Possible Occurrence of Subsurface Lithotrophic Microbial Ecosystem (SLiME) Sustained by Geologically Derived Energy and Carbon Sources: HyperSLiME in the Mid Ocean Ridges and AlkaliSLiME in the Mariana Forearc

Abstract

Subsurface microbial communities supported by geologically derived energy and carbon sources fkom the earth's interior have great interest not only with regard to the nature of primitive life before photosynthesis, but as potential analogs for extraterrestrial life. Here we present the hypothesis that hyperthennophilic subsurface lithoautotrophic microbial ecosystem (HyperSLiME) dominated by hyperthermophilic methanogens might be present beneath active deep-sea hydrothermal seafloors in the Mid Ocean Ridges (MOR) and that alkaliphilic subsurface lithotrophic microbial ecosystem (AlkaliSLiME) may occur in the deep subsurface biosphere of the serpentine-bearing seamounts in the Mariana Forearc. The existence of HyperSLiME has been recently proved in the geochemical and microbiological investigation of a deep-sea hydrothermal system in the Central Indian Ridge. Exploration of AlkaliSLiME is now underway with the samples obtained from the South Chamorro seamount by means of Ocean Drilling Project Leg#195 and Shinhi6500 cruise.