Geomicrobiology of the Deep Biosphere
Jason Sylvan, Texas A&M University (TAMU), College Station, USA
One of the great surprises in ecology during the last 20 years was the discovery of a vast microbial biome deep below the seafloor and terrestrial habitats. This environment, know as the deep biosphere, is the largest microbial habitat on the Earth. We now know that as many prokaryotic cells live in subseafloor sediment as in the entire oceanic water column, and microbial biomass in the basement rocks exposed at mid-ocean ridges and underlying sediments is currently unknown. Therefore, with sediments and basement rocks combined, there are likely more cells below the seafloor than in the water column, making the study of this biosphere critical to understanding marine microbiology, chemistry and geology. On land, study of the deep biosphere yielded insights into entire ecosystems 2.8 kilometers below the surface that are comprised of a single microbe, as well as incredibly diverse ecosystems that changed our understanding of microbial diversity and metabolism. I will present an overview of the field of geomicrobiology of the deep biosphere and also highlight my own work, which focuses on exploring geomicrobiology of marine subseafloor basement, an exciting field where first order questions such as quantifying microbial biomass and diversity are just beginning to be answered.