Current Research Projects
Mirroring my academic path, my research projects are highly interdisciplinary in nature, spanning the fields of ecology, evolution, microbiology, geology and geochemistry. I strive to combine computational modeling, bioinformatics, laboratory based experimental approaches, and analog site field work to answer fundamental questions about life’s distribution on Earth and across our universe.
Looking at Life One Cell at a Time
In my current research, I quantify the heterogeneity between single cells relative to population averages across the stages of maintenance, replication, and division. These measurements have typically been quantified for microorganisms on the population level, and it is unclear if single cells themselves exhibit very slow or fast rates of growth relative to these averages, particularly under increased environmental stress exposure. I employ synthetic constructs to help signal the timing of cell cycle events through fluorophore expression, measurements of single cell growth, and estimates of metabolic energy yield relative to maintenance costs. I am particularly interested in characterizing this heterogeneity under elevated stressors such as temperature, salinity, and pH, and across different metabolic groups, to help us understand cellular behavior in low biomass extreme environments on Earth and on other planets.
Life in an Ancient, High-Temperature South African Brine Feeds on the Products of Radiolysis
In 2018, a high temperature and near-salt saturated brine was discovered by my PhD advisor Dr. Tullis Onstott and collaborators in the deep subsurface (up to 3.1km depth) in Moab Khotsong mine, located in the Witwatersrand Basin of South Africa. This brine system has a subsurface residence time of >1Ga, making it among the longest isolated fluid bodies in Earth’s terrestrial subsurface. Through my PhD and continuing today, I work to characterize the unique geochemistry, organic chemistry, and microbiology of this ancient system. A major characteristic of the Moab Khotsong brines is the high levels of water radiolysis, found to produce the brine salinity overtime, while also generating redox substrates supporting metabolism by microbial life over long timescales in isolation. These features highlight the brine system as a superb analog for Mars and ocean worlds like Europa and Enceladus, particularly in isolated subsurface zones where radiolysis may be a dominating water-rock process.
Sri Lankan Serpentines as an Analog for Noachian Mars
In collaboration with team members from Louisiana State University and NASA’s Jet Propulsion Lab, I use geochemical software (Geochemist’s Workbench) to model the formation of serpentine mineral assemblages in Sri Lanka’s Highland and Vijayan Complexes based on field-derived X-Ray Fluorescence measurements. These computational estimates allow us to constrain the formation conditions leading to minerals observed in the field, including such conditions as past water-rock ratios, formation temperatures, and emission of biologically useful metabolic substrates like hydrogen and methane gas. The mineral zones of Sri Lanka serve as a useful analog for understanding serpentine formation conditions, distribution, and redox-based habitability for microbial populations under conditions similar to those estimated for a wetter, warmer Noachian Mars.
