假单胞菌CNB-12分解代谢3-氯硝基苯的机理研究

氯代硝基芳烃是一类具有高毒性和潜在致癌性的卤代有机化合物，广泛应用于生产各种药物、染料和除草剂。微生物可以通过多种适应性进化机制而获得多样性的代谢能力，使其成为环境中氯代硝基芳烃污染物的重要分解者。开展微生物对此类污染物的代谢机理研究，不仅丰富了对微生物代谢途径多样性的认识，也是从事生物降解、生物催化、生物转化以及生物修复等相关研究的前提。3-氯硝基苯是一种典型的氯代硝基芳烃污染物，关于其微生物代谢机理至今还未被揭示。本研究筛选到的假单胞菌CNB-12是第一株能够利用3-氯硝基苯为唯一碳氮源生长的细菌，初步实验结果显示该菌株通过还原途径分解代谢3-氯硝基苯。本研究拟鉴定菌株CNB-12分解代谢3-氯硝基苯的中间代谢产物，克隆参与代谢的基因簇，并结合基因敲除互补、体外表达、酶活性测定等方法鉴定其生理学功能。这将首次从分子、生化和遗传学水平上系统地阐明微生物降解3-氯硝基苯的代谢机理。

Chlorinated nitroaromatic compounds (CNAs), a class of highly toxic and carcinogenic halogenated organic compounds, have been widely used in the chemical syntheses of drugs, dyes, herbicides etc. Microorganisms play the most important roles in the degradation of CNAs through a variety of adaptive evolution mechanism and the diversity of metabolic capacity. The research focusing on the metabolic mechanism will be greatly helpful not only for our fully understanding of the diversity of microbial metabolic pathways, but also for the taking full advantages of the diversities and for the biodegradation, biocatalysis, biotransformation and bioremediation. So far, the microbial degradation mechanism of 3-chloronitrobenzene, a typical representative of chlorinated nitroaromatic pollutants, remains unknown. Pseudomonas sp. strain CNB-12 isolated here is the first bacterium that has the ability to utilize 3-chloronitrobenzene as a sole source of carbon and nitrogen. Our preliminary evidences indicated that strain CNB-12 degraded 3-chloronitrobenzene via a reductive pathway. The aims of this proposed project are to identify the intermediates of 3-chloronitrobenzene catabolism and to clone and identify the gene clusters involved in 3-chloronitrobenzene degradation in strain CNB-12, via gene knockout, in vitro expression and enzymatic characterization. This will fill a gap in our understanding of the microbial degradation of 3-chloronitrobenzene at the molecular, biochemical, and genetic levels.