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Title: Oxidation and methylation of dissolved elemental mercury by anaerobic bacteria

Methylmercury is a neurotoxin that poses significant health risks to humans. Some anaerobic sulphate- and iron-reducing bacteria can methylate oxidized forms of mercury, generating methylmercury1-4. One strain of sulphate-reducing bacteria (Desulfovibrio desulfuricans ND132) can also methylate elemental mercury5. The prevalence of this trait among different bacterial strains and species remains unclear, however. Here, we compare the ability of two strains of the sulphate-reducing bacterium Desulfovibrio and one strain of the iron-reducing bacterium Geobacter to oxidise and methylate elemental mercury in a series of laboratory incubations. Experiments were carried out under dark, anaerobic conditions, in the presence of environmentally-relevant concentrations of elemental mercury. We report differences in the ability of these organisms to oxidise and methylate elemental mercury. In line with recent findings5, we show that Desulfovibrio desulfuricans ND132 can both oxidise and methylate elemental mercury. However, the rate of methylation of elemental mercury is only about one third the rate of methylation of oxidized mercury. We also show that Desulfovibrio alaskensis G20 can oxidise, but not methylate, elemental mercury. Geobacter sulfurreducens PCA is able to oxidise and methylate elemental mercury in the presence of cysteine. We suggest that the activity of methylating and non-methylating bacteria may together enhance the formationmore » of methylmercury in anaerobic environments.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3] ;  [2] ;  [2] ;  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chinese Academy of Sciences (CAS), Beijing (China)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Chinese Academy of Sciences (CAS), Beijing (China)
Publication Date:
OSTI Identifier:
1092297
DOE Contract Number:
AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Geoscience; Journal Volume: 6; Journal Issue: 7
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES Methylation