A QUALITATIVE STUDY OF MICROBES IN SERPENTINITE-HOSTED SUBSURFACE ENVIRONMENTS

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Joe W. Blackburn (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Over the last two decades, serpentinizing environments have been studied with regards to the biogeochemistry of these habitats, but significantly less is known about the microbiology within these environments. Serpentinization is a metamorphic process that occurs when ultramafic rocks, originating in Earth’s upper mantle, interact with water near the Earth’s surface as a result of tectonic activity. This reaction represents multiple geochemical processes, which are responsible for the abiotic synthesis of copious amounts of hydrogen. The high concentrations of hydrogen are conducive to the formation of methane and short-chain hydrocarbons from the reduction of inorganic carbon. The proliferation of hydrogen and methane provide serpentine-hosted environments with an adequate supply of electron donors, while the availability of electron acceptors is significantly lower. Although serpentinization produces abiogenic organic compounds that can theoretically sustain microbial communities, it creates multiple challenges microbial communities must overcome, including alkaline environments (pH 10-12), highly reducing conditions and limited access to inorganic carbon. These adverse conditions make sustaining crucial physiological processes, such as maintaining a proton motive force and stabilizing RNA, difficult challenges for microbes to overcome. It is currently unknown what metabolic adaptations microbes have undergone to survive under these harsh conditions. In 2011, boreholes were drilled for core recovery and core fluid experimentation at two sites within the Coast Range Ophiolite Microbial Observatory (CROMO) near Lower Lake, CA in the McLaughlin Natural Reserve (Cardace et al., 2013). Alkaliphilic microbes were grown and isolated from recovered core samples. Genomic DNA was extracted from cultivable isolates and used to sequence their 16S rRNA gene to identify them and perform phylogenetic studies. Microbial assays provided insight into the biochemical processes of microbes that have been under the unique pressures of serpentinization. Finally, cellular proliferation was measured relative to pH tolerances. These qualitative studies allowed us to explore the metabolic capabilities of microorganisms in a serpentinite-hosted subsurface biosphere. Furthermore, this research helped us look into the habitability of microbes in extreme environments as well to examine their potential use in future bioremediation projects.

Additional Information

Publication

Thesis

Language: English

Date: 2023

Subjects

Biology

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