity and quantity of each medium ingredient is known. The term “defined,” when used in relation to a culture medium or a culture condition, refers to a culture medium or a culture condition in which the nature and amounts of approximately all the components are known. A culture, composition, or culture medium is “essentially free” of certain reagents, such as signaling inhibitors, animal components or feeder cells, when the culture, composition, and medium, respectively, have a level of these reagents lower than a detectable level using conventional detection methods known to a person of ordinary skill in the art or that these agents have not been extrinsically added to the culture, composition, or medium. 
     As used herein, “effective amount” means an amount of an agent sufficient to evoke a specified cellular effect according to the present invention. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     All references, patents and patent applications disclosed herein are incorporated by reference with respect to the subject matter for which each is cited, which in some cases may encompass the entirety of the document. 
     The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law. 
     As used herein, the terms “approximately” or “about” in reference to a number are generally taken to include numbers that fall within a range of 5% in either direction (greater than or less than) the number unless otherwise stated or otherwise evident from the context (except where such number would exceed 100% of a possible value). Where ranges are stated, the endpoints are included within the range unless otherwise stated or otherwise evident from the context. 
     EXAMPLES 
     Example 1 
     Metabolic engineering efforts in plants, yeast and bacteria have exploited numerous pathways from across taxonomies towards diverse applications (Heider and Wendisch, 2015; Nielsen, 2015; Sack et al., 2015). That same breadth has not yet been realized in mammalian systems, where the majority of efforts have focused on biopharmaceuticals (Ceroni and Ellis, 2018; Davy et al., 2017). While these efforts are by no means inferior to those in other systems, the difference in scope is stark. To date, this discrepancy is likely due at least in part to the lack of a compelling case for engineering animal cells with metabolic pathways from other taxonomies; from a bioprocess standpoint, the production of recombinant proteins, small molecules and biofuels is cheaper in bacteria, yeast or plant systems, and only the need for species-specific post-translational modifications makes mammalian bioprocesses preferable (Davy et al., 2017; Giddings, 2001). The possibility of cultured meat offers a new framework for mammalian metabolic engineering. In cultured meat production, the product is the cells themselves, and so endogenously synthesizing additional compounds becomes a purely additive endeavor, at least insofar as those efforts are biologically possible and do not hinder the bioprocess parameters or product value. Here, the fact that cultured meat is dependent only on cell growth rather than whole-animal viability—which is inherently limiting for animal transgenics—allows the consideration of an even wider range of metabolites which might be untenable in animals but harmless or even beneficial in cell culture. 
     In this example, we demonstrate the possibility of generating nutritionally enhanced meat products through cell culture by engineering the endogenous production of non-native dietary carotenoids into primary bovine and immortalized murine skeletal muscle cells. While past speculation has suggested the nutritional enhancement of cultured meat through exogenous nutrient addition, the endogenous production of nutrients is advantageous from a bioprocess-cost perspective at scale, and from the positive implications that endogenous nutrients could have for nutrient bioavailability or growth kinetics (Desmarchelier and Borel, 2017; Le Moal et al., 2017). We show that carotenoids are produced at levels capable of significantly reducing lipid oxidation, are optimizable through a range of strategies, and that optimized levels are substantially higher than those found to accumulate in beef. These compounds, along with their general nutritive value and specific relevance to meat-associated disease, offer functionality in their ability to combat lipid oxidation&#39;s role in impairing shelf-life, color stability, and flavor. They are therefore compelling candidates for a proof-of-principle of how metabolic engineering can affect numerous meat quality metrics. 
     Additionally, the positive impact that carotenoid synthesis showed on C2C12 growth suggests an exciting commensurate benefit to this approach. Namely, the improvement of cell growth could help to substantially lower the cost of production for cultured meat while simultaneously generating a more nutritious product. A limitation of this study was the dependence on primary bovine satellite cells, as immortalized bovine cells would have enabled the exploration of this possibility in a more meat-relevant cell line uncoupled from the confounding impacts of primary cell senescence and antibiotic selection pressure. Further, an immortalized cell line would have allowed for the use of less-efficient targeted gene insertion techniques (such as CRISPR/Cas9), which would have enabled the production of a homologous cell population that could more clearly elucidate achievable carotenoid yields before and after optimization. An industrial cultured meat production scheme would likely use targeted engineering of immortalized cells and avoid antibiotic selection, so follow-up exploration of carotenoid synthesis in one-such cell population would be valuable future work. 
     The embodiment described here demonstrates incorporation of a biosynthetic pathway for antioxidant phytonutrients (carotenoids), which are native to plants and some prokaryotes but not animals, into a mammalian cell and production of a cultured meat therefrom. These nutrients confer multiple benefits through their status as antioxidants, provitamins, and free radical scavengers (Botella-Pavia and Rodriguez-Concepcion, 2006). Using non-viral Sleeping Beauty transposon-mediated transgenesis of phytoene synthase (CrtB), phytoene desaturase (CrtI), and lycopene cyclase (CrtY) from the bacterium  Pantoea ananatis , we convert native geranylgeranyl pyrophosphate (GGPP) into phytoene, lycopene, and β-carotene in immortalized mouse myoblasts and primary bovine muscle stem cells (Botella- Pavia  and Rodriguez-Concepcion, 2006; Izsvák et al., 2000). This work builds on previous crop engineering efforts and evidence for CrtB efficacy in mammalian cells (Satomi et al., 1995; Ye et al., 2000). We confirm the endogenous production of all three carotenoids and show that cellular myogenicity is maintained following modification. We then quantify and optimize carotenoid production through increased enzyme expression and induced precursor accumulation, obtaining yields substantially higher than reported levels for beef (Simonne et al., 1996). Finally, we validate the antioxidant capacity of endogenous carotenoids in vitro, which points towards nutritional and food-quality functionality. This work represents the first case of nutritional engineering for cultured meat and demonstrates how cross-taxa transgenesis can broaden the scope of metabolic engineering in mammalian cells to applications beyond the clinic. 
     Materials and Methods 
     C2C12 cell culture—C2C12 mouse skeletal myoblasts (ATCC #CRL-1772, Manassas, Va., USA) were grown on tissue-culture plastic in DMEM Glutamax (ThermoFisher #10566024, Waltham, Mass., USA) supplemented with 10% FBS (ThermoFisher #26140079) and 1% antibiotic-antimycotic (ThermoFisher #15240062) (Yaffe and Saxel, 1977). For regular cell maintenance, cells were cultured to a maximum of 70% confluence, and then either passaged using 0.25% trypsin-EDTA (ThermoFisher #25200056) or frozen in FBS with 10% Dimethyl sulfoxide (DMSO, Sigma #D2650, St. Louis, Mo., USA). Cells were incubated at 37° C. in 5% CO 2 . 
     Primary bovine satellite cell isolation and culture—Primary bovine satellite cells (BSCs) were isolated using previously described methods (Simsa et al., 2019). Briefly, a small muscle excision (˜0.5 cm 3 ) was taken from the semitendinosus of a &lt;60-day-old Simmental bull raised at the Tufts Cummings School of Veterinary Medicine according to methods approved by the Tufts University IACUC (Protocol #G2018-36). Muscle tissue was dissected from fat and connective tissue, minced into a paste, and digested in 0.2% collagenase II (Worthington Biochemical #LS004176, Lakewood, N.J., USA; 275 U/mg) for one hour with regular trituration. Digestion was halted with growth media comprised of DMEM Glutamax supplemented with 20% FBS, 1 ng/mL human FGF-basic (ThermoFisher #68-8785-63), and 1% Primocin (Invivogen #ant-pm-1, San Diego, Calif., USA), and cells were filtered and plated at a density of 100,000 cells/cm 2  onto uncoated tissue-culture flasks. After 24 hours of incubation at 37° C. with 5% CO 2 , the plated suspensions (containing slowly-adherent satellite cells) were transferred to new flasks coated with 1 μg/cm 2  mouse laminin (Sigma #CC095). These flasks were left untouched for three days, at which point growth media was changed, and cells were cultured using standard practices on tissue-culture plastic coated with iMatrix recombinant laminin-511 (Iwai North America #N892021, San Carlos, Calif., USA). After two weeks of culture, Primocin in growth media was replaced with 1% antibiotic-antimycotic. Cell passaging and cryopreservation was performed as with C2C12s. To induce myogenic differentiation, cells were cultured to confluency, and then incubated for one week without changing medium. 
     Immunofluorescence and cell characterization—To confirm the identity of isolated primary BSCs, cells were stained for Pax7 and Myosin Heavy Chain (MHC) before and after differentiation, respectively. These markers confirm the primary and terminal states of satellite cell myogenesis and therefore act to verify the nature and myogenicity of isolated cells. Proliferative cells and cells after one week of differentiation were fixed with 4% paraformaldehyde (ThermoFisher #AAJ61899AK) for 30 minutes, washed in PBS, permeabilized for 15 minutes using 0.5% Triton X (Sigma #T8787) in PBS, blocked for 45 minutes using 5% goat serum (ThermoFisher #16210064) in PBS with 0.05% sodium azide (Sigma #S2002), and washed with PBS containing 0.1% Tween-20 (Sigma #P1379). Primary Pax7 antibodies (ThermoFisher #PA5-68506) were diluted 1:100 in blocking solution and added to proliferative cells. Primary MHC antibodies (Developmental studies hybridoma bank #MF-20, Iowa City, Iowa, USA) were diluted to 4 μg/mL in blocking buffer containing 1:100 Phalloidin 594 (ThermoFisher #A12381) and added to differentiated cells. Primary antibodies were incubated overnight at 4° C. The following day, cells were washed with PBS+ Tween-20, incubated with secondary antibodies for Pax7 (ThermoFisher #A-11008, 1:500) and MHC (ThermoFisher #A-11001, 1:1000) for 1 hour at room temperature, washed with PBS+tween-20, and mounted with Fluoroshield mounting medium with DAPI (Abcam #ab104139, Cambridge, UK) before imaging. 
     Molecular cloning and Sleeping Beauty construct design—Amino acid sequences for CrtB, CrtI, and CrtY from  Pantoea ananatis  were obtained from UniProt (accession numbers P21683, P21685 and P21687, respectively). Gene sequences for these proteins were optimized for expression in  Bos taurus  using codon optimization software (IDT, Coralville, Iowa). Self-cleaving 2A peptides were added to the ends of each gene to facilitate multi-cistronic expression, and all genes were flanked with multiple cloning sites (Szymczak et al., 2004). Final gene constructs were ordered through ThermoFisher&#39;s GeneArt gene synthesis service (Table 1). Next, three Sleeping Beauty transposon vectors were constructed using synthesized genes and based on plasmids available through Addgene: pCMV-GFP was a gift from Connie Cepko (Addgene #11153, Watertown, Mass., USA), pSBbi-GP and pSBbi-Pur were gifts from Eric Kowarz (Addgene #60511 &amp; #60523), and pCMV(CAT)T7-SB100 was a gift from Zsuzsanna Izsvak (Addgene #34879) (Kowarz et al., 2015; Mátés et al., 2009; Matsuda and Cepko, 2004). Transposon construction was performed using standard cloning techniques. Briefly, CrtB was cloned into pCMV-GFP using EcoRI-HF and XmaI restriction (NEB #R3101S &amp; #R0180S, Ipswich, Mass., USA) followed by T4 DNA ligation (NEB #M0202S) to generate pCMV-CrtB-P2A-eGFP, a plasmid for the transient bi-cistronic expression of CrtB and green fluorescent protein (GFP) under the cytomegalovirus (CMV) promoter. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Carotenoid synthesis genes. Gene sequences 
               
               
                 used in constructs (upper case), followed 
               
               
                 by 2A linker sequences (SEQ ID NO:37) 
               
               
                 used after each gene (lower case). 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 CrtB + 2A 
                 ATGGTCAACAACCCCAGCCTGCTGA 
               
               
                   
                 (SEQ ID 
                 ATCACGCCGTGGAAACAATGGCCGT 
               
               
                   
                 NO: 38 + 37) 
                 GGGCAGCAAGTCTTTCGCCACCGCC 
               
               
                   
                   
                 TCTAAGCTGTTCGACGCCAAGACTA 
               
               
                   
                   
                 GACGCAGCGTGCTGATGCTGTACGC 
               
               
                   
                   
                 CTGGTGCAGACACTGCGACGACGTG 
               
               
                   
                   
                 ATCGACGATCAGACCCTGGGATTCC 
               
               
                   
                   
                 AGGCCAGACAGCCTGCTCTGCAGAC 
               
               
                   
                   
                 CCCTGAACAGAGGCTGATGCAGCTG 
               
               
                   
                   
                 GAAATGAAGACCAGGCAGGCCTACG 
               
               
                   
                   
                 CCGGCTCTCAGATGCACGAACCTGC 
               
               
                   
                   
                 TTTCGCCGCCTTCCAAGAGGTGGCC 
               
               
                   
                   
                 ATGGCTCACGATATCGCCCCTGCCT 
               
               
                   
                   
                 ACGCCTTCGATCACCTGGAAGGATT 
               
               
                   
                   
                 CGCCATGGATGTGCGCGAGGCCCAG 
               
               
                   
                   
                 TACAGCCAGCTGGATGATACCCTGA 
               
               
                   
                   
                 GGTACTGCTATCACGTGGCCGGCGT 
               
               
                   
                   
                 TGTGGGACTGATGATGGCTCAGATC 
               
               
                   
                   
                 ATGGGCGTGCGCGACAACGCCACAC 
               
               
                   
                   
                 TGGACAGAGCTTGTGATCTCGGCCT 
               
               
                   
                   
                 GGCCTTCCAGCTGACCAATATCGCC 
               
               
                   
                   
                 AGAGACATCGTGGACGATGCCCACG 
               
               
                   
                   
                 CCGGCAGATGTTATCTGCCTGCCTC 
               
               
                   
                   
                 TTGGCTGGAACACGAGGGCCTGAAC 
               
               
                   
                   
                 AAAGAGAACTACGCCGCTCCTGAGA 
               
               
                   
                   
                 ACAGACAGGCCCTGAGCAGAATCGC 
               
               
                   
                   
                 TAGAAGGCTGGTGCAAGAGGCCGAG 
               
               
                   
                   
                 CCTTACTACCTGTCTGCCACAGCTG 
               
               
                   
                   
                 GACTGGCAGGACTGCCTCTGAGATC 
               
               
                   
                   
                 TGCCTGGGCCATTGCCACAGCCAAA 
               
               
                   
                   
                 CAGGTGTACAGAAAGATCGGCGTGA 
               
               
                   
                   
                 AGGTGGAACAGGCCGGACAGCAGGC 
               
               
                   
                   
                 TTGGGACCAGAGACAGTCTACCACC 
               
               
                   
                   
                 ACACCTGAGAAGCTGACCCTGCTGC 
               
               
                   
                   
                 TGGCTGCTTCTGGACAGGCTCTGAC 
               
               
                   
                   
                 CAGCAGGATGAGAGCCCATCCTCCT 
               
               
                   
                   
                 AGACCTGCTCACCTCTGGCAAAGAC 
               
               
                   
                   
                 CTCTCggatctggcgaaggcagagg 
               
               
                   
                   
                 ctctctgctgacatgtggcgacgtg 
               
               
                   
                   
                 gaagagaaccctggacct 
               
               
                   
               
               
                   
                 CrtI + 2A 
                 ATGAAGCCCACCACAGTGATCGGAG 
               
               
                   
                 (SEQ ID 
                 CCGGCTTTGGAGGACTGGCCCTGGC 
               
               
                   
                 NO: 39 + 37) 
                 TATTAGACTGCAGGCTGCTGGAATC 
               
               
                   
                   
                 CCCGTGCTGCTGCTCGAACAGAGAG 
               
               
                   
                   
                 ATAAGCCTGGCGGCAGGGCCTACGT 
               
               
                   
                   
                 GTACGAGGATCAGGGCTTCACCTTC 
               
               
                   
                   
                 GACGCCGGACCTACCGTGATCACAG 
               
               
                   
                   
                 ATCCTAGCGCCATCGAGGAACTGTT 
               
               
                   
                   
                 CGCCCTGGCTGGCAAGCAGCTGAAA 
               
               
                   
                   
                 GAGTACGTCGAGCTGCTGCCCGTGA 
               
               
                   
                   
                 CACCCTTCTACAGACTGTGTTGGGA 
               
               
                   
                   
                 GAGCGGCAAGGTGTTCAACTACGAC 
               
               
                   
                   
                 AACGACCAGACCAGGCTGGAAGCCC 
               
               
                   
                   
                 AGATCCAGCAGTTCAACCCTAGAGA 
               
               
                   
                   
                 TGTGGAAGGCTACAGGCAGTTCCTG 
               
               
                   
                   
                 GACTACAGCAGGGCCGTGTTCAAAG 
               
               
                   
