The seafloor and subsurface microbial world represents a significant portion of life on our planet. The influence on its proximate ambience and global processes, such as element cycles, has potentially been largely underestimated and not always been precisely evaluated. I am interested in the nature of deep biosphere microorganisms in rocks from the Loihi seamount, Hawai’i, the East Pacific Rise, and the Juan de Fuca Ridge, as well as in sediments from North Pond (Mid-Atlantic). In order to assess microbial diversity, metabolic activity, adaptation strategies and biogeographical signatures in the deep subseafloor biosphere, metagenomics by pyrosequencing will be used to complement previous research efforts with the most in-depth and precise data that is available to date.