bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aerobic Growth on Nitroglycerin as the Sole Carbon, Nitrogen, and Energy Source by a Mixed Bacterial Culture
Authors: Accashian John V. , Vinopal Robert T. , Kim Byung-Joon , Smets Barth F. 
Published: December 2019

ABSTRACTNitroglycerin (glycerol trinitrate [GTN]), an explosive and vasodilatory compound, was metabolized by mixed microbial cultures from aeration tank sludge previously exposed to GTN. Aerobic enrichment cultures removed GTN rapidly in the absence of a supplemental carbon source. Complete denitration of GTN, provided as the sole C and N source, was observed in aerobic batch cultures and proceeded stepwise via the dinitrate and mononitrate isomers, with successive steps occurring at lower rates. The denitration of all glycerol nitrate esters was found to be concomitant, and 1,2-glycerol dinitrate (1,2-GDN) and 2-glycerol mononitrate (2-GMN) were the primary GDN and GMN isomers observed. Denitration of GTN resulted in release of primarily nitrite-N, indicating a reductive denitration mechanism. Biomass growth at the expense of GTN was verified by optical density and plate count measurements. The kinetics of GTN biotransformation were 10-fold faster than reported for complete GTN denitration under anaerobic conditions. A maximum specific growth rate of 0.048 ± 0.005 h−1(mean ± standard deviation) was estimated for the mixed culture at 25°C. Evidence of GTN toxicity was observed at GTN concentrations above 0.3 mM. To our knowledge, this is the first report of complete denitration of GTN used as a primary growth substrate by a bacterial culture under aerobic conditions.
Biodegradation of Atrazine byAgrobacterium radiobacterJ14a and Use of This Strain in Bioremediation of Contaminated Soil
Authors: Struthers J. K. , Jayachandran K. , Moorman T. B. 
Published: December 2019

ABSTRACTWe examined the ability of a soil bacterium,Agrobacterium radiobacterJ14a, to degrade the herbicide atrazine under a variety of cultural conditions, and we used this bacterium to increase the biodegradation of atrazine in soils from agricultural chemical distribution sites. J14a cells grown in nitrogen-free medium with citrate and sucrose as carbon sources mineralized 94% of 50 μg of [14C-U-ring]atrazine ml−1in 72 h with a concurrent increase in the population size from 7.9 × 105to 5.0 × 107cells ml−1. Under these conditions cells mineralized the [ethyl-14C]atrazine and incorporated approximately 30% of the14C into the J14a biomass. Cells grown in medium without additional carbon and nitrogen sources degraded atrazine, but the cell numbers did not increase. Metabolites produced by J14a during atrazine degradation include hydroxyatrazine, deethylatrazine, and deethyl-hydroxyatrazine. The addition of 105J14a cells g−1into soil with a low indigenous population of atrazine degraders treated with 50 and 200 μg of atrazine g−1soil resulted in two to five times higher mineralization than in the noninoculated soil. Sucrose addition did not result in significantly faster mineralization rates or shorten degradation lag times. However, J14a introduction (105cells g−1) into another soil with a larger indigenous atrazine-mineralizing population reduced the atrazine degradation lag times below those in noninoculated treatments but did not generally increase total atrazine mineralization.
Genotypic and Phenotypic Responses of a Riverine Microbial Community to Polycyclic Aromatic Hydrocarbon Contamination
Authors: Langworthy Donald E. , Stapleton Raymond D. , Sayler Gary S. , Findlay Robert H. 
Published: December 2019

ABSTRACT

The phenotypic and genotypic adaptation of a freshwater sedimentary microbial community to elevated (22 to 217 μg g [dry weight] of sediment
−1
) levels of polycyclic aromatic hydrocarbons (PAHs) was determined by using an integrated biomolecular approach. Central to the approach was the use of phospholipid fatty acid (PLFA) profiles to characterize the microbial community structure and nucleic acid analysis to quantify the frequency of degradative genes. The study site was the Little Scioto River, a highly impacted, channelized riverine system located in central Ohio. This study site is a unique lotic system, with all sampling stations having similar flow and sediment characteristics both upstream and downstream from the source of contamination. These characteristics allowed for the specific analysis of PAH impact on the microbial community. PAH concentrations in impacted sediments ranged from 22 to 217 μg g (dry weight) of sediment
−1
, while PAH concentrations in ambient sediments ranged from below detection levels to 1.5 μg g (dry weight) of sediment
−1
. Total microbial biomass measured by phospholipid phosphate (PLP) analysis ranged from 95 to 345 nmol of PLP g (dry weight) of sediment
−1
. Nucleic acid analysis showed the presence of PAH-degradative genes at all sites, although observed frequencies were typically higher at contaminated sites. Principal component analysis of PLFA profiles indicated that moderate to high PAH concentrations altered microbial community structure and that seasonal changes were comparable in magnitude to the effects of PAH pollution. These data indicate that this community responded to PAH contamination at both the phenotypic and the genotypic level.
Genetic Diversity of the Biofilm Covering
Montacuta ferruginosa
(Mollusca, Bivalvia) as Evaluated by Denaturing Gradient Gel Electrophoresis Analysis and Cloning of PCR-Amplified Gene Fragments Coding for 16S rRNA
Authors: Gillan David C. , Speksnijder Arjen G. C. L. , Zwart Gabriel , De Ridder Chantal 
Published: December 2019

