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Lynne E Macaskie - One of the best experts on this subject based on the ideXlab platform.
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enhanced hydrogenation catalyst synthesized by Desulfovibrio desulfuricans exposed to a radio frequency magnetic field
Microbial Biotechnology, 2021Co-Authors: Lynne E Macaskie, I P Mikheenko, Mohamed L. Merroun, John Collins, Jaime Gomezbolivar, James A BennettAbstract:Desulfovibrio desulfuricans reduces Pd(II) to Pd(0)-nanoparticles (Pd-NPs) which are catalytically active in 2-pentyne hydrogenation. To make Pd-NPs, resting cells are challenged with Pd(II) ions (uptake), followed by addition of electron donor to promote bioreduction of cell-bound Pd(II) to Pd(0) (bio-Pd). Application of radiofrequency (RF) radiation to prepared 5 wt% bio-Pd catalyst (60 W power, 60 min) increased the hydrogenation rate by 70% with no adverse impact on selectivity to cis-2-pentene. Such treatment of a 5 wt% Pd/carbon commercial catalyst did not affect the conversion rate but reduced the selectivity. Lower-dose RF radiation (2-8 W power, 20 min) was applied to the bacteria at various stages before and during synthesis of the bio-scaffolded Pd-NPs. The reaction rate (μ mol 2-pentyne converted s-1 ) was increased by ~threefold by treatment during bacterial catalyst synthesis. Application of RF radiation (2 or 4 W power) to resting cells prior to Pd(II) exposure affected the catalyst made subsequently, increasing the reaction rate by 50% as compared to untreated cells, while nearly doubling selectivity for cis 2-pentene. The results are discussed with respect to published and related work which shows altered dispersion of the Pd-NPs made following or during RF exposure.
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Characterization of intracellular palladium nanoparticles synthesized by Desulfovibrio desulfuricans and Bacillus benzeovorans.
Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology, 2015Co-Authors: Jacob B. Omajali, I P Mikheenko, Mohamed L. Merroun, Joseph Wood, Lynne E MacaskieAbstract:Early studies have focused on the synthesis of palladium nanoparticles within the periplasmic layer or on the outer membrane of Desulfovibrio desulfuricans and on the S-layer protein of Bacillus sphaericus. However, it has remained unclear whether the synthesis of palladium nanoparticles also takes place in the bacterial cell cytoplasm. This study reports the use of high-resolution scanning transmission electron microscopy with a high-angle annular dark field detector and energy dispersive X-ray spectrometry attachment to investigate the intracellular synthesis of palladium nanoparticles (Pd NPs). We show the intracellular synthesis of Pd NPs within cells of two anaerobic strains of D. desulfuricans and an aerobic strain of B. benzeovorans using hydrogen and formate as electron donors. The Pd nanoparticles were small and largely monodispersed, between 0.2 and 8 nm, occasionally from 9 to 12 nm with occasional larger nanoparticles. With D. desulfuricans NCIMB 8307 (but not D. desulfuricans NCIMB 8326) and with B. benzeovorans NCIMB 12555, the NPs were larger when made at the expense of formate, co-localizing with phosphate in the latter, and were crystalline, but were amorphous when made with H2, with no phosphorus association. The intracellular Pd nanoparticles were mainly icosahedrons with surfaces comprising {111} facets and about 5 % distortion when compared with that of bulk palladium. The particles were more concentrated in the cell cytoplasm than the cell wall, outer membrane, or periplasm. We provide new evidence for synthesis of palladium nanoparticles within the cytoplasm of bacteria, which were confirmed to maintain cellular integrity during this synthesis.
