Microbial diversity in marine sediments from the Canterbury Basin, New Zealand (IODP Leg 317)

The subsurface realm is colonized by microbial communities at depths of more than 1000 meters below the seafloor (mbsf), but little is known about its global diversity and microbial distribution pattern at depth. Here we show that not only Bacteria and Archaea, but also Eukarya occur at record depths in the subseafloor of the Canterbury basin. Shifts in microbial community structure along the core reflect taxa vertical zonation influenced by depth and physical-geochemical conditions. Representatives of some microbial taxa were also cultivated using methods mimicking in situ conditions. These results suggest that a diversity of microorganisms could exist down to 1922 mbsf in the seafloor of the Canterbury basin and extend the previous geographical limits of life (i) from 113 to 1740 mbsf for eukaryotes and (ii) from 1626 to 1922 mbsf for prokaryotes.