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Torleiv Lien - One of the best experts on this subject based on the ideXlab platform.
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characterization of the desulforubidin operons from Desulfobacter vibrioformis and desulfobulbus rhabdoformis
Fems Microbiology Letters, 2000Co-Authors: Oivind Larsen, Torleiv Lien, Nilskare BirkelandAbstract:The genes encoding the desulforubidin type of dissimilatory sulfite reductase (Dsr) from the sulfate-reducing bacteria Desulfobacter vibrioformis and Desulfobulbus rhabdoformis were cloned and sequenced. Similar to the genes for dissimilatory sulfite reductase from the genera Archaeoglobus, Desulfovibrio and Desulfotomaculum the dsr genes were found to form an operon, dsrABD, where dsrA and dsrB encode the structural subunits, α and β, of Dsr, respectively. dsrD encodes a conserved unknown protein apparently restricted to sulfate-reducing species. In Desulfobacter vibrioformis a fourth gene, designated dsrN, was found downstream of dsrD forming a contiguous operon, dsrABDN. DsrN showed significant sequence homology to cobyrinic a,c-diamide synthase, which is involved in the biosynthesis of vitamin B12. A function for DsrN in amidation of siroheme is likely. Analysis of the dsrAB-encoded proteins confirmed that the high conservation observed for other types of dissimilatory sulfite reductase is also found in desulforubidin. The use of Dsr sequences in unravelling the phylogeny of sulfate-reducing bacteria is discussed.
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purification and characterization of a monomeric isocitrate dehydrogenase from the sulfate reducing bacterium Desulfobacter vibrioformis and demonstration of the presence of a monomeric enzyme in other bacteria
Fems Microbiology Letters, 1998Co-Authors: Ida Helene Steen, Marit Steine Madsen, Nilska Re Birkeland, Torleiv LienAbstract:NADP+-specific isocitrate dehydrogenase (EC 1.1.1.42) was purified to homogeneity from the sulfate-reducing bacterium Desulfobacter vibrioformis, and shown to be a monomeric protein with a molecular mass of 80 kDa. The pH and temperature optima were 8.5 and 45°C, respectively. The N-terminal amino acid sequence (Thr, Glu, Thr, Ile, Arg, Trp, Thr, X, Thr, Asp, Glu, Ala, Pro, Leu, Leu, Ala, Thr) showed similarity with that of other known monomeric isocitrate dehydrogenases. Catalytically active isocitrate dehydrogenase from D. vibrioformis was obtained by activity staining after SDS-PAGE and removal of SDS from the gel. This technique revealed a NADP+-dependent monomeric enzyme in other Desulfobacter spp., Desulfuromonas acetoxidans and Chlorobium tepidium. These findings imply that monomeric isocitrate dehydrogenases are present in distantly related bacteria and indicate an early evolution of monomeric isocitrate dehydrogenases in the bacterial lineage.
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Purification and characterization of a monomeric isocitrate dehydrogenase from the sulfate‐reducing bacterium Desulfobacter vibrioformis and demonstration of the presence of a monomeric enzyme in other bacteria
Fems Microbiology Letters, 1998Co-Authors: Ida Helene Steen, Marit Steine Madsen, Nilska Re Birkeland, Torleiv LienAbstract:NADP+-specific isocitrate dehydrogenase (EC 1.1.1.42) was purified to homogeneity from the sulfate-reducing bacterium Desulfobacter vibrioformis, and shown to be a monomeric protein with a molecular mass of 80 kDa. The pH and temperature optima were 8.5 and 45°C, respectively. The N-terminal amino acid sequence (Thr, Glu, Thr, Ile, Arg, Trp, Thr, X, Thr, Asp, Glu, Ala, Pro, Leu, Leu, Ala, Thr) showed similarity with that of other known monomeric isocitrate dehydrogenases. Catalytically active isocitrate dehydrogenase from D. vibrioformis was obtained by activity staining after SDS-PAGE and removal of SDS from the gel. This technique revealed a NADP+-dependent monomeric enzyme in other Desulfobacter spp., Desulfuromonas acetoxidans and Chlorobium tepidium. These findings imply that monomeric isocitrate dehydrogenases are present in distantly related bacteria and indicate an early evolution of monomeric isocitrate dehydrogenases in the bacterial lineage.
