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Rainer U. Meckenstock - One of the best experts on this subject based on the ideXlab platform.
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Anaerobic degradation of phenanthrene by a sulfate-reducing Enrichment Culture
Environmental Microbiology, 2018Co-Authors: Anne M. Himmelberg, Thomas Bruels, Zahra Farmani, Philip Weyrauch, Gabriele Barthel, Wolfgang Schrader, Rainer U. MeckenstockAbstract:Anaerobic degradation processes are very important to attenuate polycyclic aromatic hydrocarbons (PAHs) in saturated, anoxic sediments. However, PAHs are poorly degradable, leading to very slow microbial growth and thus resulting in only a few Cultures that have been enriched and studied so far. Here, we report on a new phenanthrene-degrading, sulfate-reducing Enrichment Culture, TRIP1. Genome-resolved metagenomics and strain specific cell counting with FISH and flow cytometry indicated that the Culture is dominated by a microorganism belonging to the Desulfobacteraceae family (60% of the community) and sharing 93% 16S rRNA sequence similarity to the naphthalene-degrading, sulfate-reducing strain NaphS2. The anaerobic degradation pathway was studied by metabolite analyses and revealed phenanthroic acid as the major intermediate consistent with carboxylation as the initial activation reaction. Further reduced metabolites were indicative of a stepwise reduction of the ring system. We were able to measure the presumed second enzyme reaction in the pathway, phenanthroate-CoA ligase, in crude cell extracts. The reaction was specific for 2-phenanthroic acid and did not transform other isomers. The present study provides first insights into the anaerobic degradation pathways of three-ringed PAHs. The biochemical strategy follows principles known from anaerobic naphthalene degradation, including carboxylation and reduction of the aromatic ring system.
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Anaerobic degradation of the aromatic hydrocarbon biphenyl by a sulfate‐reducing Enrichment Culture
FEMS microbiology ecology, 2009Co-Authors: Draženka Selesi, Rainer U. MeckenstockAbstract:The aromatic hydrocarbon biphenyl is a widely distributed environmental pollutant. Whereas the aerobic degradation of biphenyl has been extensively studied, knowledge of the anaerobic biphenyl-oxidizing bacteria and their biochemical degradation pathway is scarce. Here, we report on an Enrichment Culture that oxidized biphenyl completely to carbon dioxide under sulfate-reducing conditions. The biphenyl-degrading Culture was dominated by two distinct bacterial species distantly affiliated with the Gram-positive genus Desulfotomaculum. Moreover, the Enrichment Culture has the ability to grow with benzene and a mixture of anthracene and phenanthrene as the sole source of carbon, but here the microbial community composition differed substantially from the biphenyl-grown Culture. Biphenyl-4-carboxylic acid was identified as an intermediate in the biphenyl-degrading Culture. Moreover, 4-fluorobiphenyl was converted cometabolically with biphenyl because in addition to the biphenyl-4-carboxylic acid, a compound identified as its fluorinated analog was observed. These findings are consistent with the general pattern in the anaerobic catabolism of many aromatic hydrocarbons where carboxylic acids are found to be central metabolites.
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Anaerobic degradation of p-Xylene by a sulfate-reducing Enrichment Culture.
Current microbiology, 2005Co-Authors: Barbara Morasch, Rainer U. MeckenstockAbstract:A strictly anaerobic Enrichment Culture was obtained with p-xylene as organic substrate and sulfate as electron acceptor from an aquifer at a former gasworks plant contaminated with aromatic hydrocarbons. p-Xylene was completely oxidized to CO2. The Enrichment Culture depended on Fe(II) in the medium as a scavenger of the produced sulfide. 4-Methylbenzylsuccinic acid and 4-methylphenylitaconic acid were identified in supernatants of Cultures indicating that degradation of p-xylene was initiated by fumarate addition to one of the methyl groups. Therefore, p-xylene degradation probably proceeds analogously to toluene degradation by Thaueraaromatica or anaerobic degradation pathways for o- and m-xylene.
