UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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Author: search.filters.author.Kerin, ElizabethSubject: search.filters.subject.methylmercury

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    Mercury methylation in dissimilatory iron reducing bacteria
    (2007-08-13) Kerin, Elizabeth; Suzuki, Marcelino; Gilmour, Cynthia; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Microbial mercury methylation is an integral factor controlling methylmercury concentrations within aquatic ecosystems. This thesis explores the phylogenetic distribution and biochemistry of methylation among the dissimilatory iron-reducing bacteria (DIRB). When distribution of methylation capacity among DIRB was examined, strains of Geobacter spp., which are closely related to mercury-methylating, sulfate-reducing Deltaproteobacteria, methylated mercury while reducing iron or other substrates. In contrast, no tested strains of the Gammaproteobacteria genus Shewanella produced methylmercury above abiotic controls. Mercury methylation by the cobalamin-dependent methionine synthase (MetH) pathway was examined. Heterologous expression of G. sulfurreducens metH in E. coli was used to evaluate involvement of MetH in methylation. Methylation by a clone expressing MetH and a non-expressing control clone was tested in vivo and in vitro. Methylation by the expressing clone was not significantly higher than either the control or abiotic assays in either experiment, suggesting that MetH is not involved in methylation in G. sulfurreducens.