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Survey of large protein complexes D. vulgaris reveals great structural diversity

Description: An unbiased survey has been made of the stable, most abundant multi-protein complexes in Desulfovibrio vulgaris Hildenborough (DvH) that are larger than Mr {approx} 400 k. The quaternary structures for 8 of the 16 complexes purified during this work were determined by single-particle reconstruction of negatively stained specimens, a success rate {approx}10 times greater than that of previous 'proteomic' screens. In addition, the subunit compositions and stoichiometries of the remaining complexes were determined by biochemical methods. Our data show that the structures of only two of these large complexes, out of the 13 in this set that have recognizable functions, can be modeled with confidence based on the structures of known homologs. These results indicate that there is significantly greater variability in the way that homologous prokaryotic macromolecular complexes are assembled than has generally been appreciated. As a consequence, we suggest that relying solely on previously determined quaternary structures for homologous proteins may not be sufficient to properly understand their role in another cell of interest.
Date: August 15, 2009
Creator: Han, B.-G.; Dong, M.; Liu, H.; Camp, L.; Geller, J.; Singer, M. et al.
Partner: UNT Libraries Government Documents Department

Identification of Small RNAs in Desulfovibrio vulgaris Hildenborough

Description: Desulfovibrio vulgaris is an anaerobic sulfate-reducing bacterium capable of facilitating the removal of toxic metals such as uranium from contaminated sites via reduction. As such, it is essential to understand the intricate regulatory cascades involved in how D. vulgaris and its relatives respond to stressors in such sites. One approach is the identification and analysis of small non-coding RNAs (sRNAs); molecules ranging in size from 20-200 nucleotides that predominantly affect gene regulation by binding to complementary mRNA in an anti-sense fashion and therefore provide an immediate regulatory response. To identify sRNAs in D. vulgaris, a bacterium that does not possess an annotated hfq gene, RNA was pooled from stationary and exponential phases, nitrate exposure, and biofilm conditions. The subsequent RNA was size fractionated, modified, and converted to cDNA for high throughput transcriptomic deep sequencing. A computational approach to identify sRNAs via the alignment of seven separate Desulfovibrio genomes was also performed. From the deep sequencing analysis, 2,296 reads between 20 and 250 nt were identified with expression above genome background. Analysis of those reads limited the number of candidates to ~;;87 intergenic, while ~;;140 appeared to be antisense to annotated open reading frames (ORFs). Further BLAST analysis of the intergenic candidates and other Desulfovibrio genomes indicated that eight candidates were likely portions of ORFs not previously annotated in the D. vulgaris genome. Comparison of the intergenic and antisense data sets to the bioinformatical predicted candidates, resulted in ~;;54 common candidates. Current approaches using Northern analysis and qRT-PCR are being used toverify expression of the candidates and to further develop the role these sRNAs play in D. vulgaris regulation.
Date: May 17, 2010
Creator: Burns, Andrew; Joachimiak, Marcin; Deutschbauer, Adam; Arkin, Adam & Bender, Kelly
Partner: UNT Libraries Government Documents Department

Investigating the role of CheA-3 in Dusulfovibrio Vulgaris Hildenborough

Description: Multiple sets of chemotaxis genes including three cheA homologs were identified in the genome sequence of the anaerobic bacterium Desulfovibrio vulgaris Hildenborough. Each CheA is a histidine kinase (HK) and part of a two component signal transduction system. Knock out mutants in the three cheA genes were created using single cross-over homologous recombination insertion. We studied the phenotypes of the cheA mutants in detail and discovered that ?cheA-3 has a non swarming/swimming phenotype both in the soft agar plates and Palleroni chamber assays. CheA-3 shows similarity to the Shewanella oneidensis CheA-3 and the Vibrio cholerae CheA-2 that are responsible for chemotaxis in the respective organisms. We did not find any morphological or structural differences between the three Delta cheA mutants and the wild type cells in electron microscopy. Our results from these studies are presented.
Date: May 22, 2010
Creator: Ray, Jayashee; Keller, Kimberley; Krierim, Bernhard; Auer, Manfred; Keasling, Jay; Wall, Judy et al.
Partner: UNT Libraries Government Documents Department

