Developments in Marine Geology: Earth and Life Processes Discovered from Subseafloor Environments - A Decade of Science Achieved by the Integrated Ocean Drilling Program (IODP)
Editors: Ruediger Stein, Donna K. Blackman, Fumio Inagaki, Hans-Christian Larsen
Published: December 5, 2014
C-DEBI Contribution Number: 246


Gene sequencing of natural microbial communities in the deep subsurface has provided access to a biosphere of Bacteria, Archaea, and Eukaryotes, characterized by unexpected evolutionary depth and diversity. Despite phylogenetic overlaps with surface environments, the predominant groups of Bacteria and Archaea in the subseafloor differ from those found in surface seafloor environments. The extent and diversity of the deep subsurface biosphere has been mapped to a large extent using gene and genome sequence analysis; these approaches have extended ongoing cultivation efforts on subseafloor microbial communities, including new types of Bacteria, Archaea, and Eukaryotes in pure culture. This chapter starts by introducing the most commonly used, highly conserved, and phylogenetically informative marker gene, the 16S ribosomal RNA gene, then provides an overview on sequence analysis of functional genes that code for proteins and enzymes with distinct biological and process-relevant functions, and concludes with recent metagenome and single-cell sequencing surveys that allow novel insights into microbial diversity and function of the deep subseafloor biosphere.