环境异质性影响厌氧甲烷氧化耦联代谢的研究

Microbial anaerobic oxidation of methane (AOM) can couple with diverse biogeochemical processes of vital elements, including carbon, nitrogen, sulfur and iron, which plays an important role in controlling methane emission. Environmental heterogeneity (EH) as a major factor influences microbial substrates utilization, energy utilization, community structure and function, thus we hypothesized that EH is certain to impact on AOM process which is mediated by microbes. . In this proposed project, three geochemically contrasting mud volcanoes with high CH4 emissions in the Junggar Basin, Xinjiang, were selected as the research objects. First, stable isotope probes method and microcosm incubations combined with bioinformatics techniques would be used to measure CH4 emission flux and AOM reactivity, and to analysis community structures and interaction networks of microbial functional groups of AOM, illustrating the effect of EH on coupling processes of AOM on the macroscopic- regional scale. Second, based on fluorescence in situ hybridization, scanning electron microscope and transmission electron microscope combined with NanoSIMS, we should reveal how the micro-environment where microorganism lives effects on the special structure and microbial physiology of AOM-related microbial aggregates. . Our project would contribute to comprehensive understanding the influence mechanism of EH on AOM processes and related functional species. The results may strengthen the knowledge of CH4 biogeochemical cycle and provide the scientific basis for mitigating CH4-induced global climate change.

微生物介导的厌氧甲烷氧化（AOM）过程能够耦联碳、氮、硫、铁等多种元素的生物地球化学过程，对于控制甲烷排放发挥着重要作用。环境异质性作为影响微生物底物、能源利用、种群结构和功能的主要因素，必定对AOM耦联过程产生影响。本项目拟选取在地化性质等方面具有显著差异的新疆泥火山群作为研究对象，（1）应用微宇宙培养、SIP等技术，结合生物信息学分析平台，解析各样地甲烷排放通量和AOM反应活性的异同，揭示AOM功能微生物群落结构和互作网络的空间异质性，从宏观区域尺度阐明环境异质性对AOM耦联过程的影响；（2）借助荧光原位杂交、多重显微技术联合NanoSIMS等，阐明个体微生物所处微环境异质性对AOM功能菌团空间结构和生理特征的影响。本项目的开展有助于全面解析环境异质性对AOM耦联代谢的影响机制，加深人们对于甲烷生物地球化学循环的理解和认识，为缓解甲烷引起的全球气候变化提供科学依据。

微生物驱动的甲烷厌氧氧化（AOM）直接参与各种重要元素的生物地球化学循环，减少温室气体排放。环境异质性作为影响微生物底物、能源利用、种群结构和功能的主要因素，必定对AOM耦联过程产生影响。本研究主要通过微宇宙培养实验、微生物燃料电池方法、穆斯堡尔谱技术等结合生物信息学分析方法，从不同尺度揭示环境异质性对AOM耦联代谢的影响。主要研究结果如下：(1)证明了不同样地环境下甲烷代谢和微生物群落结构的差异，并初步确定新疆泥火山地区Fe-AOM的耦联代谢特征；(2)泥火山环境微生物是含铁矿物和有机物氧化还原反应不可缺少的媒介，不同功能类群的微生物可以与铁还原菌合作，参与Fe-AOM过程; (3)本研究重构了泥火山环境下不同电子受体介导的厌氧甲烷氧化代谢途径，发现在柠檬酸铁和AQDS共同作用下经典“reverse methanogenesis”的AOM过程会被一种新的结合好氧甲烷氧化途径与丝氨酸途径同化或CBB循环固定代谢模式所替代，最终实现甲烷的厌氧氧化。