New Roles for Microbes in the Mercury/Methyl Mercury Cycle
Mercury is a global pollutant released into the atmosphere during coal burning and into freshwater systems froma agricultural runoff and industrial discharge. Once in freshwater systems, microorganisms, known as d-proteobacteria, create methylmercury (MeHg), a highly toxic form of mercury that accumulates in biological systems. High concentrations of MeHg are detected in biota in the East Fork Poplar Creek in Oak Ridge, Tennessee, even though mercury producing weapons production activities at the Y-12 National Security complex were discontinued many years ago. Oak Ridge National Laboratory scientists recently characterized the impacts of mercury and uranium contamination on the diversity and structure of bacterial populations from the East Fork Poplar Creek and other nearby streams. The team sampled 6 different streams at select times over a year and demonstrated that specific microbial groupings (Verrucomicrobia and e-proteobacteria groupings) were most closely correlated with high MeHg levels, even though no bacteria in these groupings are known to have any role in MeHg generation. This is the first study to indicate an influence of MeHg on an existing microbial community, and suggests that bacteria within the Verrucomicrobia and the e-proteobacteria groupings have an important, but yet to be determined role in the overall Hg/MeHg cycle.
Vishnivetskaya T. A., J.J. Mosher, A. V. Palumbo, Z. K. Yang, M. Podar, S. D. Brown, S.C. Brooks, B. Gu, G. R. Southworth, M. M. Drake, C. C. Brandt, and D. A. Elias. 2010. “Mercury and Other Heavy Metals Influence Bacterial Community Structure in Contaminated Tennessee Streams,” Applied and Environmental Microbiology, published online ahead of print on 5 November 2010, doi:10.1128/AEM.01715-10.