Biology
Scientific paper
Jan 1998
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1998lpico.953...34s&link_type=abstract
The First International Conference on Mars Polar Science and Exploration, Proceedings of the Conference held at Camp Allen, TX.
Biology
Arctic Regions, Bacteria, Extraterrestrial Life, Glaciers, Ice Environments, Mars (Planet), Mars Surface, Microbiology, Polar Caps, Aerobes, Anaerobes, Northwest Territories
Scientific paper
Recent research on permanent-ice associated microorganisms has focused on surficial ice environments. We present evidence that, to the authors' knowledge, is the first example that aerobic and anaerobic bacteria can be cultured at 4C from sediment-rich basal ice from a large polythermal Arctic glacier (John Evans Glacier). This builds on previous work in which we demonstrated that both aerobic and anaerobic microbes exist in viable populations in subglacial meltwaters at the same glacier, and that the populations increase with sediment concentration. This high Arctic glacier (at 80N) may be a reasonable terrestrial analog for martian polar environments, and hence the findings of this study may be important in assisting sampling program development for microbiology in the martian polar regions. Sterile samples of both debris-rich basal ice and debris-poor (clean) glacier ice were taken aseptically from the glacier margin in the spring of 1997 prior to the onset of the melt season to examine whether any observed microbial activity was linked to sediment concentration. The samples were melted slowly in a sterile environment and then incubated at 4C under nutrient-amended and nutrient-unamended conditions for three months. Parallel sterile and poisoned controls were included to account for abiotic processes. In all cases microbiological activity was recorded in the sediment-rich samples amended with growth medium. This indicates that viable anaerobic and aerobic bacteria were present in the debris-rich basal ice. The dissolved organic C (DOC) concentrations and sigma-13-C DOC of unamended ice samples were also analyzed. DOC concentrations in the basal ice were 4x higher than in the clean ice. Furthermore, the sigma-13-C values of the DOC suggested different sources for the DOC in the two types of ice. The higher DOC values in the unamended basal ice samples suggest that there is in situ microbial activity in the subglacial sediments. This is supported by the presence of viable microbial populations in the basal sediments. Hence, in situ oxidation/fermentation of organic C in basal sediments beneath the ice is a tenable process in high Arctic subglacial environments. This work shows that bacteria can function in anaerobic conditions at temperatures close to freezing. Similar conditions may exist or may have existed in the basal sediments and ice at the base or margins of the martian polar ice caps. Such environments should therefore be examined for evidence of life on Mars.
Foght J.
M. Sharp.
Skidmore Mark
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