Identification of Molecular and Cellular Responses of Desulfovibrio vulgaris Biofilms under Culture Conditions Relevant to Field Conditions for Bioreduction of Toxic Metals and Radionuclides

Description: Our findings demonstrated that D. vulgaris surface-adhered populations produce extracellular structures, and that that the cells have altered carbon and energy flux compared to planktonic cells. Biofilms did not have greatly increased carbohydrate accumulation. Interestingly genes present on the native plasmid found in D. vulgaris Hildenborough were necessary for wild type biofilm formation. In addition, extracellular appendages dependent on functions or proteins encoded by flaG or fliA also contributed to biofilm formation. Studies with SRB biofilms have indicated that the reduction and precipitation of metals can occur within the biofilm matrix; however, little work has been done to elucidate the physiological state of surface-adhered cells during metal reduction (Cr6+, U6+) and how this process is affected by nutrient feed levels (i.e., the stimulant).
Date: June 9, 2011
Creator: Wall, Judy D.
Partner: UNT Libraries Government Documents Department

Development of Extraction Techniques for the Detection of Signature Lipids from Oil

Description: Pure cultures, including Desulfovibrio vulgaris and Methanococcus maripaludus, were combined with model oil samples and oil/diesel mixtures to optimize extraction techniques of signature lipids from oil in support of investigation of microbial communities in oil deposit samples targets for microbial enhanced hydrocarbon recovery. Several techniques were evaluated, including standard phospholipid extraction, ether linked lipid for Archaeal bacterial detection, and high pressure extractiontechniques. Recovery of lipids ranged from 50-80percent as compared to extraction of the pure culture. Extraction efficiency was evaluated by the use of internal standards. Field samples will also be tested for recovery of signature lipids with optimized extraction techniques.
Date: May 17, 2010
Creator: Borglin, Sharon; Geller, Jil; Chakraborty, Romy; Hazen, Terry & Mason, Olivia
Partner: UNT Libraries Government Documents Department

Development of a Model, Metal-reducing Microbial Community for a System Biology Level Assessment of Desulfovibrio vulgaris as part of a Community

Description: One of the largest experimental gaps is between the simplicity of pure cultures and the complexity of open environmental systems, particularly in metal-contaminated areas. These microbial communities form ecosystem foundations, drive biogeochemical processes, and are relevant for biotechnology and bioremediation. A model, metal-reducing microbial community was constructed as either syntrophic or competitive to study microbial cell to cell interactions, cell signaling and competition for resources. The microbial community was comprised of the metal-reducing Desulfovibrio vulgaris Hildenborough and Geobacter sulfurreducens PCA. Additionally, Methanococcus maripaludis S2 was added to study complete carbon reduction and maintain a low hydrogen partial pressure for syntrophism to occur. Further, considerable work has been published on D. vulgaris and the D. vulgaris/ Mc. maripaludis co-culture both with and without stress. We are extending this work by conducting the same stress conditions on the model community. Additionally, this comprehensive investigation includes physiological and metabolic analyses as well as specially designed mRNA microarrays with the genes for all three organisms on one slide so as to follow gene expression changes in the various cultivation conditions as well as being comparable to the co- and individual cultures. Further, state-of -the-art comprehensive AMT tag proteomics allows for these comparisons at the protein level for a systems biology assessment of a model, metal-reducing microbial community. Preliminary data revealed that lactate oxidation by D. vulgaris was sufficient to support both G. sulfurreducens and M. maripaludis via the excretion of H2 and acetate. Fumarate was utilized by G. sulfurreducens and reduced to succinate since neither of the other two organisms can reduce fumarate. Methane was quantified, suggesting acetate and H2 concentrations were sufficient for M. maripaludis. Steady state community cultivation will allow for a comprehensive, system biology level analysis of a metal-reducing microbial community.
Date: May 17, 2010
Creator: Elias, Dwayne; Schadt, Christopher; Miller, Lance; Phelps, Tommy; Brown, S. D.; Arkin, Adam et al.
Partner: UNT Libraries Government Documents Department