ABSTRACT

The shell of the bivalve
Montacuta ferruginosa
, a symbiont living in the burrow of an echinoid, is covered with a rust-colored biofilm. This biofilm includes different morphotypes of bacteria that are encrusted with a mineral rich in ferric ion and phosphate. The aim of this research was to determine the genetic diversity and phylogenetic affiliation of the biofilm bacteria. Also, the possible roles of the microorganisms in the processes of mineral deposition within the biofilm, as well as their impact on the biology of the bivalve, were assessed by phenotypic inference. The genetic diversity was determined by denaturing gradient gel electrophoresis (DGGE) analysis of short (193-bp) 16S ribosomal DNA PCR products obtained with primers specific for the domain
Bacteria
. This analysis revealed a diverse consortium; 11 to 25 sequence types were detected depending on the method of DNA extraction used. Individual biofilms analyzed by using the same DNA extraction protocol did not produce identical DGGE profiles. However, different biofilms shared common bands, suggesting that similar bacteria can be found in different biofilms. The phylogenetic affiliations of the sequence types were determined by cloning and sequencing the 16S rRNA genes. Close relatives of the genera
Pseudoalteromonas
,
Colwellia
, and
Oceanospirillum
(members of the γ-
Proteobacteria
lineage), as well as
Flexibacter maritimus
(a member of the
Cytophaga-Flavobacter-Bacteroides
lineage), were found in the biofilms. We inferred from the results that some of the biofilm bacteria could play a role in the mineral formation processes.
Biofilms on Indwelling Urethral Catheters Produce Quorum-Sensing Signal Molecules In Situ and In Vitro
Authors: Stickler David J. , Morris Nicola S. , McLean Robert J. C. , Fuqua Clay 
Published: December 2019

ABSTRACT

Acylated homoserine lactones (AHLs) are chemical signals that mediate population density-dependent (quorum-sensing) gene expression in numerous gram-negative bacteria. In this study, gram-negative bacilli isolated from catheters were screened for AHL production by a cross-feeding assay utilizing an AHL-responsive
Agrobacterium tumefaciens
reporter strain. Positive reactions were obtained from 14 isolates of
Pseudomonas aeruginosa
; negative or weakly positive reactions were recorded for isolates of five other species.
P. aeruginosa
biofilms were then produced on catheters in a physical model of the bladder. Sections of colonized all-silicone catheters gave positive reactions for the quorum-sensing signal molecules as did sections that had been cleaned of biofilm and autoclaved. Control sections of unused catheters were negative in the tests. Sections from four of nine catheters that had been freshly removed from patients gave positive reactions for AHLs. Cleaned autoclaved sections of three of these catheters also gave strongly positive reactions for AHLs. These results demonstrate that AHLs are produced by biofilms as they develop on the catheters both in vitro in the model and in vivo in the patient’s bladder. They represent the first demonstration of AHL production by biofilms in a clinical setting.
Genetically Modified Ruminal Bacteria Protect Sheep from Fluoroacetate Poisoning
Authors: Gregg Keith , Hamdorf Brenton , Henderson Kerrin , Kopecny Jan , Wong Cheryl 
Published: December 2019

ABSTRACT

Four strains of
Butyrivibrio fibrisolvens
, transformed with a gene encoding fluoroacetate dehalogenase, maintained a combined population of 10
6
to 10
7
cells ml
−1
in the rumens of test sheep. Five inoculated sheep showed markedly reduced toxicological symptoms after fluoroacetate poisoning when behavioral, physiological, and histological effects were compared with those of five uninoculated control sheep.
Pseudomonassp. Strain 273, an Aerobic α,ω-DichloroalkaneDegrading Bacterium
Authors: Wischnak Catrin , Löffler Frank E. , Li Jieran , Urbance John W. , Müller Rudolf 
Published: December 2019

