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Mireille Bruschi - One of the best experts on this subject based on the ideXlab platform.
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conformational properties of multihemic cytochromes c from Desulfuromonas acetoxidans
Thermochimica Acta, 2003Co-Authors: M T Giudiciorticoni, A A Makarov, V M Lobachov, I I Protasevich, D Lexa, Mireille BruschiAbstract:Abstract In the classification of c-type cytochromes, the class III includes multihemic cytochromes c with low redox potential constituting the cytochrome c3 superfamily. Most of the cytochromes described have been isolated from sulfate or sulfur reducing bacteria. We report here the comparison between two multihemic cytochromes, the newly characterized 50 kDa cytochrome from Desulfuromonas acetoxidans and the cytochrome c7 from the same strain in order to contribute to understanding the relationships between members of this superfamily. The thermostability of these cytochromes was studied by circular dichroism (CD) and differential scanning calorimetry (DSC). The influence of the temperature on the redox potential was also investigated. The data clearly indicate the presence of two domains in 50 kDa cytochrome and a drastic loss of stability of cytochrome c7 in comparison to cytochrome c3. The results are discussed in the light of the structural properties of the cytochrome c3 superfamily and two sub-groups in this family are proposed.
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Enzymatic reduction of chromate: comparative studies using sulfate-reducing bacteria
Applied Microbiology and Biotechnology, 2001Co-Authors: C Michel, Myriam Brugna, Alain Bernadac, Corinne Aubert, Mireille BruschiAbstract:Various sulfate-reducing bacteria of the genera Desulfovibrio and Desulfomicrobium were tested and compared for enzymatic reduction of chromate. Our study demonstrated that the ability to reduce chromate is widespread among sulfate-reducing bacteria. Among them, Desulfomicrobium norvegicum reduced Cr(VI) with the highest reaction rate. This strain grew in the presence of up to 500 μM chromate, but Cr(VI) reduction in the absence of sulfate was not associated with growth. The presence of chromate induced morphological changes and leakage of periplasmic proteins into the medium. The ability of isolated polyheme cytochromes c from sulfate- and sulfur-reducing bacteria to reduce chromate was also analyzed. Tetraheme cytochrome c3(Mr. 13,000) from Desulfomicrobium norvegicum showed twice as much activity as either tetraheme cytochrome c3 from Desulfovibrio vulgaris strain Hildenborough or triheme cytochrome c7 from Desulfuromonas acetoxidans. Results with cytochromes c3 and other c-type cytochromes altered by site-directed mutagenesis indicated that negative redox potential hemes are crucial for metal reductase activity. The present study also demonstrated that the (Fe) hydrogenase from sulfate-reducing bacteria could reduce chromate.
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resonance raman study of multihemic c type cytochromes from Desulfuromonas acetoxidans
FEBS Journal, 2000Co-Authors: Genevia Ve Chottard, Irina Kazanskaya, Mireille BruschiAbstract:Two multihemic cytochromes c from the sulfur reducing bacteria Desulfuromonas acetoxidans have been studied by optical and resonance Raman spectroscopy: cytochrome c551.5, a trihemic cytochrome and cytochrome c Mr 50 000, a recently isolated high molecular mass cytochrome. The redox and Raman characteristics of cytochrome c551.5 are compared to those of the tetrahemic cytochromes c3 from Desulfovibrio. While the redox behavior, followed by spectroelectrochemistry, is similar to that of cytochrome c3, showing the same conformational change after reduction of the highest potential heme, the Raman data show a contribution from a His− form of the axial ligands and lead to the assignment of a band at 218 cm−1 to the Fe(III)–(His)2 stretching vibration. The Raman data on cytochrome c Mr 50 000 are in favor of an entirely low spin species with two different sets of axial ligands. A partially reduced state is easily accessible by ascorbate addition.