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versatility of a new bioinorganic catalyst palladized cells of Desulfovibrio desulfuricans and application to dehalogenation of flame retardant materials
Environmental Technology, 2009Co-Authors: Kevin Deplanche, Stuart Harrad, Timothy J Snape, Sadegh Hazrati, Lynne E MacaskieAbstract:The versatility and reaction specificity of a novel bioinorganic catalyst is demonstrated in various reactions. Palladized cells (bioPd) of the sulphate‐reducing bacterium Desulfovibrio desulfuricans showed an increased product selectivity and a catalytic activity comparable to a commercial Pd catalyst in several industrially relevant hydrogenations and hydrogenolyses (reductive dehalogenations). The ability of palladized cells to promote the reductive debromination of a polybrominated diphenyl ether (PBDE #47) is demonstrated, although chemically reduced Pd(II) and commercial Pd(0) were more effective debromination agents. Polybrominated diphenyl ethers are being supplanted as flame retardants by other compounds, e.g. tris(chloroisopropyl)phosphate (TCPP), the concentration of which was seen to increase ∼10‐fold in groundwater samples between 2000 and 2004. BioPd dechlorinated TCPP in groundwater samples with >90% recovery of free chloride ion, and was five times more effective than using commercial Pd(0...
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biorecovery of gold by escherichia coli and Desulfovibrio desulfuricans
Biotechnology and Bioengineering, 2008Co-Authors: Kevin Deplanche, Lynne E MacaskieAbstract:Microbial precipitation of gold was achieved using Escherichia coli and Desulfovibrio desulfuricans provided with H2 as the electron donor. No precipitation was observed using H2 alone or with heat-killed cells. Reduction of aqueous Au(III) ions by both strains was demonstrated at pH 7 using 2 mM HAuCl4 solution and the concept was successfully applied to recover 100% of the gold from acidic leachate (115 ppm of Au(III)) obtained from jewellery waste. Bioreductive recovery of gold from aqueous solution was achieved within 2 h, giving crystalline Au(0) particles (20–50 nm), in the periplasmic space and on the cell surface, and small intracellular nanoparticles. The nanoparticle size was smaller (red suspension) at acidic pH (2.0) as compared to that obtained at pH 6.0 and 7.0 (purple) and 9.0 (dark blue). Comparable nanoparticles were obtained from Au(III) test solutions and jewellery leachate. Biotechnol. Bioeng. 2008;99: 1055–1064. © 2007 Wiley Periodicals, Inc.
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biomass supported palladium catalysts on Desulfovibrio desulfuricans and rhodobacter sphaeroides
Biotechnology and Bioengineering, 2008Co-Authors: Mark D Redwood, Victoria S Baxterplant, Kevin Deplanche, Lynne E MacaskieAbstract:A Rhodobacter sphaeroides-supported dried, ground palladium catalyst (“Rs-Pd(0)”) was compared with a Desulfovibrio desulfuricans-supported catalyst (“Dd-Pd(0)”) and with unsupported palladium metal particles made by reduction under H2 (“Chem-Pd(0)”). Cell surface-located clusters of Pd(0) nanoparticles were detected on both D. desulfuricans and R. sphaeroides but the size and location of deposits differed among comparably loaded preparations. These differences may underlie the observation of different activities of Dd-Pd(0) and Rs-Pd(0) when compared with respect to their ability to promote hydrogen release from hypophosphite and to catalyze chloride release from chlorinated aromatic compounds. Dd-Pd(0) was more effective in the reductive dehalogenation of polychlorinated biphenyls (PCBs), whereas Rs-Pd(0) was more effective in the initial dehalogenation of pentachlorophenol (PCP) although the rate of chloride release from PCP was comparable with both preparations after 2 h. Biotechnol. Bioeng. 2008;99: 1045–1054. © 2007 Wiley Periodicals, Inc.
Alain Dolla - One of the best experts on this subject based on the ideXlab platform.
