SS4.02 The Role of Microbiology in Trace Metal and Organic Contaminant Cycling in Aquatic Systems
Date: Wednesday, June 12, 2002
Time: 10:00:00 AM
Location: Esquimalt
 
EkstromEB, Princeton University, Princeton, USA, eekstrom@princeton.edu
Benoit, J, M, Wheaton College, Norton, USA, jbenoit@wheatonma.edu
Morel, F, M, Princeton University, Princeton, USA, morel@princeton.edu
 
THE ROLE OF THE ACETYL-COA PATHWAY IN MERCURY METHYLATION BY SULFATE-REDUCING BACTERIA
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The increasing levels of methylmercury in freshwater and ocean fish populations is of vital concern to animal and human populations worldwide. Sulfate-reducing bacteria (SRB) in the anoxic water column and sediments have been implicated as the major producers of methylmercury in aquatic systems. Although a considerable amount of work has been completed assessing the environmental factors that control methylmercury formation, few studies have been undertaken analyzing the biochemical mechanism of methylmercury production. Prior work has implicated the acetyl-CoA pathway as key to mercury methylation in one SRB strain, Desulfovibrio desulfuricans LS. To assess if the acetyl-CoA pathway is necessary for mercury methylation in all SRB, strains were assayed for methylmercury formation and acetyl-CoA pathway enzyme activities. Our research complements prior work in showing that a relationship exists between the ability to methylate mercury and the presence of the acetyl-CoA pathway in Desulfovibrio species and among complete oxidizing SRB. However, Desulfobulbus species methylate mercury without the presence of the acetyl-CoA pathway. This study is the first step in understanding the complex biochemistry of mercury methylation in SRB.