MICROBE-MINERAL INTERACTIONS IN A SUB-ZERO BRINE AQUIFER BENEATH TAYLOR GLACIER, ANTARCTICA

Subglacial basal materials are known to be inhabited by active microbes. Through their metabolic processes, these microbes interact with glacial till minerals, releasing nutrients and metabolic byproducts including carbon dioxide, methane and possibly other greenhouse gases. Blood Falls, a site where iron-rich subglacial brine episodically flows to the surface from a conduit within the Taylor Glacier, Antarctica, provides a rare window into a subglacial microbial world. Geophysical data indicates that Blood Falls outflow is sourced from an extensive subglacial aquifer. We seek to analyze how resident microbes interact with minerals in the basal sediment and are adapted to conditions within the brine. In this study, we show that pathways mediating the uptake and cycling of iron and sulfur are present in the brine metagenome, and that brine isolates exhibit specific adaptations for cold and salt tolerance. We also present preliminary results from microcosm experiments designed to model subglacial interactions between microbes and mineral substrates to assess microbe-mediated mineral etching and volatile organic compound production. Our work contributes to the notion that microbes beneath glaciers form active communities despite isolation from the surface. Understanding how microbial communities influence subglacial chemistry and emit volatile compounds into the atmosphere may provide insight into how glacial systems shape their environments. This work may also identify potential biomarkers for putative life on worlds with ice caps like Mars and Europa.