DATE/TIME: Friday, September 23, 2022, 2:30 pm PLACE:
University of Georgia
Mechanistic ecology across scales: microbial adaptations to heavy metals at a contaminated subsurface site
Globally, contamination of environments with elevated levels of multiple heavy metals is a widespread problem. Heavy metal contamination can disrupt biogeochemical cycling through the inhibition of key microbial processes. However, the strong selective pressure imposed by heavy metal contaminants promotes the rapid evolution and adaptation of native microbial populations, primarily facilitated by the replication and mobilization of mobile genetic elements. My work seeks to understand both genome evolution and the systems-level stress responses of microorganisms living within the complex chemical environment of the contaminated shallow subsurface of the U.S. Department of Energy (DOE) Oak Ridge Reservation (ORR; Oak Ridge, TN). This site is contaminated by nitric acid and a mixture of heavy metals due to the improper discharge and storage of uranium-processing wastes from the DOE Y-12 National Security Complex throughout the mid-twentieth century.
By integrating field measurements, metagenomic data, and systems-level multi-omic analyses, I examine microbial adaptations to the heavy metal stressors present at this site across multiple scales which I will highlight through three case studies: (1) comparisons of culture-independent, metagenome-assembled mobilomes (i.e., community-derived mobile genetic elements) originating from high- and low-contamination regions of the ORR, (2) ecophysiological and genomic analyses of a representative isolate of a dominant ORR species to understand niche-specific adaptations, and (3) multi-omics studies comparing the cellular response of a native ORR isolate during a site-relevant metals mixture exposure (U, Al, Mn, Fe, Co, Cu, Cd, and Ni at typical site concentrations) to the responses observed during individual metal exposures.