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enzymatic reactions in anaerobic 2 methylnaphthalene degradation by the sulphate reducing Enrichment Culture n 47
Fems Microbiology Letters, 2004Co-Authors: Michael Safinowski, Rainer U. MeckenstockAbstract:The upper pathway of anaerobic degradation of 2-methylnaphthalene was studied with a sulphate-reducing Enrichment Culture, which is able to grow with naphthalene or 2-methylnaphthalene as sole carbon source and electron donor. Anaerobic degradation of 2-methylnaphthalene is initiated by an addition of fumarate to the methyl-group producing the first intermediate, naphthyl-2-methyl-succinate. In a subsequent β-oxidation of the original methyl atom, the central metabolite 2-naphthoic acid is generated. In the following pathway, the aromatic ring system is reduced, cleaved, and finally oxidised to CO2. Here, we present two new enzymatic reactions of the 2-methylnaphthalene degradation pathway that were measured in crude cell extracts. All metabolites were identified with HPLC by co-elution with synthesised reference substances. The first enzyme, succinyl-CoA:naphthyl-2-methyl-succinate CoA-transferase, catalyses the activation of naphthyl-2-methyl-succinic acid to the corresponding CoA ester. The average specific activity of this enzyme was 19.6 nmol × min−1× mg of protein−1. The CoA-transfer was not inhibited by sodium borohydride and only partially by hydroxylamine, indicating that this enzyme belongs to the family III of CoA-transferases like the corresponding enzyme in the anaerobic toluene degradation pathway. The product of this CoA-transfer reaction, naphthyl-2-methyl-succinyl-CoA is then oxidised in a reaction to naphthyl-2-methylene-succinyl-CoA by the enzyme naphthyl-2-methyl-succinyl-CoA dehydrogenase. The specific activity of this enzyme was 0.115 nmol × min−1× mg of protein−1. The enzymatic activity could only be detected using phenazine methosulphate as electron acceptor. No activity was observed with natural electron acceptors such as nicotinamide adenine dinucleotide or flavin adenine dinucleotide. The two novel reactions presented here demonstrate that the original methyl-group of 2-methylnaphthalene is oxidised to the carboxyl group of 2-naphthoic acid in the upper part of the anaerobic degradation pathway.
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Anaerobic degradation of 2-methylnaphthalene by a sulfate-reducing Enrichment Culture.
Applied and environmental microbiology, 2000Co-Authors: Eva Annweiler, Hans H. Richnow, Andreas Kappler, Arne Materna, Michael Safinowski, Walter Michaelis, Rainer U. MeckenstockAbstract:Anaerobic degradation of 2-methylnaphthalene was investigated with a sulfate-reducing Enrichment Culture. Metabolite analyses revealed two groups of degradation products. The first group comprised two succinic acid adducts which were identified as naphthyl-2-methyl-succinic acid and naphthyl-2-methylene-succinic acid by comparison with chemically synthesized reference compounds. Naphthyl-2-methyl-succinic acid accumulated to 0.5 mM in Culture supernatants. Production of naphthyl-2-methyl-succinic acid was analyzed in enzyme assays with dense cell suspensions. The conversion of 2-methylnaphthalene to naphthyl-2-methyl-succinic acid was detected at a specific activity of 0.020 6 0.003 nmol min 21 mg of protein 21 only in the presence of cells and fumarate. We conclude that under anaerobic conditions 2-methylnaphthalene is activated by fumarate addition to the methyl group, as is the case in anaerobic toluene degradation. The second group of metabolites comprised 2-naphthoic acid and reduced 2-naphthoic acid derivatives, including 5,6,7,8-tetrahydro-2-naphthoic acid, octahydro-2-naphthoic acid, and decahydro-2-naphthoic acid. These compounds were also identified in an earlier study as products of anaerobic naphthalene degradation with the same Enrichment Culture. A pathway for anaerobic degradation of 2-methylnaphthalene analogous to that for anaerobic toluene degradation is proposed.
Anne Godfroy - One of the best experts on this subject based on the ideXlab platform.
