Scientists Discover how Bacteria Convert Mercury to Toxic Form

Two genes responsible for mercury methylation identified.

Image courtesy of Thomas Splettstoesser,
Researchers have identified two genes required for bacterial conversion of mercury into methylmercury, a more toxic form.

The Science

Methylmercury is a potent neurotoxin produced in natural environments from inorganic mercury by anaerobic bacteria, but until now, the genes and proteins involved have remained unidentified.

The Impact

A team of scientists from Oak Ridge National Laboratory and collaborators from the Universities of Missouri and Tennessee have identified a two-gene cluster required for mercury methylation.


For two strains of bacteria (Desulfovibrio desulfuricans ND132 and Geobacter sulfurreducens PCA), deletion of one or both genes eliminated the bacteria’s ability to methylate mercury. Among bacteria and archaea with sequenced genomes, related genes (orthologs) are present in confirmed methylators but absent in non-methylators, suggesting a common mercury methylation pathway in all methylating bacteria and archaea sequenced to date.


L. Liang
Biosciences Division, Oak Ridge National Laboratory
Oak Ridge, TN 37831


Supported by the Office of Biological and Environmental Research within the U.S. Department of Energy Office of Science


Parks, J.M. et al. “The genetic basis for bacterial mercury methylation.” Science 339,1332–1335 (2013). [DOI: 10.1126/science.1230667].

Related Links

Microbes, Mercury, and Risk: Oak Ridge researchers unlock a genetic key to mercury contamination of the food chain.

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