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Resonance Raman study of multihemic c‐type cytochromes from Desulfuromonas acetoxidans
FEBS Journal, 2000Co-Authors: Genevia Ve Chottard, Irina Kazanskaya, Mireille BruschiAbstract:Two multihemic cytochromes c from the sulfur reducing bacteria Desulfuromonas acetoxidans have been studied by optical and resonance Raman spectroscopy: cytochrome c551.5, a trihemic cytochrome and cytochrome c Mr 50 000, a recently isolated high molecular mass cytochrome. The redox and Raman characteristics of cytochrome c551.5 are compared to those of the tetrahemic cytochromes c3 from Desulfovibrio. While the redox behavior, followed by spectroelectrochemistry, is similar to that of cytochrome c3, showing the same conformational change after reduction of the highest potential heme, the Raman data show a contribution from a His− form of the axial ligands and lead to the assignment of a band at 218 cm−1 to the Fe(III)–(His)2 stretching vibration. The Raman data on cytochrome c Mr 50 000 are in favor of an entirely low spin species with two different sets of axial ligands. A partially reduced state is easily accessible by ascorbate addition.
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first evidence for the presence of a hydrogenase in the sulfur reducing bacterium Desulfuromonas acetoxidans
Journal of Bacteriology, 1999Co-Authors: Myriam Brugna, Mireille Bruschi, Wolfgang Nitschke, Rene Toci, Marietherese GiudiciorticoniAbstract:Hydrogenases, which are ubiquitous in sulfate-reducing bacteria, were previously thought to be absent from Desulfuromonas acetoxidans. For the first time, a hydrogenase from the strict anaerobic sulfur-respiring bacterium D. acetoxidans, grown on ethanol-malate, was detected and enriched. To assay the role of the hydrogenase in the energetic metabolism of D. acetoxidans, we examined the reactivity of the enzyme with polyheme cytochromes from the same bacterium.
Norbert Pfennig - One of the best experts on this subject based on the ideXlab platform.
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Desulfuromonas thiophila sp nov a new obligately sulfur reducing bacterium from anoxic freshwater sediment
International Journal of Systematic and Evolutionary Microbiology, 1997Co-Authors: Kai Finster, John D. Coates, Werner Liesack, Norbert PfennigAbstract:A mesophilic, acetate-oxidizing, sulfur-reducing bacterium, strain NZ27T, was isolated from anoxic mud from a freshwater sulfur spring. The cells were ovoid, motile, and gram negative. In addition to acetate, the strain oxidized pyruvate, succinate, and fumarate. Sulfur flower could be replaced by polysulfide as an electron acceptor. Ferric nitrilotriacetic acid was reduced in the presence of pyruvate; however, this reduction did not sustain growth. These phenotypic characteristics suggested that strain NZ27T is affiliated with the genus Desulfuromonas. A phylogenetic analysis based on the results of comparative 16S ribosomal DNA sequencing confirmed that strain NZ27T belongs to the Desulfuromonas cluster in the recently proposed family “Geobacter-aceae” in the delta subgroup of the Proteobacteria. In addition, the results of DNA-DNA hybridization studies confirmed that strain NZ27T represents a novel species. Desulfuromonas thiophila, a name tentatively used in previous publications, is the name proposed for strain NZ27T in this paper.
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Desulfuromonas acetexigens sp. nov., a dissimilatory sulfur-reducing eubacterium from anoxic freshwater sediments
Archives of Microbiology, 1994Co-Authors: Kai Finster, Norbert PfennigAbstract:Five strains of obligate anaerobic sulfur-reducing eubacteria that exclusively use acetate as energy and carbon source have been enriched and isolated from anoxic sulfide-containing freshwater mud. The strains were unable to grow in the presence of 2% NaCl. Morphologically the strains were not uniform, cells were either rod-shaped or elongated ovoid. All strains were flagellated with a single polar to subpolar flagellum. They stained gram-negative. Two of the strains were studied in detail. Malate or fumarate was used alternatively to elemental sulfur as electron acceptor. The capacity to grow on acetate as sole organic substrate and to reduce elemental sulfur or polysulfide to sulfide are traits in common with the genus Desulfuromonas . The strains differ from Desulfuromonas acetoxidans by their freshwater origin, morphology, metabolic specialization and their DNA base ratio. Therefore we consider the new isolates as a new species for which the name Desulfuromonas acetexigens is proposed.