The Role of the Tetraheme Cytochrome c3 in Desulfovibrio vulgaris Hildenborough Metabolism

Description: The role of tetraheme cytochrome c3 (CycA) in the metabolism of the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH) was investigated by deletion of the cycA gene using a marker-exchange deletion strategy. A highly abundant periplasmic cytochrome, CycA has the important function of transferring electrons from periplasmic hydrogenases (Hyd, Hyn, Hys) to transmembrane complexes which transport the electrons to the cytoplasm where sulfate is reduced. Previous studies have indicated that during its interaction with periplasmic hydrogenases, CycA is also involved in the reduction of toxic metals. Growth of the cycA mutant strain on lactate as the electron donor and sulfate as the terminal electron acceptor showed that, despite its abundance, CycA is not essential for DvH growth. However, the rate of growth of the mutant strain was significantly lower, and the extent of growth less, than rates and extents of growth of the wild type and complement strains on lactate/sulfate medium. This indicates that a portion of the electrons generated from cytoplasmic lactate oxidation are transported by CycA for energy production, possibly in a hydrogen cycling mechanism employed to generate ATP. Failure of the mutant strain to grow on either formate or H2, with sulfate or sulfite as electron acceptors, further indicated that CycA may be the only redox partner of periplasmic hydrogenases. The cycA mutant strain also did not grow as well as either the wild type or complement strains on medium supplemented with pyruvate/sulfate. Final growth on pyruvate/sulfate was comparable, but the mutant grew more slowly than the wild type and complement strains. Interestingly, the mutant grew better than the wild type or complement strains on pyruvate alone, possibly due to the release of H2 and/or CO2 in concentrations which may be somewhat inhibitory to wild type growth.
Date: May 17, 2010
Creator: Semkiw, Elizabeth; Zane, Grant & Wall, Judy
Partner: UNT Libraries Government Documents Department

Genetic Adaptation to Salt Stress in Experimental Evolution of Desulfovibrio vulgaris Hildenborough

Description: High salinity is one of the most common environmental stressors. In order to understand how environmental organisms adapt to salty environment, an experiment evolution with sulfate reducing bacteria Desulfovibrio vugaris Hildenborough was conducted. Control lines and salt-stressed lines (6 lines each) grown in minimal medium LS4D or LS4D + 100 mM NaCl were transferred for 1200 generations. The salt tolerance was tested with LS4D supplemented with 250 mM NaCl. Statistical analysis of the growth data suggested that all lines adapted to their evolutionary environment. In addition, the control lines performed better than the ancestor with faster growth rate, higher biomass yield and shorter lag phase under salty environment they did not evolve in. However, the salt-adapted lines performed better than the control lines on measures of growth rate and yield under salty environment, suggesting that the salt?evolved lines acquired mutations specific to having extra salt in LS4D. Growth data and gene transcription data suggested that populations tended to improve till 1000 generations and active mutations tended to be fixed at the stage of 1000 generations. Point mutations and insertion/deletions were identified in isolated colonies from salt-adapted and control lines via whole genome sequencing. Glu, Gln and Ala appears to be the major osmoprotectant in evolved salt-stressed line. Ongoing studies are now characterizing the contribution of specific mutations identified in the salt-evolved D. vulgaris.
Date: May 17, 2010
Creator: Zhou, Aifen; Hillesland, Kristina; He, Zhili; Joachimiak, Marcin; Zane, Grant; Dehal, Paramvir et al.
Partner: UNT Libraries Government Documents Department

Large-Scale, Continuous-Flow Production of Stressed Biomass (Desulfovibrio vulgaris Hildenborough)

