水稻田微生物催化的铁还原型甲烷厌氧氧化过程及其机理研究

近年来，在微生物甲烷厌氧氧化领域获得了两项重大突破，其一是揭示了甲烷厌氧氧化古菌与硫酸盐还原细菌之间的电子传递方式，其二是实验室证实了铁还原型甲烷厌氧氧化（Fe-AOM）过程。目前零星的研究表明，Fe-AOM过程可能存在于包括水稻土在内的许多生境中，Fe-AOM过程可能由古菌单独或古菌与细菌协作完成，但由于至今未获得“真正”的富集物，Fe-AOM过程机理尚不明确。本项目拟采用同位素示踪、高通量测序等技术，调查Fe-AOM微生物在水稻田中的分布特征，并以高Fe-AOM活性的水稻土为接种物，富集培养Fe-AOM微生物；采用光谱分析、高通量测序等技术，对富集物进行物理、化学、生物特性表征；以Fe-AOM富集物为实验材料，采用同位素示踪、宏基因组测序等技术，揭示Fe-AOM过程的代谢途径和电子传递方式。该项研究不仅能丰富人们对Fe-AOM过程的认识，还能为水稻田甲烷减排提供更多思路。

Recently, two great breakthroughs have been made in the field of anaerobic oxidation of methane: first, the mechanisms of extracellular electron transfer between anaerobic methanotrophic archaea and sulfate-reducing bacteria were revealed; second, the bioprocess of iron-dependent anaerobic oxidation of methane (Fe-AOM) was finally confirmed by laboratory evidences. At present, some sporadic studies suggest that Fe-AOM may occur in many natural habitats, such as paddy soil, and may be mediated by archaea or by archaea and bacteria together. However, due to the lack of the “true” Fe-AOM culture, microbial mechanisms of Fe-AOM, including microbial metabolism and extracellular electron transfer between microorganisms and iron minerals, remain unclear. In this project, using isotope tracer and high-throughput sequencing, the distribution of Fe-AOM microorganisms in paddy will be investigated; the paddy soil with the highest Fe-AOM activity will be collected as inoculum to enrich and cultivate Fe-AOM microorganisms. Using spectrum analysis and high-throughput sequencing, the physical, chemical and biological features of the Fe-AOM culture will be characterized; substrate affinity, substrate diversity and the response to environmental factors of Fe-AOM microorganisms will also be investigated. Using isotope tracer and metagenomic sequencing, the metabolic pathway and extracellular electron transfer of Fe-AOM microorganisms will be revealed. The results of this project will not only enrich our knowledge of Fe-AOM process, but also provide more ideas for reducing methane emission from paddy fields.