Archives of endolitic life in basalt from the Mid-oceanic ridges.

SRISAWANG, B., BIRGEL, D., GEHLKEN, P.-L., GIANI, L., SCHNETGER, B., REITNER, J., BÖTTCHER, M.E., PECKMANN, J. (2005):
Archives of endolitic life in basalt from the Mid-oceanic ridges.:

One of the most extreme environments on Earth is found within basalts at Mid-oceanic ridges. Here, endolithic microbes are dwelling in the locally extensive pore space. A fair proportion of the pore space is created by microorganisms themselves with parts being modified by the formation of secondary minerals. One key question is to what extent volcanic glass provides energy and nutrients that support endolithic life. In a comprehensive approach, we combine a number of different techniques (microscopic methods, phase analytical methods, elemental analyses, organic geochemical and stable isotope techniques) to characterize the presence and the solid phase signatures of microorganisms. The biological alteration in basaltic glass was estimated by comparing crust and core sections, and on detailed profiles. The application of element mapping and chemical extractions yields element patterns consistent with biological activity. The lipid biomarkers with an enrichment of the light isotope (d13C values between -24 to -30‰) point to a contribution from fresh biomass.
The results of work on biosignatures in extreme environments such as basalts may provide a frame for the search for extraterrestrial life.