ABSTRACTA gram-negative, aerobic bacterium was isolated from soil; this bacterium grew in 50% (vol/vol) suspensions of 1,10-dichlorodecane (1,10-DCD) as the sole source of carbon and energy. Phenotypic and small-subunit ribosomal RNA characterizations identified the organism, designated strain 273, as a member of the genusPseudomonas. After induction with 1,10-DCD,Pseudomonassp. strain 273 released stoichiometric amounts of chloride from C5to C12α,ω-dichloroalkanes in the presence of oxygen. No dehalogenation occurred under anaerobic conditions. The best substrates for dehalogenation and growth were C9to C12chloroalkanes. The isolate also grew with nonhalogenated aliphatic compounds, and decane-grown cells dechlorinated 1,10-DCD without a lag phase. In addition, cells grown on decane dechlorinated 1,10-DCD in the presence of chloramphenicol, indicating that the 1,10-DCD-dechlorinating enzyme system was also induced by decane. Other known alkane-degradingPseudomonasspecies did not grow with 1,10-DCD as a carbon source. Dechlorination of 1,10-DCD was demonstrated in cell extracts ofPseudomonassp. strain 273. Cell-free activity was strictly oxygen dependent, and NADH stimulated dechlorination, whereas EDTA had an inhibitory effect.
Chemostat Production of Plantaricin C By
Lactobacillus plantarum
LL441
Authors: Bárcena J. M. Bruno , Siñeriz F. , González de Llano D. , Rodríguez Ana , Suárez Juan E. 
Published: December 2019

ABSTRACT

Plantaricin C, a bacteriocin synthesized by
Lactobacillus plantarum
LL441, was optimally produced in chemostats kept at pH 5.0, 30°C, 150 rpm, and a dilution rate of 0.05 h
−1
when glucose was used as carbon source and a dilution rate of 0.10 to 0.12 h
−1
when sucrose or fructose was used instead. Production was abolished at high dilution rates, i.e., when the cells grew rapidly in all carbon sources.
Prevalence of the
Rhizobium etli
-Like Allele in Genes Coding for 16S rRNA among the Indigenous Rhizobial Populations Found Associated with Wild Beans from the Southern Andes in Argentina
Authors: Aguilar O. Mario , López María Verónica , Riccillo Pablo M. , González Ramón A. , Pagano Marcela , Grasso Daniel H. , Pühler Alfred , Favelukes Gabriel 
Published: December 2019

ABSTRACT

A collection of rhizobial isolates from nodules of wild beans,
Phaseolus vulgaris
var. aborigineus, found growing in virgin lands in 17 geographically separate sites in northwest Argentina was characterized on the basis of host range, growth, hybridization to a
nifH
probe, analysis of genes coding for 16S rRNA (16S rDNA), DNA fingerprinting, and plasmid profiles. Nodules in field-collected wild bean plants were largely dominated by rhizobia carrying the 16S rDNA allele of
Rhizobium etli
. A similar prevalence of the
R. etli
allele was observed among rhizobia trapped from nearby soil. Intragroup diversity of wild bean isolates with either
R. etli
-like or
Rhizobium leguminosarum
bv. phaseoli-like alleles was generally found across northwest Argentina. The predominance of the
R. etli
allele suggests that in this center of origin of
P. vulgaris
the coevolution of
Rhizobium
spp. and primitive beans has resulted in this preferential symbiotic association.
Fate of
Escherichia coli
O157:H7 on Fresh-Cut Apple Tissue and Its Potential for Transmission by Fruit Flies
Authors: Janisiewicz W. J. , Conway W. S. , Brown M. W. , Sapers G. M. , Fratamico P. , Buchanan R. L. 
Published: December 2019