                   
                 AGGGCTACCTGAAGCTGGGAACCGT 
               
               
                   
                   
                 GCCTTTCCTGAGCTTCAGGGACATG 
               
               
                   
                   
                 CTGAGAGCCGCTCCTCAGCTGGCCA 
               
               
                   
                   
                 AACTCCAGGCTTGGAGAAGCGTGTA 
               
               
                   
                   
                 CAGCAAGGTGGCCAGCTACATCGAG 
               
               
                   
                   
                 GACGAGCACCTGAGACAGGCCTTCA 
               
               
                   
                   
                 GCTTCCACTCTCTGCTCGTCGGCGG 
               
               
                   
                   
                 CAACCCTTTCGCCACCTCTTCTATC 
               
               
                   
                   
                 TACACCCTGATTCACGCCCTGGAAC 
               
               
                   
                   
                 GCGAGTGGGGAGTGTGGTTTCCTAG 
               
               
                   
                   
                 AGGTGGAACAGGCGCTCTGGTGCAG 
               
               
                   
                   
                 GGCATGATCAAGCTGTTCCAGGATC 
               
               
                   
                   
                 TCGGCGGAGAGGTGGTGCTGAACGC 
               
               
                   
                   
                 TAGAGTGTCCCACATGGAAACCACC 
               
               
                   
                   
                 GGCAACAAGATCGAGGCCGTGCATC 
               
               
                   
                   
                 TGGAAGATGGCAGAAGATTCCTGAC 
               
               
                   
                   
                 ACAGGCCGTGGCCTCTAACGCCGAT 
               
               
                   
                   
                 GTGGTGCACACCTACAGGGACCTGC 
               
               
                   
                   
                 TGTCTCAGCATCCTGCCGCCGTGAA 
               
               
                   
                   
                 GCAGAGCAACAAGCTGCAGACCAAG 
               
               
                   
                   
                 AGGATGAGCAACAGCCTGTTCGTGC 
               
               
                   
                   
                 TGTACTTCGGCCTGAACCACCACCA 
               
               
                   
                   
                 CGATCAGCTGGCTCACCACACCGTG 
               
               
                   
                   
                 TGTTTCGGCCCCAGATACAGAGAGC 
               
               
                   
                   
                 TGATCGACGAGATCTTCAACCACGA 
               
               
                   
                   
                 CGGCCTGGCCGAGGACTTCTCTCTG 
               
               
                   
                   
                 TACCTGCATGCCCCTTGCGTGACCG 
               
               
                   
                   
                 ACAGTTCTCTGGCCCCTGAAGGCTG 
               
               
                   
                   
                 CGGCTCTTACTATGTGCTGGCTCCT 
               
               
                   
                   
                 GTGCCTCACCTGGGCACCGCTAATC 
               
               
                   
                   
                 TGGATTGGACCGTGGAAGGCCCCAA 
               
               
                   
                   
                 GCTGAGGGACAGAATCTTCGCCTAC 
               
               
                   
                   
                 CTCGAACAGCACTACATGCCCGGCC 
               
               
                   
                   
                 TGAGAAGCCAGCTGGTCACCCACAG 
               
               
                   
                   
                 AATGTTCACCCCTTTCGACTTCCGC 
               
               
                   
                   
                 GACCAGCTGAACGCCTATCACGGCT 
               
               
                   
                   
                 CTGCCTTCAGCGTGGAACCTGTGCT 
               
               
                   
                   
                 GACTCAGTCCGCCTGGTTCAGACCC 
               
               
                   
                   
                 CACAACAGGGACAAGACCATCACCA 
               
               
                   
                   
                 ACCTGTACCTCGTTGGCGCCGGAAC 
               
               
                   
                   
                 ACATCCTGGTGCTGGTATTCCAGGC 
               
               
                   
                   
                 GTGATCGGATCTGCCAAAGCCACCG 
               
               
                   
                   
                 CTGGACTGATGCTCGAGGATCTGAT 
               
               
                   
                   
                 Tggaagcggcgccaccaacttcagc 
               
               
                   
                   
                 ctgctgaaacaggctggcgacgtgg 
               
               
                   
                   
                 aagagaaccctggacct 
               
               
                   
               
               
                   
                 CrtY + 2A 
                 ATGCAGCCCCACTACGATCTGATTC 
               
               
                   
                 (SEQ ID 
                 TCGTCGGAGCCGGACTGGCCAATGG 
               
               
                   
                 NO: 40 + 37) 
                 ACTGATTGCTCTGAGACTCCAGCAG 
               
               
                   
                   
                 CAGCAACCCGACATGAGGATCCTGC 
               
               
                   
                   
                 TGATCGATGCCGCTCCTCAGGCTGG 
               
               
                   
                   
                 CGGAAATCACACCTGGTCTTTCCAC 
               
               
                   
                   
                 CACGACGACCTGACCGAGAGCCAGC 
               
               
                   
                   
                 ACAGATGGATTGCTCCTCTGGTGGT 
               
               
                   
                   
                 GCATCACTGGCCCGACTACCAAGTG 
               
               
                   
                   
                 CGCTTTCCCACCAGAAGGCGCAAGC 
               
               
                   
                   
                 TGAACAGCGGCTACTTCTGCATCAC 
               
               
                   
                   
                 CAGCCAGAGATTCGCCGAGGTGCTG 
               
               
                   
                   
                 CAGAGACAGTTCGGACCTCACCTGT 
               
               
                   
                   
                 GGATGGATACCGCCGTGGCCGAAGT 
               
               
                   
                   
                 GAATGCCGAGTCTGTGCGCCTGAAG 
               
               
                   
                   
                 AAAGGCCAAGTGATCGGAGCCAGAG 
               
               
                   
                   
                 CCGTGATCGATGGCAGAGGATACGC 
               
               
                   
                   
                 CGCCAATTCTGCCCTGTCTGTGGGA 
               
               
                   
                   
                 TTCCAGGCCTTCATCGGACAAGAGT 
               
               
                   
                   
                 GGCGCCTGTCTCACCCTCACGGACT 
               
               
                   
                   
                 GTCTAGCCCCATCATCATGGACGCC 
               
               
                   
                   
                 ACCGTGGATCAGCAGAACGGCTACA 
               
               
                   
                   
                 GATTCGTGTACAGCCTGCCTCTGAG 
               
               
                   
                   
                 CCCCACCAGGCTGCTGATTGAGGAC 
               
               
                   
                   
                 ACCCACTACATCGACAACGCCACAC 
               
               
                   
                   
                 TGGACCCTGAGTGCGCCAGACAGAA 
               
               
                   
                   
                 CATCTGCGATTACGCCGCTCAGCAA 
               
               
                   
                   
                 GGCTGGCAGCTGCAGACACTGCTGA 
               
               
                   
                   
                 GAGAAGAACAGGGCGCTCTGCCCAT 
               
               
                   
                   
                 CACACTGTCTGGAAACGCCGATGCC 
               
               
                   
                   
                 TTCTGGCAGCAAAGACCTCTGGCCT 
               
               
                   
                   
                 GTTCTGGCCTGAGAGCCGGCCTGTT 
               
               
                   
                   
                 TCACCCAACAACCGGATACTCTCTG 
               
               
                   
                   
                 CCTCTGGCTGTGGCCGTGGCTGATA 
               
               
                   
                   
                 GACTGTCTGCCCTGGACGTGTTCAC 
               
               
                   
                   
                 CAGCGCCTCTATCCACCACGCCATC 
               
               
                   
                   
                 ACACACTTCGCCAGAGAGAGATGGC 
               
               
                   
                   
                 AGCAGCAGGGCTTCTTCAGGATGCT 
               
               
                   
                   
                 GAACAGAATGCTGTTCCTGGCCGGA 
               
               
                   
                   
                 CCAGCCGACTCTCGTTGGAGAGTCA 
               
               
                   
                   
                 TGCAGAGGTTCTACGGCCTGCCTGA 
               
               
                   
                   
                 GGACCTGATCGCCAGATTCTACGCC 
               
               
                   
                   
                 GGAAAGCTGACCCTGACCGACAGGC 
               
               
                   
                   
                 TGAGAATCCTGTCTGGCAAGCCTCC 
               
               
                   
                   
                 TGTGCCAGTGCTGGCTGCTCTGCAG 
               
               
                   
                   
                 GCCATCATGACCACACACAGAggat 
               
               
                   
                   
                 ctggcgaaggcagaggctctctgct 
               
               
                   
                   
                 gacatgtggcgacgtggaagagaac 
               
               
                   
                   
                 cctggacct 
               
               
                   
               
            
           
         
       
     