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Desulfobacter vibrioformis sp nov a sulfate reducer from a water oil separation system
International Journal of Systematic and Evolutionary Microbiology, 1997Co-Authors: Torleiv Lien, Janiche BeederAbstract:A mesophilic, gram-negative, vibrio-shaped, marine, acetate-oxidizing sulfate reducer (strain B54) was isolated from a water-oil separation system on a North Sea oil platform. The optimum conditions for growth were 33°C, pH 6.8 to 7.0, and concentrations of NaCI and MgCl2 6H2O of at least 1 and 0.3%, respectively. Of various organic acids tested, only acetate was used as an electron and carbon source. The presence of 2-oxoglutarate:dye oxidoreductase suggests acetate oxidation via an operative citric acid cycle. Even though growth of most Desulfobacter strains (including strain B54) did not occur on hydrogen, hydrogenase was detected at low activity. The growth yields were 4.6, 13.1, and 9.6 g of (dry weight) cells per mol of acetate oxidized with sulfate, sulfite, and thiosulfate, respectively, as electron acceptors. Strain B54 was able to fix dinitrogen. Desulforubidin and cytochromes of the c and b types were present. The G+C content of the DNA was 47 mol%. Strain B54 is most closely related to Desulfobacter latus, with a 16S rDNA sequence similarity of 98.1%. The DNA-DNA relatedness between them was 40.5%. On the basis of differences in genotypic, pheno-typic, and immunological characteristics, we propose that strain B54 is a member of a new species, D. vibrioformis. It can be easily identified and distinguished from other Desulfobacter species by its large, vibrio-shaped cells.
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hydrogenase in Desulfobacter
1990Co-Authors: Torleiv Lien, Terje TorsvikAbstract:Hydrogenase activity has been detected in all the Desulfobacter species tested. The results indicate that Desulfobacter species contain only one hydrogenase with low specific activity.
Yoshikuni Urushigawa - One of the best experts on this subject based on the ideXlab platform.
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High survival efficiency and ribosomal RNA decaying pattern of Desulfobacter latus, a highly specific acetate-utilizing organism, during starvation
FEMS Microbiology Ecology, 1996Co-Authors: Manabu Fukui, Yuichi Suwa, Yoshikuni UrushigawaAbstract:Exponentially grown Desulfobacter latus cells were transferred to anaerobically prepared minimum medium without a carbon or energy substrate and incubated under anaerobic conditions. Changes in 16S ribosomal RNA (rRNA) of individual cells and the viable fraction in a population were monitored. The cell preparation was stained with a phylogenetic DNA probe labelled with fluorescent dye and the fluorescence of each cell was determined with confocal scanning laser microscope. Viable cells were defined as those capable of reducing a tetrazolium salt (the INT method [1]). The viability of a Desulfobacter starvation culture decreased to 85% in 48 h, but further decrease was not observed during prolonged starvation. The mean amount of 16S rRNA in individual cells decreased exponentially for 48 h to 30% the mean value obtained for exponentially growing cells, but did not decrease by prolonged starvation. About 30% of the mean content of 16S rRNA in growing cells was found in the starved cell population, suggesting that most individual cells in the starved population were not metabolically active. The difference between gross pixel intensity of cells having
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high survival efficiency and ribosomal rna decaying pattern of Desulfobacter latus a highly specific acetate utilizing organism during starvation
FEMS Microbiology Ecology, 1996Co-Authors: Manabu Fukui, Yuichi Suwa, Yoshikuni UrushigawaAbstract:Exponentially grown Desulfobacter latus cells were transferred to anaerobically prepared minimum medium without a carbon or energy substrate and incubated under anaerobic conditions. Changes in 16S ribosomal RNA (rRNA) of individual cells and the viable fraction in a population were monitored. The cell preparation was stained with a phylogenetic DNA probe labelled with fluorescent dye and the fluorescence of each cell was determined with confocal scanning laser microscope. Viable cells were defined as those capable of reducing a tetrazolium salt (the INT method [1]). The viability of a Desulfobacter starvation culture decreased to 85% in 48 h, but further decrease was not observed during prolonged starvation. The mean amount of 16S rRNA in individual cells decreased exponentially for 48 h to 30% the mean value obtained for exponentially growing cells, but did not decrease by prolonged starvation. About 30% of the mean content of 16S rRNA in growing cells was found in the starved cell population, suggesting that most individual cells in the starved population were not metabolically active. The difference between gross pixel intensity of cells having <8% of 16S rRNA in growing cells and those with a negative control probe was not significant. Thus, non-viable cells may not show positive signals by phylogenetic staining.
Janiche Beeder - One of the best experts on this subject based on the ideXlab platform.
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Desulfobacter vibrioformis sp nov a sulfate reducer from a water oil separation system
International Journal of Systematic and Evolutionary Microbiology, 1997Co-Authors: Torleiv Lien, Janiche BeederAbstract:A mesophilic, gram-negative, vibrio-shaped, marine, acetate-oxidizing sulfate reducer (strain B54) was isolated from a water-oil separation system on a North Sea oil platform. The optimum conditions for growth were 33°C, pH 6.8 to 7.0, and concentrations of NaCI and MgCl2 6H2O of at least 1 and 0.3%, respectively. Of various organic acids tested, only acetate was used as an electron and carbon source. The presence of 2-oxoglutarate:dye oxidoreductase suggests acetate oxidation via an operative citric acid cycle. Even though growth of most Desulfobacter strains (including strain B54) did not occur on hydrogen, hydrogenase was detected at low activity. The growth yields were 4.6, 13.1, and 9.6 g of (dry weight) cells per mol of acetate oxidized with sulfate, sulfite, and thiosulfate, respectively, as electron acceptors. Strain B54 was able to fix dinitrogen. Desulforubidin and cytochromes of the c and b types were present. The G+C content of the DNA was 47 mol%. Strain B54 is most closely related to Desulfobacter latus, with a 16S rDNA sequence similarity of 98.1%. The DNA-DNA relatedness between them was 40.5%. On the basis of differences in genotypic, pheno-typic, and immunological characteristics, we propose that strain B54 is a member of a new species, D. vibrioformis. It can be easily identified and distinguished from other Desulfobacter species by its large, vibrio-shaped cells.
