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将氨氧化成亚硝态氮的氨氧化过程是土壤硝化作用的关键步骤,主要由氨氧化细菌(ammonia-oxidizing bacteria,AOB)和氨氧化古菌(ammonia-oxidizing archaea,AOA)驱动。其中,AOA具有丰度高、硝化能力强及特殊生态环境偏好等特征,在土壤生态系统的氮素转化过程中发挥重要作用。AOA基因组序列中氨单加氧酶基因(amo A)的发现、纯培养物的分离及其不同生境的赋存状况,为土壤古菌的氨氧化研究提供了新思路。近年研究表明,氨氧化微生物的代谢类型多为化能自养型,而复杂土壤环境中的AOA,其代谢类型呈多样化,除营化能自养生长外,还可能营化能异养和混合营养代谢。其不同代谢方式在氨氧化过程中的响应机制仍需进一步研究。本文概述了土壤中AOA的发现与分布,重点介绍了其可能的代谢途径,并探究其在环境中发挥重要作用的机理。
Ammonia oxidation of ammonia to nitrite nitrogen is a key step in soil nitrification and is driven mainly by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). Among them, AOA has the characteristics of high abundance, strong nitrification ability and special ecological environment preference, and plays an important role in the nitrogen transformation of soil ecosystem. The discovery of ammonia monooxygenase gene (amoA) in AOA genomic sequence, the isolation of pure culture and the occurrence of different habitats provide new ideas for the ammoxidation of soil archaea. In recent years, studies have shown that most of the metabolic types of ammoxidation microorganisms are autotrophic, while AOA in complex soil environment is diversified in metabolic type. In addition to autotrophic growth, Eutrophication may Mixed nutrition metabolism. The mechanism of its metabolism in the ammoxidation process needs further study. This article outlines the discovery and distribution of AOA in soil, highlights its possible metabolic pathways, and explores the mechanisms by which it plays an important role in the environment.