Microbial Activity in Solid Ice: Implications for Modifying the CO2 Record in Ice Cores

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EAR-0525567Microbial Activity in Solid Ice: Implications for Modifying the CO2 Record in Ice Cores Recent studies of microbial longevity in ancient glacial ice indicate that bacteria remain viable for hundreds of thousands of years while frozen. In the absence of metabolic activity, macromolecular damage must accumulate through amino acid racemization, DNA depurination, and exposure to natural ionizing radiation (e.g., 40K). Perhaps the species recovered are particularly successful at surviving metabolic dormancy over extended time frames, but it is also possible that such entrapped microbes might carry out a slow rate of metabolism to repair incurred macromolecular damage. The proposed study will examine the ability of bacteria isolated from glaciated environments to metabolize and respire CO2 in the liquid fraction of artificially constructed ice matrices. Experiments will be undertaken to examine the influence of temperature and unfrozen water chemistry on microbial activity under frozen conditions. In addition, we will also study the physiology of cells entrapped in ice by quantifying the fraction of viable and respiring cells and characterizing the genes and proteins expressed under frozen conditions. Importantly, the proposed research represents the first attempt to measure microbial CO2 respiration and macromolecular synthesis under environmental conditions (-5 to -20oC) in which elevated CO2 concentrations have been reported in glacial ice cores and basal ice from cold based glaciers.Results from the proposed study are relevant to the notion that microorganisms in permanently frozen environments may remain metabolically active, thus supporting the view that ice sheets are an active biome. Such information is especially vital to the ice core community, as microbial activity within glacial ice would skew paleoclimatic inferences based on gas composition of bubbles in the ice. Our results will also potentially yield biotechnologically relevant information for the identification of enzymes with improved cold-active properties. These data will have implications relevant to astrobiological discussions about microbial persistence and survival in ice on Mars or Europa. This proposal would support 2 new investigators, and provide training for a Ph.D. student, and 2 undergraduate students. The PI and CoI currently participate as mentors in the American Indian Research Opportunities (AIRO) program at Montana State University, and 2 high school students from this program will be involved in research projects during the course of this study. Web-based tools to target students interested in pursuing a career in science will be maintained and expanded upon by incorporating our results into the NSF funded (DERMEED-1) library under construction at Montana State University, as part of the national (SMETE) digital library.