White Paper Title: 
Microbial-basalt interaction

The paper by Mason et al. "First investigation of the microbiology of the deepest layer of ocean crust" (submitted) shows that microorganisms found 400 to 1400 meters below the sea floor in ocean gabbros are capable of oxidizing organic compounds. Some of the organics appear to be catalyzed at temperatures above 100°C in the crust or upper mantle in the presence of igneous minerals. This organic matter is transported in fluids to the crust where it can react with oxidants from seawater. If this oxidation occurs at temperatures below 120°C, then it can support a microbial biosphere in the crust. The paper by Heberling et al. ("The extent of the microbial biosphere in the oceanic crust" Geochemistry, Geophysics, Geosystems, 2010) indicates that this oxidation is can occur in the upper 1 to 5 kilometers of the ocean crust. The paper by Smith et al., "New method for selective enrichment of microbes in sub-seafloor minerals and glass" (in preparation) demonstrates an in situ method of obtaining microorganisms from within a borehole in the ocean crust. In that study igneous minerals were incubated in a borehole in ocean crust Layer 2A for four years and then recovered. Some to these organisms that were enriched on the minerals appear to be capable of oxidizing organic compounds and iron with nitrate. These studies indicate that within the ocean crust, organic compounds and iron from igneous minerals can be oxidized even under anaerobic conditions. This environment is certainly reproduced on Mars where water, iron-rich igneous minerals, methane, and low levels of oxidants coexist in the subsurface. These studies point to specific future goals of (1) investigating microorganisms from the ocean crust, (2) identifying organic compounds in hydrothermal fluids, (3) further development and use of in situ subsurface microbial samplers, (4) modeling of subsurface microbial environments, and (5) applying this new understanding to the search for subsurface life on Mars.