     Next, the CMV-CrtB-P2A-GFP portion of this plasmid was cloned into pSBbi-Pur via Gibson assembly (SGI-DNA #GA1100, San Diego, Calif., USA) while excising the backbone&#39;s EF1α promoter in preference for the insert&#39;s CMV promoter. This produced pSBbi-(CMV-CrtB-T2A-GFP)-pur, a Sleeping Beauty transposon vector carrying the same bi-cistronic CrtB and GFP expression cassette under the CMV promoter, as well as a puromycin resistance gene under a synthetic promoter oriented counter to CMV (Kowarz et al., 2015). Subsequent Gibson assemblies inserted CrtI and CrtY into this vector to create three final Sleeping Beauty transposon carotenoid-producing vectors: pSBbi-(CMV-CrtB-T2A-)-pur (pCrtB), pSBbi-(CMV-CrtB-T2A-CrtI-P2A-GFP)-pur (pCrtB/I), and pSBbi-(CMV-CrtY-T2A-CrtB-T2A-CrtI-P2A-GFP)-pur (pCrtB/I/Y) ( FIG. 1 ). A control Sleeping Beauty transposon vector containing only GFP (pGFP) was generated by removing the carotenoid synthesis enzymes and 2A sequences from pCrtB/I/Y, leaving only the GFP under CMV promotion ( FIG. 1 ). All constructs were maintained in 5-alpha high-efficiency chemically competent  E. coli  (NEB #C2988J), verified with Sanger sequencing (Genewiz, Cambridge, Mass., USA), and purified via GeneJet miniprep (ThermoFisher #K0503). For Gibson assembly, polymerase chain reactions were performed using Q5 high-fidelity polymerase (NEB #M0492S), run through 1% agarose gel-electrophoresis, and purified via GeneJet gel extraction (ThermoFisher #K0692). 
     Transfection and selection—C2C12s and BSCs were cultured to 80-90% confluency in 6-well plates and transfected with Lipofectamine 3000 (ThermoFisher #L3000015) according to the manufacturer&#39;s protocol adapted for simultaneous transfection of two plasmids. Briefly, 2.5 μg of the carotenoid producing vectors or the pGFP control vector were combined with 0.25 μg of pCMV(CAT)T7-SB100 in a solution of 250 uL Opti-MEM medium (ThermoFisher #31985088), 7.5 uL of Lipofectamine 3000 reagent, and 5 uL of p3000 reagent. This mixture was incubated at room temperature for 15 minutes. During incubation, cells were rinsed once with PBS and covered with 2 mL of Opti-MEM before adding lipofectamine mixtures. After 4 hours at 37° C., 2 mL of growth media was added to wells, and cells were incubated at 37° C. overnight. The next morning, media was replaced with appropriate growth media, and cells were cultured for two days before observing GFP expression with a fluorescent microscope. After two days, media was changed to growth media with 2.5 μg/mL puromycin to begin selection. Over one week, cells were passaged, and media was replaced as necessary due to cell death from selection. Once all cells were observed to express GFP, cultures were expanded and cryopreserved for later use. 
     Growth and development of engineered cells—Growth of engineered BSCs and C2C12s was analyzed using a dsDNA quantitation kit (ThermoFisher #F2962) on days 1, 2, 4, 6, and 8 of culture. Cells were plated in 96-well plates for each time-point at a density of 1000 cells/well. At each time-point, media was removed from wells and plates were frozen at −80° C. After all time-points were frozen, plates were thawed to room temperature, and 100 uL of UltraPure water (ThermoFisher #10977023) was added to wells. Plates were incubated at 37° C. for one hour, re-frozen to −80° C., and re-thawed to room temperature. Wells were stained with 100 uL of Hoechst 33258 working solution. Fluorescence was measured with a Synergy H1 microplate reader (BioTek Instruments, Winooski, Vt., USA) using excitation and emission filters centered at 360 and 460 nm, respectively. In parallel, a 96-well plate was seeded with a range of known cell densities, incubated for 12 hours, and measured using the same protocol to obtain a standard curve and convert fluorescence values to cell number. To analyze the effect of transfection on cellular phenotype, BSCs transfected with pCrtB/I/Y were differentiated and stained for Pax7 and MHC as previously described, with the exception that red (594 nm) fluorophore-conjugated antibodies were used to detect both Pax7 (ThermoFisher #A-11072) and MF20 (Abcam #ab150116), and no cytoskeletal counterstain was performed. 
     Carotenoid extraction—Cells were cultured to confluency in 175 cm 2  flasks, harvested, and counted using a hemocytometer. Collected cells (˜3-10 million for BSCs, ˜10-20 million for C2C12s) were washed 1× with PBS, resuspended in 1 mL of a 50:25:25 solution of hexane (Sigma #270504), acetone (ThermoFisher #A18-500), and ethanol (Sigma #459836), vortexed for one minute, and incubated on a shaker plate at room temperature for 30 minutes. After 30 minutes, 150 μL of deionized water was added, and suspensions were again vortexed for one minute. Solutions were centrifuged at 3,000 g for 5 minutes at 4° C., and the carotenoid-containing upper layer was collected in a Pyrex tube. Another 1 mL of hexane:acetone:ethanol solution was added to the remaining pellet, and the extraction was repeated, pooling the two carotenoid solutions in one tube. Extracts were dried at room temperature under flow of nitrogen gas, capped, and stored at −80° C. before analysis with HPLC. 
     Quantitative HPLC—Carotenoids were analyzed via HPLC following published techniques on an Agilent 1200 system (Agilent Technologies, Santa Clara, Calif., USA) with a C30 stationary phase (YMC #CT99S03-1546WT, 3 μm, 4.6×150 mm, Allentown, Pa., USA) and mobile phase solvents A—methanol (ThermoFisher #A454-1) containing 1% ammonium acetate (ThermoFisher), and B—methyl-tert-butyl ether (MTBA, ThermoFisher #AC378720010) (Melendez-Martinez et al., 2013). Briefly, carotenoid extracts were suspended in 150 μL of ethanol, vortexed, and injected (50 μL) into the HPLC system. Mobile phase solvents were pumped through the system at 1 mL/min with the following time-dependent gradients: t=0 min, 95% A, 5% B; t=15 min, 85% A, 15% B; t=30-37 min, 40% A, 60% B; t=40-55 min, 30% A, 70% B; t=59-64 min, 90% A, 10% B; t=70 min, 95% A, 5% B. Carotenoid standard curves were generated by dissolving (E/Z)-phytoene (Sigma #78903), lycopene (Sigma #SMB00706), and β-carotene (ThermoFisher #AAH6010603) standards in hexane at a concentration of ˜0.5 mg/mL. Exact concentrations were determined spectrophotometrically (SpectraMax M2, Molecular Devices, San Jose, Calif., USA) by measuring absorbances in 1 cm path-length quartz cuvettes at 286, 472, and 453 nm for phytoene, lycopene, and β-carotene, respectively, and calculating exact concentration using A 1% =915, 3450, and 2592 for phytoene, lycopene, and β-carotene, respectively. Standards were dried under nitrogen and stored at −80° C. until analyzed with samples following serial dilution. As FBS can contain trace carotenoids (from animal feed), endogenously-produced carotenoid content was captured by subtracting the area under any peaks found in extractions from pGFP cells (which have no mechanism for producing carotenoids endogenously) (Chitchumroonchokchai et al., 2017). If calculations returned negative values, or no peak was detected, endogenous carotenoid content was set to zero. Final values were converted to ng/cells*10 6  before normalizing to cellular protein. 
     Protein quantification—To normalize cellular carotenoid content under more food-relevant metrics than cell number, cellular protein content was measured. Briefly, engineered cells were cultured as previously described, harvested, and counted. One million cells were pelleted, washed 1× in PBS, and treated with 100 uL of RIPA buffer (Thermo Fisher #89900) containing 1% Halt Protease Inhibitor Cocktail EDTA-Free (ThermoFisher #78425) according to the manufacturer&#39;s instructions. Resulting cell lysates were analyzed via Pierce BCA protein assay (ThermoFisher #23225) according to the manufacturer&#39;s instruction. Absorbance at 562 nm was compared to a standard curve of known bovine serum albumin (BSA) concentrations and used to determine cellular protein per million cells (Supplementary  FIG. 1 ). These values were then used alongside carotenoid quantification per million cells ( FIGS. 4C-4D ) to obtain carotenoid content per protein mass. 
     Carotenoid optimization—Two methods were explored for optimizing carotenoid production in pCrtB/I/Y cells. The first focused on increasing gene expression by increasing puromycin selective pressure. The second focused on increasing levels of the carotenoid pathway precursor farnesyl pyrophosphate (FPP) by inhibiting downstream reactions in one of FPP&#39;s alternative metabolic pathways—cholesterol synthesis—using the small molecule ketoconazole (Sun et al., 2007). By exploring these two approaches, the possibility for a single approach to fail to address a rate-limiting step in carotenoid production was reduced. Specifically, if FPP levels were completely limiting (i.e., there was enough enzyme to fully exhaust FPP levels), then increasing enzyme expression would fail to increase carotenoid levels. Similarly, if enzyme levels were completely limiting, then ketoconazole treatment would offer no increase in carotenoid production. To determine an appropriate puromycin concentration for increasing enzyme expression, engineered cells were cultured in media containing 2.5 μg/mL puromycin (1× puro), 5 μg/mL puromycin (2× puro) or 10 μg/mL puromycin (4× puro), and relative GFP expression was determined via flow cytometry as a proximate measure of enzyme expression. Briefly, cells were cultured, harvested, and GFP was analyzed using a BD FACSCalibur (BD Sciences) or Attune N×T (ThermoFisher) flow cytometer. Appropriate gating was performed using pGFP and unmodified cells as positive and negative controls, and mean fluorescent intensity was determined. Data were analyzed with the FlowJo software (v10). To determine an appropriate ketoconazole concentration for metabolic flux modulation, a growth curve was performed as previously described using a dsDNA quantitation kit and media treated starting on day 1 with 0, 2.5, 5, 10, or 20 μg/mL ketoconazole (KTZ, ThermoFisher #455470010) dissolved in DMSO. Final DMSO concentration was held constant (0.3%) in all conditions. Following the determination of appropriate concentrations of puromycin and ketoconazole for carotenoid optimization, pCrtB/I/Y cells were cultured in media containing 1× puro plus 5 μg/mL ketoconazole, 4× puro without ketoconazole, or 4× puro plus 5 μg/mL ketoconazole, and carotenoid analysis was performed as previously described. 
     Lipid oxidation—To analyze the antioxidant functionality of carotenoids in cells, a thiobarbituric acid reactive substances (TBARS) assay was performed. This assay measures malondialdehyde (MDA), a byproduct of unsaturated fatty acid oxidation, and so serves as a measure of lipid oxidation in cells. As lipid oxidation is often catalyzed by the processes that generate oxidative pressure, such as cooking of meat, the TBARS assay was performed on both “raw” cells, and cells that had been heated to mimic cooking. Briefly, engineered BSCs were cultured as previously described, harvested, and counted. 1.5 million cells were aliquoted to tubes for heated or unheated analysis, washed 1× in PBS, pelleted, and the supernatant PBS was removed. Collected cell pellets were stored overnight at 4° C. The next day, samples designated for heating were incubated for 10 minutes in a 100° C. heat block, cooled to room temperature, and placed on ice. All cells (heated and unheated) were suspended in 500 μL of PBS, incubated for 2 hours on ice, and sonicated on ice using a probe sonicator (Branson, St. Louis, Mo., USA) at 15% intensity for 5×15 second pulses, with 20 second intervals between pulses. Next, the TBARS assay (Cayman Chemical #700870, Ann Arbor, Mich., USA) was performed with 100 μL of sonicated cell lysates, following the manufacturers protocol and determining MDA by measuring absorbance at 535 nm compared to a standard curve of known MDA concentrations. The remainders of the cell lysates were frozen at −80° C. until protein quantification was performed via Bradford assay (ThermoFisher #23200) following the manufacturers protocol. Briefly, 5 μL of cell lysates were incubated for 10 minutes with 250 uL of Coomassie reagent, and the absorbance was measured at 595 nm and compared to a BSA standard curve. TBARS measurements were normalized with protein content for each sample in order to obtain corrected cellular MDA (mg/g protein). 
     Statistical analysis—Statistical analysis was performed with GraphPad Prism 8.0 software (San Diego, Calif., USA). Carotenoid content, flow cytometry, and ketoconazole growth were analyzed via one-way ANOVA. Growth curves and TBARS assays were analyzed via two-way ANOVA. Multiple comparisons of all analyses were performed with Tukey&#39;s HSD post-hoc test. In converting carotenoid and MDA quantification to per-protein values, propagation of error was considered using σ_(A/B)=(A/B)√((σ_(A/A){circumflex over ( )}2+(σ_(B/B){circumflex over ( )}2), where σ_A is the standard deviation of the data A. P values &lt;0.05 were treated as significant. Unless otherwise stated, errors are given as ±standard deviation. 
     Results and Discussion 
     Primary bovine skeletal muscle stem cells—Immunofluorescent staining for early markers of satellite cell identity and terminal markers of myogenic differentiation were used to characterize primary bovine satellite cells (BSCs). Proliferative cells showed ubiquitous staining for Pax7, a marker of satellite cell phenotype ( FIG. 2A ), indicating that the cell isolation protocol was successful in generating a highly consistent population of myogenic stem cells. Following one week of differentiation, cells stained for myosin heavy chain (MHC) showed long, multinucleated myotubes ( FIG. 2B ). Actin and MHC staining of these myotubes revealed striated architecture indicative of sarcomere formation, and the presence of a contractile apparatus was further supported by the observation of spontaneous contractions in differentiated cultures. Together, these data indicate the isolation of a highly myogenic population of bovine skeletal muscle precursors, and the ability of these cells to undergo robust differentiation in vitro. 
     Stable transgene expression in cells—BSCs and C2C12 immortalized mouse precursor cells were engineered with multicistronic vectors for producing a range of protein conversations. These were green fluorescent protein (GFP) alone (pGFP) which did not produce any carotenoids, CrtB and GFP (pCrtB) which could produce phytoene, CrtB, CHI and GFP (pCrtB/I) which could produce phytoene and lycopene, or CrtB, CrtI, CrtY and GFP (pCrtB/I/Y) which could produce phytoene, lycopene and β-carotene ( FIGS. 2A-2B ). The multi-cistronic nature of these vectors allowed the use of GFP expression as an indicator of vector integration and gene expression. Specifically, 2A sequences between genes allowed for near stoichiometric expression of enzymes and GFP (Szymczak et al., 2004). After transfection followed by one week of selection in puromycin-containing media, all cells stably their respective gene cassettes, as was visible through GFP fluorescence ( FIG. 3A ). Fluorescence intensity was heterogenous, which was likely due to the randomness of transposition. No obvious morphological differences were seen between control pGFP cells and cells expressing carotenoid-synthesis enzymes. 
     Growth and development of engineered cells—As antioxidants are known to affect muscle progenitor proliferation, cells producing all three carotenoids were analyzed for growth-rate over eight days (Le Moal et al., 2017). For BSCs, the size of the inserted gene construct was negatively associated with growth rate ( FIG. 3B ). In contrast, C2C12s engineered with the two largest compounds (pCrtB/I and pCrtB/I/Y) showed higher growth over eight days than cells engineered with pGFP or pCrtB. This discrepancy could be due to the impact that insertion efficiency and subsequent selection has on primary cells, but not immortalized cells. Namely, cells transfected with larger constructs have a lower insertion efficiency, and so require more doublings to generate an equally large population of engineered cells (Izsvák et al., 2000). In primary cells, growth is reduced with increased doublings, and eventually cellular senescence is reached (Ding et al., 2018). In immortalized cells, however, doublings do not hinder growth. Rather, antioxidant capacity has been shown to increase cellular proliferation (Le Moal et al., 2017), and immortalized cells with increased antioxidant capacity—pCrtB/I and pCrtB/I/Y cells—showed improved growth compared to controls. It is possible that immortalized bovine cells would show similar relative kinetics. 
     To determine whether genetic modification affected myogenic potential, Pax7 and MHC staining was performed on pCrtB/I/Y BSCs ( FIG. 3C ). Staining showed maintenance of Pax7 expression and MHC-positive myotube formation. No striations were observed in differentiated cells, which could indicate less robust differentiation compared to non-engineered cells. This could be due to an antioxidant effect reducing the degree of myofiber maturation, though the ability of cells to form myotubes suggests the potential for these cells to generate differentiated cultured meat products. Together, these data point to the ability of cells to maintain their capacity for proliferation and differentiation following modification with carotenoid-synthesizing enzymes; however, this capacity may be reduced in primary cells. 
     Carotenoid production by engineered cells—Quantitative HPLC confirmed the production of phytoene in pCrtB cells, phytoene and lycopene in pCrtB/I cells, and phytoene, lycopene and β-carotene in pCrtB/I/Y cells. In all cells, carotenoids accumulated in the terminal compound though precursors (i.e., phytoene and lycopene in pCrtB/I/Y cells) were present, indicating high but non-exhaustive conversion efficiency throughout the pathway ( FIGS. 4A-4D ). In pCrtB/I cells, most of the phytoene was converted to lycopene, with high conservation of total carotenoid content compared with cells only producing phytoene. In pCrtB/I/Y cells, carotenoids accumulated in the terminal compound (β-carotene), though yields were significantly reduced compared to pCrtB or pCrtB/I cells. C2C12s produced more carotenoids for all three constructs than BSCs. Total carotenoids for C2C12 pCrtB, pCrtB/I, and pCrtB/I/Y were 505.3, 254.8, and 63.19 μg/g protein, respectively. For BSCs, these were 35.8, 31.2, and 3.7 μg/g protein, respectively. The significant reduction in total carotenoid content in BSCs compared to C2C12s and pCrtB/I/Y cells compared to pCrtB or pCrtB/I cells could be due to increased cellular burdens of selection and protein production and/or the degradation of β-carotene with endogenous enzymes (Geurts et al., 2003; Lindqvist et al., 2005). 
     Optimization of carotenoid production—Due to the relatively low carotenoid production in BSCs compared to C2C12s and pCrtB/I/Y cells compared to pCrtB or pCrtB/I cells, we hypothesized that production in these cells could be significantly improved. We explored two methods to achieve this. In the first, enzyme expression was increased by increasing selective pressure for transgenes. Puromycin was shown to induce a significant increase in GFP expression at 4× concentration (10 μg/mL) for both C2C12s and BSCs ( FIG. 7A ,  FIGS. 9A-9B ), so this concentration was used for optimization. In the second method, carotenoid precursor accumulation was induced by inhibiting cholesterol synthesis—which competes for carotenoid precursors—using the small molecule ketoconazole ( FIG. 5A ) (Sun et al., 2007). A ketoconazole concentration of 5 μg/mL was found to not significantly effect growth in C2C12s and BSCs ( FIG. 7B ), so this concentration was used. 
     To test how these treatments affected carotenoid production separately and in concert, pCrtB/I/Y BSCs were cultured with 1× puromycin+/−ketoconazole and 4× puromycin+/−ketoconazole. A clear increase in orange pigmentation was observed in cells cultured with 4× puromycin+ketoconazole ( FIG. 5B ), and quantitative HPLC showed a significant increase in β-carotene production for these cells ( FIG. 5C ). Specifically, optimized BSCs produced 10-times more β-carotene than un-optimized BSCs (22.6 vs. 2.08 μg/g protein, respectively). Notably, these levels are ˜7 times greater than literature values for β-carotene (ug/g protein) in beef from pasture-raised cattle, and ˜14 times greater than beef from feedlot-raised cattle (Simonne et al., 1996). The best-performing treatment (4× puromycin+ketoconazole) was then used to optimize pCrtB/I/Y C2C12s. The mean β-carotene concentration for un-optimized and optimized C2C12s was 35.44 and 42.43 μg/g protein, respectively, though this difference was not statistically significant. Analysis of the full carotenoid profiles of optimized cells revealed that the trend of accumulation in the terminal compound (β-carotene) held true in all cases ( FIGS. 8A-8B ). 
     The ability of both enzyme and precursor enhancement to increase carotenoids suggests that both enzyme and precursors are limiting in the system, which is likely due to the heterogenous nature of enzyme expression in cells. Specifically, in cells with high baseline enzyme levels, precursors are rate-limiting, and in cells with low baseline enzyme levels, enzyme capacity is rate-limiting. The efficacy of both optimization techniques suggests the utility of pursuing multiple avenues for optimization when engineering cultured meat. While the use of ketoconazole as a means of inducing precursor accumulation was useful for this proof-of-concept, a production-scheme for nutritionally enhanced cultured meat would likely rely on genetic strategies to achieve the same effect. 
     Lipid oxidation and antioxidant functionality—Lipid oxidation is a key mechanistic link between red or processed meat consumption and colorectal cancer, as well as a major cause of non-microbial meat quality degradation during storage (Falowo et al., 2014; Wolk, 2017). We therefore analyzed cellular malondialdehyde (MDA) levels by thiobarbituric acid reactive substance (TBARS) assay in order to probe the ability of endogenous carotenoids to reduce lipid oxidation in vitro, both in “raw” unheated cells, and in “cooked” heated cells ( FIG. 6 ). In pGFP BSCs, unheated and heated samples showed 1.9 and 4.6 mg MDA/g protein, respectively, indicating a significant effect of heating methods in promoting lipid oxidation. BSCs engineered with pCrtB showed a decrease in lipid oxidation for unheated and heated samples (1.7 and 3.6 mg/g protein, respectively), though this difference was not statistically significant in unheated samples. Cells engineered with pCrtB/I and pCrtB/I/Y showed significant reductions in lipid oxidation compared controls in both unheated and heated samples (1.0 and 1.1 mg/g protein for CrtB/I and CrtB/I/Y unheated samples, respectively, and 1.7 and 2.3 mg/g protein for heated samples, respectively). 
     It is notable that cells with lycopene and/or β-carotene offered more antioxidant capacity than cells with phytoene alone, despite total carotenoid levels being highest pCrtB cells. This could be due to the varying antioxidant capacity of these carotenoids, with phytoene offering the least (Martínez et al., 2014). Similarly, the fact that pCrtB/I/Y cells offered nearly comparable antioxidant activity to pCrtB/I cells—despite the latter offering ˜ten-fold more total carotenoids—could be due to the synergistic effects that the carotenoids have been shown to offer when present together in systems (Kotiková et al., 2011). Finally, the measure of lipid oxidation alone could impact results, as cholesterol—the synthesis of which competes with carotenoid synthesis—can improve membrane antioxidant capacity (López-Revuelta et al., 2006). It would therefore be worthwhile to measure total oxidation (including protein). That said, the simplicity and ubiquity of TBARS assays for meat science applications make this technique highly relevant, and the ˜2-fold reduction in lipid oxidation for both heated and unheated samples containing endogenously produced lycopene and/or β-carotene indicates that these nutrients would offer significant impact to nutrition and food-quality of engineered cultured meat products. 
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     Example 2 
     Meat is a key source of nutrition for many populations due to its ability to provide valuable nutrients at high density. Meat offers substantial protein content (about 30% by weight when cooked), an amino acid profile that is well proportioned for human health, a range of essential fatty acids, A, B, D and E vitamins, and key minerals in highly bioavailable formats 5-9 . The bearing of these features on human health is magnified by meat&#39;s current and predicted prevalence in global diets. Indeed, in some western diets meat constitutes up to 40% of daily protein intake, and a recent report from Food and Agriculture Organization (FAO) of the United Nations suggests that global meat production will increase 76% from 2012-2050, up to 455 million tons 5,10 . 
     However, despite this value, a growing body of work highlights the fact that meat&#39;s global impact both as a nutrient-source and as a mass-commodity extends beyond nutritional benefits. From a health standpoint, consumption of high amounts of red and processed meat is associated with increased risks for numerous pathologies, including type II diabetes, cardiovascular disease, and colorectal cancer 11-16 . While the epidemiological studies behind these associations are difficult to construct firm dietary suggestions from (and are thus often contested), enough meta-analytical evidence exists in the case of colorectal cancer to be substantially convincing to the majority of the nutrition scientists, and the World Health Organization&#39;s International Agency for Research on Cancer (IARC) has deemed red and processed meat to be ‘probably carcinogenic’ and ‘carcinogenic,’ respectively 17,18.  From a production standpoint, animal agriculture is responsible for substantial natural resource use, greenhouse gas emissions, and environmental degradation. Specifically, it is estimated that animal agriculture produces ˜15% of all anthropogenic greenhouse gases (CO 2  equivalents), contributes ˜29% of the global human water footprint, motivates ˜71% of deforestation in some regions, and is a major source of eutrophication 10,19 . At the same time, concentrated animal agriculture raises concerns around animal welfare and antibiotic resistance 10 . With meat production projected to rise substantially by 2050 these issues are likely to intensify. 
     Recently, the possibility of producing meat with cell culture (termed “cultured meat”) has been proposed to address the environmental and ethical concerns of animal agriculture 20 . Producing cultured meat involves expanding muscle and fat cells from relevant species in vitro and seeding them onto edible scaffolds to form 3D tissues 21 . By producing meat apart from the competing energy requirements present in whole animals, it is projected that cultured meat could drastically lower meat&#39;s land-use, water-use, and greenhouse-gas emissions 22 . It is also expected that cultured meat could mitigate the animal welfare and antibiotic resistance concerns of conventional meat. 
     However, despite these projected benefits, it is so far unclear exactly how cultured meat will recapitulate the nutritional features of meat, and what its nutritional advantages or disadvantages may be. On one hand, cultured meat may offer inferior protein profiles than conventional meat due to the frequent immaturity of skeletal myofibers cultured in vitro, and the importance of sarcomeric proteins to meat&#39;s nutrition value 23 . Further, the content of many nutrients such as minerals and some vitamins that are not endogenously synthesized by muscle tissue—including essential vitamins like B 12 —will be entirely dependent on cellular uptake from media components, and so could be reduced or absent in a bioprocess that is tightly constrained by media cost 24 . On the other hand, some deleterious nutrients that are present but not endogenously synthesized in muscle tissue—such as trans-saturated fatty acids—will be easy to exclude from a cultured meat product 25 . 
     Along with intrinsic differences, the cell-level control that is inherent to cultured meat offers the opportunity to tune composition towards various aims. This could be the modulation of native nutrients—such as amino acid or lipid profiles—or the addition of compounds not endogenously synthesized in meat tissues—such as vitamins or other phytochemicals. These modifications can be directed to address what might be cultured meat&#39;s nutritional deficits, augment its nutritional advantages, or add completely new nutritional functionality. Looking beyond nutrition, it is possible that composition could also be tuned towards organoleptic and food-functionality aims such as flavor, aroma, color or shelf-stability, or towards therapeutic activity, allowing the production of ‘therapeutic foods’ with favorable bioactivities upon consumption. 
     One promising technique for affecting cultured meat composition in this way is through metabolic engineering, or the genetic and regulatory control of cellular metabolism towards various goals. Metabolic engineering efforts in plants, yeast and bacteria have exploited numerous pathways from diverse taxa towards applications ranging from medicine and cosmetics to energy and agriculture 26-28 . That same breadth has not yet been realized in mammalian systems, where the majority of efforts have focused on biopharmaceuticals 29-31 . While these efforts are by no means inferior to those in other systems, the difference in scope is stark. To date, this discrepancy is likely due at least in part to the lack of a compelling case for engineering animal cells with metabolic pathways from other taxonomies; from a bioprocess standpoint, the production of recombinant proteins, small molecules and biofuels is cheaper in bacteria, yeast or plant systems, and only the need for species-specific post-translational modifications makes mammalian bioprocesses preferable 29,32 . The possibility of cultured meat offers a new framework in which the product is the cells themselves and so endogenously synthesizing additional compounds becomes a purely additive endeavor, at least insofar as those efforts are biologically possible and do not hinder the bioprocess or product value. Here, the fact that cultured meat is dependent only on cell growth rather than whole-animal viability—which is inherently limiting for animal transgenics—allows the consideration of an even wider range of metabolites which might be untenable in animals but harmless or even beneficial in cell culture. Compelling functionalities to explore include nutrition, bioactivity and food-functionality, flavor, or therapeutic activity. 
     Example 1 demonstrates mammalian cells engineered with a metabolic pathway for carotenoid synthesis, which is native to many plants and some prokaryotes, but not animals. Specifically, using non-viral Sleeping Beauty transgenesis we engineered the production of phytoene, lycopene, and β-carotene from native precursors in primary bovine and immortalized C2C12 mouse muscle cells. These nutrients were attractive targets for several reasons. First, each offers unique nutritional value; phytoene is suggested to act as a UV photo-protectant, lycopene has been shown to reduce hepatocellular carcinoma and fatty liver disease, and β-carotene is an essential vitamin A precursor in the human diet 33-35 . Second, all three compounds are antioxidants 36 . This is particularly relevant for red meat, since a key mechanistic link between red or processed meat consumption and colorectal cancer is lipid oxidation 17 . The antioxidant nature of these compounds also provides value in extending meat shelf-life, as lipid oxidation is a major cause of non-microbial degradation over time 37 . Finally, these compounds are red pigments, and so their synthesis could impact the color of a cultured meat product. We demonstrated successful synthesis of three all dietary carotenoids, the phenotypic integrity of cells following modification, and the ability to tune carotenoid yields through multiple strategies. 
