Mercury pollution is a persistent problem in the environment. Now, in a new research experiment, a team of scientists has revealed the key to how bacteria can clear mercury pollution in waterways.
Human activity has lead to increasingly large accumulations of the toxic chemical, especially in waterways, where fish and shellfish tend to act as sponges for the heavy metal.
It's that persistent and toxic nature that has flummoxed scientists for years in the quest to find ways to mitigate the dangers posed by the buildup of mercury in its most toxic form, methylmercury.
A new discovery by scientists at the University of Tennessee (UT), Knoxville, and Oak Ridge National Laboratory (ORNL), however, has shed new light on one of nature's best mercury fighters: bacteria.
"Mercury pollution is a significant environmental problem," said Jeremy Smith, a UT-ORNL Governor's Chair and lead author of the new 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," he added.
Scientists have known that a specific enzyme, known as MerB, gives the bacteria the ability to convert methylmercury into a less-toxic form of mercury that poses substantially less environmental risk, a trait that lets them survive in mercury-rich environments.
Finding out how this enzyme works potentially may be a viable way to combat methylmercury.
The UT Knoxville and ORNL researchers, working with colleagues from the University of Georgia and University of California, San Francisco, were able to determine the mechanism - at the most detailed level - of how the MerB enzyme breaks apart the dangerous methylmercury molecule.
The scientists used high-performance computers to determine how the three-dimensional structure of the enzyme uses a sort of one-two-three punch to break apart a key link in the methylmercury, between mercury and carbon atoms.
Once that bond is broken, the resulting substance is on the way to becoming substantially less harmful to the environment.
Knowing the exact layout of atoms within both the methylmercury and the MerB enzyme, the researchers found out how the enzyme creates an electric field that shifts around electrons in the methylmercury, priming the toxin for deconstruction.
The next challenge researchers face will be to find a way to take this new understanding of how methylmercury can be broken down nd apply it in an ecosystem at large.