Contrasting Effects of Dissolved Organic Matter on Mercury Methylation by G. sulfurreducens PCA and D. desulfuricans ND132
Natural dissolved organic matter (DOM) affects mercury (Hg) redox reactions and anaerobic microbial Hg methylation in the environment. Several studies have shown that DOM can enhance Hg methylation, especially under sulfidic conditions, whereas others show that DOM inhibits Hg methylation due to strong Hg-DOM complexation. Here, we investigated and compared the effects of DOM on Hg methylation by an iron-reducing bacterium Geobacter sulfurreducens PCA and a sulfate-reducing bacterium Desulfovibrio desulfuricans ND132 under non-sulfidic conditions. The methylation experiment was performed with washed cells either in the absence or presence of DOM or glutathione, both of which form strong complexes with Hg via thiol-functional groups. DOM was found to greatly inhibit Hg methylation by G. Sulfurreducens PCA but enhance Hg methylation by D. desulfuricans ND132 cells with increasing DOM concentration. Furthermore, these strain-dependent opposing effects of DOM were also observed with glutathione, suggesting that thiols in DOM likely played an essential role in affecting cell Hg uptake and methylation. Additionally, DOM and glutathione decreased Hg sorption by G. sulfurreducens PCA, but not by D. desulfuricans ND132 cells, demonstrating that ND132 has a higher affinity to sorb or take up Hg than the PCA strain. Finally, these observations indicate that DOM effects onmore »
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- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Publication Date:
- Grant/Contract Number:
- AC05-00OR22725
- Type:
- Published Article
- Journal Name:
- Environmental Science and Technology
- Additional Journal Information:
- Journal Volume: 51; Journal Issue: 18; Journal ID: ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)
- Research Org:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Org:
- USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 54 ENVIRONMENTAL SCIENCES
- OSTI Identifier:
- 1377645
- Alternate Identifier(s):
- OSTI ID: 1376646