     The possibility of one metabolite having diverse implications for a cultured meat product—such as antioxidants conferring auxiliary meat-quality benefits alongside nutritional ones—is a common feature for many potential targets. Along with aforementioned meat quality implications, antioxidants can affect cell expansion, where disregulated levels of reactive oxygen species induce cell cycle arrest and inhibit proliferation 38-40 . Indeed, carotenoid-synthesizing C2C12s with increased antioxidant capacity showed higher proliferation than controls in our previous study, though this was not seen in engineered primary cells. Other interesting cases of pro-proliferative effects from phytochemicals include those of vitamin C in teleost myoblasts, chrysanthemin (a polyphenol nutrient) in C2C12s, and D-limonene (a flavor and aroma compound found in citrus) in lymphocytes 41,42 . In contrast, phytonutrients such as the polyphenol resveratrol have been shown to have anti-proliferative but pro-differentiation effects in myoblasts, suggesting potential applicability during the differentiation phase of cultured meat production 43 . Similarly, evidence exists to suggest that cannabinoid receptor 1 (CB1) antagonists such as cannabidiol—a therapeutic phytochemical—could improve differentiation of both C2C12s and primary human myoblasts in vitro 44 . Some phytochemicals, such as the nutrient curcumin, can demonstrate both pro-proliferative and pro-differentiation effects on primary myoblasts, depending on dosing 45 . In light of these effects, it is useful to consider how engineering targets might be able to enhance a cultured meat product and process simultaneously. 
     This embodiments described in this Example demonstrate (1) baseline nutritional analyses of bovine skeletal muscle cells cultured in vitro (both proliferative and differentiated cells will be analyzed) in order to better understand the innate nutritional differences between cultured meat and conventional meat, (2) test various engineering targets for enhancing nutrition, food-quality or bioactivity in order to outline the scope of possibilities for compositional tuning of cultured meat, and (3) analyze the impacts of modifications on food-functionality such oxidation and nutrient bioavailability and on bioprocess parameters such as cell growth and differentiation. This work will help elucidate cultured meat&#39;s intrinsic nutritional features and establish a foundation for the broad use of metabolic engineering to tune composition and bioprocess parameters. 
     Cell isolation and culture—Bovine satellite cells (BSCs) are isolated from live-animal biopsies gathered at the Tufts University Cummings School of Veterinary Medicine using methods previously reported by our group 46 . Briefly, a small excision (˜0.25 cm 3 ) is taken from the semitendinosus of a &lt;30-day-old Simmental bull, minced and digested in DMEM Glutamax (Gibco) with 0.2% collagenase II (Worthington). The resulting cell suspension is diluted in growth media comprised of DMEM Glutamax with 20% fetal bovine serum (FBS), 1% primocin (Sigma), and 1 ng/mL FGF-2 (Thermo Fisher), filtered and plated onto tissue culture flasks. After 24 hours, unattached cells are moved to new tissue culture flasks that have been coated with 0.25 ug/cm2 of recombinant laminin-511 (Iwai) and left undisturbed for three days. This pre-plating isolates the slowly-adherent BSCs from quickly-adherent fibroblasts. After three days, BSCs are fed with growth media every 2-3 days and passaged at 70% confluency onto laminin-coated flasks. After two weeks, 1% antibiotic-antimycotic (Thermo Fisher) replace primocin in culture media. To differentiate BSCs, cells are cultured to confluence then cultured for one week without media change. To confirm BSC identity, immunocytochemistry is performed for the satellite cell marker Pax7 (during proliferation) and the myogenesis marker myosin heavy chain (MHC; following differentiation). 
     Protein analysis—Cells are harvested both before and after differentiation in normal media, media with 1×, 2×, and 4× levels of essential amino acids, and media formulated for an amino acid profile well suited to human nutritional requirements 1 . Bulk protein is quantified using a Pierce BCA protein Assay kit (Thermo Fisher) according to the manufacturer&#39;s instructions. Amino acid composition are quantified by HPLC as previously described 47,48 . Briefly, cells are homogenized via sonication, spiked with a known concentration of the internal standard norvaline, hydrolyzed with HCl, and quantified against amino acid standards (likewise spiked with norvaline) via HPLC following precolumn derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl-carbamate. Samples are separated with a Nova-Pak C18 (Waters) column and analyzed with fluorescence detection excited by 250 nm and emitting at 395 nm. Both bulk protein and amino acid composition are correlated to DNA content (CyQuant assay; Thermo Fisher) to compare undifferentiated and differentiated cells. Conventional meat samples are analyzed and compared with cultured cells. 
     Lipid analysis—Lipid analysis is performed using a liquid chromatograph-mass spectrometry (LC-MS) as previously described 49 . Briefly, undifferentiated and differentiated BSCs are homogenized via sonication, and lipid internal standards will be added to homogenates (comprised of a defined mixture of phosphatidylcholines (PC), phosphatidylethanolamines (PE), ceramides (Cer), phosphatidylserines (PS), phosphatidic acid (PA), and mono-, di-, and triacylglycerols (MG, DG, and TG). Cellular lipids are extracted with a solution of chloroform and methanol (2:1, v/v), centrifuged, and the lower phase will be collected and combined with external standards (comprised of isotopically labeled TGs and PCs). Samples are quantified against lipid standards via LC-MS with separation in a BEH C18 column (Waters) followed by quadrupole-time-of-flight detection. Fatty acid profiles are normalized using internal and external standards, and against DNA and protein quantification. Again, samples are analyzed at varying levels of differentiation, and compared with store-bought products. 
     Bulk protein in bovine cells is expected to be similar to that found in store-bought beef. Specifically, for bulk proteins in mammalian muscle cells, previous reports suggest expected values of ˜20% protein by wet cell weight, which is similar to concentrations found in beef 9 . At the same time, reduced extracellular protein accumulation and myotube maturation may result in reduced protein levels. Amino acid profiles are expected to be a combination of the amino acid profile of cellular growth media (i.e. input profiles) and the amino acid profile of store-bought products (i.e. innate tissue profiles). In this, a significant, though non-stoichiometric, increase in cellular amino acids following media supplementation with essential amino acids is expected. 
     Lipids represent ˜10% of dry mass for myoblasts in culture, or ˜2-5% of wet mass (based on rough estimations of 70% water) 50 . This corresponds to 20-50 mg/g protein. As store-bought samples will contain both skeletal muscle cells, extracellular matrix, and intramuscular fat cells, it is difficult to predict how lipid content will compare. On one hand, higher protein content of store-bought samples could result in comparatively less lipid per protein; however, intramuscular fat cells could result in comparatively higher lipid per protein. That said, as store-bought meat offers ˜4% lipid and ˜20% protein by mass (wet), it is expected that cellular lipid content will be similar to conventional meat 9 . Specific lipid ratios are expected to represent a combination of endogenously produced fatty acids and lipids present in the culture media. As culture media lipids will be provided by fetal bovine serum, and the cells are bovine in nature, it is expected that these ratios will match closely with store-bought beef samples. Lipidomic analysis can also be performed on bovine adipocytes instead of or alongside BSCs. 
     Genetic modification—Genetic modification of cellular pathways will be achieved through two mechanism: transposon-mediated transgenesis or CRISPR-dCas9 gene activation. For constitutive expression, transposon-mediated gene insertions will be used, due to their non-viral nature, high efficiencies, and demonstrated utility in prior carotenoid work. Specifically, the Sleeping Beauty, PiggyBac or Tol2 transposon systems will be considered depending on insert size, requirements for multiple insertions, and ease of cloning 54-56 . For gene activation, CRISPR-dCas9 systems will be used due to their high specificity, efficiency, and ease-of-use 57 . In this, guide RNA targeting specific genes will be introduced to cells alongside plasmids encoding a deactivated Cas9 (dCas9) proteins that are linked to activation domains. These will trigger transcription, thereby activating native genes. 
     Molecular cloning will be carried out using standard techniques. For genetic insertions, transposable elements will contain both the genes of interest and the genes for resistance to selection antibiotics (e.g., puromycin) to enable the selection of successfully transfected cells. Cellular transfection will be performed using the Lipofectamine 3000 reagent (Thermo Fisher). Briefly, cells will be cultured to 85% confluence, washed with OptiMEM media, and incubated with transfection reagents containing purified plasmids. After 6 hours, growth media will be added to cells and following 42 hours a selection pressure will be added to the media (e.g., puromycin). Cells will be cultured for one week under selective pressure, after which expression will be verified through immunocytochemistry, the use of fluorescent tags, or polymerase chain reaction (PCR). When multi-cistronic expression is needed, genes will be linked by 2A peptide sequences to allow for the translation of multiple proteins from a single strand of RNA which codes for multiple genes 58 . In most cases, a 2A sequence will link green fluorescent protein (GFP) to the expression cassette, so that expression can be screened for through simple fluorescence microscopy. Throughout these studies, cell health and myogenic potential will be verified by observing proliferation and differentiation of cells. 
     Vitamin C: The genes for vitamin C synthesis are present but silent in bovine muscle cells. From readily available precursors (UDP-glucose) in BSCs, this pathway involves five enzymes ( FIG. 1 ): UDP-glucose 6-dehydrogenase (UGDH), UDP glucuronosyltransferase 1 (UGT1A1), aldo-keto reductase family 1 (AKR1A1), regucalcin (RGN), and L-gulono-gamma-lactone oxidase (GULO) 59-61 . RNA-sequencing data from the muscle of beef steers show that UGT1A1 expression is the lowest of these by two orders of magnitude 62 . Therefore, UGT1A1 will be the first target addressed. The second least-expressed enzyme is GULO, followed by RGN, and so these enzymes will be addressed if UGT1A1 engineering proves ineffective. It should be noted that this transcriptomic approach to target selection has drawbacks, as RNA production does not necessarily correlate to protein production or enzymatic activity. This limitation will be kept in mind throughout process. 
     Two methods will be explored for engineering UGT1A1, RGN, and GULO expression in cells. In the first, CRISPR-dCas9 gene activation will be performed. Transposon-mediated insertion and constitutive expression of these genes can also be performed as was previously described for carotenoids. Genetic modification will be performed with Lipofectamine 3000, and vitamin C levels will be analyzed via enzymatic assay (Abcam) according to the manufacturer&#39;s instructions. 
     Alternative biosynthetic pathways are also of interest for Vitamin C production. For example, D-threo-aldose 1-dehydrogenase (CDS) and L-galactono-1,4-lactone dehydrogenase (GLDH), which are native to bacteria and synthesize vitamin C from L-galactose, can be expressed in mammalian cells to increase Vitamin C production. 59  The CDS and GLDH enzymes can be constitutively expressed in cells as an alternate path for producing endogenous Vitamin C. 
     Curcumin: From readily available precursors in mammalian cells (tyrosine), curcumin synthesis involves four enzymes ( FIG. 10 ): tyrosine ammonia-lyase (PTAL), 4-coumarate-CoA ligase (4CL), phenylpropanoyl-diketide-CoA synthase (DCS) and curcumin synthase (CURS3) 63,64 . These genes will be codon optimized, synthesized, and cloned into a multi-cistronic tetracycline-responsive expression vector. This expression vector will be stably inserted into BSCs via Lipofectamine 3000 transfection as previously mentioned. Cells will be cultured and treated with tetracycline during proliferation or after the initiation of differentiation. Curcumin will be detected by HPLC based on previously reported methods 65-67 . Briefly, cells will be harvested and homogenized via sonication. Berberine will be added to homogenates as an internal standard, and solutions will be acidified with 6 N HCl. Curcumin and berberine will be extracted with ethyl acetate:propanol (9:1, v/v), centrifuged, and the top layer will be collected for HPLC analysis via Zorbax Eclipse XDB-C18 column (Agilent) separation and detection at 420 nm. A standard curve of pure curcumin and berberine will be used to accurately quantify sample curcumin levels, which will then be normalized against cellular protein. To increase cellular curcumin levels, cells can be cultured in media containing higher levels of tyrosine. 
     Alternate pathways for using caffeoyl-CoA and feruloyl-CoA as intermediates can be used for endogenous curcumin production in mammalian cells. Likewise, phenylalanine can be used as a precursor for p-coumaroyl-CoA instead of tyrosine. 
     Cannabidiol: From readily available precursors in mammalian cells (malonyl-CoA), cannabidiol synthesis involves four enzymes ( FIG. 10 ): 3,5,7-trioxododecanoyl-CoA synthase (OLS), olivetolic acid cyclase (OAC), annabigerolic acid synthase (CPGAS), and cannabidiolic acid synthase (CBDAS) 68 . In some embodiments, CPGAS may be substituted with prenyltransferase NphB, which will have the same activity with improved expression. These genes are cloned into multi-cistronic expression vectors and inserted into BSCs as with other vectors. Cells will be cultured, harvested, and homogenized as with curcumin and vitamin C, and cannabidiol will be analyzed as with HPLC following previously described methods 69 . Briefly, homogenates will be spiked with a known concentration of the internal standard 4,4-dichlorodiphenyltrichloroethane (DDT), proteins will be precipitated with cold acetonitrile, and organic components will be separated with n-Hexane. Solutions will be centrifuged, the upper layer will be separated and dried under nitrogen and resuspended in acetonitrile. Cannabidiol and DDT will be separated in a C18-PFP HPLC column (ACE) and detected at 220 nm. As with other nutrients, readings will be normalized to a standard curve, internal standards, and cellular protein content. 
     Additional target of interest include D-limonene (a flavor compound that would require only enzyme and is shown to improve cell proliferation in some cell types), vitamin B12, flavor compounds (e.g., limonene or cinnamaldehyde), and other therapeutic compounds such as antibiotics. 
     Previous carotenoid data showed ˜35 ug/g protein in BSCs. At least these levels of vitamin C (which is native to mammalian cells) are expected in vitro, and similar levels of curcumin or cannabidiol. Carotenoid production in immortalized mouse muscle cells C2C12 (work performed alongside BSCs) reached up to 500 ug/g protein, and so it expected that proper optimization could potentially increase nutrient levels by orders of magnitude 
     Beef liver offers about 0.3 mg/100 g of vitamin C (and is ˜20% protein by weight), so it is expected that levels of at least ˜15 ug/g protein will not offer disadvantages in terms of cytotoxicity or negative cellular effects in BSCs 9 . While no data exists for predicting the potential cytotoxicity of curcumin or cannabidiol synthesis in BSCs, previous studies have shown that a curcumin range of ˜0.005 to ˜1 ug/mL in culture media did not have a negative effect on myoblasts in vitro 45 . Similarly, studies using a range of cell types have explored cannabidiol treatment ranging from 1-50 uM (0.313-15.65 ug/mL) without mention of excess cell death 70 . These correspond to significantly lower levels than was produced for carotenoids, and so it is possible that curcumin and cannabidiol synthesis will need to be controlled in vitro. However, these results are by no means a definitive indication of endogenous nutrients&#39; cytotoxicities, and so higher levels could be achievable. 
     Growth and differentiation of engineered cells: To understand how metabolic engineering affects growth kinetics, cellular growth curves will be generated using dsDNA-based fluorometric assays (Molecular Probes) for engineered and control cells, as well as cells treated with pure compounds (i.e., vitamin C, curcumin, and cannabidiol). Additionally, cell cycle analysis will be performed on an NC-3000 image cytometer (ChemoMetec). To probe cellular senescence in engineered cells, quantitative PCR will be performed for Pax7—a marker of BSC stemness—throughout culture of engineered cells, control cells, and cells treated with compounds 73 . To understand the effect on cellular differentiation, cells (engineered, control, and cells treated with pure compounds) will be differentiated as before and stained for myosin heavy chain (MHC). For further analysis, quantitative PCR will be performed for middle and terminal myogenic markers myogenin and MHC. 
     Bioavailability: Nutrient bioavailability is dependent on the surrounding food matrix 4,74 . Bioavailability assays for both raw and cooked samples of all engineered cells (including carotenoid-producing cells) will therefore be performed via in vitro digestion followed by intestinal cell uptake assays 4,75 . Briefly, nutrient-producing cells will be cultured, harvested, and cell pellets will be kept “raw” or “cooked” by heating cell pellets to 100° C. for ten minutes. Samples will be added to a saline solution containing 140 mM NaCl, 5 mM KCl, and 150 uM butylated hydroxytoluene. To simulate gastric digestion, HCl will be added to a final pH of 2.0, samples will be mixed 36:1 with a solution of 4% w/v of pepsin in 0.1 M HCl, and samples will be incubated in a shaking water bath at 37° C. for one hour. The pH of the digesta will be raised to 6.9 with NaHCO 3 , and further intestinal digestion will be performed by mixing samples 7.4:1 with a pancreatin-bile solution (1.2% w/v of bile extract and 0.2% of pancreatin in 0.1 M NaHCO 3 ) and incubating samples in a shaking water bath at 37° C. for two hours. 
     Caco-2 intestinal cells (ATCC) will be maintained in growth media of DMEM Glutamax, 5% FBS and 1% Antibiotic-Antimycotic, passaging cells at 70% confluency. To analyze bioavailability of nutrients in digesta, Caco-2 cells will be cultured to confluency in well-plates. Digestion solutions will be centrifuged, supernatants will be diluted 1:4 in Williams&#39; Medium E (Gibco), and the resulting solution will be added to Caco-2 cell cultures following a PBS rinse. Cells will be incubated at 37° C. for 12 hours, after which cells will be washed 3× with PBS, and nutrient analysis will be performed on Caco-2 cells as before and as appropriate for the nutrient in question. Similar bioavailability assays will be performed for control cells and pure compounds added to Williams&#39; Medium E in DMSO. 
     Lipid oxidation: Vitamin C, curcumin and cannabidiol are all reported to offer antioxidant activity 76-78 . As lipid peroxidation is a significant contributor to meat quality degradation during storage, an additive&#39;s antioxidant capacity could hold particular relevance to the food quality of cultured meat 79 . Therefore, lipid peroxidation assays will be performed using a thiobarbituric acid reactive substance (TBARS) assay (Cayman Chemical) according to the manufacturer&#39;s instructions before and after one week of storage at 4° C. and before and after “cooking” as with bioavailability assays. 
     Previous studies have shown that bioavailability of many phytochemicals is higher from non-plant sources because compounds are not trapped in cellulose networks 80 . High bioavailability is therefore expected for endogenously expressed nutrients including carotenoids, vitamin C, curcumin, and cannabidiol. Vitamin C producing cells are expected to increase iron bioavailability 81 . A reduction in lipid oxidation is expected with all samples of cells producing vitamin C, curcumin and cannabidiol 76-78 . 
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     Example 3 
     Oral administration is an ideal form of drug delivery due to its convenience, non-invasiveness, and safety. However, significant challenges to oral delivery—particularly for protein therapeutics—exist in terms of drug stability, release kinetics, and permeability 1 . To address these challenges, highly engineered, complex drug formulations have been designed, but these carry high developmental and manufacturing costs, with lingering issues of efficacy. To address these issues, the embodiments described in the present example demonstrate an approach based on mammalian cell engineering and on recent advances in using in vitro tissue engineered muscle and fat to produce food for human consumption (termed “cultured meat”). Specifically, the cell-level control that is available in cultured meat production offers the potential to tune food composition towards diverse outcomes, ranging from personalized nutrition and improved public health, to personalized medicine and drug delivery. We have recently demonstrated this possibility by engineering the endogenous synthesis of antioxidant phytonutrients (carotenoids) in bovine muscle stem cells to impart novel micro-nutritional and functional value to the cell-cultured foods 2 . See Example 1. This example describes engineering animal muscle cells for the synthesis of therapeutics in disease-responsive, edible formulations. These “therapeutic foods” would offer a novel form of oral (food-based) drug delivery which could offer improved drug absorption, patient compliance, drug activity, and cost-savings. Therapeutic foods can provide significant benefit in terms of patient compliance, lower drug costs, and improved pharmacokinetic/pharmacodynamic outcomes. 
     Cell Engineering. (a) Drug production in mammalian cells: We will engineer bovine muscle cells grown in a defined, serum-free medium to synthesize three drug types to demonstrate a broad approach. These will be: 1) the physiochemically stable anti-TNFα nanobody V565, which targets IBD, and 2) the proteolytically-stable antimicrobial peptide (AMP), here termed AMP16, which is effective against  Salmonella  infection 3,4 . Cells will be engineered using approaches described herein and molecular biology techniques known in the art. Production, stability and activity/bioavailability of the cell-encapsulated drugs with or without thermal treatment (e.g., cooking) will be analyzed. The outcomes will be the production of therapeutic compounds in mammalian cells. (b) Optimize cell-encapsulated therapeutics: Drug yield will be tuned through metabolic engineering. To optimize delivery, cells will be engineered to produce adjuvants for increasing stability of protein drugs. Specifically, the production of serpin pepsin inhibitors will be engineered into drug-producing cells using recombinase-mediated cassette exchange (RMCE) to mitigate drug breakdown in the gastric environment 22 . The outcomes will be control of drug synthesis levels and improved pharmacokinetic profiles. 
     Engineering disease-responsive drug formulations: Drug activity will be made disease-responsive by leveraging the elevated levels of specific digestive enzymes that are present during disease 5,6 . Specifically, for V565, a previously reported “antibody-masking” technique will be exploited in which V565 will be linked to its epitope by a flexible peptide linker rich in the trypsin-cleavage sites lysine and arginine 7 . Upon exposure to a trypsin-rich intestine (a feature of IBD), the linker will be cleaved and V565 will be activated; however, in a non-inflamed intestine, drug activity will be reduced. Unmasking efficacy will be analyzed by in vitro digestion in trypsin-rich conditions nanobody binding affinity analysis 7 . For AMP16, a similar approach will express peptides in a long chain comprised of AMP16 repeats linked by the elastase-cleavable domain NPV 8 . Upon exposure to increased levels of elastase (a feature of  Salmonella enterica  infection), increased linker cleavage will release more AMP16, thus increasing activity. Cleavability and antibiotic effects of linked AMP16 peptides will be analyzed by in vitro digestion in elastase-rich conditions and application to  S. enterica  cultures. To explore the possibility of a single therapeutic food product acting towards multiple pathologies in a disease-responsive manner, cells will be engineered to produce both disease-responsive drugs. In vitro digestion in enzyme-rich environments will be performed, and activity of both drugs will be tested to determine the specificity of the engineered disease-response systems. The outcomes will be a multi-drug disease-responsive formulation that is capable of responding to multiple pathologies, and which demonstrates the flexibility of these systems. 
     Assessing drug bioactivity in vitro: Drug bioactivity will be analyzed using a 3D intestinal tissue model previously described, which has been engineered to model inflammatory diseases (i.e., IBD), and to allow the incorporation of gut-colonizing bacteria (i.e.,  S. enterica ), and immune cells (i.e., macrophages, which are the proposed target of V565) 9-12 . As such, the effect of anti-inflammatory and antibiotic drugs will be assessable with this system. Trypsin and elastase levels will be modulated to model the protease profile of IBD and  S. enterica  gastroenteritis, respectively, and drug activity will be analyzed compared with standard oral formulations as controls, both in inflamed tissue models and in models that have been inoculated with  S. enterica . Relative effects of individual or combined engineering strategies will be assessed. 
     Oral therapeutics offer significant advantages over alternatives (e.g., parenteral delivery) in terms of patient compliance, comfort, safety, and convenience. They are therefore the preferred method of drug delivery, and indeed represent over half of recent new drugs approved by the FDA 13 . However, significant challenges facing oral drug delivery of biologic (e.g., protein or peptide) therapeutics mean that fewer than 5% of FDA-approved peptide therapeutics are deliverable via the oral route, despite growing interest in their potential 14,15 . These challenges include a harsh gastrointestinal environment and limited intestinal absorption which result in limited bioavailability (&lt;1%) 13 . To reconcile the promise of therapeutic biologics with the challenges of their oral delivery, novel drug formulations are necessary. Beyond drug stability, the bioavailability of both biologics and small-molecule therapeutics can be significantly impacted by the food that is consumed contemporaneously, which can complicate clinical prescriptions 16 . As such, drug formulations that are incorporated into a defined food matrix could offer improved pharmacological consistency and predictability, thus improving patient outcomes. Finally, disease-responsive “smart” drug delivery systems that could act selectively towards active diseases are promising possibilities that have gained interest in recent years 17,18 . These drugs would become active only when needed (i.e., when presented to a diseased environment), and could therefore improve pharmacological outcomes by reducing off-target effects, avoiding excessive drug exposure, and modulating release to steady-state levels. The edible therapeutic systems described herein would explore the potential of therapeutic cell-based foods to address all three of these pharmaceutical targets, with improved bioavailability and disease-specificity for both biologic and small-molecule therapeutics. 
     Scientific Premise—The bioavailability of many oral drugs is significantly affected by the food that is consumed in parallel 19-21 . This leads to substantial pharmacokinetic uncertainty 22 . The possibility of delivering drugs as part of a defined food matrix offers tight control over food-drug interactions and thus drug delivery. Second, the capabilities of mammalian cells to synthesize a myriad of proteins and metabolites allows for complex formulations to address the barriers associated with oral delivery, while also eliminating the costly purification steps used to extract, stabilize and formulate oral therapeutics 23 . For instance, through metabolic engineering, food-based delivery systems can leverage the simultaneous synthesis of stable drug formulations within the mammalian cells, digestive enzyme inhibitors (to improve gut stability of the ingested drug), and permeation enhancers to improve absorption 3 . At the same time, the “natural liposome” of cell lipid bilayers provides further control of stability and delivery 24 . Finally, when engineered as environmentally responsive systems, these therapeutic foods could offer high specificity towards diseases 5 . For instance, numerous pathologies result in changes in the gut enzymatic profile, and so protease-triggered drug activity could enhance the release/bioavailability of drugs to enable disease-responsive activity towards a range of pathologies 5,6 . 
     Therapeutic foods—Along with the aforementioned benefits, an edible, cultured-meat-based therapeutic formulation would offer an entirely novel kind of drug delivery system that could hold significant implications for patients and clinicians alike. For instance, the most common form of medication noncompliance in the elderly is underuse, with dominant reasons being forgetfulness and polypharmacy 25,26 . It is possible that directly combining medicine and meals—inextricably tying medication to a much more ingrained and pleasurable daily ritual—would help mitigate these issues. Additionally, the potential to formulate foods with complex combinations of disease-responsive medications could mitigate the issues presented by polypharmacy. Finally, trouble swallowing solid oral medications is seen across age groups, and ad-hoc oral drug modification (i.e., crushing, cutting, dispersing in liquid, etc.) can increase variability and pose risks to patients 27 . An edible formulation would help to alleviate these issues by making drug consumption simply a matter of chewing one&#39;s food. Cultured meat is a promising emerging technology with the potential to reduce the environmental, ethical, and public-health concerns associated with meat production. Specifically, speculative life cycle analyses estimate that cultured meat could emit 78-96% less greenhouse gases, use 99% less land, use 82-96% less water, and use 7-45% less energy compared to a range of livestock species 28 . 
