青藏高原典型湿地甲烷氧化微生物的分布与功能

Natural wetlands are the major sources of global methane. However, up to 90% of methane can be oxidized by methanotrophs before escaping to the atmosphere. Therefore, methanotrophs play a critical role in carbon cycle of wetland ecosystems. Qinghai-Tibet Plateau (QTP) is the sensitive areas responding to global climate change. It is estimated that the annual methane emissions from the QTP wetlands account for more than 30% of the total methane emissions from all the wetlands in China. However, the spatial distribution and its driving mechanism of methanotrophs in the QTP wetlands remain unknown. In this project, soil samples of typical wetlands across the QTP will be collected on a large spatial scale to study the spatial distribution patterns and the environmental driving factors of methanotrophic communities by using high-throughput sequencing and bioinformatic analyses. In addition, the community assembly processes and co-occurrence network interactions of methanotrophic communities will be analyzed. Furthermore, representative soil samples will be selected to explore the active methanotrophs and their functions in the methane oxidation processes by using DNA-based stable isotope probing technology. Taken together, this project will elucidate the spatial distribution patterns and functions of methanotrophic communities in typical wetlands in the QTP, which is favorable for further understanding the carbon cycle processes in alpine wetland ecosystems. This study will also provide scientific basics for the protection of microbial diversity and the exertions of ecological functions.

自然湿地是全球甲烷的重要排放源。然而，有高达90%的甲烷在释放到大气前就被甲烷氧化微生物所氧化。因此，甲烷氧化微生物在湿地生态系统碳循环过程中起着关键作用。青藏高原是全球气候变化的敏感区，据估计，每年从青藏高原湿地排放的甲烷占我国湿地甲烷排放总量的30%以上。然而，青藏高原湿地甲烷氧化微生物的空间分布规律及其驱动机制尚不明确。本申请项目拟在较大空间尺度下采集青藏高原典型湿地土壤样品，利用高通量测序、生物信息分析等技术，系统研究甲烷氧化微生物群落的空间分布及其环境驱动因子，并解析甲烷氧化微生物的群落构建过程与共存网络关系。进而，选择具有代表性的湿地土壤样品，利用稳定性同位素核酸探针技术，研究甲烷氧化过程中的活性微生物类群及其功能。本研究将阐明青藏高原典型湿地甲烷氧化微生物的空间分布规律及其功能，研究成果有助于进一步认识高寒湿地的碳循环过程，并为微生物多样性保护和生态服务功能发挥提供科学依据。

平均海拔超过4000米的青藏高原具有独特的地理和气候条件，孕育了类型多样并且分布广泛的高寒湿地生态系统。而且青藏高原高寒湿地作为气候变化的敏感区是重要的甲烷排放源，其独特的生态环境孕育着丰富的在湿地碳循环过程中起着关键作用的甲烷氧化微生物。然而，青藏高原高寒湿地甲烷氧化微生物的空间分布规律及其驱动机制尚不明确。本项目通过采集青藏高原高寒湿地土壤样品结合开展室内同位素标记实验，采用高通量测序和定量PCR等技术，研究了青藏高原不同空间尺度下高寒湿地细菌和古菌的分布情况、甲烷氧化微生物的多样性和群落组成、甲烷氧化潜势及其与甲烷氧化微生物之间的关联。研究发现：（1）羌塘高原高寒湿地土壤细菌和古菌的多样性及群落组成在不同盐分类型湿地中分异显著；（2）羌塘高原高寒湿地中甲烷氧化菌多样性和组成同样主要受到盐分影响；（3）藏东南高寒湿地沉积物中细菌多样性高于水体，主要受多种氮素的影响，而水体中细菌多样性和群落结构更易受气候扰动；（4）藏东南高寒湿地中甲烷氧化菌多样性与土壤pH显著相关，地貌类型对群落影响差异显著；（5）增温显著影响甲烷氧化势并改变活性甲烷氧化菌群落，I型甲烷氧化菌主导甲烷氧化过程。这些结果加深了对青藏高原高寒湿地微生物分布与甲烷循环转化耦合机制的理解，并可为气候变化背景下的高原高寒湿地生态系统综合管理提供科学依据