苯高效降解菌Corynebacterium sp.AL-5的筛选及其降解机理研究

Isolation and degradation characteristics of high-efficiency benzene-degrading strain Corynebacterium sp.AL-5

在产石化企业污染场地风险防控日益受到关注,高性能生物降解菌剂是在产企业成功原位生物修复的关键.本研究从苯系物降解菌群中筛选并分离出高效苯降解菌株,经细菌形态和16S rRNA序列分析鉴定菌株,通过改变单一因素研究降解菌株的降解特性,并通过LC-QTOF-MS/MS检测中间代谢产物,进而推测菌株的苯降解途径.结果表明,高效苯降解菌株经鉴定命名为Corynebacterium sp.AL-5.菌株AL-5在28℃、pH=8.0、添加100 mg·L^(-1)酵母粉的培养条件下,10 h内可完全降解初始浓度为100 mg·L^(-1)的苯,并阐明了菌株AL-5通过苯酚和邻苯二酚途径降解苯.此外,菌株AL-5可在混合BTEX体系中同时降解苯和甲苯,半衰期分别为3.3 h和12.9 h,符合零级动力学方程和一级动力学方程.本研究可为在产石化企业苯污染土壤和地下水原位生物修复提供菌种资源和理论支撑.

The risk prevention and control of contaminated sites in in-service petrochemical enterprises had attracted increasing attention.The efficiently degrading strains was the key to successful in situ bioremediation.In this study,a high-efficiency benzene-degrading strain was screened and isolated from BTEX degrading consortium.The strain was identified by bacterial morphology and 16S rRNA sequence analysis.The degradation characteristics of the degrading strain were studied by changing a single factor,and the benzene degradation pathway was inferred with the detection of intermediate metabolites by LC-Q-TOF-MS/MS.The results showed that the high-efficiency benzene-degrading strain was identified and named Corynebacterium sp.AL-5.Under the culture conditions of 28℃,pH=8.0 and adding 100 mg·L^(-1) yeast in medium,strain AL-5 completely degraded benzene with an initial concentration of 100 mg·L^(-1) within 10 h.In the process,phenol and catechol were resolved as the main metabolites,so strain AL-5 degraded benzene via phenol and catechol pathway.In addition,strain AL-5 could simultaneously degrade benzene and toluene in the mixed BTEX system.The degradation kinetics of benzene and toluene were conformed to the zero-order kinetic equation and the first-order kinetic equation within the initial concentrations of 50 mg·L^(-1),with half-lives of 3.3 h and 12.9 h respectively.This study provides strain resources and theoretical support for in situ bioremediation of benzene-contaminated soil and groundwater in in-service petrochemical enterprises.