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

Abstract

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.

Keywords:

• biogeochemical cycling
• biomineralization
• deep biosphere
• molecular ecology
• subsurface microbiology

The authors thank the Co-Chief scientists and staff scientists for ODP Legs 192, 205, and 206 for accommodating and facilitating the sampling techniques required for microbiological and molecular biological analyses. Also, Dr. Jay Miller (IODP) provided information regarding sewage release regulations and sanitation procedures. This research used samples and data provided by the Ocean Drilling Program (ODP). ODP was sponsored by the NSF and participating countries under management of Joint Oceanographic Institutions (JOI), Inc. Funding for this research was provided by a Schlanger Ocean Drilling Fellowship to C.M.S. and U.S.S.S.P Post-Cruise Award #TX A&M F001724 to C.M.S. and K.J.E. Participation for NB on ODP Legs 192 and 206 was provided by Canada ODP.