Microbial life in oceanic crust Institutional Repository Document

Oceanic crust comprises a vast but virtually unexplored habitat for life on Earth, characterized by massive global flows of water, heat, and dissolved chemicals. Uncovering where and how life exists in oceanic crust is important because chemical reactions occurring in this environment impact broader ocean systems and also because it is an earth analog for considering the possibility of extraterrestrial life on other ocean worlds. Over the past decade, several major oceanographic expeditions focused on characterizing the ocean crust microbiome, enabled by advances in seafloor drilling and observatory technologies. Here we review what is known about the crustal ocean microbial biosphere, focusing on a new synthesis of recent studies on the diversity of microbial life in oceanic crust to reveal common and unique taxa in this environment.