Grant Probst, “Microbial Physiology of Mercury Methylation: Investigating the Influence of Dissolved Organic Matter from Diverse Ecosystems on Microbial Methylmercury Production”
Mentor: Benjamin Peterson, Freshwater Sciences, Freshwater Sciences (School of)
Poster #190
Mercury methylation is a biochemical process in which inorganic mercury (Hg(II)i) is transformed into methylmercury (MeHg), a highly toxic and bioaccumulative substance. This reaction is primarily driven by specific bacteria and archaea that carry the hgcAB gene cluster, which enables mercury methylation. These MeHg-producing microbes generally thrive in anaerobic (oxygen-deprived) environments such as wetlands and sediments. Since MeHg is a neurotoxin and bioaccumulative, its production poses significant health risks to humans and wildlife, particularly through water contamination. Through previous research, dissolved organic matter (DOM) is a key factor influencing metal bioavailability, particularly concerning mercury. Here we are investigating how different types of DOM, specifically DOM from the Everglades and Lake Michigan, influence the production of MeHg in microbial cultures. Using cultures of Pseudodesulfovibrio mercurii sp. nov which are sulfate-reducing bacteria (SRB) known to produce MeHg, we are investigating how DOM characteristics influence MeHg production over a span of 50 hours (approx. two days). Utilizing the MerxM MeHg analyzer, we are quantifying MeHg production in these SRB cultures and measuring its response to varying conditions in units of nanograms per liter (ng/L). By analyzing the effects of these DOM sources on MeHg production over time, we can evaluate their impact on Hg(II)i bioavailability. In uncovering factors that drive microbial MeHg production, we are enabling more effective risk management of this environmental pollutant, increasing the lab’s ability to simulate the microbes’ habitat and achieving a greater understanding of the ecological role of MeHg within the food web.