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Allen, CC ; Albert, FG ; Chafetz, HS ; Combie, J ; Graham, CR ; Kieft, TL ; Kivett, SJ ; McKay, DS ; Steele, A ; Taunton, AE ; Taylor, MR ; Thomas-Keprta, KL ; Westall, F

Microscopic physical biomarkers in carbonate hot springs : Implications in the search for life on Mars

Icarus 147 (1) 49-67

par Administrateur - publié le

Abstract :

Physical evidence of life (physical biomarkers) from the deposits of carbonate hot springs were documented at the scale of microorganisms-submillimeter to submicrometer. The four moderate-temperature (57 to 72 degrees C), neutral pH springs reported on in this study, support diverse communities of bacteria adapted to specific physical and chemical conditions. Some of the microbes coexist with travertine deposits in endolithic communities. In other cases, the microbes are rapidly coated and destroyed by precipitates but leave distinctive mineral fabrics. Some microbes adapted to carbonate hot springs produce an extracellular polymeric substance which forms a three-dimensional matrix with living cells and cell remains, known as a biofilm.