Diversity of dissimilatory sulfite reductase genes (dsrAB) in a salt marsh impacted by long-term acid mine drainage

Moreau, J. W. , Zierenberg, R. A. and Banfield, J. F. (2010) Diversity of dissimilatory sulfite reductase genes (dsrAB) in a salt marsh impacted by long-term acid mine drainage. Applied and Environmental Microbiology, 76(14), pp. 4819-4828. (doi: 10.1128/AEM.03006-09) (PMID:20472728) (PMCID:PMC2901737)

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Sulfate-reducing bacteria (SRB) play a major role in the coupled biogeochemical cycling of sulfur and chalcophilic metal(loid)s. By implication, they can exert a strong influence on the speciation and mobility of multiple metal(loid) contaminants. In this study, we combined DsrAB gene sequencing and sulfur isotopic profiling to identify the phylogeny and distribution of SRB and to assess their metabolic activity in salt marsh sediments exposed to acid mine drainage (AMD) for over 100 years. Recovered dsrAB sequences from three sites sampled along an AMD flow path indicated the dominance of a single Desulfovibrio species. Other major sequence clades were related most closely to Desulfosarcina, Desulfococcus, Desulfobulbus, and Desulfosporosinus species. The presence of metal sulfides with low δ34S values relative to δ34S values of pore water sulfate showed that sediment SRB populations were actively reducing sulfate under ambient conditions (pH of ∼2), although possibly within less acidic microenvironments. Interestingly, δ34S values for pore water sulfate were lower than those for sulfate delivered during tidal inundation of marsh sediments. 16S rRNA gene sequence data from sediments and sulfur isotope data confirmed that sulfur-oxidizing bacteria drove the reoxidation of biogenic sulfide coupled to oxygen or nitrate reduction over a timescale of hours. Collectively, these findings imply a highly dynamic microbially mediated cycling of sulfate and sulfide, and thus the speciation and mobility of chalcophilic contaminant metal(loid)s, in AMD-impacted marsh sediments.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Moreau, Dr John
Authors: Moreau, J. W., Zierenberg, R. A., and Banfield, J. F.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences > Earth Sciences
Journal Name:Applied and Environmental Microbiology
Publisher:American Society for Microbiology
ISSN (Online):1098-5336
Published Online:07 July 2010

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