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immunological properties of Desulfobacter
1990Co-Authors: Janiche Beeder, Torleiv Lien, Terje TorsvikAbstract:Sulfate reducing bacteria of the genera Desulfobacter, Desulfococcus and Desulfobulbus were shown to possess common antigens. Using monoclonal antibodies and polyclonal antiserum, it was possible to identify bacteria, within these genera, at genus, species and strain level.
Manabu Fukui - One of the best experts on this subject based on the ideXlab platform.
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High survival efficiency and ribosomal RNA decaying pattern of Desulfobacter latus, a highly specific acetate-utilizing organism, during starvation
FEMS Microbiology Ecology, 1996Co-Authors: Manabu Fukui, Yuichi Suwa, Yoshikuni UrushigawaAbstract:Exponentially grown Desulfobacter latus cells were transferred to anaerobically prepared minimum medium without a carbon or energy substrate and incubated under anaerobic conditions. Changes in 16S ribosomal RNA (rRNA) of individual cells and the viable fraction in a population were monitored. The cell preparation was stained with a phylogenetic DNA probe labelled with fluorescent dye and the fluorescence of each cell was determined with confocal scanning laser microscope. Viable cells were defined as those capable of reducing a tetrazolium salt (the INT method [1]). The viability of a Desulfobacter starvation culture decreased to 85% in 48 h, but further decrease was not observed during prolonged starvation. The mean amount of 16S rRNA in individual cells decreased exponentially for 48 h to 30% the mean value obtained for exponentially growing cells, but did not decrease by prolonged starvation. About 30% of the mean content of 16S rRNA in growing cells was found in the starved cell population, suggesting that most individual cells in the starved population were not metabolically active. The difference between gross pixel intensity of cells having
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high survival efficiency and ribosomal rna decaying pattern of Desulfobacter latus a highly specific acetate utilizing organism during starvation
FEMS Microbiology Ecology, 1996Co-Authors: Manabu Fukui, Yuichi Suwa, Yoshikuni UrushigawaAbstract:Exponentially grown Desulfobacter latus cells were transferred to anaerobically prepared minimum medium without a carbon or energy substrate and incubated under anaerobic conditions. Changes in 16S ribosomal RNA (rRNA) of individual cells and the viable fraction in a population were monitored. The cell preparation was stained with a phylogenetic DNA probe labelled with fluorescent dye and the fluorescence of each cell was determined with confocal scanning laser microscope. Viable cells were defined as those capable of reducing a tetrazolium salt (the INT method [1]). The viability of a Desulfobacter starvation culture decreased to 85% in 48 h, but further decrease was not observed during prolonged starvation. The mean amount of 16S rRNA in individual cells decreased exponentially for 48 h to 30% the mean value obtained for exponentially growing cells, but did not decrease by prolonged starvation. About 30% of the mean content of 16S rRNA in growing cells was found in the starved cell population, suggesting that most individual cells in the starved population were not metabolically active. The difference between gross pixel intensity of cells having <8% of 16S rRNA in growing cells and those with a negative control probe was not significant. Thus, non-viable cells may not show positive signals by phylogenetic staining.
T Eckert - One of the best experts on this subject based on the ideXlab platform.
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microbially mediated re oxidation of sulfide during dissimilatory sulfate reduction by Desulfobacter latus
Geochimica et Cosmochimica Acta, 2011Co-Authors: T Eckert, Benjamin Brunner, E Edwards, Ulrich G WortmannAbstract:Enzymatic reactions during dissimilatory sulfate reduction (DSR) are often treated as unidirectional with respect to dissolved sulfide. However, quantitative models describing kinetic sulfur isotope fractionations during DSR consider the individual enzymatic reactions as reversible (Rees, 1973). Brunner and Bernasconi (2005) extended this line of thought, and suggested that as long as cell external sulfide (CES) concentrations are high enough, CES may diffuse back across the cytoplasmic cell membrane and may subsequently be re-oxidized to sulfate. Here, we test this hypothesis by measuring the time evolution of the d 34 S-sulfate signal during DSR in closed system experiments under different levels of sulfide stress (0–20 mM and 0–40 mM total dissolved sulfide). Our results show that the measured d 34 S-sulfate signal is markedly different in the latter case and that the observed sulfate S-isotope time-evolution is incompatible with a Rayleigh type fractionation model. In contrast, our results are consistent with a sulfate reduction and fractionation model that allows for a cell internal oxidation of dissolved sulfide by a sulfate reducer. 2011 Elsevier Ltd. All rights reserved.