稻秸对典型水稻土反硝化型甲烷厌氧氧化的影响及微生物学机制

Methane (CH4) is one of the most important greenhouse gases. Paddy fields are an important emission source of CH4 emission. The recent study found a novel pathway named nitrite-dependent anaerobic methane oxidation (DAMO) which couples the methane oxidation to nitrite reduction under strictly anaerobic condition. The DAMO process is catalyzed by “Candidatus Methylomirabilis oxyfera (M. oxyfera)”. Paddy fields are characterized by cultivation pattern, and the anoxic soil conditions theoretically provide suitable habitats for the M. oxyfera bacteria. Rice straw application serves as an important carbon source for CH4 production, and the mineralization of straw increases soil N content. However, effects of straw on the DAMO and microbiological mechanisms in typical paddy soil are not well understood. The objective of this project is to investigate the influences of rice straw amendment on the DAMO process in three different paddy soils. Straw will be applied in field plots, and soil samples of 0-100 cm will be collected during the jointing stage and flowering stage of rice. The DAMO process will be confirmed using isotope trace experiments. Meanwhile, the community structures, abundance and diversity which are based on the 16S rRNA gene and pomA gene will be analyzed to obtain a microbiological mechanistic understanding for the effect of rice straw on the DAMO process. The results of this study would provide a scientific basis for evaluation of the effects of rice straw application on the DAMO process in typical paddy soils, and reveal the microbial mechanism, as well as provide important suggestion for understanding the C and N biogeochemical cycles, and the regulation of CH4 emission from rice field soils.

甲烷是最重要的温室气体之一。稻田是甲烷排放的重要源。最新发现甲烷在厌氧环境中通过反硝化型甲烷厌氧氧化过程（DAMO）进行氧化，该过程由Candidatus Methylomirabilis oxyfera细菌（M.oxyfera细菌）主导发生。稻田以特有的土壤环境为M.oxyfera细菌提供了适宜的生存条件。稻秸还田促进甲烷产生，增加土壤氮含量，然而有关稻秸添加对水稻土DAMO过程的影响及微生物学机制尚不清楚。本项目采用3种典型水稻土，田间添加稻秸，在水稻拔节期和开花期采集0-100 cm的土样，通过13CH4同位素示踪实验研究稻秸对水稻土DAMO过程的影响，同时利用微生物分子分析手段，以细菌16S rRNA基因及pmoA基因为分子标记，研究M.oxyfera细菌的时空变化特征，揭示稻秸影响水稻土DAMO过程的微生物学机制，为我国稻田甲烷排放量的估算及制定合理的减排措施提供科学依据。

甲烷是最重要的温室气体之一。稻田是甲烷排放的重要源。最新研究发现甲烷在厌氧环境中通过反硝化型甲烷厌氧氧化过程（DAMO）进行氧化，该过程有Candidatus Methylomirabilis oxyfera细菌（M. oxyfera细菌）主导发生。稻秸还田促进甲烷产生，增加土壤氮含量。稻田以特有的土壤环境为M. oxyfera细菌提供了适宜的生存条件。本项目中我们以典型水稻土为研究对象，以稻秸和不同形态氮素为研究因素开展研究，通过微宇宙实验研究不同实验因素处理下CH4排放量及功能微生物丰度变化，重点关注反硝化型甲烷厌氧氧化过程（DAMO）的功能微生物M. oxyfera细菌的变化特征。同时，项目开展了秸秆添加对镉砷污染典型水稻土CH4排放及其DAMO过程关键微生物M. oxyfera细菌菌群的影响及机制研究。以不同程度镉砷污染的两种典型水稻土为研究对象，以不同C:N比作物秸秆为实验因素进行盆栽实验，通过箱式法监测了水稻关键生育期CH4的排放通量。利用Illumina高通量测序技术研究了产甲烷古菌群落结构、多样性及丰度等变化特征。另外，结合一代测序及Illumina高通量测序技术重点研究了DAMO过程的功能微生物M. oxyfera 菌的响应变化，分析秸秆添加对M. oxyfera菌群的影响，探寻秸秆影响CH4排放及DAMO过程的微生物学机制，为我国稻田甲烷排放量的估算及制定合理的减排措施提供科学依据。