     Recently, drug production in plants has been proposed as a means of generating edible therapeutics, including antibodies or vaccines 23,32 . For instance, vaccines against hepatitis B, Norwalk virus, rabies and HIV have been expressed in tobacco plants, potatoes, lettuce, tomatoes and maize, and human clinical trials have validated efficacy of edible vaccines in transgenic potatoes 33,34 . The proposed benefits of these products largely centered around reducing costs by eliminating purification steps and harnessing the immense scale of agricultural production. However, despite the promise of early results for multiple drug types, variability of drug concentration and differences in plant versus human glycosylation patterns have contributed to limiting further development 32 . Mammalian cell-based edible therapeutics offer a potential means of overcoming these obstacles. Specifically, the high degree of control that would be present in cultured meat production could circumvent this variability, as cells would be grown in contained culture environments without the variables that affect crops (e.g., weather patterns). More, the use of animal cells would easily facilitate correct glycosylation. Finally, the encapsulation and delivery of therapeutics in whole animal cells is an as-yet unexplored idea, with expansive white-space to explore and innovate on targets and applications. 
     The cell-level control that is inherent to cultured meat (at the gene, transcript, protein, and metabolic level) offers the opportunity to tune composition towards various aims, enabling the production of entirely novel foods with tuned meat quality and added functionality. To demonstrate this, we recently engineered mammalian cells with the metabolic pathway for the synthesis of three different carotenoids, which are essential micronutrients that are native to many plants and some prokaryotes, but not animals 2 . Ultimately, novel food functionality in cultured meat products could be applied to nutrition (general and personalized), food quality (i.e., flavor, texture, and other sensorial properties), diet-related disease (e.g., diabetes or colorectal cancer), therapeutics (as explored in this proposal), edible vaccines, or other enhancements not considered here. 
     Bovine muscle and fat cell culture—To date, our group has explored several topics with direct relevance to this proposal. From a culture system standpoint, we have established protocols for generating populations of primary bovine satellite cells (BSCs) that are pure (ubiquitous expression of the satellite cell marker Paired-box seven (Pax7) in imaged cells) ( FIG. 13A ) and myogenic, capable of generating long multinucleated myotubes which express myosin heavy chain (MHC) and which form actin/myosin contractile apparatuses ( FIG. 13B ) 42,43 . Further, we have validated a serum-free, growth-factor based media formulation (B8) for BSC culture based on previously reported formulations 44 , and observed superior BSC growth in B8 medium compared to serum-containing growth medium (GM) ( FIG. 13C ). We have also established an adipogenic transdifferentiation method to convert myogenic BSCs into lipid-accumulating fat cells by treating cells with a free fatty acid (FFA) mixture ( FIG. 13D ). We have shown robust and tunable lipid accumulation using this method ( FIG. 13E ), indicating that a single cell population (i.e., bovine satellite cells) could be used to generate both muscle and fat for cultured meat, which could significantly simplify an industrial production process 45 . This work demonstrates broad experience with relevant bovine muscle precursor cell cultures. 
     Bovine satellite cell metabolic engineering—From a synthetic biology and metabolic engineering standpoint, we engineered BSCs to endogenously synthesize the carotenoids phytoene, lycopene, and β-carotene 2 . These nutrients were attractive targets for several reasons. First, each offers unique nutritional value; phytoene is suggested to act as a UV photo-protectant, lycopene has been shown to reduce hepatocellular carcinoma and fatty liver disease, and β-carotene is an essential vitamin A precursor in the human diet 46-48 . Second, all three compounds are antioxidants 49 . This is particularly relevant for red meat, since a key mechanistic link between red or processed meat consumption and colorectal cancer is lipid oxidation 50 . The antioxidant nature of these compounds also provides value in extending meat shelf-life, as lipid oxidation is a major cause of non-microbial degradation over time 51 . 
     Cells were engineered via Sleeping Beauty transposon-mediated transgenesis to express green fluorescent protein (GFP) alone (pGFP) which did not produce any carotenoids, CrtB and GFP (pCrtB) which could produce phytoene, CrtB, CrtI and GFP (pCrtB/I) which could produce phytoene and lycopene, or CrtB, CrtI, CrtY and GFP (pCrtB/I/Y) which could produce phytoene, lycopene and β-carotene. The multi-cistronic nature of these vectors allowed the use of GFP expression as a marker of vector integration and gene expression. All cells also expressed a puromycin resistance gene to allow for the selection of engineered cells. We first demonstrated successful synthesis of three all carotenoids in cells ( FIG. 14A ). Next, we showed that carotenoid levels could be tuned by increasing puromycin concentrations (i.e., increasing pressure to select for cells whose transgenes were positioned in more transcriptionally-active loci) or adding ketoconazole to the culture medium (a small molecule that inhibits cholesterol synthesis, a metabolic pathway which competes with carotenoids for a shared precursor) ( FIG. 14B ). We showed food functionality in reducing lipid oxidation in vitro ( FIG. 14C ). Along with prior carotenoid work, we have engineered cells to express enzymes involved in the synthesis of cannabidiol, a small molecule anti-inflammatory and pain-mediating therapeutic 52,53 . BSCs were engineered by Sleeping Beauty transgenesis to express 3,5,7-trioxododecanoyl-CoA synthase (OLS), olivetolic acid cyclase (OAC), annabigerolic acid synthase (CPGAS), cannabidiolic acid synthase (CBDAS), and GFP (plasmid name pCBD) to convert Malonyl-CoA to CBD 54 . Cells showed successful gene expression ( FIG. 14D ). 
     3D intestinal disease model—This model is formed by casting silk fibroin protein in a polydimethylsiloxane (PDMS) mold around a central wire that serves to generate a geometrically engineered hollow lumen, and subsequently and inducing β-sheet formation ( FIGS. 15A-15B ). We have shown that these scaffolds, when seeded with human intestinal cells (e.g., organoids), show robust cell development, including the generation of microvilli, expression of intestinal cell markers, and production of mucous layers ( FIGS. 15C, 15D , &amp;  15 I). When additionally seeded with macrophages and treated with  E. coli  O111:B4 lipopolysaccharide (LPS) and interferon γ (IFNγ), cultures are capable of modeling intestinal inflammation, showing increased secretion of pro-inflammatory cytokines that are associated with IBD (i.e., CXCL10, IL-1β, IL-6, MCP-2, and MIP-1β) 55 . When inoculated with oocytes of  Cryptosporidium parvum , an apicomplexan parasite that infects the intestine, 3D models showed the ability to support infection for over two weeks. Further, parasites showed physiological development, progression, and pathological effects in vitro, demonstrating the ability of this system to accurately recapitulated intestinal infection 56 . Ultimately, our preliminary data supports the use of this model to test a range of drug activities in vitro, towards both inflammatory and infectious diseases. In this, the use of human cells makes the model particularly relevant for this proof-of-principle look at edible therapeutics. 
     Drug production and optimization in mammalian cells—Because the bioavailability of drugs can vary significantly with the composition of the surrounding food matrix, and because there are substantial compositional changes to muscle cells during differentiation, drug delivery with both undifferentiated and differentiated muscle tissue will be explored 58 . Specifically, we explore drug production in undifferentiated bovine satellite cells (BSCs) and BSCs that have been differentiated into multinucleated myotubes ( FIG. 13A ). A non-viral transposon-mediated gene editing technique will be used due to its non-viral nature, high efficiencies, and demonstrated utility in prior work 59,60    
     Drug Production in Mammalian Cells 
     Bovine satellite cell isolation and culture—Bovine satellite cells (BSCs) will be isolated from the Tufts Cummings School of Veterinary medicine using protocols approved by the Tufts University Institutional Animal Care and Use Committee (IACUC Protocol #G2018-36), and reported by our lab 43 . Briefly, a ˜0.5 cm 3  muscle excision will be taken from the semitendinosus of a &lt;60-day-old Simmental bull and transported to a tissue culture lab in DMEM+Glutamax with 1× penicillin/streptomycin. Tissue will be minced and digested in an 0.2% collagenase II solution for one hour with regular trituration. Digestion will be halted with growth media comprised of DMEM Glutamax supplemented with 20% fetal bovine serum (FBS), 1% primocin, and 1 ng/mL human FGF-2, and cells will be filtered and plated at a density of 100,000 cells/cm 2  onto uncoated tissue-culture flasks. After 24 hours of incubation at 37° C. with 5% CO 2 , unattached cells (which comprise the slowly-adherent satellite cells) will be moved to new tissue culture flasks that have been coated with 0.375 ug/cm 2  of recombinant laminin-511. Satellite cells will be left undisturbed for three days, after which cells will be fed with growth media every 2-3 days and passaged at 70% confluency. Media will be supplemented with primocin only for the first two weeks of culture. Due to the importance of using serum-free media in cultured meat production, experiments will take place in serum-free growth medium using a previously reported medium (B8) comprised of DMEM:F12 (1:1) supplemented with L-ascorbic acid 2-phosphate (200 ug/mL), insulin (20 ug/mL), transferrin (20 ug/mL), sodium selenite (20 ng/mL), FGF-2 (10 ng/mL), neuregulin 1 (NRG-1; 0.1 ng/mL), and TGFβ-3 (0.1 ng/uL) ( FIGS. 13A-13E ) 44 . To verify cell identity, immunocytochemistry will be performed for satellite cell markers. Cells will be fixed using 4% paraformaldehyde, permeabilized using a Triton-X solution, blocked, and stained for paired-box 7 (Pax7). Positive staining for these markers will be considered determinative of BSC phenotype as previously reported, and as visible in  FIG. 2   43 . 
     Myogenic differentiation—To differentiate satellite cells into myotubes (under serum-free conditions), cells will be cultured to confluency in B8, and media will be changed to a previously reported differentiation media comprised of a Neurobasal/L15 (1:1) basal media supplemented with epidermal growth factor (EGF; 0.5 ng/mL), insulin-like growth factor 1 (IGF-1; 0.05 ng/mL), and 1% Antibiotic-Antimycotic 61 . Cells will be differentiated for 1-2 weeks, fixed as before and stained for Myosin Heavy Chain (MHC) as previously demonstrated ( FIG. 2 ) 43 . 
     Genetic modification techniques—Molecular cloning will be carried out using standard techniques. For genetic insertions, transposable elements will contain both the genes of interest (controlled by a CMV promoter) and the genes for resistance to selection antibiotics (puromycin) to enable the selection of successfully transfected cells. Additionally, to simplify future engineering efforts, the puromycin resistance cassette will be engineered to be preceded by a flip-recombinase target (FRT) sequence to allow for future gene insertion through recombinase-mediated cassette exchange (RMCE) 62,63 . Cellular transfection will be performed using the Lipofectamine 3000 reagent (Thermo Fisher). Briefly, cells will be cultured to 85% confluence, washed with OptiMEM media, and incubated with transfection reagents containing purified plasmids. After 6 hours, growth media will be added to cells and following 42 hours a selection pressure will be added to the media (e.g., puromycin). Cells will be cultured for one week under selective pressure, after which expression will be verified through immunocytochemistry, the use of fluorescent tags, or polymerase chain reaction (PCR). When multi-cistronic expression is needed, genes will be linked by 2A peptide sequences to allow for the translation of multiple proteins from a single strand of RNA which codes for multiple genes 64 . In most cases, a 2A sequence will link green fluorescent protein (GFP) to the expression cassette, so that expression can be screened for through simple fluorescence microscopy. Throughout these studies, cell health and myogenic potential will be verified by observing proliferation and differentiation of cells. 
     V565 production and activity—The V565 amino acid sequence (DVQLVESGGGLVQPGGSLKLSCAASGFDFSSHWMYWVRQAPGKELEWLSEINTNGLIT HYGDSVKGRFTVSRNNAANKMYLELTRLEPEDTALYYCARNQHGLNKGQGTQVTVSS; SEQ ID NO:7) 3,65  will be codon optimized for bovine expression, modified with a 6×His-tag sequence for quantification, and cloned into a multi-cistronic expression vector for V565 and GFP as described above. Cells will be transfected, selected, and gene expression will be verified by fluorescence imaging. Cells will be cultured, harvested (10 million cells, as proliferative BSCs or differentiated myotubes), and V565 production will be quantified with a competitive His-tag ELISA on cell lysates. As an orthogonal measure of gene expression, GFP will be quantified from cell lysates with a GFP quantification kit (abcam #ab235672). That 2A sequences allow for stoichiometric expression of multiple proteins should allow for GFP quantification to act as an accurate proxy for V565 levels 66 . Readings will be normalized to a standard curve, cell count, and cellular protein content (determined by Bradford assay). 
     To analyze V565 in an edible format, cells will be harvested (10 million cells) and either kept “raw” or “cooked” by heating cell pellets to 100° C. for 1-10 minutes. Samples will be lysed using a standard cell lysis buffer, or through in vitro digestion based on previously reported methods 67,68 . Briefly, samples will be added to a saline solution containing 140 mM NaCl, 5 mM KCl, and 150 uM butylated hydroxytoluene. To simulate gastric digestion, HCl will be added to a final pH of 2.0, samples will be mixed 36:1 with a solution of 4% w/v of pepsin in 0.1 M HCl, and samples will be incubated in a shaking water bath at 37° C. for one hour. The pH of the digesta will be raised to 6.9 with NaHCO 3 , and further intestinal digestion will be performed by mixing samples 7.4:1 with a pancreatin-bile solution (1.2% w/v of bile extract and 0.2% of pancreatin with 550 U/mL trypsin and 3.3 U/mL chymotrypsin in 0.1 M NaHCO 3 ) and incubating samples in a shaking water bath at 37° C. for two hours. Following in vitro digestion, samples will be analyzed by His-tag quantification and by competitive ELISA to determine binding activity as previously described 69 . Briefly, plates will be coated with TNFα, washed, blocked, and treated with digesta. An Anti-His secondary antibody and horseradish peroxidase (HRP) conjugated tertiary antibody will be added, followed by treatment with 3,3′,5,5′ tetramethyl benzidine (TMB). Absorbance at 450 nm will be used to quantify binding. Results will be compared between cooked, uncooked, digested and undigested samples. 
     AMP16 production and activity—the AMP16 peptide amino acid sequence (IRPI IRPI IRPI IRPI IRPI IRPI IRPI; SEQ ID NO:8) 4  will be codon optimized for bovine expression and cloned into two multi-cistronic expression vectors for AMP16 and GFP and either with or without a 6×His-tag included. Cells will be transfected, selected, and gene expression will be verified by fluorescence imaging. As with V565, cells will be cultured, differentiated into muscle and fat, harvested (10 million cells), and both His-tag quantification and GFP quantification will be used to analyze expression levels. The use of both methods will allow for quantification of non-tagged peptides, as the 6×His-tag could ultimately confound peptide activity. As with other drugs, readings will be normalized to a standard curve, cell count, and cellular protein content. 
     To analyze AMP16 antimicrobial activity in an edible format, cells will be harvested (10 million cells), treated, and “digested” as with V565 cells. Following in vitro digestion, paper discs will be soaked in digesta and placed on agar plates previously inoculated with  S. enterica  and cultured at 37° C. After 1-24 hours of incubation, zones-of-inhibition will be measured and compared between samples. 
     It has been previously shown that while V565 is largely stable in the gastric environment, it is sensitive to pepsin 3 . Similarly, degradation of small peptide therapeutics in gastric fluid has been shown to be largely pepsin-dependent 70 . As such, both V565 and AMP16 delivery could be dramatically improved by inhibition of pepsin activity during digestion. 
     Enhancing drug yields—Drug yields in cells will be enhanced by increasing gene expression and increasing drug precursor levels in culture. To increase gene expression, cells will be cultured in increasing levels of the selection antibiotic puromycin in order to select for cells whose transgenes have inserted in more transcriptionally active loci. Our previous work with carotenoids has shown that this can increase gene expression (as shown by GFP expression) ˜two-fold, and subsequent carotenoid levels ˜3-fold ( FIG. 14B ). To increase drug precursor levels for V565 and AMP16, culture media will be supplemented with the most prevalent amino acids in these two drugs, as amino acid depletion is a potential bottleneck in therapeutic protein production 71 . Specifically, glycine, leucine, and serine are the three most common amino acids in V565 (representing over 30% of the total sequence), and so media will be supplemented with additional G, L, and S (100-200% of standard media levels). For AMP16, isoleucine arginine, and proline together represent 100% of the total sequence, and so media will be supplemented with these amino acids (100-200% of standard media levels). Drug yields will be analyzed as before. 
     Reducing gastric degradation—Pepsin inhibition will be engineered into cells via the production of serpins as previously described and engineered using the Flp-In system (ThermoFisher) 72 . Briefly, the serpin Tsp03044 sequence (Genbank accession #XM_003379333) will be codon optimized and cloned into the pcDNA5/FRT plasmid (ThermoFisher). This plasmid and the pOG44 plasmid (ThermoFisher) coding the Flp recombinase will be doubly transfected into engineered cells expressing V565 or AMP16. Flp-mediated RMCE will facilitate the insertion of Tsp03044 and a hygromycin resistance gene (from the pcDNA5/FRT plasmid) into V565 and AMP16-producing cells, and so treatment of cells with puromycin and hygromycin will ensure the production of V565 or AMP16 as well as Tsp03044. Tsp03044 expression will be verified by RT-PCR. Serpin efficacy in maintaining drug activity will be analyzed by in vitro digestion and activity analyses as described previously. Results will be compared to undigested cell lysates and cell lysates treated with pepsin only. 
     Alternative IBD-targeting drugs could also be expressed in mammalian cells, including the peptide PTG-200 73  or the Microbial Anti-inflammatory Molecule (MAM) or it&#39;s constitutive peptides, which have been shown to offer anti-inflammatory activity in a murine colitis model 74 . Alternate antibiotics could include other small-peptide antibiotics or small-molecule antibiotics such as penicillin 75 . Additionally, small molecule therapeutics could be explored, including cannabidiol or anti-inflammatory compounds such as curcumin or the immunosuppressant FK506 53,76,77 . If puromycin conditioning proves ineffective in increasing drug yields, protein copy-number can be increased by engineering plasmids to contain multiple copies drug sequences, either in a multi-cistronic format that is separated by 2A sequences, or with distinct promoters for each copy. If protein stability is insufficient following serpin synthesis, cells can be encapsulated in alginate or chitosan scaffolds—a promising scaffold for cultured meat production—to slow enzymatic degradation 13,78 . Lastly, alternate cell types can be considered, such as transdifferentiated bovine fat cells, immortalized bovine muscle cells, or immortalized mouse muscle cells (C2C12s). 
     Engineering disease-responsive drug formulations—Numerous pathologies result in changes in the gut enzymatic profile. Specifically, fecal profiling has shown a &gt;5-fold increase in trypsin-like proteases in patients with IBD compared with healthy patients, and  S. enterica  infection has been shown to raise elastase levels ˜2-fold 5,6 . In light of this, protease-triggered drug release/activity could tailor drugs to enable disease-responsive activity in edible therapeutics. Disease-responsiveness will be engineered into V565 and AMP16 systems for IBD and  S. enterica  infection, respectively. 
     Engineering IBD-response for V565—Disease response to IBD will leverage a previously reported epitope-masking strategy 7 . Specifically, V565 will be synthesized linked to fragments of its target antigen—TNFα—in order to mask V565&#39;s ability to TNFα in tissue. The linker used will be susceptible to trypsin cleavage, so when this construct is exposed to a trypsin-rich intestinal environment (as is seen in IBD), the antigen will be released and V565 will be free to bind to tissue TNFα. To engineer these systems, the human TNFα sequence will be codon optimized for bovine expression and appended to the V565 sequence along with a flexible linker (GGG SGG GSG GGS GGK GGK GGK GGK GGG SGG GSG AQG; SEQ ID NO:9) with numerous lysine residues to facilitate trypsin cleavage. Cloned sequences will be engineered into cells as before (including RMCE-mediated serpin integration). To analyze drug response to trypsin, cells will be cultured, harvested (10 million cells, pre- or post-differentiation), heated or left unheated, lysed, and treated with a range of trypsin concentrations. Drug activity will be analyzed via competitive ELISA as before. At the same time, cells will undergo harvesting, cooking, and in vitro digestion in varying levels of trypsin, and activity will be assessed. 
     Engineering  Salmonella -response for AMP16—Response to  S. enterica  infection will likewise leverage variable enzyme levels in disease. Specifically,  S. enterica  infection has been shown to be associated with increases in intestinal elastase. As such, the elastase-cleavage linker NPV will be engineered into AMP16 peptide sequences 8 . Specifically, a 10× repeat of AMP16 with NPV sequences between each 28-mer peptide will be assembled and cloned into plasmids. Cells will be transfected, modified via RMCE to include Tsp03044, cultured, harvested (10 million cells, pre- or post-differentiation), heated or left unheated, and lysed as before. Cell lysates will be treated with varying levels of elastase, and drug activity will be analyzed by zone-of-inhibition analysis as before. At the same time, cells will undergo harvesting, cooking, and in vitro digestion in varying levels of elastase, and drug activity will be assessed. 
     Combining drugs into one disease-responsive system—To engineer a truly “smart” system that is capable of addressing numerous pathologies in a disease-responsive manner, we will combine the above components into a single cell line. Specifically, V565-epitope, 10×AMP16, and GFP will be linked by 2A sequences to form a single multi-cistronic fragment. This fragment will be cloned into a Sleeping Beauty transposon vector as before and transfected into cells. Cells will undergo transfection and RMCE to generate a single cell line containing all of the previously described disease-responsive drug components. Cells will be cultured, harvested (10 million cells, pre- or post-differentiation), heated or left unheated, and treated via in vitro digestion under a range of trypsin and/or elastase concentrations in order to represent patients with IBD,  S. enterica  infection, both, and neither. V565 and AMP16 drug activity will be analyzed as before. 
     Alternatively, copies of V565 together with trypsin-cleavable linkers can be explored as a means of masking the binding domain of these nanobodies. Alternately, if linking of AMP16 peptides proves ineffective in imparting disease-responsiveness during  S. enterica  infection, the use of antimicrobial nanobodies with activity towards  E. coli  infection can be explored, with enzyme-cleavable epitope masking similar to what is being explored for V565 79 . Additionally, alternate enzyme-cleavable linkers or environmental cues (such as changes in pH) can be leveraged to engineer disease-response 3,80-83 . If synthesis of both drug systems in a single cell proves challenging, then two populations of single-drug-system cells can be developed and later combined into a multi-drug food. 
     Assessing drug bioactivity in vitro—Functional in vitro 3D human intestinal models are a promising option for early validation of edible drug formulations due to their use of human cells and ability to recapitulate relevant tissue features and geometries 84 . To this end, a 3D intestinal tissue model was previously developed by our group ( FIGS. 15A-15L ). This model will be applied to assess the efficacy of engineered therapeutic foods in vitro. 
     Cells—Human colonoids previously isolated and cultured by our group will be cultured in matrigel droplets and appropriate medium as previously described 55 . Human monocytes previously isolated and cultured by our group will be cultured in appropriate medium as previously described 55 . Monocytes will be differentiated into macrophages by treatment with 50 ng/mL macrophage colony-stimulating factor; for M1 polarization, macrophages will subsequently be cultured in media supplemented with lipopolysaccharides (LPS) and interferon interferon γ (IFNγ). 
     3D model IBD—The intestinal models will be fabricated and seeded with human cells as previously described 55 . Briefly, a solution of silk fibroin extracted from  Bombyx mori  silkworm cocoons will be poured into a cylindrical mold of PDMS containing a 2 mm diameter Teflon-coated steel wire that has been inserted through the cross section of the mold to form a channel. The solution will be frozen, lyophilized, and autoclaved to induce β-sheet formation. Scaffolds will be soaked in water and cut into 8 mm sections. Biopsy punches will be used to cut out “inner scaffolds” (length 8 mm, outer diameter 6 mm, inner lumen 2 mm) and “outer scaffolds” (length 8 mm, outer diameter 10 mm, inner diameter 6 mm). To seed scaffolds, human colonoids will first be seeded into the 2 mm lumen following previously reported methods 55 . Briefly, silk scaffolds will be coated with collagen gel, human colonoids will be dissociated in trypsin-EDTA, and cell suspensions will be pipetted to equally coat the inner lumen of the inner scaffolds. These scaffolds will be cultured for one week in appropriate media as previously reported. Next, monocytes will be suspended in collagen gel and seeded throughout the bulk of the outer scaffold. Monocytes will be differentiated to uncommitted macrophages by six days of appropriate medium as previously reported 55 . Outer scaffolds will then be cultured in macrophage media with LPS and IFNγ to induce polarization. Cell-seeded outer scaffolds will be combined with cell-seeded inner scaffolds to form complete IBD models. Models will be verified through immunofluorescence, cytokine analysis, and mucus thickness measurements as previously described before use in testing therapeutic food efficacy 55 . 
     3D model of  Salmonella  infection—Scaffolds will be prepared and seeded as before, though without LPS or IFNγ treatment. Models will be validated through immunofluorescence to ensure accurate intestinal recapitulation, and to obtain an understanding of the number of cells on the inner lumen. With this information, inner lumens of scaffolds will be infected by inoculating with  S. enterica  at a multiplicity of infection of 10-100, and dosing will be adjusted pending epithelial cell responses in culture for up to one week 85 . 
     Drug delivery to disease models—Drug delivery in all formats will be explored in 3D models, including pure compounds, cell-encapsulated therapeutics without disease-responsiveness and with or without excipients, and cell-encapsulated therapeutics with disease responsiveness and excipients (either separately or in cells engineered with all drug components). Cells will be cultured, harvested (10 million cells, pre- or post-differentiation), and heated or not heated as before. Samples will be lysed or undergo in vitro digestion with a range of trypsin and/or elastase concentrations. Culture media will be removed from scaffolds and replaced with digesta for 2, 3, or 4 hours to capture a range of feasible intestinal residence times, after which digesta will be removed and replaced with cell culture media. One hour, two-hours, six-hours, and 24-hours after treatment, scaffolds will be analyzed for drug efficacy. 
     Analyzing drug effect—The effect of drugs on IBD will be analyzed by profiling inflammatory cytokines in treated and untreated scaffolds. Specifically, interleukins 1β and 6 (IL-1β &amp; IL-6), monocyte chemoattractant proteins 1 and 2 (MCP-1 &amp; MCP-2), and macrophage inflammatory protein 1β (MIP-1(3/CCL4) will be measured by commercial chemiluminescence arrays. Additionally, epithelial integrity will be analyzed by immunohistochemistry towards mucin-2, CD68, and ZO-1. The effect of drugs on  S. enterica  infection will be analyzed by homogenizing scaffolds in lysis solution containing Triton-X, serially diluting homogenates, and determining colony-forming units of  S. enterica  by plating onto LB Agar culture plates 86 . Results will be compared between all drug types, samples, and conditions. 
     If 3D disease models prove inappropriate for use in this study, 2D studies can be performed with Caco-2 intestinal cells and Transwell systems. If single dosing proves ineffective for generating a response, dosing with larger cell harvests, or repeat dosing with edible therapeutics can be performed (i.e., two to three times per day at “meal times” for one week). Finally, if in vitro models prove ineffective, ex vivo analysis can be performed using biopsies obtained during routine endoscopies of consenting IBD patients. Specifically, biopsies can be cultured ex vivo, treated with in vitro digests of therapeutic food samples, and analyzed for markers of inflammation and drug activity as previously reported 3,87 . Lastly, in vivo animal models can be considered. 
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         86. Aabo, S., Christensen, J. P., Chadfield, M. S., Carstensen, B., Olsen, J. E. &amp; Bisgaard, M. Quantitative comparison of intestinal invasion of zoonotic serotypes of  Salmonella enterica  in poultry.  Avian Pathology  31, 41-47 (2002). 
         87. de Filippis, D., Esposito, G., Cirillo, C., Cipriano, M., de Winter, B. Y., Scuderi, C., Sarnelli, G., Cuomo, R., Steardo, L., de Man, J. G. &amp; Iuvone, T. Cannabidiol reduces intestinal inflammation through the control of neuroimmune axis.  PLoS ONE  6, (2011). 
         88. Ruiz de Huidobro, F., Miguel, E., Onega, E. &amp; Blázquez, B. Changes in meat quality characteristics of bovine meat during the first 6 days post mortem.  Meat Science  65, 1439-1446 (2003). 
         89. Seideman, S. C. &amp; Crouse, J. D. The effects of sex condition, genotype and diet on bovine muscle fiber characteristics.  Meat Science  17, 55-72 (1986). 
       
