Exploration of microbial biodiversity in polar glacial ice cores

极地冰帽在了解过去8个冰期旋回的气候变化方面发挥着关键作用，并可能提供有关过去古环境特征和微生物多样性变化的信息。对极地冰芯的微生物学研究很少，迄今为止主要集中在粉质冰或堆积的冰上，这些冰不再包含气候记录。该项目的目的是对北极和南极不同深度和不同钻探项目的冰中的原核生物多样性进行检测、表征和比较，以进一步了解过去和最近群落的关系以及古代群落与气候变化的潜在变化。从这些数据集可以推导出气候/生态变化的新代用物。此外，还将评估冰内细菌细胞的生存能力和代谢活性，以便从生物学角度更好地了解在冰点以下温度下的生存/代谢，以及从地球化学角度了解冰中气体记录的持久性。关于过去细菌群落的定性和定量信息将通过培养技术和广泛的分子生物学方法和显微技术获得。为了最大限度地减少宝贵的冰芯材料的消耗，并使我们的项目合作伙伴能够在共同的初始样品上工作，我们在支持的第一年特别优化了冰芯样品的具体要求的制备和分析方法。这还包括为冰芯分析建立单独的实验室设施，以及为冰芯分析开发和制造专用设备。此外，我们还开发了用于定性和定量PCR以及CARD-FISH应用的特异性引物和探针。这些引物和探针针对细菌DNA中16S rDNA的特定区域，这些细菌DNA是从南极洲Dronning Maud Land的冰川冰芯中分离出来的。包含DNA的视界可以追溯到距今2154年前。这些寡核苷酸引物和探针识别的细菌的存在可能是冰川冰芯N2O异常的共同原因。

The polar ice caps play a key part in providing an understanding of climate variability over the last eight glacial cycles and may give information about paleoenvironmental features and changes of microbial diversity in the past. Microbiological studies on polar ice cores are rare and focused so far on silty ice or accreted ice, which does not contain a climatic record anymore. Aim of this project is to detect, characterize, and compare the prokaryotic diversity in ice of different depths and different drilling projects in Arctic and Antarctic, in order to learn more about relations of past and recent communities and about potential alterations of ancient communities in relation to climatic changes. From this data set new proxies for climatic/ecological changes may be derived. Further, viability and metabolic activity of the bacterial cells within the ice will be evaluated to gain from the biological perspective a better understanding about survival/metabolism at subfreezing temperatures and from the geochemical perspective about persistence of gas records in the ice. Qualitative and quantitative information about bacterial communities of the past will be obtained by cultural techniques and a broad spectrum of molecular biological methods and microscopical techniques. To minimize the consumption of the valuable ice core material and enable work on common initial samples with our project partners, we optimized particularly the preparation and analytical methods for the specific requirements of ice core samples during the first year of support. This included also the establishment of separate laboratory facilities for ice core analytics and the development and generation of special equipment for ice core analytics. Furthermore, we developed specific primer and probes for qualitative and quantitative PCR and also for CARD-FISH applications. These primer and probes targeting a specific region of the 16S rDNA from bacterial DNA, which was isolated from a glacial ice core, from Dronning Maud Land, Antarctica. The horizon containing the DNA is dated to approximately 2154 years before present. The presence of the bacteria recognized by these oligonucleotide primer and probes could jointly be responsible for N2O abnormalities in glacial ice cores.