稻田人工湿地系统中控制养分循环的土壤微生物组成特征与地理学格局

Microbial community is the largest reservoir of functional genes and enzymes, and one of key players mediating global ecosystem change and soil nutrient cycling, which has significant impact on ecosystem services and environment. However, due to its micro-scale, technical difficulties of isolation and culturing, and complexity of community structures, it has been a long time that microbial ecology is the weakest link of ecology studies. This project will focus on microbial biodiversity and biogeography of China's constructed wetlands, with a focus on paddy fields, and the functional mechanism of microbes to regulate soil nutrient cycling. We will select constructed wetlands representing typical rice-growing regions throughout the country, conduct large-scale metagenomics and functional studies for wetland soils with several spatial scales. Combined with bioinformatics and network biology approaches, we will profile microbial biodiversity and understand the underlying shaping mechanism. We will also reveal the microbial biogeographic rules and therefore make a breakthrough in microbial ecology theories. Meanwhile, we will identify key functional genes involved in soil nutrient cycling, and establish a predictive system for evaluating and monitoring wetland soil, which provides the scientific basis and potential regulatory strategies for constructed wetland management. This project, with its cutting-edge, interdisciplinary characters, has important theoretical and practical values.

环境微生物是地球上最大的功能基因和酶资源的提供者，也是驱动地质化学循环的的关键因素之一，对生态系统的功能及其环境效应有重要影响。但由于微生物尺度、分离培养的困难、群落结构的复杂性等因素，长久以来，对微生物分布和演变的相关机理研究十分薄弱。本项目针对我国典型的人工湿地－稻田，重点研究淹水厌氧环境下土壤生物多样性及生物地理学分布规律，识别控制养分循环的功能微生物组成。项目选择我国从南到北的典型稻田生态系统产区为主的人工湿地，结合生物信息学和网络生物学方法，利用宏基因组学在样点－样地－样带的多个空间尺度研究我国不同气候带人工土微生物组成和生物多样性特征、形成机制和控制因素，完善和更新微生物地理学分布理论；通过识别参与土壤养分循环的关键功能微生物和基因，建立评价人工湿地土壤功能的指标体系，为调控人工湿地功能的土壤管理措施提供科学依据。项目是多学科交叉的一个前沿性方向，具有重要的理论和实践意义。

本项目依托我国稻田资源丰富的优势，广泛收集我国境内的水稻田土壤样品，获取微生物基因组DNA，通过对于针对细菌和古菌的16S rRNA 基因、针对真菌的ITS和部分功能基因的序列分析，结合多种统计方法，考察水稻田土壤微生物的空间分布特征及形成机制，并探讨宏观生态学对于土壤微生物的适用性。取得的主要进展包括（1）发现了温度是驱动全国范围内我国稻田土壤微生物空间周转率纬度分布特征的主要因素，且微生物的空间周转率随温度变化符合代谢生态理论；（2）证明了水稻田土壤微生物在不同空间尺度下（区域尺度、中尺度、景观尺度）均有显著的距离-衰减关系；（3）比较了功能种群、细菌、真菌异同，发现不同气候带下细菌-真菌网络结构差异显著，不同水稻土共有的核心物种作为微生物生态网络的关键物种调控了氮素转化过程；（4）识别了一批可表征稻田土壤N2O排放、厌氧条件下甲烷排放的功能微生物。本项目为微生物生态学理论框架的建立提供了依据，在本项目的资助下已发表SCI论文14篇，另有3篇论文在审；培养研究生15名，博士后3名。