Low pressure and desiccation effects on methanogens: Implications for life on Mars |
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| Authors: | Timothy A. Kral Travis S. Altheide Adrienne E. Lueders Andrew C. Schuerger |
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| Affiliation: | 1. Arkansas Center for Space and Planetary Sciences, MUSE 202, University of Arkansas, Fayetteville, AR 72701, USA;2. Department of Biological Sciences, SCEN-632, University of Arkansas, Fayetteville, AR 72701, USA;3. University of Florida, Bldg. M6-1025, Space Life Sciences Lab, Kennedy Space Center, FL 32899, USA;1. Research and Scientific Support Dept., ESA/ESTEC, Noordwijk, Netherlands;2. Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, AR 72701;3. Space Physics Research Laboratory, University of Michigan, Ann Arbor, MI 48109-2143, USA;4. Department of Physics, University of California, Berkeley, CA94720, USA;1. Organic Geochemistry Group, MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany;2. Department of Marine Sciences, University of Georgia, 30602 Athens, GA, USA;3. Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, 27599 NC, USA;1. Elle-Di and San Raffaele Research Institute, Rome, Italy;2. Third Age Health Inc. Culpeper, VA, USA;1. Department of Social Sciences, University of Information Technology and Management in Rzeszow, Sucharskiego 2 Street, 35-225, Rzeszów, Poland;2. Institute of Security Sciences, Pedagogical University in Cracow, Podchor??ych 2 Street, 30-084, Kraków, Poland;3. Sherwood Observatory, Mansfield and Sutton Astronomical Society, Nottinghamshire, United Kingdom |
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| Abstract: | Conditions on the surface of Mars would appear to be too hostile for life as we know it. But the subsurface is another matter. If liquid water is present, even intermittently, life forms present would at least be protected from the lethal radiation bombarding the surface. However, life would have to contend with variations in pressure and possibly extended periods of desiccation. The research reported here involves both active metabolism (methanogenesis) at 400 and 50 mbar of pressure, pressures that would be found in the near subsurface of Mars, and survival following desiccation at both 1 bar (a pressure that would be found in the Martian subsurface) and 6 mbar (the lowest pressure at the surface and very near subsurface). The three methanogens tested for active metabolism, Methanothermobacter wolfeii, Methanosarcina barkeri and Methanobacterium formicicum, all demonstrated methane production at both 400 and 50 mbar on JSC Mars-1, a Mars soil simulant. Methane production at 50 mbar was much reduced compared to that at 400 mbar, most likely due to the greater stress at the lower pressure. In desiccation survival experiments, M. barkeri had survived 330 days of desiccation at 1 bar, while M. wolfeii and M. formicicum survived 180 and 120 days, respectively. Methanococcus maripaludis did not survive desiccation at all at 1 bar. At 6 mbar, M. wolfeii, M. barkeri and M. formicicum survived 120 days of desiccation while M. maripaludis survived 60 days. These results along with results from previous research would seem to indicate that there is no reason that methanogens could not inhabit the subsurface of Mars. |
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