Microorganisms often mediate many key biogeochemical processes that control the environmental fate and transport of contaminants; however, these microbes and their metabolic processes are often poorly understood and treated as a “black box”. Thus, my primary research goal is to develop a mechanistic understanding of microbial-contaminant dynamics in freshwater ecosystems to improve modeling of contaminant fate in response to local and global change. I propose that this will lead to improved management and engineering strategies to manage contaminants in complex ecosystems post-release and strive to develop collaborations that allow me to see this through.

In my laboratory, we have several ongoing areas of focus under this overall objective:

1. Develop field sites and studies that are conducive to long-term study and identifying key parameters controlling methylmercury formation: The formation of toxic methylmercury from inorganic mercury is a complex process controlled by many different biogeochemical cycles that leads to food web accumulation of methylmercury. Thus, we seek to understand how this microbial process is controlled across a wide range of ecosystems; past work has focused on Lake Mendota, the Florida Everglades, hydroelectric reservoirs along the Snake River, mining-impacted lakes in the Upper Pennisula of Michigan, and thawing permafrost systems in Alaska. Currently, we are developing projects to look at mercury methylation in the Laurentian Great Lakes in the backyard of the School of the Freshwater Sciences.

2. Explore new microbial methods to enable a more detailed mechanistic understanding of the microbial community impacts on mercury methylation: While the discovery of the mercury-methylating hgcAB gene cluster and the rapid improvements in molecular sequencing tools have drastically expanded our understanding of the microbial populations capable of producing methylmercury, recent efforts have highlighted how limited these tools can be in illustrating the mechanistic underpinnings of mercury methylation. To further our knowledge, it is key that we (1) apply new methods from microbiology, such as next-generation ecophysiology tools, and (2) develop new tools and strategies, both with the aim of improving our ability to link microbial physiology to mercury methylation in situ.

3. Implement culture-based methods to improve our ecological understanding of the role of methylmercury formation in microbial physiology: While our understanding of the mercury methylation process is improving, there remains a key knowledge gap surrounding the physiological role of the hgcAB gene cluster. It is unclear if the mercury methylation process is the intended function of hgcAB, perhaps as a detoxification method, or if there is another “native function” of the gene cluster. We are developing projects focused on this knowledge gap using microbial cultures and bioinformatic analyses of phylogeny and metabolic gene pathways.

4. Expand this approach to focus on additional contaminants, particularly legacy contaminants of concern in the Great Lakes and their watersheds: While the bulk of my research has focused on the mercury methylation pathway, the tools, skills, and perspective for this area are broadly applicable across microbial-contaminant interactions. Thus, we are seeking to apply these tools and approaches described above to other contaminants of concern in the Great Lakes region, such as PCBs in Areas of Concern.

 

Beyond these areas of emphasis, I am open to new collaborations with academic, government, or industry partners, so please reach out if you are interested.