Microbial Community And Structure From Core Samples In Qiangtang Basin,Qinghai-Tibetan Plateau, China

This study focuses on microbial community structure of the drilling core samples from permafrost area using culturable dependent methods (selective culture medium) and culturable independent (Quantity PCR and Roche454high-through put pyrosequencing techbology), and moreover,its relationship with the physicochemical properties of drilling cores. Furthermore, analyse the unique microorganism communities and structure in core samples contain oil-gas seepage or nature-gas hydrate if any existed.1.Culturable microbes were isolated purified using agar plate spread technique from total22core samples of three drilling well:QK1(lat&Ion:32°47’7.07"N,88°48’27.89"E; altitude:4985m; well depth:882.01m), QK2(lat&Ion:33°04’59.9"N,89°18’10.4"E; altitude:4965m; well depth:389.85m), QK3(lat&Ion:32°49’50.9"N,88°54’56.5"E; altitude:4995m; well depth:441.14m).16S rDNA gene sequences of the isolates were amplified by PCR method and sequenced, then submitted to the Genbank Blast programme (http://blast.ncbi.nlm.nih.gov/Blast.cgi) to ensure the microbial communities structure of culturable microbes. The predominant community in QK1was actinobacteria (38%), and QK2actinobacteria (30.4%) gammaproteobacteria (31.4%), QK3actinobacteria (43%) alphaproteobacteria (20.3%)2. Total DNA of the core samples were extracted using soil DNA kit (Omega), and real-time quantitative PCR was used in this study to examine the copy numbers of each unqiue gene and/or specific communit of microorganism. Results showed that, total bacterial gene copies in QK1and QK3were about1×10which had magnitude difference with that of the QK2samples and other samples in QK1and QK3(l×106), the same trend presented in the phylum Bacteroid. Furthermore, methanol dehydrogenase gene in QK3samples is genereal higher than in QK1and QK2.3. To get a more precise microbial communities structure, metegenomic sequencing was applied to the analysis. The next generation sequencing (NGS) methods are technologies with extraordinary high-throughput sequencing capacity and are possible for the well processing of huge amount of data. Every unique or specific microbial DNA fragment can be independently amplified and analysed. Thus, the microorganism communities distribution can be more detailedly obtain. In our study, the Roche454sequencing method was used for the purpose described above. Bacterial communities in the all of the drilling cores of the three drilling wells were dominated by phylum Proteobacteria. And the in most of the samples, Euryarchaeota, especially the methanogen community, was the predominant community of archaea, and only a small part of the community was Crenarchaeota.4. In this study, a special strain F3"was found to be a novel species of genus Flavobacterium based on the phenotypic, genotypic and chemotaxonomic analysis and the name Flavobacterium qiangtangensis was proposed.