|Title||A hydrogen-based subsurface microbial community dominated by methanogens.|
|Publication Type||Journal Article|
|Year of Publication||2002|
|Authors||Chapelle FH, O'Neill K, Bradley PM, Methé BA, Ciufo SA, Knobel LRL, Lovley DR|
|Date Published||2002 Jan 17|
|Keywords||Bacteria, DNA, Archaeal, DNA, Bacterial, Ecosystem, Euryarchaeota, Exobiology, Hydrogen, Molecular Sequence Data, Phylogeny, RNA, Ribosomal, 16S, Water Microbiology|
The search for extraterrestrial life may be facilitated if ecosystems can be found on Earth that exist under conditions analogous to those present on other planets or moons. It has been proposed, on the basis of geochemical and thermodynamic considerations, that geologically derived hydrogen might support subsurface microbial communities on Mars and Europa in which methanogens form the base of the ecosystem. Here we describe a unique subsurface microbial community in which hydrogen-consuming, methane-producing Archaea far outnumber the Bacteria. More than 90% of the 16S ribosomal DNA sequences recovered from hydrothermal waters circulating through deeply buried igneous rocks in Idaho are related to hydrogen-using methanogenic microorganisms. Geochemical characterization indicates that geothermal hydrogen, not organic carbon, is the primary energy source for this methanogen-dominated microbial community. These results demonstrate that hydrogen-based methanogenic communities do occur in Earth's subsurface, providing an analogue for possible subsurface microbial ecosystems on other planets.