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Coordinated response of the Desulfovibrio desulfuricans 27774 transcriptome to nitrate, nitrite and nitric oxide
Scientific Reports, 2017Co-Authors: Ian Cadby, Alain Dolla, Matthew Faulkner, Jeanne Chèneby, Justine Long, Jacques Van Helden, Jeffrey ColeAbstract:The sulfate reducing bacterium Desulfovibrio desulfuricans inhabits both the human gut and external environments. It can reduce nitrate and nitrite as alternative electron acceptors to sulfate to support growth. Like other sulphate reducing bacteria, it can also protect itself against nitrosative stress caused by NO generated when nitrite accumulates. By combining in vitro experiments with bioinformatic and RNA-seq data, metabolic responses to nitrate or NO and how nitrate and nitrite reduction are coordinated with the response to nitrosative stress were revealed. Although nitrate and nitrite reduction are tightly regulated in response to substrate availability, the global responses to nitrate or NO were largely regulated independently. Multiple NADH dehydrogenases, transcription factors of unknown function and genes for iron uptake were differentially expressed in response to electron acceptor availability or nitrosative stress. Amongst many fascinating problems for future research, the data revealed a YtfE orthologue, Ddes_1165, that is implicated in the repair of nitrosative damage. The combined data suggest that three transcription factors coordinate this regulation in which NrfS-NrfR coordinates nitrate and nitrite reduction to minimize toxicity due to nitrite accumulation, HcpR1 serves a global role in regulating the response to nitrate, and HcpR2 regulates the response to nitrosative stress.
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cytochrome c 3 mutants of Desulfovibrio desulfuricans
Applied and Environmental Microbiology, 2000Co-Authors: Barbara J Rappgiles, Laurence Casalot, Alain Dolla, R S English, Joseph A Ringbauer, Judy D. WallAbstract:To explore the physiological role of tetraheme cytochrome c3 in the sulfate-reducing bacterium Desulfovibrio desulfuricans G20, the gene encoding the preapoprotein was cloned, sequenced, and mutated by plasmid insertion. The physical analysis of the DNA from the strain carrying the integrated plasmid showed that the insertion was successful. The growth rate of the mutant on lactate with sulfate was comparable to that of the wild type; however, mutant cultures did not achieve the same cell densities. Pyruvate, the oxidation product of lactate, served as a poor electron source for the mutant. Unexpectedly, the mutant was able to grow on hydrogen-sulfate medium. These data support a role for tetraheme cytochrome c3 in the electron transport pathway from pyruvate to sulfate or sulfite in D. desulfuricans G20.
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the desulfuromonas acetoxidans triheme cytochrome c7 produced in Desulfovibrio desulfuricans retains its metal reductase activity
Applied and Environmental Microbiology, 1998Co-Authors: Corinne Aubert, Marieclaire Durand, Marc Rousset, Mireille Bruschi, Pierre Bianco, Elisabeth Lojou, Alain DollaAbstract:Multiheme cytochrome c proteins that belong to class III have been recently shown to exhibit a metal reductase activity, which could be of great environmental interest, especially in metal bioremediation. To get a better understanding of these activities, the gene encoding cytochrome c7 from the sulfur-reducing bacterium Desulfuromonas acetoxidans was cloned from genomic DNA by PCR and expressed in Desulfovibrio desulfuricans G201. The expression system was based on the cyc transcription unit from Desulfovibrio vulgaris Hildenborough and led to the synthesis of holocytochrome c7 when transferred by electrotransformation into the sulfate reducer Desulfovibrio desulfuricans G201. The produced cytochrome was indistinguishable from the protein purified from Desulfuromonas acetoxidans cells with respect to several biochemical and biophysical criteria and exhibited the same metal reductase activities as determined from electrochemical experiments. This suggests that the molecule was correctly folded in the host organism. Desulfovibrio desulfuricans produces functional multiheme c-type cytochromes from bacteria belonging to a different genus and may be considered a suitable host for the heterologous biogenesis of multiheme c-type cytochromes for either structural or engineering studies. This report, which presents the first example of the transformation of a Desulfovibrio desulfuricans strain by electrotransformation, describes work that is the first necessary step of a protein engineering program that aims to specify the structural features that are responsible for the metal reductase activities of multiheme cytochrome c7.
Mireille Bruschi - One of the best experts on this subject based on the ideXlab platform.