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Photoproduction of H2 from acetate by syntrophic cocultures of green sulfur bacteria and sulfur-reducing bacteria
Archives of Microbiology, 1992Co-Authors: Rolf Warthmann, Heribert Cypionka, Norbert PfennigAbstract:The marine green sulfur bacterium Chlorobium vibrioforme strain 1930 produced H2 and elemental sulfur from sulfide or thiosulfate under N limitation in the light. H2 production depended on nitrogenase and occurred only in the absence of ammonia. Methionine sulfoximine, an inhibitor of glutamine synthetase, prevented the switch-off by ammonia. In defined syntrophic cocultures of the acetate-oxidizing, sulfur-reducing bacterium Desulfuromonas acetoxidans with green sulfur bacteria, H2 was produced from acetate via a light-driven sulfur cycle. The sulfur-reducing bacterium could not be replaced by sulfate-reducing bacteria in these experiments. In a coculture of the marine Chlorobium vibrioforme strain 1930 and the sulfur-reducing bacterium Desulfuromonas acetoxidans strain 5071, optimum long-term H2 production from acetate was obtained with molecular nitrogen as N source, at low light intensity (110 μmol · m-2 · s-1), in sulfide-reduced mineral medium (2 mM Na2S) at pH 6.8. Traces of sulfide (10 μM) were sufficient to keep the sulfur cycle running. The coculture formed no poly-β-hydroxyalkanoates (PHA), but 20%–40% polysaccharide per cell dry mass. Per mol acetate added, the coculture formed 3.1 mol of H2 (78% of the theoretical maximum). Only 8% of the reducing equivalents was incorporated into biomass. The maximum rate of H2 production was 1300 ml H2 per day and g cell dry mass.
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the genus Desulfuromonas and other gram negative sulfur reducing eubacteria
1992Co-Authors: Friedrich Widdel, Norbert PfennigAbstract:The ability to gain energy for growth by dissimilatory reduction of elemental sulfur in a respiratory type of metabolism (with the formation of sulfide) is found in several genera of eubacteria and archaebacteria. H2 or organic substrates, mainly simple organic acids, serve as electron donors. There are, however, other organisms, including some eukaryotes, that reduce sulfur in a nonrespiratory manner; in this case, sulfur acts merely as a hydrogen sink in a “facilitated fermentation,” or is reduced in a by-reaction without obvious bioenergetic significance. An overview and details of physiology and biochemistry of sulfur reduction are given in Chapter 24.
Frank E Loffler - One of the best experts on this subject based on the ideXlab platform.
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Characterization of microbial community structure and population dynamics of tetrachloroethene-dechlorinating tidal mudflat communities
Biodegradation, 2011Co-Authors: Frank E Loffler, Joonhong ParkAbstract:Tetrachloroethene (PCE) and trichloroethene (TCE) are common groundwater contaminants that also impact tidal flats, especially near urban and industrial areas. However, very little is known about dechlorinating microbial communities in tidal flats. Titanium pyrosequencing, 16S rRNA gene clone libraries, and dechlorinator-targeted quantitative real-time PCR (qPCR) characterized reductive dechlorinating activities and populations in tidal flat sediments collected from South Korea’s central west coast near Kangwha. In microcosms established with surface sediments, PCE dechlorination to TCE began within 10 days and 100% of the initial amount of PCE was converted to TCE after 37 days. cis -1,2-Dichloroethene ( cis -DCE) was observed as dechlorination end product in microcosms containing sediments collected from deeper zones (i.e., 35–40 cm below ground surface). Pyrosequencing of bacterial 16S rRNA genes and 16S rRNA gene-targeted qPCR results revealed Desulfuromonas michiganensis -like populations predominanted in both TCE and cis -DCE producing microcosms. Other abundant groups included Desulfuromonas thiophila and Pelobacter acidigallici -like populations in the surface sediment microcosms, and Desulfovibrio dechloracetivorans and Fusibacter paucivorans -like populations in the deeper sediment microcosms. Dehalococcoides spp. populations were not detected in these sediments before and after incubation with PCE. The results suggest that tidal flats harbor novel, salt-tolerant dechlorinating populations and that titanium pyrosequencing provides more detailed insight into community structure dynamics of the dechlorinating microcosms than conventional 16S rRNA gene sequencing or fingerprinting methods.
