硝化作用(NH₄⁺→NO₂^-→NO₃^- )是氮的生物地球化学循环的关键环节，氨氧化古菌(AOA)纯培养物和富集物的获得，以及古菌 amo 基因在各种生态环境中的发现，说明AOA 也是氨氧化作用的贡献者;特别是很多环境中 AOA amo 的丰度是氨氧化细菌 AOBamo 的数十倍甚至上万倍，而且 AOA 具有比 AOB 更高的氨氮亲和性，这些进一步说明了氨氧化细菌(AOA)可能是氨氧化作用的主要贡献者．文中综述了 AOA 菌株和富集物的来源及基因组信息、基于系统发育的 AOA 分类、AOA 氨氧化作用在环境中的重要性，以及 AOA 反硝化作用的发现，并对今后的研究方向进行了展望．

Nitrification,namely the oxidation of ammonia to nitrite via nitrate,has been suggested to be a key partof the global biogeochemical nitrogen cycle.The cultivation of pure isolates and enrichments of ammonia- oxidizingarchaea (AOA) as well as the discovery of archaeal amo gene in different kinds of environments has proved thecontribution of AOA to the nitrification in the earth.Especially,the abundance of archaeal amo in most environ-ments is higher than that of bacterial amo,and the affinity of AOA to ammonia nitrogen is higher than that of AOB.All these suggest that AOA might predominately contribute to the global nitrification.This paper gives an overviewof the sources and genomic information of pure AOA cultures and enrichments,the AOA taxa based on phylogeneticanalysis,the importance of ammonia oxidation to the environment and the discovery of AOA denitrification.It alsoproposes several research prospects in the future.