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the desulfuromonas acetoxidans triheme cytochrome c7 produced in Desulfovibrio desulfuricans retains its metal reductase activity
Applied and Environmental Microbiology, 1998Co-Authors: Corinne Aubert, Marieclaire Durand, Marc Rousset, Mireille Bruschi, Pierre Bianco, Elisabeth Lojou, Alain DollaAbstract:Multiheme cytochrome c proteins that belong to class III have been recently shown to exhibit a metal reductase activity, which could be of great environmental interest, especially in metal bioremediation. To get a better understanding of these activities, the gene encoding cytochrome c7 from the sulfur-reducing bacterium Desulfuromonas acetoxidans was cloned from genomic DNA by PCR and expressed in Desulfovibrio desulfuricans G201. The expression system was based on the cyc transcription unit from Desulfovibrio vulgaris Hildenborough and led to the synthesis of holocytochrome c7 when transferred by electrotransformation into the sulfate reducer Desulfovibrio desulfuricans G201. The produced cytochrome was indistinguishable from the protein purified from Desulfuromonas acetoxidans cells with respect to several biochemical and biophysical criteria and exhibited the same metal reductase activities as determined from electrochemical experiments. This suggests that the molecule was correctly folded in the host organism. Desulfovibrio desulfuricans produces functional multiheme c-type cytochromes from bacteria belonging to a different genus and may be considered a suitable host for the heterologous biogenesis of multiheme c-type cytochromes for either structural or engineering studies. This report, which presents the first example of the transformation of a Desulfovibrio desulfuricans strain by electrotransformation, describes work that is the first necessary step of a protein engineering program that aims to specify the structural features that are responsible for the metal reductase activities of multiheme cytochrome c7.
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Crystal structure of cytochrome c3 from Desulfovibrio desulfuricans Norway at 1.7 A resolution.
Journal of molecular biology, 1994Co-Authors: Mirjam Czjzek, Mireille Bruschi, Françoise Guerlesquin, Françoise Payan, R. HaserAbstract:Abstract The crystal structure of cytochrome c3 (Mr 13,000) from Desulfovibrio desulfuricans (118 residues, four heme groups) has been crystallographically refined to 1.7 A resolution using a annealing method, based on the structure-model at 2.5 A resolution, already published. The final R-factor for 10,549 reflections was 0·198 covering the range from 5·5 to 1·7 A resolution. The individual temperature factors were refined for a total of 1059 protein atoms, together with 126 bound solvent molecules. The structure has been analyzed with respect to its detailed conformational properties, secondary structure features, temperature factor behaviour, bound solvent sites and heme geometery and ligation. The characteristic secondary structures of the polypeptide chain of this molecule are one extended α-helix, a short β-strand and 13 reverse turns. The four heme groups are located in different structural environments, all highly exposed to solvent. The particular structural features of the heme environments are compared to the four hemes of the cytochrome c3 from Desulfovibrio vulgaris Miyazaki.
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kinetic studies of the electron exchange reaction between the octaheme cytochrome c3 mr 26000 and the hydrogenase from Desulfovibrio desulfuricans norway
Biochemical and Biophysical Research Communications, 1991Co-Authors: Jean Haladjian, Pierre Bianco, Françoise Guerlesquin, Mireille BruschiAbstract:Abstract The octaheme cytochrome c 3 (Mr 26000) from Desulfovibrio desulfuricans Norway was studied using cyclic voltammetry at the pyrolytic graphite electrode. The kinetics of reduction of the octaheme cytochrome c 3 (Mr 26000) from D. desulfuricans Norway by the Ni-Fe-Se hydrogenase purified from the same organism was investigated by an electrochemical method. From cyclic voltammetry experiments a value of 8.10 8 M −1 s −1 was obtained for the second order homogenous rate constant of the electron transfer between the two proteins. Results are compared with similar experiments performed on the electron exchange between the tetrahemic cytochrome c 3 (Mr 13000) and hydrogenase.
Ligia M Saraiva - One of the best experts on this subject based on the ideXlab platform.