Description: The Protein Complex Analysis Project (PCAP, http://pcap.lbl.gov/), focuses on high-throughput analysis of microbial protein complexes in the anaerobic, sulfate-reducing organism, DesulfovibriovulgarisHildenborough(DvH).Interest in DvHas a model organism for bioremediation of contaminated groundwater sites arises from its ability to reduce heavy metals. D. vulgarishas been isolated from contaminated groundwater of sites in the DOE complex. To understand the effect of environmental changes on the organism, midlog-phase cultures are exposed to nitrate and salt stresses (at the minimum inhibitory concentration, which reduces growth rates by 50percent), and compared to controls of cultures at midlogand stationary phases. Large volumes of culture of consistent quality (up to 100 liters) are needed because of the relatively low cell density of DvHcultures (one order of magnitude lower than E. coli, for example) and PCAP's challenge to characterize low-abundance membrane proteins. Cultures are grown in continuous flow stirred tank reactors (CFSTRs) to produce consistent cell densities. Stressor is added to the outflow from the CFSTR, and the mixture is pumped through a plug flow reactor (PFR), to provide a stress exposure time of 2 hours. Effluent is chilled and held in large carboys until it is centrifuged. A variety of analyses -- including metabolites, total proteins, cell density and phospholipidfatty-acids -- track culture consistency within a production run, and differences due to stress exposure and growth phase for the different conditions used. With our system we are able to produce the requisite 100 L of culture for a given condition within a week.
Date: May 1, 2010
Creator: Geller, Jil T.; Borglin, Sharon E.; Fortney, Julian L.; Lam, Bonita R.; Hazen, Terry C. & Biggin, Mark D.
Partner: UNT Libraries Government Documents Department

Effect of the deletion of qmoABC and the promoter distal gene encoding a hypothetical protein on sulfate-reduction in Desulfovibrio vulgaris Hildenborough

Description: The pathway of electrons required for the reduction of sulfate in sulfate-reducing bacteria (SRB) is not yet fully characterized. In order to determine the role of a transmembrane protein complex suggested to be involved in this process, a deletion of Desulfovibrio vulgaris Hildenborough was created by marker exchange mutagenesis that eliminated four genes putatively encoding the QmoABC complex and a hypothetical protein (DVU0851). The Qmo complex (quinone-interacting membrane-bound oxidoreductase) is proposed to be responsible for transporting electrons to the dissimilatory adenosine-5?phosphosulfate (APS) reductase in SRB. In support of the predicted role of this complex, the deletion mutant was unable to grow using sulfate as its sole electron acceptor with a range of electron donors. To explore a possible role for the hypothetical protein in sulfate reduction, a second mutant was constructed that had lost only the gene that codes for DVU0851. The second constructed mutant grew with sulfate as the sole electron acceptor; however, there was a lag that was not present with the wild-type or complemented strain. Neither deletion strain was significantly impaired for growth with sulfite or thiosulfate as terminal electron acceptor. Complementation of the D(qmoABC-DVU0851) mutant with all four genes or only the qmoABC genes restored its ability to grow by sulfate respiration. These results confirmed the prediction that the Qmo complex is in the electron pathway for sulfate-reduction and revealed that no other transmembrane complex could compensate when Qmo was lacking.
Date: March 18, 2010
Creator: Zane, Grant M.; Yen, Huei-chi Bill & Wall, Judy D.
Partner: UNT Libraries Government Documents Department

Transcriptional Response of Desulfovibrio vulgaris Hildenborough to Oxidative Stress Mimicking Environmental Conditions

Description: Sulphate-reducing bacteria are anaerobes readily found in oxic-anoxic interfaces. Multiple defence pathways against oxidative conditions were identified in these organisms and proposed to be differentially expressed under different concentrations of oxygen, contributing to their ability to survive oxic conditions. In this study, Desulfovibrio vulgaris Hildenborough cells were exposed to the highest concentration of oxygen that sulphate-reducing bacteria are likely to encounter in natural habitats, and the global transcriptomic response was determined. 307 genes were responsive, with cellular roles in energy metabolism, protein fate, cell envelope and regulatory functions, including multiple genes encoding heat shock proteins, peptidases and proteins with heat shock promoters. Of the oxygen reducing mechanisms of D. vulgaris only the periplasmic hydrogen-dependent mechanism is up-regulated, involving the [NiFeSe]hydrogenase, formate dehydrogenase(s) and the Hmc membrane complex. The oxidative defence response concentrates on damage repair by metal-free enzymes. These data, together with the down regulation of the Fur operon, which restricts the availability of iron, and the lack of response of the PerR operon, suggest that a major effect of this oxygen stress is the inactivation and/or degradation of multiple metalloproteins present in D. vulgaris as a consequence of oxidative damage to their metal clusters.
Date: March 12, 2008
Creator: Pereira, Patricia M.; He, Qiang; Xavier, Antonio V.; Zhou, Jizhong; Pereira, Ines A.C. & Louro, Ricardo O.
Partner: UNT Libraries Government Documents Department

The influence of desulfovibrio desulfuricans on neptunium chemistry.