    
     Example 4 
     The embodiments described herein demonstrate 
     Preliminary Data—To date, our group has explored several topics with direct relevance to this proposal. From a culture system standpoint, we have adapted invertebrate muscle cells to serum-free growth for use in cultured meat, and established protocols for generating populations of primary bovine satellite cells (BSCs) that are highly myogenic ( FIG. 16A-16B ) 22,23 . We have further validated a serum-free, growth-factor based media formulation (B8) for BSC culture based on previously reported formulations ( FIG. 16A ) 24 . With this formulation, we have observed superior BSC growth compared to serum-containing media and shown that growth is dependent on fibroblast growth-factor 2 (FGF-2) in a concentration-dependent manner ( FIG. 16B ). 
     Additionally, we have established an adipogenic transdifferentiation method to convert myogenic BSCs into lipid-accumulating fat cells by treating cells with a free fatty acid (FFA) mixture ( FIG. 17A ). We have shown robust lipid accumulation using this method, indicating that a single cell population (i.e., satellite cells) could be used to generate both muscle and fat for cultured meat, which could significantly simplify an industrial production process ( FIG. 17B ) 25 . 
     From a nutrition standpoint, we have genetically engineered BSCs to endogenously synthesize the carotenoids phytoene, lycopene, and β-carotene, and shown resulting reductions in lipid oxidation (a key mechanistic driver linking red meat consumption and colorectal cancer;  FIG. 3 ) 19,26 . 
     Finally, from a quality standpoint, we have shown that exogenous heme proteins in culture media can improve the color similarity of cultured meat compared to conventional beef (Table 2) 23 . 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Color analysis of 3D BSC tissue cultures cultured with or without 
               