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the anaerobe Desulfovibrio desulfuricans atcc 27774 grows at nearly atmospheric oxygen levels
FEBS Letters, 2007Co-Authors: Susana A L Lobo, Miguel Teixeira, Ana M P Melo, Joao N Carita, Ligia M SaraivaAbstract:Sulfate reducing bacteria of the Desulfovibrio genus are considered anaerobes, in spite of the fact that they are frequently isolated close to oxic habitats. However, until now, growth in the presence of high concentrations of oxygen was not reported for members of this genus. This work shows for the first time that the sulfate reducing bacterium Desulfovibrio desulfuricans ATCC 27774 is able to grow in the presence of nearly atmospheric oxygen levels. In addition, the activity and expression profile of several key enzymes was analyzed under different oxygen concentrations.
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a novel membrane bound respiratory complex from Desulfovibrio desulfuricans atcc 27774
Biochimica et Biophysica Acta, 2003Co-Authors: Ricardo H Pires, Antonio V Xavier, Miguel Teixeira, Ligia M Saraiva, Alexandra Lourenco, Francisco Morais, Ines A C PereiraAbstract:Abstract In the anaerobic respiration of sulfate, performed by sulfate-reducing prokaryotes, reduction of the terminal electron acceptor takes place in the cytoplasm. The membrane-associated electron transport chain that feeds electrons to the cytoplasmic reductases is still very poorly characterized. In this study we report the isolation and characterization of a novel membrane-bound redox complex from Desulfovibrio desulfuricans ATCC 27774. This complex is formed by three subunits, and contains two hemes b , two FAD groups and several iron–sulfur centers. The two hemes b are low-spin, with macroscopic redox potentials of +75 and −20 mV at pH 7.6. Both hemes are reduced by menadiol, a menaquinone analogue, indicating a function for this complex in the respiratory electron-transport chain. EPR studies of the as-isolated and dithionite-reduced complex support the presence of a [3Fe–4S] 1+/0 center and at least four [4Fe–4S] 2+/1+ centers. Cloning of the genes coding for the complex subunits revealed that they form a putative transcription unit and have homology to subunits of heterodisulfide reductases (Hdr). The first and second genes code for soluble proteins that have homology to HdrA, whereas the third gene codes for a novel type of membrane-associated protein that contains both a hydrophobic domain with homology to the heme b protein HdrE and a hydrophilic domain with homology to the iron–sulfur protein HdrC. Homologous operons are found in the genomes of other sulfate-reducing organisms and in the genome of the green-sulfur bacterium Chlorobium tepidum TLS. The isolated complex is the first example of a new family of respiratory complexes present in anaerobic prokaryotes.
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in the facultative sulphate nitrate reducer Desulfovibrio desulfuricans atcc 27774 the nine haem cytochrome c is part of a membrane bound redox complex mainly expressed in sulphate grown cells
Biochimica et Biophysica Acta, 2001Co-Authors: Ligia M Saraiva, Antonio V Xavier, Patricia N Da Costa, Cristiano Conte, Jean LegallAbstract:The bacterium Desulfovibrio desulfuricans ATCC 27774 belongs to the group of sulphate reducers also capable of utilising nitrate as its terminal electron acceptor for anaerobic growth. One of the complex multihaem proteins found in nitrate- or sulphate-grown cells of Desulfovibrio desulfuricans ATCC 27774 is the nine-haem cytochrome c. The present work shows that the gene encoding for Desulfovibrio desulfuricans ATCC 27774 nine-haem cytochrome c is part of an operon formed by the gene cluster 9hcA-D. Besides 9hcA, the gene encoding for the nine-haem cytochrome c, genes 9hcB to D encode for a protein containing four [4Fe-4S](2+/1+) centres, for a dihaem transmembrane cytochrome b and for an unknown hydrophobic protein, respectively. The four proteins have a predicted topology that is in accordance with the formation of a membrane-bound redox complex. Furthermore, the transcriptional studies show that not only the expression of the 9HcA-D complex is dependent on the growth phase, but also is markedly increased in sulphate-grown cells.
Judy D. Wall - One of the best experts on this subject based on the ideXlab platform.
