title: Effects of sulfate reducing bacteria and sulfate concentrations on mercury methylation in freshwater sediments.
abstract: Methylmercury (MeHg) is the most poisonous form of mercury (Hg) and it enters the human body primarily through consumption of Hg contaminated fish. Sulfate reducing bacteria (SRB) are major producers of MeHg in anoxic sediments. The dsrAB gene was isolated from freshwater fish pond sediments. Sequence analyses showed that the SRB in sediments was mainly composed of Desulfobulbus propionicus and Desulfovibrio vulgaris. The two species of SRB were cultured from freshwater sediments. The addition of inorganic Hg to these freshwater sediments caused an increase in MeHg concentrations at 30 days incubation. MeHg levels were sensitive to sulfate concentrations; a medium sulfate level (0.11 mg/g) produced higher levels than treatments lacking sulfate addition or when amended with 0.55 mg/g. Assessment of bacterial levels by PCR measurements of microbial DNA indicated that the MeHg levels were correlated with cell growth.
authors.affiliation: School of Environmental and Resource Sciences, Zhejiang Agriculture and Forestry University, Linan, PR China.
authors.forename: Dingding
authors.initials: D
authors.lastname: Shao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Kang
authors.forename: Shengchun
authors.initials: S
authors.lastname: Wu
authors.forename: Ming H
authors.initials: MH
authors.lastname: Wong
mesh_terms: D002681:China; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D020564:Deltaproteobacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016969:Desulfovibrio vulgaris / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D019015:Geologic Sediments / Q000382:microbiology; D050885:Hydrogensulfite Reductase / Q000032:analysis / Q000235:genetics; D008628:Mercury / Q000378:metabolism*; D008745:Methylation; D008767:Methylmercury Compounds / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D061005:Ponds / Q000382:microbiology; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013431:Sulfates / Q000032:analysis* / Q000378:metabolism; D016999:Sulfur-Reducing Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D008767:Methylmercury Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical; D050885:Hydrogensulfite Reductase; D008628:Mercury