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characterization of two tetrachloroethene reducing acetate oxidizing anaerobic bacteria and their description as Desulfuromonas michiganensis sp nov
Applied and Environmental Microbiology, 2003Co-Authors: Youlboong Sung, James M Tiedje, Kirsti M Ritalahti, Robert A Sanford, John W Urbance, Shannon J Flynn, Frank E LofflerAbstract:Two tetrachlorethene (PCE)-dechlorinating populations, designated strains BB1 and BRS1, were isolated from pristine river sediment and chloroethene-contaminated aquifer material, respectively. PCE-to-cis-1,2-dichloroethene-dechlorinating activity could be transferred in defined basal salts medium with acetate as the electron donor and PCE as the electron acceptor. Taxonomic analysis based on 16S rRNA gene sequencing placed both isolates within the Desulfuromonas cluster in the δ subdivision of the Proteobacteria. PCE was dechlorinated at rates of at least 139 nmol min−1 mg of protein−1 at pH values between 7.0 and 7.5 and temperatures between 25 and 30°C. Dechlorination also occurred at 10°C. The electron donors that supported dechlorination included acetate, lactate, pyruvate, succinate, malate, and fumarate but not hydrogen, formate, ethanol, propionate, or sulfide. Growth occurred with malate or fumarate alone, whereas oxidation of the other electron donors depended strictly on the presence of fumarate, malate, ferric iron, sulfur, PCE, or TCE as an electron acceptor. Nitrate, sulfate, sulfite, thiosulfate, and other chlorinated compounds were not used as electron acceptors. Sulfite had a strong inhibitory effect on growth and dechlorination. Alternate electron acceptors (e.g., fumarate or ferric iron) did not inhibit PCE dechlorination and were consumed concomitantly. The putative fumarate, PCE, and ferric iron reductases were induced by their respective substrates and were not constitutively present. Sulfide was required for growth. Both strains tolerated high concentrations of PCE, and dechlorination occurred in the presence of free-phase PCE (dense non-aqueous-phase liquids). Repeated growth with acetate and fumarate as substrates yielded a BB1 variant that had lost the ability to dechlorinate PCE. Due to the 16S rRNA gene sequence differences with the closest relatives and the unique phenotypic characteristics, we propose that the new isolates are members of a new species, Desulfuromonas michiganensis, within the Desulfuromonas cluster of the Geobacteraceae.
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Bioreactive Barriers: A Comparison of Bioaugmentation and Biostimulation for Chlorinated Solvent Remediation
Environmental Science & Technology, 2003Co-Authors: John M. Lendvay, Frank E Loffler, M. Dollhopf, Michael R. Aiello, G. Daniels, Babu Z. Fathepure, M. Gebhard, R. Heine, R. HeltonAbstract:A side-by-side comparison of bioaugmentation, biostimulation, and a recirculation-only control was implemented in a chloroethene-contaminated aquifer. The objective was to develop a contaminant mass balance based on the analysis of groundwater and aquifer solids and to quantify key dechlorinating populations during treatment to determine their relation to the rate of chloroethenes removed. The bioaugmentation strategy, using a Dehalococcoides-containing PCE-to-ethene dechlorinating inoculum enriched from the same aquifer, resulted in a near-stoichiometric dechlorination of both sorbed and dissolved chloroethenes to ethene within 6 weeks. In the biostimulation plot, continuous lactate and nutrient injection resulted in dechlorination but only following a 3-month lag period. Molecular tools targeting the 16S rRNA genes of Dehalococcoides and Desulfuromonas spp. were used to qualitatively monitor the distribution and quantitatively (Real-Time PCR) measure the abundance of the dechlorinating populations durin...