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Biogeochemical insights into microbe–mineral–fluid interactions in hydrothermal chimneys using Enrichment Culture
Extremophiles, 2015Co-Authors: Nolwenn Callac, Olivier Rouxel, Françoise Lesongeur, Céline Liorzou, Claire Bollinger, Patricia Pignet, Sandrine Chéron, Yves Fouquet, Céline Rommevaux-jestin, Anne GodfroyAbstract:Active hydrothermal chimneys host diverse microbial communities exhibiting various metabolisms including those involved in various biogeochemical cycles. To investigate microbe–mineral–fluid interactions in hydrothermal chimney and the driver of microbial diversity, a cultural approach using a gas-lift bioreactor was chosen. An Enrichment Culture was performed using crushed active chimney sample as inoculum and diluted hydrothermal fluid from the same vent as Culture medium. Daily sampling provided time-series access to active microbial diversity and medium composition. Active archaeal and bacterial communities consisted mainly of sulfur, sulfate and iron reducers and hydrogen oxidizers with the detection of Thermococcus , Archaeoglobus , Geoglobus , Sulfurimonas and Thermotoga sequences. The simultaneous presence of active Geoglobus sp. and Archaeoglobus sp. argues against competition for available carbon sources and electron donors between sulfate and iron reducers at high temperature. This approach allowed the cultivation of microbial populations that were under-represented in the initial environmental sample. The microbial communities are heterogeneously distributed within the gas-lift bioreactor; it is unlikely that bulk mineralogy or fluid chemistry is the drivers of microbial community structure. Instead, we propose that micro-environmental niche characteristics, created by the interaction between the mineral grains and the fluid chemistry, are the main drivers of microbial diversity in natural systems.
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Continuous Enrichment Culture and molecular monitoring to investigate the microbial diversity of thermophiles inhabiting deep-sea hydrothermal ecosystems.
Current Microbiology, 2005Co-Authors: Anne Postec, Françoise Lesongeur, Laurent Urios, Bernard Ollivier, Joël Querellou, Anne GodfroyAbstract:The microflora developing during a continuous Enrichment Culture from a hydrothermal chimney sample was investigated by molecular methods. The Culture was performed in a gas-lift bioreactor under anaerobic conditions, at 90 degrees C and pH 6.5, on a complex medium containing sulfur as the terminal electron acceptor. Archaeal and bacterial diversity was studied. Microorganisms affiliated with the genera Pyrococcus, Marinitoga, and Bacillus were detected through DGGE analysis of 16S rDNA. Additional sequences phylogenetically related to Thermococcus and epsilon-Proteobacteria were detected by cloning and sequencing of 16S rDNA from two samples of the Enrichment Culture. In comparison, the sequences retrieved from cloning analysis from an Enrichment Culture performed in a flask (batch condition) using the same Culture medium showed that only members of the genus Thermococcus were cultivated. Therefore, continuous Enrichment Culture using the gas-lift bioreactor can be considered as an efficient and improved method for investigating microbial communities originating from deep-sea hydrothermal vents.
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Continuous Enrichment Culture and Molecular Monitoring to Investigate the Microbial Diversity of Thermophiles Inhabiting Deep-Sea Hydrothermal Ecosystems
Current Microbiology, 2005Co-Authors: Anne Postec, Françoise Lesongeur, Laurent Urios, Bernard Ollivier, Joël Querellou, Anne GodfroyAbstract:The microflora developing during a continuous Enrichment Culture from a hydrothermal chimney sample was investigated by molecular methods. The Culture was performed in a gas-lift bioreactor under anaerobic conditions, at 90°C and pH 6.5, on a complex medium containing sulfur as the terminal electron acceptor. Archaeal and bacterial diversity was studied. Microorganisms affiliated with the genera Pyrococcus , Marinitoga , and Bacillus were detected through DGGE analysis of 16S rDNA. Additional sequences phylogenetically related to Thermococcus and ε- Proteobacteria were detected by cloning and sequencing of 16S rDNA from two samples of the Enrichment Culture. In comparison, the sequences retrieved from cloning analysis from an Enrichment Culture performed in a flask (batch condition) using the same Culture medium showed that only members of the genus Thermococcus were cultivated. Therefore, continuous Enrichment Culture using the gas-lift bioreactor can be considered as an efficient and improved method for investigating microbial communities originating from deep-sea hydrothermal vents.
