Tapping the Subsurface Ocean Crust Biosphere: Low Biomass and Drilling-Related Contamination Calls for Improved Quality Controls

Microbial communities inhabiting subseafloor ocean crust were analyzed using culture-dependent and -independent techniques of volcanic basement drill-cores from various locations in the Pacific Ocean. Our results suggest that a low-diversity community of bacteria belonging to the Betaproteobacteria, Alphaproteobacteria, and Bacteroidetes exists in this rocky habitat. Drilling-related contamination was observed, however, identification of these phylotypes was (and will continue to be) beneficial for distinguishing indigenous from contamination-related communities. Due to difficulties in accessing the subseafloor crustal environment, this study further highlights the necessity for innovative approaches in future drilling-based microbiological studies conducted in ocean crust.