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16s rrna gene based detection of tetrachloroethene dechlorinating Desulfuromonas and dehalococcoides species
Applied and Environmental Microbiology, 2000Co-Authors: Frank E Loffler, Jieran Li, James M TiedjeAbstract:Members of the genera Desulfuromonas and Dehalococcoides reductively dechlorinate tetrachloroethene (PCE) and trichloroethene. Two primer pairs specific to hypervariable regions of the 16S rRNA genes of the Dehalococcoides group (comprising Dehalococcoides ethenogenes and Dehalococcoides sp. strain FL2) and the acetate-oxidizing, PCE-dechlorinating Desulfuromonas group (comprising Desulfuromonas sp. strain BB1 and Desulfuromonas chloroethenica) were designed. The detection threshold of a nested PCR approach using universal bacterial primers followed by a second PCR with the Desulfuromonas dechlorinator-targeted primer pair was 1 x 10{sup 3} BB1 cells added per gram (wet weight) of sandy aquifer material. Total community DNA isolated from sediments of three Michigan rivers and six different chloroethene-contaminated aquifer samples was used as template in nested PCR. All river sediment samples yielded positive signals with the BB1- and the Dehalococcoides-targeted primers. One chloroethene-contaminated aquifer tested positive with the Dehalococcoides-targeted primers, and another contaminated aquifer tested positive with the Desulfuromonas dechlorinator-targeted primer pair. Restriction fragment analysis of the amplicons could discriminate strain BB1 from other known Desulfuromonas species. Microcosm studies confirmed the presence of PCE-dechlorinating, acetate-oxidizing Desulfuromonas and hydrogenotrophic Dehalococcoides species in samples yielding positive PCR signals with the specific primers.
Derek R Lovley - One of the best experts on this subject based on the ideXlab platform.
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sulfur oxidation to sulfate coupled with electron transfer to electrodes by Desulfuromonas strain tz1
Microbiology, 2014Co-Authors: Tian Zhang, Timothy S Bain, Melissa Barlett, Oona Snoeyenboswest, Kelly P Nevin, Derek R LovleyAbstract:Microbial oxidation of elemental sulfur with an electrode serving as the electron acceptor is of interest because this may play an important role in the recovery of electrons from sulfidic wastes and for current production in marine benthic microbial fuel cells. Enrichments initiated with a marine sediment inoculum, with elemental sulfur as the electron donor and a positively poised (+300 mV versus Ag/AgCl) anode as the electron acceptor, yielded an anode biofilm with a diversity of micro-organisms, including Thiobacillus, Sulfurimonas, Pseudomonas, Clostridium and Desulfuromonas species. Further enrichment of the anode biofilm inoculum in medium with elemental sulfur as the electron donor and Fe(III) oxide as the electron acceptor, followed by isolation in solidified sulfur/Fe(III) medium yielded a strain of Desulfuromonas, designated strain TZ1. Strain TZ1 effectively oxidized elemental sulfur to sulfate with an anode serving as the sole electron acceptor, at rates faster than Desulfobulbus propionicus, the only other organism in pure culture previously shown to oxidize S° with current production. The abundance of Desulfuromonas species enriched on the anodes of marine benthic fuel cells has previously been interpreted as acetate oxidation driving current production, but the results presented here suggest that sulfur-driven current production is a likely alternative.
