Abstract: Mercury is a globally important contaminant of concern that is elevated by anthropogenic activities and can bioaccumulate and biomagnify to toxic levels. Food web accumulation occurs as methylmercury, which is produced by microorganisms in the environment from inorganic mercury. Thus, this process is a key gateway controlling mercury accumulation in aquatic food webs. The identification of the mercury methylation gene cluster hgcAB has greatly accelerated our understanding of these microbes; however, significant questions remain regarding their functional diversity and relative activity, environmental distribution and relevance, as well as the physiological role of the hgcAB genes. In this presentation, I will outline several projects that deploy omic’s sequencing methods, enriched stable isotope incubation assays, and biogeochemical measurements to use microbes as a window into understanding biogeochemical controls on methylmercury formation. While the work represents a significant advancement in our conceptual model of environmental mercury methylation, it also highlights the knowledge gaps that preclude a mechanistic understanding and quantitative modeling of this globally important process.
Bio: Dr. Benjamin Peterson is an Assistant Professor in the School of Freshwater Sciences at the University of Wisconsin – Milwaukee. He received his Bachelor of Science in Biochemistry from the State University of New York at Geneseo. He received his PhD in the Environmental Chemistry and Technology program at the University of Wisconsin – Madison on The ecophysiology of mercury-methylating microorganisms in freshwater ecosystems. He continued his work on microbial mercury transformations as a postdoctoral scholar at the University of California – Davis. At UW – Milwaukee, his overall research objective is to develop a mechanistic understanding of how microbial communities link biogeochemical cycles to contaminant fate and transport in environmental ecosystems, with a continued emphasis on mercury. To do this, he uses an interdisciplinary approach including environmental omic’s and bioinformatics, stable isotope biogeochemistry, mesocosm experiments, modeling, and anaerobic laboratory cultivation. He has worked across the United States, from coastal wetland in the Florida Everglades to thawing permafrost in northwest Alaska but now has a specific focus on the Laurentian Great Lakes.
