Organic thiols are prevalent on cell envelopes and interact with various soft metals such as Hg and Cd in the environment, thus affecting the fate, transport, and toxicity of these contaminants, but the estimation of their concentration and speciation has been difficult. We have developed a fluorescence spectroscopy-based technique for quantifying thiols on bacterial cell envelopes suspended in water, and have used high-energy spectroscopy techniques to characterize the thiol content on the cell membranes of both Gram-positive and Gram-negative bacteria. Our studies indicate that the membrane-bound thiols interact with Hg strongly, and the number of coordinated thiols around Hg decreases with an increase in Hg concentration. Hg-thiol speciation and toxicity experiments have been conducted on a non-methylating organism, Shewanella oneidensis MR-1, to determine whether this organism forms certain Hg-thiol complexes on its surface as a defense mechanism against Hg contamination. A summary of these results will be presented.

Nature of reactive thiols on bacterial cell envelopes and their reactivity with aqueous Hg

245th National Meeting (2013)

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