Description: The role of biotic Np(V) reduction is studied in light of its potential role in the environmental immobilization of this hazardous radionuclide. The speciation of Np in Desulfovibrio desulfuricans cultures is compared with Np speciation in the spent medium and in the uninoculated medium. Precipitates formed in all three samples. Optical spectroscopy and X-ray absorption near edge structure (XANES) were used to determine that Np(V) is almost quantitatively reduced in all three samples and that the precipitate is an amorphous Np(IV) species. These results demonstrate that the reduction of Np is independent of Desulfovibrio desulfuricans. The underlying chemistry associated with these results is discussed.
Date: December 20, 1999
Creator: Soderholm, L.; Williams, C.; Antonio, M. R.; Tischler, M. L. & Markos, M.
Partner: UNT Libraries Government Documents Department

Using Cytochrome c{sub 3} to Make Selenium Nanowires

Description: We report on a new method to make nanostructures, in this case selenium nanowires, in aqueous solution at room temperature. We used the protein cytochrome c{sub 3} to reduce selenate (SeO{sub 4}{sup 2{minus}}) to selenium (Se{sup 0}). Cytochrome c{sub 3} is known for its ability to catalyze reduction of metals including U{sup VI} {yields} U{sup IV}, Cr{sup VI} {yields} Cr{sup III}, Mo{sup VI} {yields} Mo{sup IV}, Cu{sup II} {yields} Cu{sup 0}, Pb{sup II} {yields} Pb{sup 0}, Hg{sup II} {yields} Hg{sup 0}. Nanoparticles of Se{sup 0} precipitated from an aqueous solution at room temperature, followed by spontaneous self-assembling into nanowires. Cytochrome c{sub 3} was extracted from the sulfate-reducing bacteria Desulfovibrio vulgaris (strain Holdenborough) and isolated by the procedure of DerVartanian and Legall.
Date: November 24, 1999
Creator: ABDELOUAS,A.; FRANCO,R.; GONG,W.L.; LUTZE,W.; MOURA,I. & SHELNUTT,JOHN A.
Partner: UNT Libraries Government Documents Department

How sulphate-reducing microorganisms cope with stress: Lessons from systems biology

Description: Sulphate-reducing microorganisms (SRMs) are a phylogenetically diverse group of anaerobes encompassing distinct physiologies with a broad ecological distribution. As SRMs have important roles in the biogeochemical cycling of carbon, nitrogen, sulphur and various metals, an understanding of how these organisms respond to environmental stresses is of fundamental and practical importance. In this Review, we highlight recent applications of systems biology tools in studying the stress responses of SRMs, particularly Desulfovibrio spp., at the cell, population, community and ecosystem levels. The syntrophic lifestyle of SRMs is also discussed, with a focus on system-level analyses of adaptive mechanisms. Such information is important for understanding the microbiology of the global sulphur cycle and for developing biotechnological applications of SRMs for environmental remediation, energy production, biocorrosion control, wastewater treatment and mineral recovery.
Date: April 1, 2011
Creator: Zhou, J.; He, Q.; Hemme, C.L.; Mukhopadhyay, A.; Hillesland, K.; Zhou, A. et al.
Partner: UNT Libraries Government Documents Department

Reference set of regulons in Desulfovibrionales inferred by comparative genomics approach

Description: in this study, we carried out large-scale comparative genomics analysis of regulatory interactions in Desulfovibrio vulgaris and 12 related genomes from Desulfovibrionales order using our recently developed web server RegPredict (http://regpredict.lbl.gov). An overall reference collection of 26 Desulfovibrionales regulogs can be accessed through RegPrecise database (http://regpredict.lbl.gov).
Date: November 15, 2010
Creator: Kazakov, A.E.; Rodionov, D.A.; Price, M.N.; Arkin, A.P.; Dubchak, I. & Novichkov, P.S.
Partner: UNT Libraries Government Documents Department

