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Project Progress

Our focus is to identify forms of microbial life that are chemosynthetically supported by water-rock interaction, and to develop high-resolution geochemical techniques capable of measuring the biological signatures of their activity. We are specifically interrogating microbial interactions with the crust in the deep ocean and subsurface, which together comprise the largest unexplored habitats on Earth.

We are using Vailulu’u Seamount, an active submarine volcano in American Samoa, as a source of recently erupted basaltic rocks to investigate the phylogeny of microbial organisms associated with basalt surfaces, their modes of metabolism, and the temporal evolution of these communities over both short and long (geological) timescales. We have achieved rapid success in culturing psychrophilic to thermophilic Mn-oxidizing bacteria driving rapid weathering and biomineralization reactions. We also recovered 3-month in-situ deployments of fresh basalt surfaces for analysis by highly surface-sensitive, synchrotron-based x-ray spectroscopic and scattering techniques. These techniques enable us to measure nanoscale chemical gradients and biosignatures that form at the rock-water interface and resolve the specific activity of Fe and Mn-oxidizing bacteria. We have also initiated x-ray mapping and spectroscopic analysis of deeper crustal rocks recovered by drilling that contain putative bioalteration features 5-10 million years old.

New work was also initiated in a deep subsurface mine in Colorado, where ancient fluids rich in dissolved metals and CO₂ are issuing into tunnels >3,000 ft below the surface. The major and minor element geochemistry is entirely dominated by water-rock interaction, and organic carbon is absent, making this an excellent site to search for microbial organisms that can use geochemical sources of energy for growth. Fluids and biofilms that form at oxic-anoxic interfaces were used to successfully establish enrichment cultures for novel thermophilic metal-oxidizing consortia.