细菌降解杀真菌剂异菌脲的分子机制研究

Hexi corridor of Gansu is the largest supplier of maize seeds, where iprodione is widely used as an effective fungicide. The long-term and large-scale application of iprodione has led to high residues in environment, which brings huge threat to food safety and human health. Microbial metabolism is the main mechanism responsible for the degradation of iprodione in the environment. However, only a few reports focus on the biodegradation metabolites of iprodione. In addition, no literature is available on the genetic and biochemical mechanisms involved in iprodione degradation. We have isolated a highly effective iprodione-degrading strain Arthrobacter sp. CQH in the previous study. The target of this project is to elucidate complete degrading pathway of iprodione by the method of substrates utilization and metabolites identification, to clone the key genes involved in the pathway by the method of trasponson mutagenesis combined with SEFA-PCR technique and to investigate the characteristics of their encoding proteins after the expression and purification. The results of this study will elucidate degradation pathway of iprodione by Arthrobacter sp. CQH and its molecular mechanism, and provide the theoretical and technical foundation for the bioremediation of the iprodione-contaminated environments.

河西走廊是全国最大的制种玉米生产基地，在其生产过程中异菌脲作为有效的杀真菌剂被广泛使用。异菌脲的长期和大面积使用，导致环境中产生较高残留，给食品安全和人类健康带来巨大隐患。异菌脲在环境中的降解主要是微生物的作用。目前国内外有关异菌脲生物降解的报道很少，异菌脲生物降解的途径还没有被阐明，与异菌脲降解相关的酶及其编码基因未见报道。申请人分离到一株高效降解异菌脲的菌株，本项目拟通过底物利用和产物鉴定技术解析完整的异菌脲降解途径，通过转座子诱变法和SEFA-PCR技术相结合的方法克隆降解异菌脲的关键酶基因，并表达和纯化其编码的蛋白，研究关键酶的酶学特性。预期结果将阐明细菌降解异菌脲的途径及其分子机理，为微生物修复异菌脲污染的环境提供理论依据。

异菌脲作为有效的杀真菌剂被广泛使用。异菌脲的长期和大面积使用，导致环境中产生较高残留，给食品安全和人类健康带来巨大隐患。异菌脲在环境中的降解主要是微生物的作用。但目前对微生物降解异菌脲的机理研究还很不充分，完整的降解途径及参与的基因还不清楚。本课题组分离到四株能以异菌脲为唯一碳、氮源生长且降解异菌脲的菌株。本项目以这些菌株为研究对象，通过底物利用和产物鉴定技术解析了异菌脲的生物降解途径；并克隆了催化该途径第一步反应的异菌脲水解酶的基因，从基因水平上阐明了细菌降解异菌脲的机理，为异菌脲污染环境的生物修复提供理论和技术支撑。