中文摘要：

硝化过程是自然界氨氮污染降解的主要生化机制，氨氧化细菌对于富营养的河流、海洋及土壤环境等自然生境具有重要作用。氨氧化细菌的群落结构很复杂，且在不同研究区的时空上存在很大差异性。随着分子生物技术的发展，各种自然环境中存在的氨氧化细菌得到了研究。目前，中国对氨氧化细菌的研究多集中于污水处理、土壤等方面，采用非培养方法对自然环境中氨氧化细菌的研究较少。首先介绍了氨氧化细菌的发现过程和生理特性，其次论述了不同的分子生物学方法对土壤和水生生态环境等自然生境中氨氧化细菌研究进展和研究方法，最后提出了自然生境中氨氧化细菌研究的问题和展望。

英文摘要：

Nitrification is a biochemical process in which ammonia oxidized into nitrite,it is the major mechanism for ammonia degradation in natural environment. Ammonia-oxidizing bacteria are widely existed in eutrophic lake, ocean and soil; they play an critical role in natural habitats. The community structure of ammonia-oxidizing bacteria is extremely complex;it shows large differences in spatio-temporal distribution. With the rapid development of molecular biological technology, ammonia-oxidizing bacteria existing in different natural habitats have been studied in depth. At present,most research about ammonia-oxidizing bacteria in China focuses on sewage treatment and soil,while less re- search have done on cultureqndependent environment samples. The discovery process and physiological characteristics of ammonia-oxidizing bacteria are introduced in this paper, the research progress and method of different molecular techniques applied for ammonia-oxidizing bacteria study are discussed. Finally, problems and future prospects in cur- rent knowledge about ammonia-oxidizing in natural environment are put forward.