青藏高原高寒荒漠微生物群落结构特征及其生态适应机制研究

Increasing reports of the studies in Qinghai-Tibet Plateau have aroused growing concern and generated a lot of attention for the desertification problems in cold alphine area. Lots of studies regards ecosystems in alphine cold deserts were reported and the majority of them focused on desert vegetation. Microbial community is an important part of ecological system, yet, there is no reported research regard microbial community in alpine cold deserts. This project plan to collect samples from the 9 major areas of alpine cold deserts in Qinghai-Tibet Plateau, and apply quantitative PCR, high-throughput sequencing technique, and Biolog identificatio system, to reveal the temporal and spatial distribution characteristics of microbial community structures in alpine cold deserts and their dynamics traits in the process of desertification. By comparisons with the sequence data from the Earth Microbiome Project database, and to combine the results from investigation of vegetation, analyses of soil properties and climate environmental data, the pattern and shaping mechanisms of microbial biogeographic distribution in alpine cold deserts ecosystem. The project will also isolate unique or wide-spread micribal strains of these areas of alpine cold deserts in Qinghai-Tibet Plateau and study their mechanisms of ecological adaptation to provide scientific support for conservation and restoration of ecosystem in Qinghai-Tibet Plateau.

随着青藏高原研究的不断深入，高寒荒漠化问题引起了人们的广泛关注。高寒荒漠生态系统已有大量研究，研究对象多关注于荒漠植被，而关于生态系统重要组成部分的微生物系统研究尚未见报道。本项目拟以青藏高原高寒荒漠主要分布的九大区域为研究位点，运用定量PCR、高通量测序技术及BioLog分析，揭示研究区域内高寒荒漠微生物群落结构时空分布特征及荒漠化进程中微生物的变化规律；借助地球环境微生物计划数据库，结合植被调查、土壤性质分析和气候环境数据，探讨高寒荒漠生态系统下微生物生物地理分布格局及成因；筛选出研究区域内特异或广泛分布的菌株，并在全基因组层面探讨青藏高原高寒荒漠典型微生物的生态适应机制，为青藏高原生态保护与修复提供科技支撑。

通过对青藏高原不同区域高寒荒漠微生物的研究，阐明了青藏高原高寒荒漠微生物的地理分布格局及其影响因素；揭示了青藏高原荒漠化进程中微生物群落结构的变化规律；筛选出了1株抗氧化活性突出的功能菌株，阐明了其抗氧化的生态适应机制；获得并鉴定了3株青藏高原高寒荒漠的菌株新种，自菌株全基因组层面探讨了其分子适应机制，为后期资源开发提供了科学依据及种质资源。主要结果如下：.1）青藏高原高寒荒漠微生物量主要受地上植被影响，其微生物群落结构以变形菌门、放线菌门及厚壁菌门为优势菌群。青藏高原荒漠微生物分布特征受地理格局及土壤理化因子影响，有机碳及总氮含量是影响青藏高原荒漠微生物群落结构组成的主要环境因子。.2）青藏高原铁路沿线荒漠化使得区域内微生物物种种类增加但均匀度下降，微生物群落结构以变形菌门、放线菌门、拟杆菌门为优势类群，优势菌属及功能菌属相对丰度随荒漠化程度而发生规律性变化，人为扰动使得青藏高原铁路沿线荒漠化过程中微生物群落结构的变化更为复杂..3）通过抗氧化活性筛选，获得了1株抗氧化活性突出的功能菌株——海床动性微菌AX6，阐明了菌株AX6以多种抗氧化酶的表达来应对不同的自由基胁迫的抗氧化生理生化适应机制，并通过转录组分析阐明了菌株AX6通过上调胞内物质转运、合成以及新陈代谢过程相关基因的表达来应对氧化胁迫的分子适应机制。.4）自青藏高原高寒荒漠分离获得3株新种资源，通过分子生物学及生理生化特征分析完成了其新种鉴定工作，分别命名为Streptomyces qaidamensis、Nocardia mangyaensis和Planococcus antioxidans。通过青藏高原高寒荒漠新种菌株全基因组测序，阐明了其适应青藏高原高寒荒漠环境的分子机制。