| The sub-seafloor biosphere may contain two thirds of Earth's total prokaryotic biomass. The large and active microbial populations buried in the sub-seafloor play a key role in global biogeochemical cycles. However, little is known about these prokaryotic communities. The depth limit of this sub-seafloor biosphere is still unreached, and elevated temperatures as well as insufficient energy sources are the likely factors limiting life at depth. Interestingly, archaeal communities with unknown physiologies and no cultured relatives seem to have a key role in deep marine sediments and hydrothermal ecosystems. As most deep biosphere microorganisms detected so far have been extremely resistant to cultivation, molecular approaches remain to date the most... |