Methods for Engineering Sulfate Reducing Bacteria of the Genus Desulfovibrio

Description: Sulfate reducing bacteria are physiologically important given their nearly ubiquitous presence and have important applications in the areas of bioremediation and bioenergy. This chapter provides details on the steps used for homologous-recombination mediated chromosomal manipulation of Desulfovibrio vulgaris Hildenborough, a well-studied sulfate reducer. More specifically, we focus on the implementation of a 'parts' based approach for suicide vector assembly, important aspects of anaerobic culturing, choices for antibiotic selection, electroporation-based DNA transformation, as well as tools for screening and verifying genetically modified constructs. These methods, which in principle may be extended to other sulfate-reducing bacteria, are applicable for functional genomics investigations, as well as metabolic engineering manipulations.
Date: March 15, 2011
Creator: Chhabra, Swapnil R; Keller, Kimberly L. & Wall, Judy D.
Partner: UNT Libraries Government Documents Department

EVELOPMENT OF AN ENVIRONMENTALLY BENIGN MICROBIAL INHIBITOR TO CONTROL INTERNAL PIPELINE CORROSION

Description: The overall program objective is to develop and evaluate environmentally benign agents or products that are effective in the prevention, inhibition, and mitigation of microbially influenced corrosion (MIC) in the internal surfaces of metallic natural gas pipelines. The goal is to develop one or more environmentally benign (a.k.a. ''green'') products that can be applied to maintain the structure and dependability of the natural gas infrastructure. Previous testing of pepper extracts resulted in preliminary data indicating that some pepper extracts inhibit the growth of some corrosion-associated microorganisms. This quarter additional tests were performed to more specifically investigate the ability of three pepper extracts to inhibit the growth, and to influence the metal corrosion caused by two microbial species: Desulfovibrio vulgaris, and Comomonas denitrificans. All three pepper extracts rapidly killed Desulfovibrio vulgaris, but did not appear to inhibit Comomonas denitrificans. While corrosion rates were at control levels in experiments with Desulfovibrio vulgaris that received pepper extract, corrosion rates were increased in the presence of Comomonas denitrificans plus pepper extract. Further testing with a wider range of pure bacterial cultures, and more importantly, with mixed bacterial cultures should be performed to determine the potential effectiveness of pepper extracts to inhibit MIC.
Date: April 30, 2004
Creator: Bogan, Bill W.; Sullivan, Wendy R.; Cruz, Kristine M. H.; Lowe, Kristine L. & II, John J. Kilbane
Partner: UNT Libraries Government Documents Department

Effects of Chromium(VI) and Chromium(III) on Desulfovibrio vulgaris Cells

Description: Desulfovibrio vulgaris ATCC 29579 is a well studied sulfate reducer that has known capabilities of reducing heavy metals and radionuclides, like chromium and uranium. Cultures grown in a defined medium (i.e. LS4D) had a lag period of approximately 40 h when exposed to 50 ╬╝Mof Cr(VI). Substrate analysis revealed that although chromium is reduced within the first 5 h, growth does not resume for another 35 h. During this time, small amounts of lactate are still utilized but the reduction of sulfate does not occur. Sulfate reduction occurs concurrently with the accumulation of acetate approximately 40 h after inoculation, when growth resumes. Similar amounts of hydrogen are produced during this time compared to hydrogen production by cells not exposed to Cr(VI); therefore an accumulation of hydrogen cannot account for the utilization of lactate. There is a significant decrease in the carbohydrate to protein ratio at approximately 25 h, and this result indicated that lactate is not converted to glycogen. Most probable number analysis indicated that cell viability decreased steadily after inoculation and reached approximately 6 x 104 cells/ml 20 h post-chromium exposure. Regeneration of reducing conditions during chromium exposure does not induce growth and in fact may make the growth conditions even more unfavorable. This result suggested that an increase in Eh was not solely responsible for the decline in viability. Cell pellets collected 10 h after chromium-exposure were unable to resume growth when suspended into fresh medium. Supernatants from these pellets were able to support cell growth upon re- inoculation. D. vulgaris cells treated with a non-dose dependent addition of ascorbate at the same time of Cr(VI) addition did not enter a lag period. Ascorbate added 3 h post-Cr(VI) exposure did not prevent the growth lag. These results indicated that Desulfovibrio utilized lactate to reduce Cr(VI) without the reduction ...
Date: April 19, 2007
Creator: Clark, M.E.; Klonowska, A.; Thieman, S.B.; Giles, B.; Wall, J.D. & Fields, and M.W.
Partner: UNT Libraries Government Documents Department

