Mechanistic principles of methylmercury formation in anaerobe microbial biofilms

The global spread of mercury (Hg) is a major threat to ecosystem viability and human health, mainly due to microbially mediated formation of methylmercury (MeHg). This neurotoxic form of Hg can accumulate in aquatic food webs and cause high exposure to wildlife and humans.

Attempts to parameterize predictive models for MeHg formation rates and amounts in the environment have been unsuccessful.

Mechanistic studies on MeHg formation have been done on planktonic cell cultures while in nature microbes are present as biofilms, which show high MeHg production but the reasons and mechanisms are elusive. Our overall aim is to formulate mechanistic principles for MeHg formation in microbial biofilms.

We will identify how the chemistry of the biofilm matrix controls Hg cellular uptake, determine if MeHg formation rate is limited by uptake, expression of methylation genes or biofilm cell metabolic status and study metabolic pathways for MeHg formation.

We will combine key expertise in molecular-level studies of MeHg formation and of biofilms and use novel experimental strategies based on advanced spectroscopy methods.

By using biofilms, the derived mechanistic framework will be more relevant to natural conditions and a major step towards the so far unattainable goal of predicting MeHg formation in the environment.

It will also provide a new basis for developing mechanistic models for both scientific and societal use to mitigate the adverse environmental and health effects of MeHg.