基于表面展示技术的拟除虫菊酯降解工程菌的构建及降解机制研究

疏水性有机化合物（HOCs）如拟除虫菊酯类农药等，难于被微生物“吸附”和“摄取”，导致其生物可利用性差，容易在环境中大量残留和积累，给人类健康和生态系统造成了巨大的威胁。利用表面展示技术，将降解酶锚定在微生物细胞表面，可以克服底物和产物穿过细胞膜的障碍，解除了“吸附-摄取” 的限制，极大提高了降解效率。本课题前期首次报道了一种氨肽酶类的拟除虫菊酯水解酶，能水解一系列拟除虫菊酯的酯键，生成水溶性的3-苯氧基苯甲酸和相应的菊酸。拟利用表面展示技术构建一种新的组成型表达的基因工程菌，表征展示效果、测定催化特性和遗传稳定性；考察工程菌对拟除虫菊酯降解的影响规律及作用机理；将该工程菌用于拟除虫菊酯农药污染的土壤修复，评估该工程菌在土壤环境中的适应能力和污染修复效果，分析对土壤微生物群落的可能影响，为拟除虫菊酯类农药的原位生物修复提供理论基础，也为其它HOCs的环境生物修复提供有益的借鉴。

Hydrophobic organic compounds, such as pyrethroid pesticides, are difficult to be "adhesion " and "uptake" by microorganisms, resulting in poor bioavailability and easy to reside and accumulate in the environment, posing a great threat to human health and ecosystems. Using surface display technology, the degrading enzyme is anchored on the surface of the microbial cells, which can overcome the obstacles that the macromolecular substrates and products pass through the cell membrane, so the degradation efficiency is greatly increased. Based on a previous report, a pyrethroid hydrolase belonging to aminopeptidase was first reported to hydrolyze a series of pyrethroid’s ester bonds to produce water-soluble 3-phenoxybenzoic acid and the corresponding chrysanthemic acid. It is planned to use surface display technology to construct a new constitutive-expression genetically engineering strain, followed by characterization of the display effect and determination of the catalytic properties as well as stability. In addition, the influence factor and mechanism of engineered bacteria on pyrethroid degradation will be investigated. The engineered bacteria will be used for soil remediation of pyrethroid pesticides, the adaptability of the engineered bacteria in the soil environment and the effect of pollution remediation will be evaluated, and the possible effects on soil microbial communities will be analyzed. These provide a theoretical basis for the in-situ bioremediation of pyrethroid pesticides and also provide a useful reference for the bioremediation of other HOCs.