Microbial Sulfur Cycling in Extreme Environments:

I investigate microbial communities involved in sulfur cycling within serpentinizing systems and hydrothermal vents—environments shaped by steep redox gradients and extreme chemistry that serve as analogs for extraterrestrial habitats. Serpentinizing systems are enriched in H₂ and CH₄, while Yellowstone’s hydrothermal springs are dominated by sulfur- and sulfate-rich fluids; both provide unique niches for sulfate-reducing microorganisms. My work combines metagenomic and transcriptomic analyses to identify key sulfate-reduction genes (sat, apr, dsrAB) and links their distribution to environmental chemistry and thermodynamic models. By integrating sequencing data with field geochemistry from global serpentinizing sites and Yellowstone hot springs, I map how sulfate-reducing microorganisms adapt to energy-limited ecosystems and define the geochemical controls on their activity.

Enzyme Adaptations Under High Hydrostatic Pressure

At the molecular scale, I study how enzymes essential to sulfate reduction—particularly the dissimilatory sulfite reductase complex (DsrAB with its partner DsrC)—function under extreme pressures like those found in Europa’s subsurface ocean. I extract, clone, and purify these enzymes from Yellowstone sulfate reducers and then expose them to simulated high-pressure conditions in the lab. By measuring catalytic efficiency, substrate affinity, and structural stability across pressures up to ~200–260 MPa, I test how microbial metabolisms might remain viable under Europa-like conditions and what adaptations make enzyme activity possible in such extremes.

Astrobiological Implications and Planetary Habitability

Bridging geomicrobiology, enzymology, and planetary science, I apply my Earth-based findings to questions of life beyond Earth. Studying microbial sulfate reduction in serpentinizing and hydrothermal systems allows me to refine models of how similar processes might operate on icy moons such as Europa and Enceladus. My current research links enzyme behavior, thermodynamic predictions, and field observations to astrobiological exploration, identifying potential biomarkers like DsrAB for detection by instruments on upcoming missions such as NASA’s Europa Clipper, and advancing our understanding of planetary habitability in ocean worlds.