               
                 the addition of 3 mg/mL hemoglobin (Hb) or myoglobin (Mb). 
               
               
                 Data for L* (lightness), a* (red/green spectra) and b* (blue/yellow 
               
               
                 spectra) are used to generate a ΔE, a measure of color similarity 
               
               
                 to fresh or cooked beef. Low ΔE indicates more similarity. 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Beef 
                 BSC 
                 BSC + Hb 
                 BSC + Mb 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 Fresh 
                 Cooked 
                 Day 1 
                 Day 9 
                 Day 1 
                 Day 9 
                 Day 1 
                 Day 9 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 L* 
                 45.9 ± 3.2 
                 44.5 ± 0.9 
                 76.4 ± 1.5 
                 66.3 ± 3.7 
                 60.9 ± 1.1 
                 47.5 ± 1.7 
                 64.5 ± 1.5 
                 42.8 ± 4.1 
               
               
                 a* 
                 37.2 ± 0.6 
                 12.9 ± 0.9 
                  3.5 ± 0.9 
                 20.8 ± 3.3 
                 11.4 ± 1.0 
                 20.9 ± 0.9 
                  8.1 ± 0.7 
                 15.6 ± 1.0 
               
               
                 b* 
                 37.7 ± 0.8 
                 33.7 ± 0.7 
                 32.7 ± 0.9 
                 26.8 ± 0.7 
                 42.3 ± 0.6 
                 36.1 ± 0.4 
                 43.1 ± 1.3 
                 31.7 ± 1.4 
               
               
                 ΔE 
                   
                   
                 45.7 ± 1.5 
                 28.4 ± 4.2 
                 30.1 ± 1.1 
                 16.4 ± 0.9 
                 34.9 ± 1.1 
                 23.0 ± 1.3 
               
               
                 (fresh) 3   
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 ΔE 
                   
                   
                 33.3 ± 1.6 
                 24.5 ± 2.4 
                 18.6 ± 0.8 
                  9.0 ± 0.9 
                 22.6 ± 1.2 
                  5.4 ± 2.1 
               
               
                 (cooked) 
               
               
                   
               
            
           
         
       
     