ABSTRACT

Pathogenic
Escherichia coli
O157:H7, as well as nonpathogenic strains ATCC 11775 and ATCC 23716, grew exponentially in wounds on Golden Delicious apple fruit. The exponential growth occurred over a longer time period on fruit inoculated with a lower concentration of the bacterium than on fruit inoculated with a higher concentration. The bacterium reached the maximum population supported in the wounds regardless of the initial inoculum concentrations. Populations of
E. coli
O157:H7 in various concentrations of sterilized apple juice and unsterilized cider declined over time and declined more quickly in diluted juice and cider. The decline was greater in the unsterilized cider than in juice, which may have resulted from the interaction of
E. coli
O157:H7 with natural populations of yeasts that increased with time. Experiments on the transmission of
E. coli
by fruit flies, collected from a compost pile of decaying apples and peaches, were conducted with strain F-11775, a fluorescent transformant of nonpathogenic
E. coli
ATCC 11775. Fruit flies were easily contaminated externally and internally with
E. coli
F-11775 after contact with the bacterium source. The flies transmitted this bacterium to uncontaminated apple wounds, resulting in a high incidence of contaminated wounds. Populations of the bacterium in apple wounds increased significantly during the first 48 h after transmission. Further studies under commercial conditions are necessary to confirm these findings.
Identification of Enzymes and Quantification of Metabolic Fluxes in the Wild Type and in a Recombinant
Aspergillus oryzae
Strain
Authors: Pedersen Henrik , Carlsen Morten , Nielsen Jens 
Published: December 2019

ABSTRACT

Two α-amylase-producing strains of
Aspergillus oryzae
, a wild-type strain and a recombinant containing additional copies of the α-amylase gene, were characterized with respect to enzyme activities, localization of enzymes to the mitochondria or cytosol, macromolecular composition, and metabolic fluxes through the central metabolism during glucose-limited chemostat cultivations. Citrate synthase and isocitrate dehydrogenase (NAD) activities were found only in the mitochondria, glucose-6-phosphate dehydrogenase and glutamate dehydrogenase (NADP) activities were found only in the cytosol, and isocitrate dehydrogenase (NADP), glutamate oxaloacetate transaminase, malate dehydrogenase, and glutamate dehydrogenase (NAD) activities were found in both the mitochondria and the cytosol. The measured biomass components and ash could account for 95% (wt/wt) of the biomass. The protein and RNA contents increased linearly with increasing specific growth rate, but the carbohydrate and chitin contents decreased. A metabolic model consisting of 69 fluxes and 59 intracellular metabolites was used to calculate the metabolic fluxes through the central metabolism at several specific growth rates, with ammonia or nitrate as the nitrogen source. The flux through the pentose phosphate pathway increased with increasing specific growth rate. The fluxes through the pentose phosphate pathway were 15 to 26% higher for the recombinant strain than for the wild-type strain.
Bacterial Adhesion to Soil Contaminants in the Presence of Surfactants
Authors: Stelmack Patricia L. , Gray Murray R. , Pickard Michael A. 
Published: December 2019

ABSTRACT

It has been proposed that addition of surfactants to contaminated soil enhances the solubility of target compounds; however, surfactants may simultaneously reduce the adhesion of bacteria to hydrophobic surfaces. If the latter mechanism is important for the biodegradation of virtually insoluble contaminants, then the use of surfactants may not be beneficial. The adhesion of a
Mycobacterium
strain and a
Pseudomonas
strain, isolated from a creosote-contaminated soil, to the surfaces of highly viscous non-aqueous-phase liquids (NAPLs) was measured. The NAPLs were organic material extracted from soils from two creosote-contaminated sites and two petroleum-contaminated sites. Cells suspended in media with and without surfactant were placed in test tubes coated with an NAPL, and the percentages of cells that adhered to the surface of the NAPL in the presence and absence of surfactant were compared by measuring optical density. Test tubes without NAPLs were used as controls. The presence of either Triton X-100 or Dowfax 8390 at a concentration that was one-half the critical micelle concentration (CMC) inhibited adhesion of both species of bacteria to the NAPLs. Both surfactants, when added at concentrations that were one-half the CMCs to test tubes containing previously adhered bacteria, also promoted the removal of the cells from the surfaces of the NAPL-coated test tubes. Neither surfactant was toxic to the bacteria. Further investigation showed that a low concentration of surfactant also inhibited the growth of both species on anthracene, indicating that the presence of a surfactant resulted in a reduction in the uptake of the solid carbon source.
Bacterial Filament Formation, a Defense Mechanism against Flagellate Grazing, Is Growth Rate Controlled in Bacteria of Different Phyla
Authors: Hahn Martin W. , Moore Edward R. B. , Höfle Manfred G. 
Published: December 2019