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Sulfide-Driven Microbial Electrosynthesis
Environmental Science & Technology, 2012Co-Authors: Yanming Gong, Tian Zhang, Derek R Lovley, Ali Ebrahim, Adam M. Feist, Mallory Embree, Karsten ZenglerAbstract:Microbial electrosynthesis, the conversion of carbon dioxide to organic molecules using electricity, has recently been demonstrated for acetogenic microorganisms, such as Sporomusa ovata. The energy for reduction of carbon dioxide originates from the hydrolysis of water on the anode, requiring a sufficiently low potential. Here we evaluate the use of sulfide as an electron source for microbial electrosynthesis. Abiotically oxidation of sulfide on the anode yields two electrons. The oxidation product, elemental sulfur, can be further oxidized to sulfate by Desulfobulbus propionicus, generating six additional electrons in the process. The eight electrons generated from the combined abiotic and biotic steps were used to reduce carbon dioxide to acetate on a graphite cathode by Sporomusa ovata at a rate of 24.8 mmol/day·m2. Using a strain of Desulfuromonas as biocatalyst on the anode resulted in an acetate production rate of 49.9 mmol/day·m2, with a Coulombic efficiency of over 90%. These results demonstrate ...
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Constraint-based modeling analysis of the metabolism of two Pelobacter species
BMC Systems Biology, 2010Co-Authors: Shelley A. Haveman, Tom R Fahland, Derek R LovleyAbstract:Background Pelobacter species are commonly found in a number of subsurface environments, and are unique members of the Geobacteraceae family. They are phylogenetically intertwined with both Geobacter and Desulfuromonas species. Pelobacter species likely play important roles in the fermentative degradation of unusual organic matters and syntrophic metabolism in the natural environments, and are of interest for applications in bioremediation and microbial fuel cells.
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comparison of 16s rrna nifd reca gyrb rpob and fusa genes within the family geobacteraceae fam nov
International Journal of Systematic and Evolutionary Microbiology, 2004Co-Authors: Dawn E Holmes, Kelly P Nevin, Derek R LovleyAbstract:The sequences of five conserved genes, in addition to the 16S rRNA gene, were investigated in 30 members of the Geobacteraceae fam. nov. All members of the Geobacteraceae examined contained nifD, suggesting that they are capable of nitrogen fixation, which may explain their ability to compete effectively in nitrogen-poor subsurface environments undergoing remediation for petroleum or metal contamination. The phylogenies predicted from rpoB, gyrB, fusA, recA and nifD were generally in agreement with the phylogeny predicted from 16S rRNA gene sequences. Furthermore, phylogenetic analysis of concatemers constructed from all five protein-coding genes corresponded closely with the 16S rRNA gene-based phylogeny. This study demonstrated that the Geobacteraceae is a phylogenetically coherent family within the δ-subclass of the Proteobacteria that is composed of three distinct phylogenetic clusters: Geobacter, Desulfuromonas and Desulfuromusa. The sequence data provided here will make it possible to discriminate better between physiologically distinct members of the Geobacteraceae, such as Pelobacter propionicus and Geobacter species, in geobacteraceae-dominated microbial communities and greatly expands the potential to identify geobacteraceae sequences in libraries of environmental genomic DNA.