Analysis of a Ferric Uptake Regulator (Fur) Mutant ofDesulfovibrio vulgaris Hildenborough

Description: Previous experiments examining the transcriptional profileof the anaerobe Desulfovibrio vulgaris demonstrated up-regulation of theFur regulon in response to various environmental stressors. To test theinvolvement of Fur in the growth response and transcriptional regulationof D. vulgaris, a targeted mutagenesis procedure was used for deletingthe fur gene. Growth of the resulting ?fur mutant (JW707) was notaffected by iron availability, but the mutant did exhibit increasedsensitivity to nitrite and osmotic stresses compared to the wild type.Transcriptional profiling of JW707 indicated that iron-bound Fur acts asa traditional repressor for ferrous iron uptake genes (feoAB) and othergenes containing a predicted Fur binding site within their promoter.Despite the apparent lack of siderophore biosynthesis genes within the D.vulgaris genome, a large 12-gene operon encoding orthologs to TonB andTolQR also appeared to be repressed by iron-bound Fur. While other genespredicted to be involved in iron homeostasis were unaffected by thepresence or absence of Fur, alternative expression patterns that could beinterpreted as repression or activation by iron-free Fur were observed.Both the physiological and transcriptional data implicate a globalregulatory role for Fur in the sulfate-reducing bacterium D.vulgaris.
Date: September 21, 2007
Creator: Bender, Kelly S.; Yen, Huei-Che Bill; Hemme, Christopher L.; Yang, Zamin K.; He, Zhili; He, Qiang et al.
Partner: UNT Libraries Government Documents Department

Cell wide responses to low oxygen exposure in Desulfovibriovulgaris Hildenborough

Description: The responses of the anaerobic, sulfate-reducing Desulfovibrio vulgaris Hildenborough to low oxygen exposure (0.1% O{sub 2}) were monitored via transcriptomics and proteomics. Exposure to 0.1% O{sub 2} caused a decrease in growth rate without affecting viability. A concerted up regulation in the predicted peroxide stress response regulon (PerR) genes was observed in response to the 0.1% O{sub 2} exposure. Several of these candidates also showed increases in protein abundance. Among the remaining small number of transcript changes was the up regulation of the predicted transmembrane tetraheme cytochrome c3 complex. Other known oxidative stress response candidates remained unchanged during this low O{sub 2} exposure. To fully understand the results of the 0.1% O{sub 2} exposure, transcriptomics and proteomics data were collected for exposure to air using a similar experimental protocol. In contrast to the 0.1% O{sub 2} exposure, air exposure was detrimental to both the growth rate and viability and caused dramatic changes at both the transcriptome and proteome levels. Interestingly, the transcripts of the predicted PerR regulon genes were down regulated during air exposure. Our results highlight the differences in the cell wide response to low and high O{sub 2} levels of in D. vulgaris and suggest that while exposure to air is highly detrimental to D. vulgaris, this bacterium can successfully cope with periodic exposure to low O{sub 2} levels in its environment.
Date: March 11, 2007
Creator: Mukhopadhyay, A.; Redding, A.; Joachimiak, M.; Arkin, A.; Borglin, S.; Dehal, P. et al.
Partner: UNT Libraries Government Documents Department

