I recently received a FINESST Award for my proposal “Interpreting acidic gypsum deposits as host for past and present microbial life.” I am currently a PhD Candidate in Geobiology at the New Mexico Institute of Mining and Technology (New Mexico Tech) Department of Earth and Environmental Science and in my third year in the program, working with Dr. Daniel S Jones (my advisor and FINESST project PI). Coming into my Ph.D., my background was in biology, and I received both my bachelor’s and master’s degrees from the Biology Department at New Mexico Tech. My foray into geobiological research started during my master’s, where I assessed the growth of destructive photosynthetic biofilms that proliferate near artificially lit areas in Carlsbad Caverns National Park in New Mexico. That project was funded by the National Park Service, and a manuscript from my research was published at the beginning of this year in Applied and Environmental Microbiology.
For my FINESST award and dissertation project, I will combine molecular geomicrobiology, organic geochemistry, and mineralogy to examine acidic gypsum from sulfidic cave systems as potential recorders of past and present microbial life. Sulfidic caves are perfect “natural laboratories” for studying biosignature preservation because their environments are free from overprinting by phototrophic organisms. In these caves, hydrogen sulfide gas from anoxic groundwaters condenses on cave walls, where acidophilic sulfide-oxidizing microorganisms catalyze the production of corrosive sulfuric acid. Microcrystalline gypsum forms as paste-like residue coating the walls and ceilings near degassing zones, and gypsum deposits build up over time as these crusts fall and form breakdown piles on the floor of the cave. This gypsum can persist in sulfidic caves for millions of years. My project will address how these gypsum deposits preserve biosignatures of the organisms that formed them, and whether chemosynthetic microbes continue to use them as a habitat for long periods of time.
With my FINESST project, I will be working with my advisor as well as Dr. Heather Graham at NASA Goddard. We will expand the approach we have been taking in the active Frasassi caves (Italy) to three additional systems representing a range of gypsum deposit ages: Acquasanta caves in Italy, Carlsbad Caverns, and Lehman Caves in Great Basin National Park in Nevada USA. Gypsum deposits in these caves are a few years to more than 10 million years old, and this timescale of aging gypsum is key to understanding of how well this mineral may or may not preserve evidence of life. If we find that biomarkers from chemolithotrophic microbes are preserved in these acidic gypsum deposits over millions of years, this could serve as a very promising basis for future detection of extinct or extant life on Mars.