手性农药对映体在土壤内选择性降解过程中降解基因及微生物群落结构的差异研究

After the application of chiral pesticides, the bioactivity, metabolism, bioaccumulation, toxicity and degradation rates of enantiomers differ from each of the two enantiomers and cause the enantiomer selectivity pollution. This research investigates the differences in degradation gene and microbial community structure during the enantioselective degradation process of chiral pesticide isomers in soil, and then reveals the molecular biological mechanisms of the selective degradation behavior of them. Obtains and analyzes the influence of the key rate-limiting functional genes on the target analyte degradation during the degradation process. Establishes the quantitative response model between the degradation rate of optically pure isomers and key rate-limiting functional genes, and proves the selective degradation reason of chiral pesticides by the gene level. Constructs the composition and evolutionary tree of degradation associated microbial community structure via marker genes. Reveals the composition and abundance differences of microbial community structure during the degradation process of different isomers. By changing the environmental factors, analyzes the temporal evolution rule among degradation rate, process products, functional degradation genes, and soil microbial community structure of chiral isomers, under the different soil conditions. Provides the scientific basis for evaluating the hazards to the environment and human health after the application of chiral pesticides.

具有手性特征的农药施用后，两个互为对映异构体的化合物在生物活性、毒性毒理、降解速率以及代谢行为等方面往往存在着显著差别，进而产生对映体的选择性污染。本项目针对手性农药施用后在土壤中会产生选择性降解的特点，研究不同对映异构体降解过程中降解功能基因、土壤微生物群落结构的差异性，进而揭示产生选择性降解的分子生态机理。获取并解析降解过程中关键限速功能基因对目标分析物降解的影响，建立光学纯异构体降解速率与关键限速功能基因之间的定量响应关系模型，从基因水平上探明手性农药选择性降解的原因；通过标志基因构建降解相关微生物群落结构组成及进化树，揭示不同异构体降解过程中微生物群落结构组成和丰度的差异性；通过改变环境因子，分析不同土壤条件下手性异构体降解速率、过程产物、降解功能基因、土壤微生物菌群结构的时空演化规律，为评价手性农药施用后对环境及人类健康的危害提供科学依据。

本项目以手性农药三唑酮、高效氯氰菊酯为目标分析物，三种不同pH值土壤为供试样本，考察了手性农药在土壤中的立体选择性行为，并利用高通量测序技术从关键基因、环境微生物层面考察了手性农药产生立体选择性行为的分子生态机理，主要研究结果如下：.1).利用高效液相色谱建立手性农药三唑酮、高效氯氰菊酯对映体拆分方法，并进行准确定性、定量研究；.2).建立手性农药三唑酮、高效氯氰菊酯在三种供试土壤中的提取、净化、富集方法；.3).考察待测农药在不同土壤中的立体选择性行为，并进行比较分析，获取产生选择性行为的关键环境因子；.4).待测农药降解过程中代谢产物的定性、定量分析，并获取降解过程及相关降解基因；.5).手性农药降解为小分子化合物过程中，关键降解基因的研究及降解基因绝对丰度与降解速率之间的定量响应关系研究；.6).手性农药降解过程中环境微生物群落组成的研究，立体选择性行为关键微生物的获取与探索性研究；.7).从降解基因、环境微生物层面揭示手性农药产生立体选择性行为的分子生态机理。