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genome sequence of the mercury methylating strain Desulfovibrio desulfuricans nd132
Journal of Bacteriology, 2011Co-Authors: Steven D Brown, Judy D. Wall, Cynthia C Gilmour, Amy M Kucken, Dwayne A Elias, Craig C Brandt, Mircea Podar, Olga Chertkov, Brittany HeldAbstract:Desulfovibrio desulfuricans strain ND132 is an anaerobic sulfate-reducing bacterium (SRB) capable of producing methylmercury (MeHg), a potent human neurotoxin. The mechanism of methylation by this and other organisms is unknown. We present the 3.8-Mb genome sequence to provide further insight into microbial mercury methylation.
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A Molybdopterin Oxidoreductase Is Involved in H2 Oxidation in Desulfovibrio desulfuricans G20
Journal of bacteriology, 2009Co-Authors: Qingwei Luo, Judy D. Wall, Neil Q. Wofford, Kimberly L. Keller, Michael J. Mcinerney, Lee R. KrumholzAbstract:Three mutants deficient in hydrogen/formate uptake were obtained through screening of a transposon mutant library containing 5,760 mutants of Desulfovibrio desulfuricans G20. Mutations were in the genes encoding the type I tetraheme cytochrome c3 (cycA), Fe hydrogenase (hydB), and molybdopterin oxidoreductase (mopB). Mutations did not decrease the ability of cells to produce H2 or formate during growth. Complementation of the cycA and mopB mutants with a plasmid carrying the intact cycA and/or mopB gene and the putative promoter from the parental strain allowed the recovery of H2 uptake ability, showing that these specific genes are involved in H2 oxidation. The mop operon encodes a periplasm-facing transmembrane protein complex which may shuttle electrons from periplasmic cytochrome c3 to the menaquinone pool. Electrons can then be used for sulfate reduction in the cytoplasm.
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Interaction between uranium and the cytochrome c3 of Desulfovibrio desulfuricans strain G20
Archives of Microbiology, 2004Co-Authors: Rayford B. Payne, Tessa Rivere, Jeff Terry, Lise Larsen, Barbara J. Giles, Laurence Casalot, Judy D. WallAbstract:Cytochrome c3 of Desulfovibrio desulfuricans strain G20 is an electron carrier for uranium (VI) reduction. When D. desulfuricans G20 was grown in medium containing a non-lethal concentration of uranyl acetate (1 mM), the rate at which the cells reduced U(VI) was decreased compared to cells grown in the absence of uranium. Western analysis did not detect cytochrome c3 in periplasmic extracts from cells grown in the presence of uranium. The expression of this predominant tetraheme cytochrome was not detectably altered by uranium during growth of the cells as monitored through a translational fusion of the gene encoding cytochrome c3 (cycA) to lacZ. Instead, cytochrome c3 protein was found tightly associated with insoluble U(IV), uraninite, after the periplasmic contents of cells were harvested by a pH shift. The association of cytochrome c3 with U(IV) was interpreted to be non-specific, since pure cytochrome c3 adsorbed to other insoluble metal oxides, including cupric oxide (CuO), ferric oxide (Fe2O3), and commercially available U(IV) oxide.
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cytochrome c 3 mutants of Desulfovibrio desulfuricans
Applied and Environmental Microbiology, 2000Co-Authors: Barbara J Rappgiles, Laurence Casalot, Alain Dolla, R S English, Joseph A Ringbauer, Judy D. WallAbstract:To explore the physiological role of tetraheme cytochrome c3 in the sulfate-reducing bacterium Desulfovibrio desulfuricans G20, the gene encoding the preapoprotein was cloned, sequenced, and mutated by plasmid insertion. The physical analysis of the DNA from the strain carrying the integrated plasmid showed that the insertion was successful. The growth rate of the mutant on lactate with sulfate was comparable to that of the wild type; however, mutant cultures did not achieve the same cell densities. Pyruvate, the oxidation product of lactate, served as a poor electron source for the mutant. Unexpectedly, the mutant was able to grow on hydrogen-sulfate medium. These data support a role for tetraheme cytochrome c3 in the electron transport pathway from pyruvate to sulfate or sulfite in D. desulfuricans G20.