title: Fractionation of sulfur and hydrogen isotopes in Desulfovibrio vulgaris with perturbed DsrC expression.
abstract: Dissimilatory sulfate reduction is the central microbial metabolism in global sulfur cycling. Understanding the importance of sulfate reduction to Earth's biogeochemical S cycle requires aggregating single-cell processes with geochemical signals. For sulfate reduction, these signals include the ratio of stable sulfur isotopes preserved in minerals, as well as the hydrogen isotope ratios and structures of microbial membrane lipids preserved in organic matter. In this study, we cultivated the model sulfate reducer, Desulfovibrio vulgaris DSM 644T, to investigate how these parameters were perturbed by changes in expression of the protein DsrC. DsrC is critical to the final metabolic step in sulfate reduction to sulfide. S and H isotopic fractionation imposed by the wild type was compared to three mutants. Discrimination against34S in sulfate, as calculated from the residual reactant, did not discernibly differ among all strains. However, a closed-system sulfur isotope distillation model, based on accumulated sulfide, produced inconsistent results in one mutant strain IPFG09. Lipids produced by IPFG09 were also slightly enriched in2H. These results suggest that DsrC alone does not have a major impact on sulfate-S, though may influence sulfide-S and lipid-H isotopic compositions. While intriguing, a mechanistic explanation requires further study under continuous culture conditions.
authors.affiliation: Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA william.d.leavitt@dartmouth.edu abradley@eps.wustl.edu.|Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA.
authors.forename: William D
authors.initials: WD
authors.lastname: Leavitt
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2780-157, Portugal.
authors.forename: Sofia S
authors.initials: SS
authors.lastname: Venceslau
authors.affiliation: Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras 2780-157, Portugal.
authors.forename: Inês A C
authors.initials: IA
authors.lastname: Pereira
authors.affiliation: Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Johnston
authors.affiliation: Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA william.d.leavitt@dartmouth.edu abradley@eps.wustl.edu.|Division of Biology and Biomedical Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA.
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Bradley
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005591:Chemical Fractionation / Q000379:methods*; D016969:Desulfovibrio vulgaris / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism; D006859:Hydrogen / Q000737:chemistry*; D009249:NADP / Q000737:chemistry; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000235:genetics / Q000378:metabolism*; D013431:Sulfates / Q000737:chemistry*; D013460:Sulfur Isotopes / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D005227:Fatty Acids; D013431:Sulfates; D013460:Sulfur Isotopes; D009249:NADP; D006859:Hydrogen; D050862:Oxidoreductases Acting on Sulfur Group Donors
keywords: anaerobic energy metabolism; biomarkers; compound specific hydrogen isotopes; dissimilatory sulfate reduction; sulfur isotopes