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Project Progress

Microbial Communities in Subpermafrost saline fracture water at the Lupin Au Mine, Nunavut, Canada

If subsurface life exists on Mars it does so beneath a few kilometers of permafrost. Similar environments on Earth have not been characterized due to their inaccessibility. Lupin Au Mine provided an opportunity to collect samples of fracture water beneath 500 meters of permafrost to determine whether the extant microbial communities were similar to those found in South Africa. Gross phylogenetic similarities were recognized in terms of the dominance of sulfate reducing bacteria, but methanogens were strangely absent. These sulfate-reducing bacteria likely colonized the sub-permafrost during the Pleistocene; whereas aerobic bacteria may have entered the fracture water networks either during deglaciation prior to permafrost formation 9,000 years BP or from the nearby talik through the hydrologic gradient created during dewatering of the mine.

Detailed thermodynamic analyses of the fracture water chemistry combined with a hydrological and microbial model revealed that the methanogens were likely excluded from the subpermafrost environment due to a high pH-induced, energy bottle-neck. A manuscript describing the geochemistry and microbiology of the Lupin Au mine has been submitted to Microbial Ecology. Because underground mining activity at Lupin Au mine has been terminated, we no longer have access to this wonderful window into the subpermafrost biosphere.

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