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

固态冰中的微生物活动：对冰芯中CO2记录的修改的影响最近对古冰川冰中微生物寿命的研究表明，细菌在冷冻时可以存活数十万年。在缺乏代谢活性的情况下，大分子损伤必须通过氨基酸外消旋化、DNA脱嘌呤和暴露于天然电离辐射（例如，40K）。也许恢复的物种在延长的时间框架内存活代谢休眠方面特别成功，但也有可能这些被捕获的微生物可能进行缓慢的代谢以修复所造成的大分子损伤。这项拟议中的研究将研究从冰川环境中分离出来的细菌在人工构建的冰基质的液体部分中代谢和呼吸二氧化碳的能力。将进行实验，以研究温度和解冻水化学对冻结条件下微生物活动的影响。 此外，我们还将通过定量活细胞和呼吸细胞的分数并表征在冷冻条件下表达的基因和蛋白质来研究冰包埋细胞的生理学。 重要的是，拟议的研究代表了在环境条件下测量微生物CO2呼吸和大分子合成的首次尝试（-5至-20 ℃），据报道，在冰川冰芯和冷基冰川的基冰中，二氧化碳浓度升高。拟议研究的结果与永久冻结环境中的微生物可能保持代谢活性的概念有关，从而支持冰盖是一个活跃的生物群落的观点。这些信息对冰芯群落尤其重要，因为冰川冰内的微生物活动会扭曲基于冰中气泡气体成分的古气候推断。我们的研究结果也可能产生生物技术相关的信息，用于识别具有改进的冷活性特性的酶。这些数据将对有关火星或木卫二冰中微生物持久性和生存的天体生物学讨论产生影响。该提案将支持2名新研究者，并为1名博士提供培训。学生，2名本科生。PI和CoI目前作为导师参与蒙大拿州立大学的美洲印第安人研究机会（AIRO）项目，该项目的2名高中生将在本研究期间参与研究项目。基于网络的工具，以目标学生有兴趣在追求科学的职业生涯将保持和扩大后，将我们的结果纳入美国国家科学基金会资助（DERMEED-1）在蒙大拿州立大学正在建设的图书馆，作为国家（SMETE）数字图书馆的一部分。

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.