农田土壤硝化微生物的生态学研究进展

Advances in Microbial Ecology of Nitrifying Communities in Agricultural Soils

硝化作用是农田生态系统的重要过程。传统硝化作用是指微生物将氨氧化成亚硝酸盐再氧化为硝酸盐的两步反应,氨氧化过程是硝化过程的第一步也是限速步骤。该过程是由编码氨单加氧酶基因(amoA)的氨氧化细菌(AOB)和氨氧化古菌(AOA)催化完成。2015年底,可以进行一步硝化的完全氨氧化菌(comammox)的发现颠覆了人们对硝化过程近百年的认知,并引发众多对comammox生理代谢、分布特征和相对贡献的深入思考。本文重点阐述农田土壤硝化微生物的生态学研究进展,通过比较AOB、AOA和comammox的发现、系统发育以及对环境因子的响应等方面的差异,对农田土壤硝化微生物相关研究成果进行概括和总结,以期深入了解农田土壤中氮素转化机制,为农田尺度氮素养分管理、面源污染防控及温室气体减排提供理论依据。

Nitrification is an essential process in agricultural ecosystems.The classical two-step nitrification,the oxidation of ammonia to nitrate via nitrite,is radically challenged by the recent discovery of complete ammonia oxidation(comammox).The first and rate-limiting step of nitrification,ammonia oxidation is mainly performed by ammonia-oxidizing bacteria(AOB)and ammonia-oxidizing archaea(AOA)which carry the ammonia monooxygenase(amoA)gene.The first report of comammox has triggered many scientific issues and deeply thoughts concerning physiology,distributing characteristic,relative contributions of comammox to nitrification since 2015.Here,current knowledge of differences in the discovery,phylogeny and environmental responses between AOB,AOA and comammox were summarized,in order to significantly improve our fundamental understanding of nitrogen transformation in agricultural soils,and to provide important scientific evidence for nitrogen fertilizer management,thus helping mitigate agricultural non-point pollution and nitrous oxide emissions.