水稻田常用除草剂的微生物降解研究进展

Research progress on microbial degradation of herbicides commonly used in rice paddy fields

水稻是中国乃至世界最重要的粮食作物之一,除草剂是保障水稻产量的一个重要因素.然而除草剂的长期大量使用带来了严重的环境残留问题,致使除草剂成为一类环境污染物,威胁到水稻与生态环境的安全和人类健康.微生物降解代谢是消除环境残留除草剂最有力的方式.围绕水稻田中常用的10种除草剂(二氯喹啉酸、乙草胺、丁草胺、苄嘧磺隆、吡嘧磺隆、氯嘧磺隆、五氟磺草胺、氰氟草酯、草甘膦、二甲四氯)的微生物降解展开综述,总结分离到的各种除草剂的高效降解菌株、归纳除草剂的降解代谢途径以及克隆到的降解关键酶基因.现阶段水稻田常用的这10种除草剂降解研究更多集中于降解纯品系菌株的筛选,并根据分析化学方法鉴定的中间代谢产物结构进行代谢途径的分析,以及基于代谢途径的研究克隆到部分参与降解过程的关键酶基因.但是目前分离到的除草剂高效降解菌株不多,尤其是五氟磺草胺的降解菌株更是鲜见报道,此外代谢途径的研究往往停滞于降解过程的前几步,多数除草剂的完整代谢通路以及参与其中的基因和酶还未得到阐明.建议未来充分利用生物信息学技术挖掘高效的降解菌株和降解基因新资源,为解决除草剂稻田环境污染问题提供优良资源和理论基础.

Rice is one of the most important food crops in China and the world, and herbicides are a critical factor in stable rice production. However, long-term and extensive use of herbicides has caused serious environmental problems. As a result, herbicides have become a class of environmental pollutants that threaten the safety of rice cultivation, the ecological environment, and human health. Microbial degradation is considered the most efficient dissipation method for herbicides in the environment. In this study, the microbial degradation of 10 herbicides commonly used in paddy fields(quinclorac, acetochlor, butachlor, bensulfuronmethyl, pyrazosulfuron-ethyl, chlorimuron-ethyl, penoxsulam, cyhalofop-butyl, glyphosate, and 2-methyl-4-chlorophenoxyacetic acid) was reviewed. This includes review of selected pure strains with high degradation efficiency, the analysis of metabolic pathways, and the associated degrading enzymes/genes. However, there is still a lack of highly efficient degrading strains among the strains currently available, especially penoxsulamdegrading strains. In addition, the study of metabolic pathways always stagnates in the first few steps of the degradation process, and the complete metabolic pathways of most herbicides and the genes/enzymes involved have not been clarified. In future research, bioinformatics technology should be fully utilized to mine newly identified degrading microorganisms and accompanying gene resources, so as to provide excellent resources and theoretical basis for solving the problem of environmental pollution caused by herbicides in the rice fields.