可替宁（1-甲基-5-[3-吡啶基]-2-吡咯烷酮）是尼古丁在人体内最主要的代谢产物和排泄物，在市政污水和地表水中广泛存在。因可替宁具有较强的毒性，研究其在环境中的降解和归趋以及生态毒理具有非常重要的意义。已有研究表明微生物代谢是环境中可替宁降解的主要因素，但目前关于微生物降解可替宁的代谢过程和分子生物学机制还未见报道。申请人从市政污水处理系统活性污泥中分离到一株能利用可替宁为唯一碳源生长的细菌Nocardioides sp. JQ2195，并检测到两个新的降解产物。本项目拟以菌株JQ2195为材料，通过降解中间产物鉴定、基因组和比较转录组/蛋白组分析、基因敲除与回补等技术，揭示细菌降解可替宁的代谢途径，克隆可替宁的降解相关基因（簇），鉴定降解基因的生理学功能以及转录调控机制。本研究将在生化和遗传水平上揭示微生物降解可替宁的代谢机制，为深入可替宁在环境中的降解和归趋以及毒理学提供理论依据。

Cotinine (1-methyl-5-[3-pyridyl]-2-pyrrolidone) is the primary metabolite and excretion of nicotine in human body. It is ubiquitous in municipal sewage and surface water. Cotinine is highly toxic. The fate and ecotoxicity of cotinine in the natural environment are of great interest. Reported studies demonstrated that cotinine was mostly degraded by microorganisms in the environment. However, the degradation processes and biological mechanisms for the degradation of cotinine by microorganisms are still unknown. Nocardioides sp. strain JQ2195, which is able to utilize cotinine as sole carbon source for growth, has been isolated in our laboratory and two new intermediate metabolites have been identified. This project was designed to investigate the degradation pathwayof cotinine and identify the genes (cluster) involved in cotinine degradation in Nocardioides sp. strain JQ2195 by genomics, comparative transcriptome/proteome analysis, gene knockout and complementation technologies. This study will reveal the processes and regulatory mechanisms of cotinine degradation at the biochemical and genetic levels. Moreover, the research will be greatly helpful in understanding the fate and ecotoxicity of cotinine in the natural environment.