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continuous Enrichment Culture and molecular monitoring to investigate the microbial diversity of thermophiles inhabiting deep sea hydrothermal ecosystems
Current Microbiology, 2005Co-Authors: Anne Postec, Françoise Lesongeur, Laurent Urios, Bernard Ollivier, Joël Querellou, Anne GodfroyAbstract:The microflora developing during a continuous Enrichment Culture from a hydrothermal chimney sample was investigated by molecular methods. The Culture was performed in a gas-lift bioreactor under anaerobic conditions, at 90°C and pH 6.5, on a complex medium containing sulfur as the terminal electron acceptor. Archaeal and bacterial diversity was studied. Microorganisms affiliated with the genera Pyrococcus, Marinitoga, and Bacillus were detected through DGGE analysis of 16S rDNA. Additional sequences phylogenetically related to Thermococcus and e-Proteobacteria were detected by cloning and sequencing of 16S rDNA from two samples of the Enrichment Culture. In comparison, the sequences retrieved from cloning analysis from an Enrichment Culture performed in a flask (batch condition) using the same Culture medium showed that only members of the genus Thermococcus were cultivated. Therefore, continuous Enrichment Culture using the gas-lift bioreactor can be considered as an efficient and improved method for investigating microbial communities originating from deep-sea hydrothermal vents.
Françoise Lesongeur - One of the best experts on this subject based on the ideXlab platform.
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Biogeochemical insights into microbe–mineral–fluid interactions in hydrothermal chimneys using Enrichment Culture
Extremophiles, 2015Co-Authors: Nolwenn Callac, Olivier Rouxel, Françoise Lesongeur, Céline Liorzou, Claire Bollinger, Patricia Pignet, Sandrine Chéron, Yves Fouquet, Céline Rommevaux-jestin, Anne GodfroyAbstract:Active hydrothermal chimneys host diverse microbial communities exhibiting various metabolisms including those involved in various biogeochemical cycles. To investigate microbe–mineral–fluid interactions in hydrothermal chimney and the driver of microbial diversity, a cultural approach using a gas-lift bioreactor was chosen. An Enrichment Culture was performed using crushed active chimney sample as inoculum and diluted hydrothermal fluid from the same vent as Culture medium. Daily sampling provided time-series access to active microbial diversity and medium composition. Active archaeal and bacterial communities consisted mainly of sulfur, sulfate and iron reducers and hydrogen oxidizers with the detection of Thermococcus , Archaeoglobus , Geoglobus , Sulfurimonas and Thermotoga sequences. The simultaneous presence of active Geoglobus sp. and Archaeoglobus sp. argues against competition for available carbon sources and electron donors between sulfate and iron reducers at high temperature. This approach allowed the cultivation of microbial populations that were under-represented in the initial environmental sample. The microbial communities are heterogeneously distributed within the gas-lift bioreactor; it is unlikely that bulk mineralogy or fluid chemistry is the drivers of microbial community structure. Instead, we propose that micro-environmental niche characteristics, created by the interaction between the mineral grains and the fluid chemistry, are the main drivers of microbial diversity in natural systems.
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biogeochemical insights into microbe mineral fluid interactions in hydrothermal chimneys using Enrichment Culture
Extremophiles, 2015Co-Authors: Nolwenn Callac, Olivier Rouxel, Françoise Lesongeur, Céline Liorzou, Claire Bollinger, Patricia Pignet, Sandrine Chéron, Yves FouquetAbstract:Active hydrothermal chimneys host diverse microbial communities exhibiting various metabolisms including those involved in various biogeochemical cycles. To investigate microbe-mineral-fluid interactions in hydrothermal chimney and the driver of microbial diversity, a cultural approach using a gas-lift bioreactor was chosen. An Enrichment Culture was performed using crushed active chimney sample as inoculum and diluted hydrothermal fluid from the same vent as Culture medium. Daily sampling provided time-series access to active microbial diversity and medium composition. Active archaeal and bacterial communities consisted mainly of sulfur, sulfate and iron reducers and hydrogen oxidizers with the detection of Thermococcus, Archaeoglobus, Geoglobus, Sulfurimonas and Thermotoga sequences. The simultaneous presence of active Geoglobus sp. and Archaeoglobus sp. argues against competition for available carbon sources and electron donors between sulfate and iron reducers at high temperature. This approach allowed the cultivation of microbial populations that were under-represented in the initial environmental sample. The microbial communities are heterogeneously distributed within the gas-lift bioreactor; it is unlikely that bulk mineralogy or fluid chemistry is the drivers of microbial community structure. Instead, we propose that micro-environmental niche characteristics, created by the interaction between the mineral grains and the fluid chemistry, are the main drivers of microbial diversity in natural systems.
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Continuous Enrichment Culture and molecular monitoring to investigate the microbial diversity of thermophiles inhabiting deep-sea hydrothermal ecosystems.
