TY - JOUR
T1 - Fractionation of sulfur and hydrogen isotopes in Desulfovibrio vulgaris with perturbed DsrC expression
AU - Leavitt, William D.
AU - Venceslau, Sofia S.
AU - Pereira, Inês A.C.
AU - Johnston, David T.
AU - Bradley, Alexander S.
N1 - Funding Information:
The authors thank Richard Boden, Aubrey Zerkle and an anonymous reviewer for insights which improved an earlier version of this manuscript. Many thanks to Melanie Suess (WashU) for analytical assistance with compound-specific H-isotope measurements; Andy Masterson (Northwestern) for a concise explanation of chromium/sulfur chemistry; Maggie Osburn (Northwestern) and Xiahong Feng (Dartmouth) for mediumwater H-isotope measurements, Erin Beirne (Harvard) for assistance with sulfur isotope analyses, as well as Colleen Hansel, Emily Estes and Adiari Rodriguez-Vasquez (WHOI) for assistance with ion chromatography. This work was supported by National Aeronautics and Space Administration (NASA) Exobiology grant 13-EXO13-0082 (to ASB and WDL), National Science Foundation (NSF)-EAR 1225980 (to DTJ and IACP), NSF-CAREER EAR-1149555 (DTJ), Fundação para a Ciência e a Tecnologia (FCT) Portugal and co-funded by FEDER under the PT2020 Partnership Agreement (UID/Multi/04551/2013 and UID/CBQ/04612/2013 to ITQB, and PTDC/BIA-MIC/6512/2014 to SV and IACP), the Steve Fossett Postdoctoral Fellowship, Washington University in St. Louis, Department of Earth and Planetary Sciences (WDL) and FCT Fellowship (SFRH/BPD/79823/2011 to SSV).
Publisher Copyright:
© FEMS 2016. All rights reserved.
PY - 2016/10
Y1 - 2016/10
N2 - 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 against 34S 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 in 2H. 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.
AB - 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 against 34S 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 in 2H. 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.
KW - Anaerobic energy metabolism
KW - Biomarkers
KW - Compound specific hydrogen isotopes
KW - Dissimilatory sulfate reduction
KW - Sulfur isotopes
UR - http://www.scopus.com/inward/record.url?scp=84995948263&partnerID=8YFLogxK
U2 - 10.1093/femsle/fnw226
DO - 10.1093/femsle/fnw226
M3 - Article
C2 - 27702753
AN - SCOPUS:84995948263
SN - 0378-1097
VL - 363
JO - FEMS Microbiology Letters
JF - FEMS Microbiology Letters
IS - 20
M1 - fnw226
ER -