October 5, 2009

Study finds how bacteria combat mercury

U.S. scientists say they've found how bacteria convert methylmercury into a less-toxic form, allowing the bacteria to survive in mercury-rich environments.

The discovery by scientists at the University of Tennessee-Knoxville and Oak Ridge National Laboratory may provide a solution for some mercury pollution in waterways, where fish and shellfish tend to act as sponges for the heavy metal.

Mercury pollution is a significant environmental problem, said Professor Jeremy Smith, lead author of the study. That's especially true for organisms at or near the top of the food chain, such as fish, shellfish, and ultimately, humans. But some bacteria seem to know how to break down the worst forms of it. Understanding how they do this is valuable information.

The researchers, working with colleagues from the University of Georgia and University of California-San Francisco, used high-performance computers to determine how the three-dimensional structure of the enzyme breaks apart a key link in the methylmercury, between mercury and carbon atoms. Once that bond is broken, the resulting substance becomes substantially less harmful to the environment.

The researchers, whose work appears in the online edition of the Journal of the American Chemical Society, said their study is a feat that would have been technologically impossible only a year ago.