     Methods 
     Cell Culture 
     Bovine satellite cells—Bovine satellite cells (BSCs) will be isolated from the Tufts Cummings School of Veterinary medicine using protocols approved by the Tufts University Institutional Animal Care and Use Committee (IACUC Protocol #G2018-36), and reported by our lab 23 . Briefly, a ˜0.5 cm 3  muscle excision will be taken from the semitendinosus of a &lt;60-day-old Simmental bull and transported to a tissue culture lab in DMEM+Glutamax with 1× penicillin/streptomycin. Tissue will be minced and digested in an 0.2% collagenase II solution for one hour with regular trituration. Digestion will be halted with growth media comprised of DMEM Glutamax supplemented with 20% fetal bovine serum (FBS), 1% primocin, and 1 ng/mL human FGF-2, and cells will be filtered and plated at a density of 100,000 cells/cm 2  onto uncoated tissue-culture flasks. After 24 hours of incubation at 37° C. with 5% CO 2 , unattached cells (which comprise the slowly-adherent satellite cells) will be moved to new tissue culture flasks that have been coated with 0.375 ug/cm 2  of recombinant laminin-511. Satellite cells will be left undisturbed for three days, after which cells will be fed with growth media every 2-3 days and passaged at 70% confluency. Media will be supplemented with primocin only for the first two weeks of culture. 
     To verify cell identity, immunocytochemistry will be performed for satellite cell markers. Cells will be fixed using 4% paraformaldehyde, permeabilized using a Triton-X solution, blocked, and stained for paired-box 7 (Pax7). Positive staining for these markers will be considered determinative of BSC phenotype as previously reported, and as visible in  FIG. 1   23 . 
     Myogenic differentiation—To differentiate satellite cells into mature myotubes (under serum-containing conditions), cells will be cultured to confluency, and media will be changed to differentiation media comprised of DMEM Glutamax supplemented with 2% FBS and 1% Antibiotic-Antimycotic. To differentiate satellite cells under serum-free conditions, a previously reported differentiation media comprised of a Neurobasal/L15 (1:1) basal media supplemented with epidermal growth factor (EGF; 0.5 ng/mL), insulin-like growth factor 1 (IGF-1; 0.05 ng/mL), and 1% Antibiotic-Antimycotic 54 . Cells will be differentiated for 1-2 weeks, fixed as before and stained for Myosin Heavy Chain (MHC) as previously reported, and as visible in  FIGS. 16A-16B   23 . 
     Adipogenic transdifferentiation—While satellite cells are preferentially myogenic, we have successfully induced lipid accumulation using a differentiation media containing a combination of free fatty acids (FFAs) ( FIGS. 17A-17B ). Specifically, a 3-FFA cocktail of linoleic acid, erucic acid, and elaidic acid at equal concentrations of 125 uM induced robust accumulation of intracellular lipids over six days. This adipogenic transdifferentiation protocol will be further optimized through a fractional factorial experimental design, testing various concentrations oleic, myristoleic, linoleic, erucic, and elaidic acid. Lipid accumulation will be verified qualitatively with Oil Red O staining and quantified with the AdipoRed plate reader assay (Lonza). Transdifferentiation of satellite cells into mature adipocytes will enable muscle and fat components of cultured meat to be generated from a single cell source throughout this proposal, thus increasing project efficiency and impact. 
     Serum Free Media 
     Media formulation for serum replacement—Growth factor-dependent serum-free media (B8) will be generated based on previously reported formulations and as successfully demonstrated for by our group (preliminary data;  FIGS. 16A-16B ) 24 . Briefly, B8 media will be comprised of DMEM:F12 (1:1) supplemented with L-ascorbic acid 2-phosphate (200 ug/mL), insulin (20 ug/mL), transferrin (20 ug/mL), sodium selenite (20 ng/mL), FGF-2 (10 ng/mL), neuregulin 1 (NRG-1; 0.1 ng/mL), TGFβ-3 (0.1 ng/uL), and insulin-like growth factor 1 (IGF-1; 10 ng/mL). Formulations absent one or more growth factors will simultaneously generated, as will formulations lacking all growth factors but containing previously reported serum-replacements made from rapeseed peptide fractions, maitake mushroom extract, and silk-derived sericin proteins. 
     Media containing rapeseed peptide fractions will be generated as previously described 41 . Briefly, rapeseed protein concentrates will be hydrolyzed with Alcalase 2.4 L (Novozymes) for five hours at 60° C. and a pH of 9.0. Fractions will be precipitated at a pH of 4.0 and centrifuged. The supernatant will undergo ultrafiltration through 3 kDa membrane and nanofiltration through a 0.5 kDa membrane. The nanofiltration retentate will again undergo ultrafiltration (1 kDa) and the retentate of this final filtration step will be added to growth-factor free basal media at a concentration of 10 mg/mL. Media containing maitake mushroom extracts will be generated as previously described 55 . Briefly, dried Maitake mushrooms will be blended in growth-factor free basal media at a concentration of 0.2% w/v and sterilized through an 0.2 μm filter. Finally, media containing sericin will be generated by diluting purified sericin—which can be obtained either from silk (i.e., as a byproduct of the textile industry) or through recombinant production—in growth-factor free basal media at a concentration of 30 ug/mL. 
     Formulations of varying concentrations and combinations of growth factors and serum-replacements will be generated by combining media. BSCs will be cultured as previously described in these media formulations. 
     Bioprocess kinetics—To understand how media formulations affect bioprocess growth kinetics, cellular growth curves will be generated using dsDNA-based fluorometric assays of engineered and primary BSCs cultured in serum control media and media with serum and antibiotic alternatives. To understand the effect of these culture systems on mitotic activity, cell cycle analysis will simultaneously be performed on an NC-3000 image cytometer (ChemoMetec). To probe cellular senescence in engineered cells, quantitative PCR will be performed for Pax7—a marker of BSC stemness—throughout culture of control cells, and cells treated with serum and antibiotic alternatives 59 . Based on preliminary data with B8, we expect to achieve cell growth that is similar to or better than with serum-containing media. 
     In combination with the mentioned cellular analyses, bioprocess kinetics will be tested throughout culture by analyzing media for nutrient uptake and byproduct accumulation. Specifically, glucose consumption, glutamine consumption, lactate production and ammonia production will be analyzed throughout culture using enzymatic assay kits for all media formulations and all cell types 60 . 
     Cell differentiation analysis—To understand the effects of media composition on cellular differentiation, cells cultured in all media formulations will be differentiated as before (both myogenic and adipogenic) and analyzed for relevant markers. For myogenic differentiation, myogenin and myosin heavy chain (MHC) expression will be assessed with immunostaining and quantitative PCR (qPCR), and myotube formation will be analyzed by determining fusion index, or the percentage of nuclei within fused myotubes 63 . For adipogenic differentiation, peroxisome proliferator-activated receptor gamma (PPARγ) expression will be analyzed via immunostaining and qPCR, and lipid accumulation will be analyzed with Oil-O red staining, extraction and quantification 64 . We expect comparable differentiation capacity for cells cultured in serum-containing or serum-free media formulations. 
     Genetic modifications for serum replacement—To explore cost-effective serum-free media development that is orthogonal to the aforementioned serum alternatives, BSCs will be engineered to endogenously produce growth factors and growth factor receptors. These “self-signaling” cells would require media with fewer inputs, and so could lower the cost of culture further. Targets will correspond to B8. Specifically, cells will be engineered to produce the growth factors FGF-2, TGFβ-3, NRG-1 and IGF-1, as well as the signaling and transport proteins insulin and transferrin. 
     Constitutive gene expression will be achieved via Sleeping Beauty transposon-mediated gene insertion due to this systems non-viral nature, high efficiencies, and demonstrated utility in our preliminary work 56,57 . Molecular cloning will be carried out using standard techniques. For genetic insertions, transposable elements will contain both the genes of interest (e.g., FGF-2) and the genes for resistance to selection antibiotics (i.e., puromycin) to enable the selection of successfully transfected cells. Cellular transfection will be performed using the Lipofectamine 3000 reagent (Thermo Fisher, #L3000008). Briefly, cells will be cultured to 85% confluence, washed with OptiMEM media, and incubated with transfection reagents and purified plasmids. Following 4-6 hours, growth media will be added to cells, and following 48 hours a selection pressure will be added to the media (i.e., puromycin). Cells will be cultured for one week under selective pressure, after which expression will be verified through immunocytochemistry, the use of fluorescent tags, or polymerase chain reaction (PCR). When multicistronic expression is needed (i.e., for the simultaneous expression of all growth factors), genes will be linked by 2A peptide sequences, to allow for the translation of multiple proteins from a single strand of RNA which codes for multiple genes 58 . In most cases, a 2A sequence will link green fluorescent protein (GFP) to the expression cassette, so that expression can be screened for through simple fluorescence microscopy. Finally, transgenes will be inserted under the control inducible promoters that can be “turned off” for cellular differentiation to halt the expression of pro-proliferative factors. Successfully engineered cells will be cultured in various growth-factor-lacking media formulations described herein. 
     Antibiotic Free Media 
     Media formulation for antibiotic replacement—Cinnamon, monolaurin (a derivative of coconut lauric acid), and honey are natural compounds that have demonstrated potential utility as food-safe antimicrobials 46,65,66.  Each of these substances will be explored alone and in combination as media additives to protect against microbial contamination. They will first be added to B8 serum-free media with growth factors and used to culture BSCs. Dose response curves (DRCs) will be generated to determine the effects of each additive on cell health and identify the maximum concentrations that can be used without impeding growth, viability and differentiation. Following assessment of antimicrobial activity, successful candidates will be incorporated into the serum- and growth factor-free media described herein and again assessed for impacts on culture performance. 
     Analysis of antimicrobial effects in cell culture—Antimicrobial activity of media supplemented with cinnamon, monolaurin, and honey will be tested with agar well diffusion tests. Bacterial and yeast extracts will be spread over the entire surface of agar plates and a biopsy punch will be used to remove a 6 mm diameter cylinder of agar. 100 uL of media containing various concentrations of the antimicrobials will then be added into the well and the zone of inhibition will be measured after an 18 to 24-hour incubation period 69 . Efficacy of the alternative antimicrobials with be compared with the common cell-culture antimicrobials Penicillin-Streptomycin (Pen-Strep) and Antibiotic-Antimycotic (Anti-Anti). 
     Analysis of antimicrobial effects in cooked products—To further assess the efficacy of alternative antimicrobials and their utility in commercial production of cultured meat, we will test the ability of the target antimicrobials to inactivate and/or enhance thermal destruction of  Escherichia coli  in cell-based and conventional meat samples. Antimicrobials used as media additives (cinnamon, fatty acids, honey) will be tested. Additionally, cell-based samples comprised of engineered cells will be tested without the addition of exogenous compounds. All samples will be inoculated with a mixture of  E. coli  strains isolated from meat and dairy, treated with various concentrations of each antimicrobial where appropriate, then stored for 5 days at 4° C.  E. coli  O157:H7 content will be quantified by surface plating of homogenized samples and colony counting before and after cooking at multiple timepoints. 
     Analysis of cell growth and differentiation—The effects of each alternative antimicrobial on cell proliferation will be assessed (i.e., growth curve analysis with dsDNA-based fluorometric assays and nutrient/waste uptake/production analysis with enzymatic assays). Effects on myogenic and adipogenic differentiation will be assessed through immunostaining for myosin heavy chain (MHC) or Oil-O red staining, as well as qPCR for MHC and PPARγ. These analyses will be used to determine the concentrations of cinnamon, honey, and monolaurin that can be added to media without detrimental effects on performance. 
     Genetic modifications for antibiotic replacement—As a secondary strategy to the media additives described herein, metabolic engineering of the BSCs will be used to achieve constitutive endogenous production of food-safe compounds with antimicrobial activity. Specifically, the metabolic pathways for synthesis of cinnamaldehyde and limonene from common precursor molecules will be engineered into the BSCs using Sleeping Beauty transposon-mediated gene insertions as utilized in our prior work. Synthesis of cinnamaldehyde from the precursor phenylalanine will be achieved through insertion of a three-enzyme pathway: phenylalanine ammonia-lyase, 4-coumarate-CoA ligase, and cinnamoyl-CoA reductase. Synthesis of (+)-limonene from the precursor geranyl pyrophosphate will be accomplished through insertion of a single enzyme: (R)-limonene synthase. The concentrations of cinnamaldehyde and limonene secreted into the media will be assessed with high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GM-MS), respectively 67,68 . Cell health and development will be analyzed as previously described. 
     Food-Quality Analysis 
     Protein and amino acids—Engineered and primary cells will be harvested following culture in all media formulations, and both before and after myogenic and adipogenic differentiation. Bulk protein will be quantified using a Pierce BCA protein assay. Amino acid composition will be quantified by HPLC as previously described 70,71 . Briefly, cells will be homogenized via sonication, spiked with a known concentration of the internal standard norvaline, hydrolyzed with HCl, and quantified against amino acid standards (likewise spiked with norvaline) via HPLC following precolumn derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl-carbamate. Samples will be separated with a Nova-Pak C18 (Waters) column and analyzed with fluorescence detection excited by 250 nm and emitting at 395 nm. Both bulk protein and amino acid composition will be correlated to DNA content (CyQuant assay; Thermo Fisher) to compare undifferentiated and differentiated cells. Conventional meat samples will be analyzed and compared with cultured cells. 
     We expect bulk protein in bovine cells to be similar to that found in store-bought beef, though reduced extracellular protein accumulation may result in reduced protein levels. We expect amino acid profiles that are a combination of the amino acid profile of cellular growth media and the amino acid profile of store-bought products. 
     Fats and fatty acids—Lipid analysis will be performed using a liquid chromatograph-mass spectrometry (LC-MS) as previously describer. Briefly, undifferentiated and differentiated (myogenic and adipogenic) BSCs from all culture conditions will be homogenized via sonication, and lipid internal standards will be added to homogenates (comprised of phosphatidylcholines (PC), phosphatidylethanolamines (PE), ceramides (Cer), phosphatidylserines (PS), phosphatidic acid (PA), and mono-, di-, and triacylglycerols (MG, DG, and TG). Cellular lipids will be extracted with a solution of chloroform and methanol (2:1, v/v), centrifuged, and the lower phase will be collected and combined with external standards (comprised of isotopically labeled TGs and PCs). Samples will be quantified against lipid standards via LC-MS with separation in a BEH C18 column (Waters) followed by quadrupole-time-of-flight detection. Fatty acid profiles will be normalized using internal and external standards, and against DNA and protein quantification. Again, samples will be analyzed at varying levels of differentiation, and compared with store-bought products. Based on previous data comparing murine adipose tissue and murine adipose progenitor cells pre- and post-differentiation, we expect bovine lipid profiles to differ significantly from store-bought beef pre-differentiation, but converge post-differentiation 73 . 
     Cholesterol will be analyzed by fluorometric assay (Abcam, #ab65390) and compared with total lipid measured by fluorometric assay (Abcam, #ab242307). Samples will be analyzed at varying levels of differentiation, and again compared with store-bought products before and after cooking. Based on published data, we expect cholesterol to represent ˜1 mg/g of lipid for bovine fat cells 73 . 
     Micronutrients—Water- and fat-soluble vitamins (vitamin A, B 1 , B 2 , B 3 , B 5 , B 6 , B 9 , B 12 , E, K, D, E, C) will be analyzed using core services provided by the Nutrition Evaluation Laboratory (NEL) at the Jean Mayer USDA Human Nutrition Research Center on Aging (HNRCA) at Tufts university. Techniques will include HPLC, spectrophotometric measures of enzymatic activity, radioassays, or colorimetric assays, as appropriate and previously described and performed by the NEL 75,76 . Iron and zinc will be quantified by an Iron Assay Kit (Abcam, #ab83366) and Zinc Assay Kit (Abcam, #ab102507), respectively. Again, micronutrient results will be compared with results obtained from store-bought beef products. 
     While the bovine genome contains synthesis pathways for vitamins B3, D, and C, these functions primarily performed in the liver or skin, respectively, and tissue concentrations of niacin are typically hepatically controlled. 77,78 . We therefore expect vitamin compositions that are predominately defined by culture media. Likewise, as minerals are only obtainable exogenously, we expect zinc and iron to be similarly defined by culture media. This may not be true in the case of media supplementation by some plant extracts (such as bulk maitake mushroom extracts), as it is likely that these will contain some micronutrient components that will be incorporated by cells. 
     Myoglobin content—Myoglobin content will be analyzed using a modified Warriss method 82 . Pre- and post-differentiated BSCs and store-bought beef will be mechanically homogenized in PBS, centrifuged at 5,000×g for 30 minutes and filtered (Whatman No. 1 filter paper) to obtain extract. The extract will be oxidized with 60 mM K 3 F(III) (CN) 6  and subsequently treated with 80 mM NaCN to induce a color change from yellow to red. The absorbance will be measured at 540 nm and the cyanmetmyoglobin molar extinction coefficient (11300) will be used to determine myoglobin concentration. 
     We expect myoglobin content to be significantly lower in BSCs than in store-bought beef 23 . We expect myoglobin content to be higher post-differentiation 83 . The average myoglobin content in beef is 8 mg/g which correlates to a “cherry red” color. Values for lamb and pork are 6 mg/g (light red) and 2 mg/g (pink) respectively 84 . Strategies for regulating in vitro myoglobin content include induced hypoxia, lipid supplementation and direct exogenous myoglobin supplementation, and can be explored in the case of insufficient myoglobin content 23,85 . 
     Gelling properties—Thermal gelation properties will be assessed using actomyosin extraction followed by gel strength and dynamic rheological measurements. Actomyosin (the actin/myosin complex) will be extracted from pre- and post-differentiated bovine satellite cells and store-bought beef by modifying the Ogawa method 86 . Samples will be mechanically homogenized in cold isolation buffer (50 mM KCl, 20 mM K 2 HPO 4 /KH 2 PO 4 ) and filtered (0.9 mm mesh). The suspension will be centrifuged at 10,000×g for 5 minutes and the pellet will be homogenized in 0.6 M KCl buffer. After another round of centrifugation and filtration, the supernatant will be mixed with 20 mM potassium phosphate buffer and precipitate will be collected by centrifugation and re-suspension in isolation buffer. A final centrifugation step will deliver the actomyosin fragment; the concentration of which will be determined by the Biuret reaction. Gel strength will be determined by texture analysis. Actomyosin concentrations will be standardized and samples will be sealed in a beaker heated to 80° C. for 20 minutes before cooling and overnight refrigeration (4° C.). Gels will be acclimated to ambient temperature and evaluated with a penetration test (1 mm/s) on a Texture Analyzer. Actomyosin gels will also be evaluated by dynamic rheological analysis during heating from ambient temperature to 80° C. (1° C./min.) 87 . 
     Food-quality optimization—Depending on the results of nutritional and meat-quality analyses, culture systems will be adapted to address insufficiencies. For instance, in the case of nutritional deficiencies (e.g. inadequate essential amino acids), media will be supplemented with relevant nutrients in order to increase cellular concentrations. Additionally, metabolic engineering techniques—such as those used in our preliminary carotenoid work—can be utilized to increase nutrient levels through endogenous production (e.g., the incorporation of essential amino acid biosynthesis pathways). In cases where meat science metrics are insufficient in cultured samples compared with conventional meats, several techniques are possible for tuning cultured meat features. For instance, as previously mentioned, myoglobin content can be tuned through exogenous media supplementation or culturing cells under hypoxic conditions 44,85 . In cases where metabolite profiles differ significantly, key metabolic processes can be regulated through metabolic pathway engineering (as demonstrated by our group for nutritional engineering of BSCs) or by treatment with small-molecules 19,88,89 . Finally, in cases where gelling properties differ significantly from conventional meats, various mechanical cues (e.g., through 3D tissue constructs) can be employed to increase myofiber formation and myosin expression 90 . 
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     The present invention has been described in terms of one or more preferred embodiments, and it should be appreciated that many equivalents, alternatives, variations, and modifications, aside from those expressly stated, are possible and within the scope of the invention.