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Trichlorobacter thiogenes Should Be Renamed as a Geobacter Species
Applied and Environmental Microbiology, 2001Co-Authors: Oona Snoeyenbos-west, Catherine V. Gaw Van Praagh, Derek R LovleyAbstract:In a recent paper by De Wever et al. (2), it is proposed that the recently isolated microorganism strain K1 be assigned to a new genus within the delta Proteobacteria. Those authors state that the 16S ribosomal DNA (rDNA) sequence of strain K1 places it within a “cluster of mixed taxonomic affiliation” within the delta Proteobacteria. From this statement it is apparent that De Wever et al. (2) are unaware of several previous phylogenetic analyses of this group within the delta Proteobacteria, most notably, a study by Lonergan et al. (5). As De Wever et al. (2) note, the 16S rDNA sequence of strain K1 is nearly identical (99% sequence identity) to a 16S rDNA sequence recovered from a bioreactor that they misidentify as “environmental sp. 2” but that is actually an environmental sequence first described as a population type 1 sequence (Desulfuromonas-like sp.) (1) and listed by both GenBank and the Ribosomal Database Project (RDP) II (9) release 7.1 as Desulfuromonas sp. (GenBank accession number {"type":"entrez-nucleotide","attrs":{"text":"M80618","term_id":"174326","term_text":"M80618"}}M80618). If De Wever et al. (2) had known about the study by Lonergan et al. (5), they would have realized that detailed analysis of this sequence has demonstrated that it rests squarely within the Geobacter cluster of the family Geobacteraceae (5). Our own analysis of the strain K1 sequence confirms not only that the overall sequence of strain K1 is closely related to organisms in the Geobacter cluster (Fig. (Fig.1)1) but also that the sequence contains the signature secondary structures characteristic of the Geobacter cluster (5). FIG. 1 Phylogenetic tree inferred from 16S rRNA sequences showing the phylogenetic placement of “Trichlorobacter thiogenes” strain K1. Phylogenetic relationships shown here were inferred by using neighbor joining and Kimura two-parameter genetic ... At this time, the Geobacter cluster contains only one organism, Pelobacter propionicus, that does not have the genus designation Geobacter (Fig. (Fig.1).1). There are four more species of Pelobacter within the Geobacteraceae family, but these other Pelobacter species are interspersed throughout two other genera outside the Geobacter cluster. Thus, it is clear that the genus Pelobacter is not phylogenetically coherent and that organisms in the Geobacter cluster cannot be renamed Pelobacter as this would result in organisms of different phylogenetic clusters being placed within the same genus. It has been suggested that the simplest way to avoid confusion with the phylogeny is to place P. propionicus in the genus Geobacter (5). Therefore, designation of strain K1 as a new genus within the Geobacter cluster, as suggested by De Wever et al. (2), creates havoc within an otherwise logical grouping of organisms, comprised of predominantly a single genus within a phylogenetically coherent cluster. Designation of a new genus might be warranted if strain K1 had some unique physiological characteristics that distinguished it from previously described Geobacter species, but this does not appear to be the case. Strain K1 uses acetate as an electron donor for the reduction of S0 and fumarate, and it has been suggested that it might also use Fe(III) as an electron acceptor (2). The oxidation of acetate coupled to the reduction of S0 and Fe(III) is one of the defining physiological characteristics of Geobacter species, and many Geobacter species can also use fumarate as an electron acceptor for acetate oxidation (6, 7, 8). Strain K1 does reductively dechlorinate trichloroacetic acid, a physiological capacity not previously reported for Geobacter species. However, to our knowledge, no other organisms in the Geobacter cluster have been evaluated for the ability to carry out this reaction. Therefore, it is not clear that strain K1 is unique among organisms in the Geobacter cluster in this ability. Furthermore, De Wever et al. (2) suggest that at least part of the reductive dechlorination observed with strain K1 is the result of strain K1 reducing S0 to sulfide, with the subsequent reduction of the trichloroacetic acid by sulfide. Since all organisms in the Geobacter cluster have the ability to reduce S0 to sulfide, it is likely that all Geobacter species have the ability to dechlorinate trichloroacetic acid via this electron shuttling mechanism. Furthermore, even if all the organisms in the Geobacter cluster other than strain K1 were found to not be able to reductively dechlorinate trichloroacetic acid, precedence suggests that the designation of a new genus would not be warranted. When the first organism in the Desulfuromonas cluster of the Geobacteraceae found to have the ability to carry out reductive dechlorination was described (4), it was not assigned to a new genus; rather, it was designated a new species in the genus Desulfuromonas (3). This is consistent with the concept of not cluttering phylogenetically coherent groups with multiple genus designations. In summary, designating strain K1 as a new genus in the Geobacter cluster at this time advances neither clarity in phylogeny or understanding of physiology. It is suggested that, once the characterization of the physiology of strain K1 is completed, it be designated a new species in the genus Geobacter.
