咪唑乙烟酸降解菌分离鉴定、降解条件优化及去毒效应研究

Isolation and Identification of Imazethapyr Degradable Bacteria,and Study on its Biodegradation Conditions Optimization and Detoxication Effect

为了获得咪唑乙烟酸高效降解菌,采用高压富集驯化的方法从长期施用咪唑乙烟酸的土壤中分离筛选出一株对咪唑乙烟酸具有较高降解能力的菌株MZ-1,经形态特征、生理生化特征及16S rRNA序列分析,鉴定该菌株为蜡状芽孢杆菌(Bacillus cereus)。利用响应面法优化该菌株对咪唑乙烟酸的降解条件。结果表明菌株MZ-1的最佳降解条件为:温度32℃、pH=6.6、接菌量为3%。在最优条件下,当咪唑乙烟酸初始浓度为200 mg/L时,5 d后降解率可达73.12%。以油菜种子作为生物材料,发现经菌株MZ-1降解后的咪唑乙烟酸培养液和未经降解的培养液相比对根生长的抑制率明显降低,仅为不接菌处理抑制率的52.45%。本研究结果可为菌株MZ-1高效修复咪唑乙烟酸残留污染提供技术支撑。

In order to obtain efficient strains for degradation of imazethapyr,a bacterial strain capable of degrading imazethapyr was isolated from imazethapyr-contaminated field soil using the method of high pressure enrichment and acclimation.Based on morphological,physio-biochemical characteristics,and phylogenetic analysis of 16S rRNA,the strain was identified as Bacillus cereus and named MZ-1.The degradation conditions were optimized by Box-Behnken design and response surface analysis.Results showed that the optimal degradation conditions of MZ-1 were as follows temperature of 32℃,pH of 6.6 and inoculum amount of 3%.Under the optimal conditions,the degradation rate reached 73.12%after 5 days when the initial concentration of imazethapyr was 200 mg/L.Using rape seeds as biomaterial,we found that the inhibiton rate of imazethapyr on root growth was significantly reduced after degradation by strain MZ-1.The inhibition rate was only 52.45%of the treatment without inoculation.The results of this study provide a foundation for efficient remediation of imazethapyr-contaminated envrionment using strain MZ-1.