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2014 Abstracts

Genetic Origins of Mercury Resistance in Great Salt Lake Halophiles

Ashtyn Smith, Westminster College

Life Sciences

Methylmercury (CH3Hg) is a neurotoxin that accumulates in lakes and streams due to the action of microorganisms, which can produce this biologically relevant organic form from elemental mercury (Hg). Therefore, the activities of microorganisms become key to understanding the balance of Hg and CH3Hg in the movement through the food chain in any ecosystem. Many species of microorganisms are resistant to Hg and can thrive in polluted waters. Recent studies have shown that Hg resistance in microbes can stem from one of two gene pairs, merAB or hgcAB. The merAB system allows the organism to covert CH3Hg into elemental Hg. Conversely, the hgcAB system coverts Hg into CH3Hg. Thus, it is important to determine how the microbial community of Great Salt Lake, Utah is affecting the CH3Hg concentrations in the lake. In order to determine the genotype of the lake’s halophiles, “salt-loving” organisms, microorganisms were collected from the deep brine layer in eight areas of the lake. The microorganisms were then isolated and cultivated on increasing concentrations of HgCl2. Halophiles from these samples have been isolated on 25 ppm HgCl2 at various salinities, demonstrating a robust resistance to Hg. PCR amplification and genetic sequencing will be used to determine the gene mechanism of mercury resistance (merAB or hgcAB) as well as the 16S rRNA gene, which will aid in identification of the species. Should this study identify GSL microorganisms that exhibit the merAB genotype, these organisms could potentially be utilized as bioremediators of the CH3Hg pollution in the lake.