Metagenomic studies of the diversity and function of chemosynthetic microbial communities at oceanic spreading zones

了解洛加切夫喷口区等热液地点的生物和非生物因素的相互作用，对于了解大洋中部扩张轴的微生物群落以及能量和物质从地幔向海洋的转移至关重要。因此，最近发展起来的分子生物学方法-宏基因组学被提出。宏基因组被定义为在限定位点中发现的基因组的总和，例如，从特定的通风口或渗漏处释放的流体中。与地质学家、流体地球化学家和微生物学家合作，将选择特征采样点。将收集生物量并提取高分子量环境DNA。将产生含有约40 kb插入片段的大型fosmid文库，并筛选系统发育标记16 S rRNA和参与a）CO2和N2固定和B）海洋微生物化学合成的两种最常见底物甲烷和硫化物的转化的功能基因。这些研究将首次深入了解采样点主要微生物群落成员的基因组装备、它们的代谢和生化潜力以及它们的进化。这些结果将与培养和基于PCR的序列检索获得的数据进行比较，并与流体化学和物理相关。将检索有关微生物催化相关地球化学反应的详细信息。

Understanding the interaction of biotic and abiotic factors at hydrothermal locations such as the Logatchev vent area is of fundamental importance for understanding of microbial communities at the mid-oceanic spreading axes and the transfer of energy and material from the mantle to the ocean. Thereforea recently developed molecular biological approach, metagenomics, is proposed. The metagenome is defined as the sum of genomes found in a defined site, e.g., in the fluid released from a particular vent or seep. In collaboration with geologists, fluid geochemists, and microbiologists, charateristic sampling sites will be chosen. Biomass will be collected and high molecular weight environmental DNA will be extracted. Large fosmid libraries containing inserts of approximately 40 kb will be produced and screened for the phylogenetic marker 16S rRNA and for funtional genes involved in a) CO2 and N2 fixation, and b) the transformation of the two most common substrates of marine microbial chemosynthesis, methane and sulfide. The studies will offer first insights into the genomic equipment of the main microbial community members at the sampling sites, their metabolic and biochemical potential, and their evolution. These results will be compard to data obtained by cultivation and PCR-based sequence retrieval, and correlated to fluid chemistry and physics. Detailed information on the microbial catalysis of relevant biogeochemical reactions will be retrieved.