Deep Subsurface Basalts Metagenome
Approximately 42% of the continental crust is composed of mafic magmatic rocks, such as basalts. These rocks often manifest themselves as massive areas known as large igneous provinces (LIPs). LIPs cover thousands to millions of square kilometers and thus comprise major portions of the subsurface and the biosphere. LIPs, and more specifically basalts, are known to be chemically reactive and favorable for microbial life due to the abundance of reduced compounds in the rock. LIPs exist both in marine systems and terrestrial systems. In marine systems, microorganisms are known to extensively interact with minerals in basalt and may play a large role in the global biogeochemical cycles of C, Fe, and S. Sources of energy available to lithoautotrophic microorganisms below the seafloor include minerals containing reduced Fe and S and also H2 generated from water-rock reactions. Hydrogen is of particular interest in terrestrial subsurface basalt systems, where the subsurface lithoautotrophic microbial ecosystem (SLiME) hypothesis originated. SLiMEs are microbial communities that subsist in deep oligotrophic environments without utilizing energy rich reduced organic compounds that originated from photosynthesis. SLiMEs were first hypothesized to exist in the Columbia River Basalt Group (CRBG). Basalt systems also host diverse communities apart from SLiMEs, such as microbial communities consisting of iron reducers, sulfate reducers, acetogens, and methanogens. In the basaltic Snake River Plain Aquifer (SRPA) in Idaho, microbial communities cycle carbon by forming and oxidizing methane. Today, LIPs are being examined as potential geological storage sites for carbon dioxide in an attempt to sequester CO2 away from the atmosphere to alleviate temperature increases due to climate changes. The Wallula pilot well being used for a geologic carbon sequestration project in eastern Washington State and located in the CRBG provides a window to the subsurface where the microbial diversity of these geologically important regions can be explored. In addition, the well will provide insight into the microbial communities present in the basalts that could play a role in carbon cycling in the deep subsurface where supercritical CO2 (scCO2) is injected. Analyzing samples from the CRBG using deep DNA sequencing technology will further the understanding of the unique microbial diversity of the subsurface, especially with respect to community composition of LIPS and different members contained in different formations. These metagenomic datasets complement marker gene sequencing submitted as PRJNA251746, PI Heather Lavalleur