Bo Barker Jorgensen - One of the best experts on this subject based on the ideXlab platform.
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Desulfuromonas svalbardensis sp. nov. and Desulfuromusa ferrireducens sp. nov., psychrophilic, Fe(III)-reducing bacteria isolated from Arctic sediments, Svalbard.
International journal of systematic and evolutionary microbiology, 2020Co-Authors: Verona Vandieken, Marc Mussmann, Helge Niemann, Bo Barker JorgensenAbstract:Two psychrophilic, Gram-negative, rod-shaped, motile bacteria (strains 112T and 102T) that conserved energy from dissimilatory Fe(III) reduction concomitant with acetate oxidation were isolated from permanently cold Arctic marine sediments. Both strains grew at temperatures down to -2 degrees C, with respective temperature optima of 14 degrees C and 14-17 degrees C for strains 112T and 102T. The isolated strains reduced Fe(III) using common fermentation products such as acetate, lactate, propionate, formate or hydrogen as electron donors, and they also grew with fumarate as the sole substrate. As alternatives to Fe(III), they reduced fumarate, S0 and Mn(IV). Based on 16S rRNA gene sequence similarity, strain 112T was most closely related to Desulfuromonas acetoxidans (97.0 %) and Desulfuromonas thiophila NZ27T (95.5 %), and strain 102T to Malonomonas rubra Gra Mal 1T (96.3 %) and Desulfuromusa succinoxidans GylacT (95.9 %) within the Deltaproteobacteria. Strains 112T and 102T therefore represent novel species, for which the names Desulfuromonas svalbardensis sp. nov. (type strain 112T=DSM 16958T=JCM 12927T) and Desulfuromusa ferrireducens sp. nov. (type strain 102T=DSM 16956T=JCM 12926T) are proposed.
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Desulfuromonas svalbardensis sp nov and desulfuromusa ferrireducens sp nov psychrophilic fe iii reducing bacteria isolated from arctic sediments svalbard
International Journal of Systematic and Evolutionary Microbiology, 2006Co-Authors: Verona Vandieken, Marc Mussmann, Helge Niemann, Bo Barker JorgensenAbstract:Two psychrophilic, Gram-negative, rod-shaped, motile bacteria (strains 112T and 102T) that conserved energy from dissimilatory Fe(III) reduction concomitant with acetate oxidation were isolated from permanently cold Arctic marine sediments. Both strains grew at temperatures down to −2 °C, with respective temperature optima of 14 °C and 14–17 °C for strains 112T and 102T. The isolated strains reduced Fe(III) using common fermentation products such as acetate, lactate, propionate, formate or hydrogen as electron donors, and they also grew with fumarate as the sole substrate. As alternatives to Fe(III), they reduced fumarate, S0 and Mn(IV). Based on 16S rRNA gene sequence similarity, strain 112T was most closely related to Desulfuromonas acetoxidans (97.0 %) and Desulfuromonas thiophila NZ27T (95.5 %), and strain 102T to Malonomonas rubra Gra Mal 1T (96.3 %) and Desulfuromusa succinoxidans GylacT (95.9 %) within the Deltaproteobacteria. Strains 112T and 102T therefore represent novel species, for which the names Desulfuromonas svalbardensis sp. nov. (type strain 112T=DSM 16958T=JCM 12927T) and Desulfuromusa ferrireducens sp. nov. (type strain 102T=DSM 16956T=JCM 12926T) are proposed.