ABSTRACT

Nitrogen cycle, a most important elemental cycle in earth ecosystem, is carried out by three major microbial processes including nitrogen fixation, nitrification and denitrification. Nitrification is particularly important in agricultural soil ecosystems because it is involved in nitrogen loss, groundwater pollution by nitrogen leaching, and greenhouse gas nitrous oxide emission. Recent genomic, metagenomic and physiological analysis of nitrifying microorganisms gives new insights into their ecology and functions in soils. In the last decade, there have been a number of important findings regarding nitrification. The discovery of nitrifying archaea and complete nitrifying bacteria has overturned the conventional theory that nitrification is driven by ammonia-oxidizing and nitrite-oxidizing bacteria. Each of the newly discovered nitrifying microorganisms has unique properties, for example, a different affinity for ammonia. These nitrifying microorganisms have been shown to actually play important roles in nitrification in agricultural soils. Soil conditions and agricultural practices such as fertilization and tillage have been shown to influence the contribution of each nitrifying microorganism to the activity of nitrification. In addition, nitrification inhibition technologies have been developed to prevent the loss of nitrogen fertilizer and the of nitrous oxide emission. This review provides an overview of recent researches on the diversity and characteristics of nitrifying microorganisms, soil factors affecting their ecology in soil, their involvement in nitrous oxide emissions, and nitrification control technologies.

摘要

氮循环是地球生态系统中最重要的元素循环，由固氮、硝化和反硝化三大微生物过程进行。硝化在农业土壤生态系统中尤为重要，因为它涉及氮流失、氮浸出造成的地下水污染和温室气体一氧化二氮排放。最近对硝化微生物的基因组、宏基因组和生理学分析为它们在土壤中的生态和功能提供了新的见解。在过去的十年中，有许多关于硝化作用的重要发现。硝化古菌和完全硝化细菌的发现，颠覆了传统的硝化作用是由氨氧化菌和亚硝酸盐氧化菌驱动的理论。每种新发现的硝化微生物都具有独特的特性，例如对氨的不同亲和力。这些硝化微生物已被证明在农业土壤中的硝化作用中发挥着重要作用。土壤条件和农业实践（如施肥和耕作）已被证明会影响每种硝化微生物对硝化活性的贡献。此外，还开发了硝化抑制技术，以防止氮肥流失和一氧化二氮排放。本文综述了近年来硝化微生物的多样性和特征、影响其在土壤中生态的土壤因素、它们对一氧化二氮排放的参与以及硝化控制技术的研究进展。