The Mystery of Microbial Mercury Methylation: who’s doing it, how, where, and why?

This recently published paper in Nature Microbiology is a great example of a productive collaboration between one of the Centre’s Associate Members, John Moreau and the Holt lab.

Caitlin M. Gionfriddo, Michael T. Tate, Ryan R. Wick, Mark B. Schultz, Adam Zemla, Michael P. Thelen, Robyn Schofield, David P. Krabbenhoft, Kathryn E. Holt and John W. Moreau. Microbial mercury methylation in Antarctic sea iceNature Microbiology 1, Article number: 16127 (2016); doi:10.1038/nmicrobiol.2016.127.

Methylmercury is a potent microbially-produced neurotoxin found  globally in flooded sediments, waterways, estuaries, and seawater.  Although global atmospheric mercury emissions have been declining, global temperature increases could result in increased enzymatic conversion of previously deposited mercury to methylmercury.  After over a half-century of research into its mechanism of formation, the key functional genes involved in the transformation of Hg^2+ to CH(sub)3Hg^+ were only discovered within the last several years.  However, we still do not understand the geographical or phylogenetic distribution of these genes, their evolution, their expression or relationship to metabolism and physiology, or their impacts on environmental biogeochemical mercury cycling.  This paper will review what we know, what we think we know, and what we don’t know, as well as show some Picture1data from our recent finding of methylmercury formation by a major marine bacterium in supposedly “pristine” Antarctic waters.

Dr. John W Moreau, Geomicrobiology Lab, School of Earth Sciences