河西走廊石生微生物群落结构特征及其生态适应机制研究

The lithobiotic organisms played role in the process lithospheric material circulation process, and have significant feedback effect with climate system. Study of lithobiotic organisms significantly improved the understanding in ecological adaptive mechanisms of life in extreme environments, extraterrestrial life detection, and protection of stone relics. Hexi Corridor is main gobi distribution area of China, which provided ideal place for microbial colonization. Such environments are extremely dry, thus the research about the lithobiotic organisms of this area has significant ecological meaning. However, no former studies were found in this area. This study plan to collect samples from different types of gobi in Hexi Corridor, apply high-throughput sequencing technique and culture-dependent method to reveal the community structure of lithobiotic organisms. By combining with climate environmental data to reveal the extremely environmental factors of the lithobiotic organism colonization and the nfluencing factor of its community structure. This project also plan to explain the mechanisms of lithobiotic organism ecological adaptation by combining the genome sequencing of representative strains and their physiological and biochemical characters. The results could provide theoretical support for microbial resource protection and development , and protection of historic reservation in study area

石生微生物参与了岩石圈的物质循环过程，并且对气候系统具有重要的反馈作用，其研究对极端环境生态适应机制、探索地外生命以及保护石质文物等方面都有重要指导作用。河西走廊是我国的主要戈壁分布地区之一，为研究石生微生物提供了理想场所。同时，这些戈壁生境极端干旱，生态环境脆弱，其相关石生微生物研究生态学意义突出。本项目拟以河西走廊不同类型戈壁中石生微生物为研究对象，运用培养及高通量测序结合的方法，阐明河西走廊石生微生物群落结构特征；结合气候、环境要素，揭示河西走廊石生微生物群落定殖极限环境条件，阐明河西走廊石生微生物分布的影响因素；通过典型菌株全基因组及生理生化特征分析，阐明河西走廊石生微生物的生态适应机制，对区域内微生物资源保护和开发提供理论依据，为当地文物保护提供借鉴。

过对河西走廊石生微生物的研究，阐明了河西走廊石生微生物群落结构分布特征及其影响因素；揭示了河西走廊石生微生物的生态适应机制；获得并鉴定了2株河西走廊石生微生物菌株新种，结合菌株全基因组及生理生化特征探讨了其分子适应机制；获得了一批具抗氧化、抗辐射及抑菌活性的菌株资源；拓展了研究区域，揭示了青藏高原地区冰川前缘裸岩和荒漠草地中石生微生物群落结构及功能特征。主要结果如下：.(1）河西走廊石生微生物定殖率在河西走廊自东向西方向逐渐减小，土壤温度、电导率和pH是影响石下生微生物定殖率的主要因素。河西走廊石生微生物群落组成存在显著的季节性变化，冷期石下生微生物比热期具有更高的丰富度和均匀度。在结构上，热期优势细菌为变形菌门，冷期则为蓝藻门；在功能上，热期有较高的异养、氮代谢和以次生代谢物为主的防御和修复功能，冷期则是较高的光合作用、固碳和在DNA和蛋白质水平上的防御和修复功能。石生环境中水热条件的季节性变化是石生微生物季节性变化的驱动因素。.(2）河西走廊石下生可培养细菌数量为3×104-3.6×105 CFU/g，优势菌属为链霉菌属、芽孢杆菌属及节杆菌属，可培养细菌数量与海拔、TN和pH呈负相关。.(3）分离获得2株河西走廊石生微生物新种资源，经表型、生理生化特征、化学分类特征和分子分类特征鉴定并分别命名为耐盐链霉菌（Streptomyces halobius sp. nov.）和戈壁链霉菌（Streptomyces gobiensis sp.nov.）。.(4）结合典型菌株全基因组及生理生化特征分析，探讨了菌株存在多种抗逆基因来应对环境胁迫的分子机制，同时菌株可产胞外多糖来应对辐射造成的氧化胁迫。.(5）获得了一批具抗氧化、抗辐射及抑菌活性的菌株资源。