ABSTRACTA facultatively filamentous bacterium was isolated from eutrophic lake water and was identified asFlectobacillussp. strain MWH38 (a member of theCytophaga-Flavobacterium-Bacteroidesphylum) by comparative 16S rRNA gene sequence analysis. Filament formation byFlectobacillussp. strain MWH38 and filament formation byFlectobacillus major, the closest known relative of strain MWH38, were studied in chemostat cultures under grazing pressure by the bacterivorous flagellateOchromonassp. strain DS and without predation at several growth rates. The results clearly demonstrated that filament formation by the two flectobacilli is growth rate controlled and thus independent of the presence of a predator. However, flagellate grazing positively influenced bacterial growth rates by decreasing bacterial biomass and thus indirectly stimulated filament formation. The results of investigations of cell elongation and filament formation byComamonas acidovoransPX54 (a member of the β subclass of the classProteobacteria) supported the recent proposal that in this species the mechanism of filament formation is growth rate controlled. The finding that the grazing defense mechanism consisting of filament formation is growth rate controlled in the flectobacilli investigated andC. acidovoransPX54 (i.e., in bacteria belonging to divergent evolutionary phyla) may indicate that this mechanism is a phylogenetically widely distributed defense strategy against grazing.
Homologs of Aflatoxin Biosynthesis Genes and Sequence of
aflR
in
Aspergillus oryzae
and
Aspergillus sojae
Authors: Watson Adrian J. , Fuller Linda J. , Jeenes David J. , Archer David B. 
Published: December 2019

ABSTRACT

The presence, but not expression, of homologs of three structural genes and a regulatory gene necessary for aflatoxin biosynthesis in
Aspergillus parasiticus
and
A. flavus
was shown for
A. oryzae
and
A. sojae
. Homologs of the regulatory gene
aflR
were cloned and sequenced from
A. oryzae
and
A. sojae
.
StableEscherichia coli-Clostridium acetobutylicumShuttle Vector for Secretion of Murine Tumor Necrosis Factor Alpha
Authors: Theys J. , Nuyts S. , Landuyt W. , Van Mellaert L. , Dillen C. , Böhringer M. , Dürre P. , Lambin P. , Anné J. 
Published: December 2019

ABSTRACTRecombinant plasmids were constructed to secrete mouse tumor necrosis factor alpha (mTNF-α) fromClostridium acetobutylicum. The shuttle plasmids contained the clostridial endo-β1,4-glucanase (eglA) promoter and signal sequence that was fused in frame to the mTNF-α cDNA. The construction was first tested inEscherichia coliand then introduced inC. acetobutylicumDSM792 by electroporation. Controls confirmed the presence and stability of the recombinant plasmids in this organism. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and an in vitro cytotoxic assay were used to monitor expression and secretion of mTNF-α during growth. Significant levels of biologically active mTNF-α were measured in both lysates and supernatants. The present report deals with investigations on the elaboration of a gene transfer system for cancer treatment using anaerobic bacteria.
Localization and In Situ Activities of Homoacetogenic Bacteria in the Highly Compartmentalized Hindgut of Soil-Feeding Higher Termites (
Cubitermes
spp.)
Authors: Tholen Anne , Brune Andreas 
Published: December 2019

ABSTRACT

Methanogenesis and homoacetogenesis occur simultaneously in the hindguts of almost all termites, but the reasons for the apparent predominance of methanogenesis over homoacetogenesis in the hindgut of the humivorous species is not known. We found that in gut homogenates of soil-feeding
Cubitermes
spp., methanogens outcompete homoacetogens for endogenous reductant. The rates of methanogenesis were always significantly higher than those of reductive acetogenesis, whereas the stimulation of acetogenesis by the addition of exogenous H
2
or formate was more pronounced than that of methanogenesis. In a companion paper, we reported that the anterior gut regions of
Cubitermes
spp. accumulated hydrogen to high partial pressures, whereas H
2
was always below the detection limit (<100 Pa) in the posterior hindgut, and that all hindgut compartments turned into efficient H
2
sinks when external H
2
was provided (D. Schmitt-Wagner and A. Brune, Appl. Environ. Microbiol. 65:4490–4496, 1999). Using a microinjection technique, we found that only the posterior gut sections P3/4a and P4b, which harbored methanogenic activities, formed labeled acetate from H
14
CO
3
−
. Enumeration of methanogenic and homoacetogenic populations in the different gut sections confirmed the coexistence of both metabolic groups in the same compartments. However, the in situ rates of acetogenesis were strongly hydrogen limited; in the P4b section, no activity was detected unless external H
2
was added. Endogenous rates of reductive acetogenesis in isolated guts were about 10-fold lower than the in vivo rates of methanogenesis, but were almost equal when exogenous H
2
was supplied. We conclude that the homoacetogenic populations in the posterior hindgut are supported by either substrates other than H
2
or by a cross-epithelial H
2
transfer from the anterior gut regions, which may create microniches favorable for H
2
-dependent acetogenesis.