用纯培养和宏基因组测序相结合的方法对北极MLB冰川前缘微生物群落功能活性的研究

Microbial community function and its role in the ecological succession after glacial retreat have been widely concerned, especially for the potential activities during carbon and nitrogen turnover. The study about microbial community function on the carbon and nitrogen cycling processes in a glacier forefield by using pure culture and metagenomic approaches is not reported. For the good research background and historical data, Midtre Lovénbre glacier forefield is ideal ecosystem to study the primary succession. In the project, we plan to investigate the function of microbial community on carbon and nitrogen turnover and the effects of environmental factors using both pure culture and metagenomic approaches: (1) Metagenomic sequence the samples along a soil chronosequence in the forefield of MLB glacier and analysis the data; Compare the functional genes and metabolic networks of carbon and nitrogen cycling in the samples; explore the variation of the microbial community function; (2) Clone functional genes，express its in vitro and design of better culturing strategies to screen representative and special microbes base on the metagenomic sequence information. Effects of environmental factors on culturable microbes and recombinant proteins will be tested to verify and improve the predicted variation principle. Also the study will facilitate the isolation of genes and microorganisms for application and environmental monitoring.

冰川退缩区域的微生物群落及其在生态演替中的作用已引起极大关注，其中碳、氮转化功能尤为重要。目前，用纯培养和宏基因组测序相结合的方法来研究冰川前缘微生物群落的碳、氮功能还鲜见报道。北极Midtre Lovénbre冰川前缘区域演变记载全面，是研究物种演替的理想场所。本项目将采用纯培养和宏基因组方法研究MLB冰川前缘微生物群落碳、氮转化功能的演替，并进而揭示其与环境因素的关系：（1）对MLB冰川前缘不同暴露时期的样品进行全基因组测序及分析；研究比较各样品碳、氮循环相关功能基因及代谢网络的异同；探究微生物群落功能的演替规律；（2）根据宏基因组信息寻找关键功能基因进行克隆、体外表达和纯化；设计特定的培养条件，定向筛选、鉴定有代表性和特殊功能的微生物；测试环境因素对可培养微生物和功能基因体外表达产物的影响以验证微生物及其功能的环境响应趋势。并为获得有应用价值和环境检测功能的基因和微生物资源奠定基础。

利用平板稀释法从冰川前缘分离培养获得两千余株微生物，发表了4个北极新属和20个北极新种。利用高通量测序技术对北极新奥尔松地区冰川前沿裸露地样品进行宏基因组和宏转录组分析，通过比较不同冰川退缩时间土壤中微生物群落结构的差异获得了该地区土壤中细菌、古菌、真菌及病毒群落的演替规律；分析了参与碳、氮、铁、磷和硫等元素循环和基因水平转移相关微生物和功能基因的变化。通过比较不同季节中微生物群落结构和功能的差异了解了该地区土壤微生物如何响应环境的变化；探究了该地区土壤中不同微生物的代谢活性强度。并且，通过对一株聚磷菌的研究，发现ppk和ppx这两种基因的转录与磷积累和分解相关，有可能成为研究宏基因组和转录组中磷元素代谢的分子指示物。