Current Microbiology, 2005Co-Authors: Anne Postec, Françoise Lesongeur, Laurent Urios, Bernard Ollivier, Joël Querellou, Anne GodfroyAbstract:The microflora developing during a continuous Enrichment Culture from a hydrothermal chimney sample was investigated by molecular methods. The Culture was performed in a gas-lift bioreactor under anaerobic conditions, at 90 degrees C and pH 6.5, on a complex medium containing sulfur as the terminal electron acceptor. Archaeal and bacterial diversity was studied. Microorganisms affiliated with the genera Pyrococcus, Marinitoga, and Bacillus were detected through DGGE analysis of 16S rDNA. Additional sequences phylogenetically related to Thermococcus and epsilon-Proteobacteria were detected by cloning and sequencing of 16S rDNA from two samples of the Enrichment Culture. In comparison, the sequences retrieved from cloning analysis from an Enrichment Culture performed in a flask (batch condition) using the same Culture medium showed that only members of the genus Thermococcus were cultivated. Therefore, continuous Enrichment Culture using the gas-lift bioreactor can be considered as an efficient and improved method for investigating microbial communities originating from deep-sea hydrothermal vents.
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Continuous Enrichment Culture and Molecular Monitoring to Investigate the Microbial Diversity of Thermophiles Inhabiting Deep-Sea Hydrothermal Ecosystems
Current Microbiology, 2005Co-Authors: Anne Postec, Françoise Lesongeur, Laurent Urios, Bernard Ollivier, Joël Querellou, Anne GodfroyAbstract:The microflora developing during a continuous Enrichment Culture from a hydrothermal chimney sample was investigated by molecular methods. The Culture was performed in a gas-lift bioreactor under anaerobic conditions, at 90°C and pH 6.5, on a complex medium containing sulfur as the terminal electron acceptor. Archaeal and bacterial diversity was studied. Microorganisms affiliated with the genera Pyrococcus , Marinitoga , and Bacillus were detected through DGGE analysis of 16S rDNA. Additional sequences phylogenetically related to Thermococcus and ε- Proteobacteria were detected by cloning and sequencing of 16S rDNA from two samples of the Enrichment Culture. In comparison, the sequences retrieved from cloning analysis from an Enrichment Culture performed in a flask (batch condition) using the same Culture medium showed that only members of the genus Thermococcus were cultivated. Therefore, continuous Enrichment Culture using the gas-lift bioreactor can be considered as an efficient and improved method for investigating microbial communities originating from deep-sea hydrothermal vents.
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continuous Enrichment Culture and molecular monitoring to investigate the microbial diversity of thermophiles inhabiting deep sea hydrothermal ecosystems
Current Microbiology, 2005Co-Authors: Anne Postec, Françoise Lesongeur, Laurent Urios, Bernard Ollivier, Joël Querellou, Anne GodfroyAbstract:The microflora developing during a continuous Enrichment Culture from a hydrothermal chimney sample was investigated by molecular methods. The Culture was performed in a gas-lift bioreactor under anaerobic conditions, at 90°C and pH 6.5, on a complex medium containing sulfur as the terminal electron acceptor. Archaeal and bacterial diversity was studied. Microorganisms affiliated with the genera Pyrococcus, Marinitoga, and Bacillus were detected through DGGE analysis of 16S rDNA. Additional sequences phylogenetically related to Thermococcus and e-Proteobacteria were detected by cloning and sequencing of 16S rDNA from two samples of the Enrichment Culture. In comparison, the sequences retrieved from cloning analysis from an Enrichment Culture performed in a flask (batch condition) using the same Culture medium showed that only members of the genus Thermococcus were cultivated. Therefore, continuous Enrichment Culture using the gas-lift bioreactor can be considered as an efficient and improved method for investigating microbial communities originating from deep-sea hydrothermal vents.
Carsten Vogt - One of the best experts on this subject based on the ideXlab platform.
