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Applied and Environmental Microbiology, August 2000, p. 3214-3220, Vol. 66, No. 8
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Microbial Life beneath a High Arctic Glacier†

Mark L. Skidmore,1,* Julia M. Foght,2 and Martin J. Sharp1

Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E3,1 and Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E92

Received 27 January 2000/Accepted 26 May 2000

The debris-rich basal ice layers of a high Arctic glacier were shown to contain metabolically diverse microbes that could be cultured oligotrophically at low temperatures (0.3 to 4°C). These organisms included aerobic chemoheterotrophs and anaerobic nitrate reducers, sulfate reducers, and methanogens. Colonies purified from subglacial samples at 4°C appeared to be predominantly psychrophilic. Aerobic chemoheterotrophs were metabolically active in unfrozen basal sediments when they were cultured at 0.3°C in the dark (to simulate nearly in situ conditions), producing 14CO2 from radiolabeled sodium acetate with minimal organic amendment (>= 38 µM C). In contrast, no activity was observed when samples were cultured at subfreezing temperatures (<= -1.8°C) for 66 days. Electron microscopy of thawed basal ice samples revealed various cell morphologies, including dividing cells. This suggests that the subglacial environment beneath a polythermal glacier provides a viable habitat for life and that microbes may be widespread where the basal ice is temperate and water is present at the base of the glacier and where organic carbon from glacially overridden soils is present. Our observations raise the possibility that in situ microbial production of CO2 and CH4 beneath ice masses (e.g., the Northern Hemisphere ice sheets) is an important factor in carbon cycling during glacial periods. Moreover, this terrestrial environment may provide a model for viable habitats for life on Mars, since similar conditions may exist or may have existed in the basal sediments beneath the Martian north polar ice cap.

* Corresponding author. Present address: Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, United Kingdom. Phone: (44) (117) 928 8186. Fax: (44) (117) 928 7878. E-mail: Mark.Skidmore{at}bristol.ac.uk.

dagger This is Polar Continental Shelf Project contribution 00199.

Applied and Environmental Microbiology, August 2000, p. 3214-3220, Vol. 66, No. 8
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


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