Visualization of Growth Curve Data from Phenotype Microarray Experiments

Description: Phenotype microarrays provide a technology to simultaneouslysurvey the response of an organism to nearly 2,000 substrates, includingcarbon, nitrogen and potassium sources; varying pH; varying saltconcentrations; and antibiotics. In order to more quickly and easily viewand compare the large number of growth curves produced by phenotypemicroarray experiments, we have developed software to produce and displaycolor images, each of which corresponds to a set of 96 growth curves.Using color images to represent growth curves data has proven to be avaluable way to assess experiment quality, compare replicates, facilitatecomparison of the responses of different organisms, and identifysignificant phenotypes. The color images are linked to traditional plotsof growth versus time, as well as to information about the experiment,organism, and substrate. In order to share and view information and dataproject-wide, all information, plots, and data are accessible using onlya Web browser.
Date: April 19, 2007
Creator: Jacobsen, Janet S.; Joyner, Dominique C.; Borglin, Sharon E.; Hazen, Terry C.; Arkin, Adam P. & Bethel, E. Wes
Partner: UNT Libraries Government Documents Department

Interspecies acetate transfer influences the extent of anaerobic benzoate degradation by syntrophic consortia

Description: Benzoate degradation by an anaerobic, syntrophic bacterium, strain SB, in coculture with Desulfovibrio strain G-11 reached a threshold value which depended on the amount of acetate added, and ranged from about 2.5 to 29.9 {mu}M. Increasing acetate concentrations also uncompetitively inhibited benzoate degradation. The apparent V{sub max} and K{sub m} for benzoate degradation decreased with increasing acetate concentration, but the benzoate degradation capacity (V{sub max}/K{sub m}) of cell suspensions remained comparable. The addition of an acetate-using bacterium to cocultures after the threshold was reached resulted in the degradation of benzoate to below the detection limit. Mathematical simulations showed that the benzoate threshold was not predicted by the inhibitory effect of acetate on benzoate degradation kinetics. With nitrate instead of sulfate as the terminal electron acceptor, no benzoate threshold was observed in the presence of 20 mM acetate even though the degradation capacity was lower with nitrate than with sulfate. When strain SB was grown with a hydrogen-using partner that had a 5-fold lower hydrogen utilization capacity, a 5 to 9-fold lower the benzoate degradation capacity was observed compared to SB/G-11 cocultures. The Gibb`s free energy for benzoate degradation was less negative in cell suspensions with threshold compared to those without threshold. These studies showed that the threshold was not a function of the inhibition of benzoate degradation capacity by acetate, or the toxicity of the undissociated form of acetate. Rather a critical or minimal Gibb`s free energy may exist where thermodynamic constraints preclude further benzoate degradation.
Date: March 1, 1997
Creator: Warikoo, V.; McInerney, M.J. & Suflita, J.M.
Partner: UNT Libraries Government Documents Department

Genes for Uranium Bioremediation in the Anaerobic Sulfate-Reducing Bacteria

Description: Surprising results were obtained following an attempt to induce or derepress the machinery for U(VI) reduction by growing Desulfovibrio desulfuricans G20 in the presence of 1 mM uranyl acetate. G20 cells grown on lactate-sulfate medium amended with U(VI) reduced uranium at a slower rate than cells grown in the absence of this metal. When periplasmic extracts of these cells were prepared, Western analysis of the proteins revealed that the cytochrome c3 was absent. This observation has been further investigated.
Date: June 1, 2003
Creator: Wall, Judy D.
Partner: UNT Libraries Government Documents Department

Identification of Molecular and Cellular Responses of Desulfovibrio vulgaris Biofilms under Culture Conditions Relevant to Field Conditions for Bioreduction of

Description: Desulfovibrio vulgaris Hildenborough forms biofilms under stress and nutrient limitation conditions. Analysis of the transcriptional responses to acid exposure suggested that genes encoding arginine and polyamine biosynthesis were increased in expression. A literature search showed that polyamines had been suggested to stimulate biofilm formation in some bacteria. Therefore, biofilm formation by D. vulgaris was then examined. Two different assay methods were used to estimate the biofilm formation. First, the classical crystal violet stainable material attached to glass test tubes was measured. Second protein attached to the test tube sides and especially precipitated at the bottom was measured.
Date: June 1, 2006
Creator: Wall, Judy D.
Partner: UNT Libraries Government Documents Department