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Anaerobic biotransformation of hexachlorocyclohexane isomers by Dehalococcoides species and an Enrichment Culture
Biodegradation, 2018Co-Authors: Safdar Bashir, Kevin Kuntze, Carsten Vogt, Ivonne NijenhuisAbstract:The biotransformation of hexachlorocyclohexane isomers (HCH) by two Dehalococcoides mccartyi strains (195 and BTF08) and an Enrichment Culture was investigated and compared to conversion by the obligate anaerobic strain Clostridium pasteurianum strain DSMZ 525. The D. mccartyi strains preferentially transformed γ-HCH over α-HCH and δ-HCH isomers while β-HCH biotransformation was not significant. In case of the Enrichment Culture, γ-HCH was preferentially transformed over the δ-HCH, β-HCH and α-HCH isomers. Major observed metabolites in both cases were tetrachlorocyclohexene and as end products monochlorobenzene (MCB) and benzene. Dechlorination of the γ-HCH isomer was linked to an increase in cell numbers for strain 195. γ-HCH transformation was linked to considerable carbon stable isotope fractionation with the Enrichment factor ε_c = − 5.5 ± 0.8‰ for D. mccartyi strain 195, ε_c = − 3.1 ± 0.4‰ for the Enrichment Culture and ε_c = − 4.1 ± 0.6‰ for co-metabolic transformation by C. pasteurianum .
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Anaerobic biotransformation of hexachlorocyclohexane isomers by Dehalococcoides species and an Enrichment Culture.
Biodegradation, 2018Co-Authors: Safdar Bashir, Kevin Kuntze, Carsten Vogt, Ivonne NijenhuisAbstract:The biotransformation of hexachlorocyclohexane isomers (HCH) by two Dehalococcoides mccartyi strains (195 and BTF08) and an Enrichment Culture was investigated and compared to conversion by the obligate anaerobic strain Clostridium pasteurianum strain DSMZ 525. The D. mccartyi strains preferentially transformed γ-HCH over α-HCH and δ-HCH isomers while β-HCH biotransformation was not significant. In case of the Enrichment Culture, γ-HCH was preferentially transformed over the δ-HCH, β-HCH and α-HCH isomers. Major observed metabolites in both cases were tetrachlorocyclohexene and as end products monochlorobenzene (MCB) and benzene. Dechlorination of the γ-HCH isomer was linked to an increase in cell numbers for strain 195. γ-HCH transformation was linked to considerable carbon stable isotope fractionation with the Enrichment factor ec = − 5.5 ± 0.8‰ for D. mccartyi strain 195, ec = − 3.1 ± 0.4‰ for the Enrichment Culture and ec = − 4.1 ± 0.6‰ for co-metabolic transformation by C. pasteurianum.
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Metaproteogenomic analysis of a sulfate-reducing Enrichment Culture reveals genomic organization of key enzymes in the m-xylene degradation pathway and metabolic activity of proteobacteria.
Systematic and Applied Microbiology, 2014Co-Authors: Dragana Bozinovski, Carsten Vogt, Martin Von Bergen, Martin Taubert, Sabine Kleinsteuber, Hans H. Richnow, Jana SeifertAbstract:Abstract This study aimed to ascertain the functional and phylogenetic relationships within an m-xylene degrading sulfate-reducing Enrichment Culture, which had been maintained for several years in the laboratory with m-xylene as the sole source of carbon and energy. Previous studies indicated that a phylotype affiliated to the Desulfobacteraceae was the main m-xylene assimilating organism. In the present study, genes and gene products were identified by a metaproteogenomic approach using LC-MS/MS analysis of the microbial community, and 2426 peptides were identified from 576 proteins. In the metagenome of the community, gene clusters encoding enzymes involved in fumarate addition to a methyl moiety of m-xylene (nms, bss), as well as gene clusters coding for enzymes involved in modified beta-oxidation to (3-methyl)benzoyl-CoA (bns), were identified in two separate contigs. Additionally, gene clusters containing homologues to bam genes encoding benzoyl-CoA reductase (Bcr) class II, catalyzing the dearomatization of (3-methyl)benzoyl-CoA, were identified. Time-resolved protein stable isotope probing (protein-SIP) experiments using 13C-labeled m-xylene showed that the respective gene products were highly 13C-labeled. The present data suggested the identification of gene products that were similar to those involved in methylnaphthalene degradation even though the consortium was not capable of growing in the presence of naphthalene, methylnaphthalene or toluene as substrates. Thus, a novel branch of enzymes was found that was probably specific for anaerobic m-xylene degradation.
