Because of extreme environmental conditions, deep sea subsurface sediments were traditionally regarded as a huge ‘desert’ unable to support any kind of life-form. However, 30 years’ investigation by the successive DSDP and ODP deep drilling projects indicated that microbes are extensively distributed in the deeply buried sediments and some shallow oceanic crusts in the world oceans. The subseafloor deep biosphere has huge microbial biomass and great biological and molecular diversity, and carries out a series of complicated and diverse physio-ecological functions. Study of the deep subseafloor biosphere microorganisms became the foci of studies on life’s origin and evolution, earth system evolution and transformation, global climate change, biotechnological development and exploitation of marine life and subseafloor natural energy resources. This review discusses the significances of the subseafloor deep biosphere microbial study and summarizes the progresses newly made in this field, in order to promote the initiation and development of related researches in our country for the active engagement in global marine resource exploitation and in international cooperation in tackling profound scientific issues in the new millennium.
