玫瑰杆菌类群细菌Ruegeria sp. PrR005降解芘的新机制研究

芘是监测环境中多环芳烃污染的指示物和研究多环芳烃生物降解的模型分子。近年来人们已经解析了细菌降解芘的两种机制。令我们倍感兴趣的是，玫瑰杆菌类群细菌Ruegeria sp. PrR005可能通过一种新的分子机制催化芘降解，即在上游途径中，该菌株通过单加氧酶、环氧化物水解酶、脱氢酶、醌氧化酶等催化芘进入菲代谢途径进一步降解，这与已知的两种催化机制显著不同。本项目针对这一发现，拟首先通过中间产物检测，解析菌株Ruegeria sp. PrR005降解芘的途径；继而借助转录组差异表达分析和关键功能基因异源表达和敲除，系统揭示该菌株降解芘的分子机制；最后，通过对玫瑰杆菌类群其它菌株降解芘能力的评价和功能基因表达的检测，探究上述机制是否为该类群细菌降解芘的通用分子机制。本项目的研究结果能够揭示细菌降解芘的一种新机制，并能够为玫瑰杆菌类群细菌在污染环境修复中的应用提供理论依据。

Pyrene is an indicator of polycyclic aromatic hydrocarbons (PAHs) caused pollution and a model chemical for investigating the molecular transformation mechanism of PAHs. Two different molecular mechanisms of pyrene degradation by different bacteria have been revealed. Interestingly, in our previous studies, we found that the bacterium Ruegeria sp. PrR005 in the Roseobacter clade could efficiently degrade pyrene via a potentially novel biochemical pathway. The bacterium strain PrR005 could catalyze pyrene by monooxygenase, epoxide hydrolase, quinol oxidase to 3,4-Dihydroxyphenanthrene and further degrade via phenanthrene pathway. In this study, the pyrene metabolic pathway by the strain PrR005 will be first elucidated by detecting metabolites produced in the process of degradation. Transcriptomics analysis will then be applied to investigate functional genes involved in the biodegradation. Functions of these genes will be verified by exogenous expression and gene knock-out. Further, the pyrene degrading ability and functional gene expression of other bacterial strains in Roseobacter clade will be detected to reveal if all Roseobacter clade bacteria could degrade pyrene via the same metabolic pathway. This study will reveal a novel molecular mechanism of catalyzing pyrene biodegradation by bacteria, and provide theoretical basis for the application of Roseobacter clade in bioremediation.