产胞外ROS细菌共代谢典型有机微污染物机理研究

Cometabolic degradation is a crucial transformation way of organic micropollutants (OMPs) in the environment. At present, the bacterial cometabolic mechanism of OMPs is mainly based on the induction and degradation of individual key enzymes, the role and underlying mechanism of extracellular reactive oxygen species (ROS) in bacterial cometabolic degradation of OMPs remain unclear. The project will focus on the scientific issue that formation characteristics and reaction mechanism of extracellular ROS in the bacterial cometabolic degradation of OMPs. The main contents include that, key factors affecting extracellular ROS formation in the bacterial cometabolic degradation of OMPs; the kinetic characteristics of extracellular ROS formation and OMPs degradation; the relationship between both extracellular ROS and degrading enzymes and OMPs degradation; the comprehensive analysis of the key genes and their functions in the target OMPs cometabolism, based on the integrated information of genomics, transcriptomics and metabolites; the understanding of the formation mechanism of extracellular ROS, OMPs degradation pathway and metabolic network; systematic elucidation of OMPs cometabolic mechanism by extracellular ROS-forming bacteria. The cometabolism degradation process of OMPs will be conducted from a new perspective. It provides new ideas for the study of cometabolic degradation of environmental pollutants, and new insight into OMPs biotransformation process as well as novel bioremediation technology development.

共代谢降解作用是环境中有机微污染物（OMPs）极其重要的转化方式。目前OMPs细菌共代谢降解机理研究主要是基于个别关键降解酶的诱导及其降解作用，而胞外活性氧（ROS）在OMPs细菌共代谢降解中的作用及机制尚不清晰。本项目围绕探明OMPs细菌共代谢降解中胞外ROS形成规律及作用机制这一科学问题而展开。研究内容主要包括：识别影响典型OMPs细菌共代谢中胞外ROS形成的关键因素；明确胞外ROS形成及OMPs降解动力学规律；探明胞外ROS和降解酶与OMPs降解的关系；整合基因组学、转录组学及代谢产物信息，全面解析目标OMPs共代谢中关键基因及其功能；揭示胞外ROS形成机理、OMPs降解途径及代谢网络，系统地阐明产胞外ROS细菌共代谢OMPs作用机制。本项目从全新的角度研究OMPs共代谢降解过程，将为环境污染物共代谢降解研究提供新思路，同时为研究OMPs生物转化过程及生物修复新工艺提供新的启示。

目前有机微污染物（OMPs）共代谢降解机理研究主要是基于个别关键降解酶的诱导及其降解作用，而胞外活性氧（ROS）在OMPs细菌共代谢降解中的作用及机制尚不清晰。本项目围绕这一科学问题开展了如下研究内容：识别影响典型OMPs细菌共代谢中胞外ROS形成的关键因素；明确胞外ROS形成及OMPs降解动力学规律；探明胞外ROS和降解酶与OMPs降解的关系；整合基因组学、转录组学及代谢产物信息，全面解析目标OMPs共代谢中关键基因及其功能；揭示胞外ROS形成机理、OMPs降解途径及代谢网络，系统地阐明产胞外ROS细菌共代谢OMPs作用机制。. 结果表明，共底物对Pseudoalteromonas sp. GCY胞外ROS形成具有显著影响，且生物膜形成可促进GCY胞外产生ROS。环境中细菌在黑暗条件下产生胞外ROS，并共代谢降解OMPs具有一定的普遍性；GCY菌对典型OMPs的共代谢降解符合准一级反应动力学规律。GCY可胞外合成铁载体；nadB等基因负责产生H2O2；nqrA-F编码NADH氧化还原酶催化O2还原为O2•-；胞外H2O2与铁载体通过Fenton-like反应形成•OH。典型OMPs布洛芬（IBP）触发了GCY的抗氧化机制，上调了一系列抗氧化基因，且IBP促进了菌株分泌胞外聚合物以抵御外界不良环境，从而确保了GCY的生物活性以及降解IBP。在胞外•OH与O2•-作用下IBP通过羟基化、异丁基裂解、氧化和脱羧反应形成中间产物4-乙基间苯二酚；该产物然后进入细胞，在胞内4-羟基苯丙酮酸双加氧酶和龙胆酸1,2-双加氧酶作用下开环，再经β-氧化和TCA循环完全矿化。本项目为难降解污染物共代谢降解以及环境中OMPs生物转化过程提供了新的启示；同时为研发基于产胞外ROS细菌共代谢作用的OMPs污染环境生物修复新工艺奠定了理论基础。