NASA Astrobiology Institute (NAI)

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

   Project Investigators: Corien Bakermans, Terry Hazen, Tullis Onstott, Lisa Pratt

   Other Project Members

   Shaun Frape (Collaborator)

   Timo Ruskeeniemi (Collaborator)

   Randy Stotler (Collaborator)

   Summary

   As scientists prepare to search for life in the subsurface of Mars, it is increasingly clear that we have little experience characterizing microbial life in permafrost environments on Earth. Lupin gold mine in Nunavut Territory Canada provides scientists with an opportunity to collect samples of ground water beneath 500 meters of permafrost. These subpermafrost water samples contain extant microbial communities that are dominated by sulfate-reducing bacteria. It remains to be determined how and when this microbial community became established.

   Astrobiology Roadmap Objectives:

   • Objective 2.1: Mars exploration
   • Objective 5.1: Environment-dependent, molecular evolution in microorganisms
   • Objective 5.2: Co-evolution of microbial communities
   • Objective 5.3: Biochemical adaptation to extreme environments
   • Objective 7.1: Biosignatures to be sought in Solar System materials

   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.

   
   

   Cross-section showing the spatial relationship between the mine and the assumed conduit of groundwater beneath Contwoyto Lake. The mine workings are delineated down to about the 1400 m level by the dashed contours.

   Mission Involvement

   MSR

   Onstott and Pratt are both involved with NASA committees outlining the goals and strategies for a future Mars Sample Return mission. Their experience working in permafrost and subpermafrost environments on Earth provides invaluable perspective on the difficulties of looking for life in permafrost and subpermafrost environments on Mars.

   Cross-Team Collaborations

   Corien Bakermans (Michigan State University, Montana State University) has been a participant in field campaigns to Lupin and has successfully cultured subpermafrost microbes from Lupin water samples.

Publications

Bakermans, C.  (2008).  Geochemical and Microbial Characterization of the Cold, Deep Subsurface within the Canadian Shield—Habitat Analog for the Martian Subsurface.  AbSciCon.  Santa Clara CA.

Chan, E.  (2008).  Geochemical constraints in deep permafrost microbial communities in an Archean metavolcanic terrane.  AbSciCon.  Santa Clara CA.

Pfiffner, S.M.  (2008).  Challenges for coring deep permafrost on Earth and Mars.  Astrobiology Journal, 8(3).