经典的生物脱氮是基于自养菌和异养菌分别在好氧和缺（厌）氧条件下的硝化和反硝化作用序批进行的。但已有研究证实在完全好氧条件下某些异养细菌能独立完成整个生物脱氮过程。对此，可能存在NH4+→NH2OH→N2O→N2这一新的脱氮代谢途径。但上述途径目前尚缺乏足够的科学与实验证据。本项目以申请人已经分离获得的异养菌A. faecalis strain NR为研究对象，拟采用同位素示踪、关键酶分离纯化、编码基因测序和化学计量学原理，通过对其异养脱氮性能、物质代谢途径、关键功能酶及其编码基因的研究，确认其异养脱氮的途径，优化影响其脱氮性能的工艺因素，初步揭示这一脱氮途径产生的根源与调控机制，为深入了解异养菌的脱氮性能、丰富和发展生物脱氮理论提供知识积累，为构建高效生物脱氮工程菌进而开发新型生物脱氮技术提供理论依据。

Conventional biological nitrogen removal consists of two steps: nitrification by autorophs under aerobic conditions and denitrification by heterotrophs under anaerobic conditions. However, some heterotrophic microorganisms could complete the whole biological nitrogen removal process only under aerobic conditions. Moreover, a possible biological nitrogen removal pathway of NH4+→NH2OH→N2O→N2 might exist in heterotrophic microorganisms, but there is a lack of enough evidences for this metabolic pathway. In this study, a heterotrophic microorganism of A. faecalis strain NR is aimed to investigate. Based on 15N isotope technology, key enzyme assay, gene sequencing and chemical analysis, the metabolic pathway will be demonstrated and the affecting factors of heterotrophic nitrogen removal will be optimized. Furthermore, the mechanism for this pathway will be explored. This study is of great significance to understand the heterotrophic nitrogen removal capability and its metabolic mechanism, and also provide necessary knowledge to construct nitrogen removal engineering strains and develop novel nitrogen removal technology.