Exploration of microbial biodiversity in polar glacial ice cores

极地冰帽在提供对过去八个冰川周期气候变化的理解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研究很少，迄今为止主要集中在粉质冰或增生冰上，这些冰不再包含气候记录。该项目的目的是检测、表征和比较北极和南极不同深度和不同钻探项目冰中的原核生物多样性，以便更多地了解过去和现代群落的关系以及与气候变化有关的古代群落的潜在变化。从这套数据中可以得出气候/生态变化的新代用指标。此外，冰内的细菌细胞的生存能力和代谢活性将进行评估，以获得从生物学角度更好地了解生存/代谢在冰点以下的温度和从地球化学角度对冰中的气体记录的持久性。 过去的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镜技术获得。为了最大限度地减少宝贵的冰芯材料的消耗，并与我们的项目合作伙伴一起使用常见的初始样品，我们在第一年的支持期间针对冰芯样品的特定要求特别优化了制备和分析方法。这还包括建立单独的冰芯分析实验室设施，以及开发和生产冰芯分析专用设备。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。这些引物和探针靶向来自细菌DNA的16 S rDNA的特定区域，所述细菌DNA分离自南极洲德龙宁毛德地的冰川冰芯。含有DNA的地平线可以追溯到大约2154年前。这些寡核苷酸引物和探针识别的细菌的存在可能共同负责冰川冰芯中的N2 O异常。

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.