土壤氨氧化细菌的氨氧化作用是氮循环硝化作用的第一步反应，是限速步骤，氮循环的微生物过程不仅受微生物种群、结构特征、环境因子的影响，还受微生物本身产生的信号分子的调控。群体感应（Quorum sensing,QS）是微生物种群内与微生物种群间的一种通讯方式，它通过群体感应信号分子来调节种群表达与代谢，使个体行为成为群体行为。研究发现,群体感应信号分子不仅调控细胞密度，同时能调控细菌的多个代谢网络。本申请拟回答以下科学问题：氨氧化细菌是否具有QS基因单元？QS系统是否对氨氧化细菌的关键功能产生调控？QS如何影响硝化过程中的种群关系？项目的完成预期可以在个体水平以及微生物生态学层面上初步认识QS对微生物氨氧化过程的作用机制、调控原理及其生态学功能。

Ammonia oxidation is the first and rate-limiting step in the nitrification process of the nitrogen cycle.The process is not only influenced by microbial communities,composition and environmental factors,but also driven by signal molecules secreted by microbes themselves.Microbes communicate with one another using quorum sensing (QS). QS bacteria produce and release chemical signal molecules termed autoinducers to regulate the gene expression and metabolism. This process allows bacteria to monitor the environment for other bacteria and to alter behavior on a population-wide scale. Recent evidence shows that autoinducers not only control cell density, but also alter the metabolic network in bacterial cells. However, there is no clear answer for autoinducers produced by ammonia oxidizing bacteria (AOB) and the association between QS and process of ammoxidation regulation. So this project is designed to answer a few scientific questions: 1) whether there are QS signals produced by AOB which play a key role in the nitrogen cycle; 2) to discuss the mechanisms of control and regulation of the ammoxidation process by autoinducers; 3) whether these QS signals have effects on community structure of ammonia oxidizing microbes in soil environment. Identification of the communication networks and the unraveling of QS metabolic process will present a meaningful story to complete the nitrogen cycle.