吲哚乙酸是一种重要的吲哚衍生物，适宜浓度的吲哚乙酸是土壤保持活力的重要因素。过量的吲哚乙酸会对植物和微生物造成危害，吲哚乙酸降解微生物能够调节土壤中吲哚乙酸的浓度，解除过量吲哚乙酸造成的危害，对维持土壤健康起到了重要作用。研究吲哚乙酸的微生物降解十分必要，然而该方向的研究长期被忽视。申请人团队分离并鉴定了一株吲哚乙酸降解菌株Pseudomonas sp. LY1，本项目在该菌株现有工作基础上拟进行以下研究：以基因组、转录组数据为基础，利用基因敲除和回补定位功能基因，对关键基因进行体外克隆表达，蛋白纯化；研究酶的基本生化性质，利用Stopped-Flow、圆二色谱等技术研究关键酶的催化机理，揭示菌株LY1吲哚乙酸上游降解途径的分子机理。本研究将为微生物代谢吲哚类化合物的分子机理研究提供参考。

Indole-3-acetic acid, an important indole derivative, is a central phytohormone, which regulates the whole repertoire of plant developmental processes. The balance of indole-3-acetic acid concentration is important for the health of plant, and excess indole-3-acetic acid produced by rhizosphere microorganisms is harmful to the plant and other microorganisms. Indole-3-acetic acid degradation microorganisms can regulate the concentration of indole-3-acetic acid in soil, and decrease the inhibition caused by high concentration of indole-3-acetic acid. Therefore, the microbial degradation of indole-3-acetic acid is important for the health of soil. However, in the past years, the study of indole-3-acetic acid degradation process by microorganisms has been neglected for a long time..In this study, the upper pathway of idole-3-acetic acid degradation in the strain Pseudomonas sp. LY1 will be characterized. Based on the genome and transcriptome information of strain LY1, the key genes in indole-3-acetic acid degradation will be identified by gene knockout and gene complement. The essential genes in indole-3-acetic acid degradation will be cloned and expressed in E. coli, and the proteins expressed by the genes will be purified. The basic biochemical properties of the enzymes will be characterized, and the catalyzing mechanism of these enzymes will be investigated by isotope labeling, Stopped-Flow and circular dichroism spectrum experiments. The results of this study will lay a solid foundation for the in-depth study of the mechanism and physiological of microbial degradation of indole and its derivatives.