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functional characterization of an anaerobic benzene degrading Enrichment Culture by dna stable isotope probing
Environmental Microbiology, 2010Co-Authors: Steffi Herrmann, Sabine Kleinsteuber, Hans H. Richnow, Antonis Chatzinotas, Steffen Kuppardt, Tillmann Lueders, Carsten VogtAbstract:Summary The flow of carbon under sulfate-reducing conditions within a benzene-mineralizing Enrichment Culture was analysed using fully labelled [13C6]-benzene. Over 180 days of incubation, 95% of added 13C-benzene was released as 13C-carbon dioxide. DNA extracted from Cultures that had degraded different amounts of unlabelled or 13C-labelled benzene was centrifuged in CsCl density gradients to identify 13C-benzene-assimilating organisms by density-resolved terminal restriction fragment length polymorphism analysis and cloning of 16S rRNA gene fragments. Two phylotypes showed significantly increased relative abundance of their terminal restriction fragments in ‘heavy’ fractions of 13C-benzene-incubated microcosms compared with a 12C-benzene-incubated control: a member of the Cryptanaerobacter/Pelotomaculum group within the Peptococcaceae, and a phylotype belonging to the Epsilonproteobacteria. The Cryptanaerobacter/Pelotomaculum phylotype was the most frequent sequence type. A small amount of 13C-methane was aceticlastically produced, as concluded from the linear relationship between methane production and benzene degradation and the detection of Methanosaetaceae as the only methanogens present. Other phylotypes detected but not 13C-labelled belong to several genera of sulfate-reducing bacteria, that may act as hydrogen scavengers for benzene oxidation. Our results strongly support the hypothesis that benzene is mineralized by a consortium consisting of syntrophs, hydrogenotrophic sulfate reducers and to a minor extent of aceticlastic methanogens.
Frank E Loffler - One of the best experts on this subject based on the ideXlab platform.
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dichloromethane fermentation by a dehalobacter sp in an Enrichment Culture derived from pristine river sediment
Applied and Environmental Microbiology, 2012Co-Authors: Shandra D Justicialeon, Kirsti M Ritalahti, Erin E Mack, Frank E LofflerAbstract:Dichloromethane (DCM) as the sole substrate supported growth of a Dehalobacter sp. in an Enrichment Culture derived from noncontaminated river sediment. DCM was not reductively dechlorinated, and acetate was produced, indicating DCM fermentation and further suggesting Dehalobacter growth is not limited to organohalide respiration.
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complete detoxification of vinyl chloride by an anaerobic Enrichment Culture and identification of the reductively dechlorinating population as a dehalococcoides species
Applied and Environmental Microbiology, 2003Co-Authors: Kirsti M Ritalahti, Michael R Aiello, Frank E LofflerAbstract:A major obstacle in the implementation of the reductive dechlorination process at chloroethene-contaminated sites is the accumulation of the intermediate vinyl chloride (VC), a proven human carcinogen. To shed light on the microbiology involved in the final critical dechlorination step, a sediment-free, nonmethanogenic, VC-dechlorinating Enrichment Culture was derived from tetrachloroethene (PCE)-to-ethene-dechlorinating microcosms established with material from the chloroethene-contaminated Bachman Road site aquifer in Oscoda, Mich. After 40 consecutive transfers in defined, reduced mineral salts medium amended with VC, the Culture lost the ability to use PCE and trichloroethene (TCE) as metabolic electron acceptors. PCE and TCE dechlorination occurred in the presence of VC, presumably in a cometabolic process. Enrichment Cultures supplied with lactate or pyruvate as electron donor dechlorinated VC to ethene at rates up to 54 μmol liter−1day−1, and dichloroethenes (DCEs) were dechlorinated at about 50% of this rate. The half-saturation constant (KS) for VC was 5.8 μM, which was about one-third lower than the concentrations determined for cis-DCE and trans-DCE. Similar VC dechlorination rates were observed at temperatures between 22 and 30°C, and negligible dechlorination occurred at 4 and 35°C. Reductive dechlorination in medium amended with ampicillin was strictly dependent on H2 as electron donor. VC-dechlorinating Cultures consumed H2 to threshold concentrations of 0.12 ppm by volume. 16S rRNA gene-based tools identified a Dehalococcoides population, and Dehalococcoides-targeted quantitative real-time PCR confirmed VC-dependent growth of this population. These findings demonstrate that Dehalococcoides populations exist that use DCEs and VC but not PCE or TCE as metabolic electron acceptors.