氯嘧磺隆降解菌的筛选及对污染土壤的生物修复

Screening of a chlorimuron-ethyl-degrading strain and chlorimuron-ethyl-contaminated soil bioremediation

采用富集培养方法从江苏某激素研究所污水处理池排污口污泥中分离得到1株氯嘧磺隆降解菌,经菌株形态学特征和26S r DNA序列分析,鉴定为胶红酵母菌(Rhodotorula mucilaginosa).经降解条件优化,菌株对含100mg/L氯嘧磺隆的无机盐培养基中氯嘧磺隆的最佳降解条件为:接种量2.5%,培养温度28℃,pH 6.0,培养5d后降解率为87.33%;在氯嘧磺隆初始浓度为10mg/kg(干土)的模拟污染土壤中,菌株最佳降解条件为:接种量2.5%,温度25℃,pH 6.0,土壤含水量30%,静息培养30d后降解率为90.74%.土壤修复实验结果表明,施加胶红酵母菌后减轻了氯嘧磺隆对小麦幼苗的药害,在氯嘧磺隆浓度为10mg/kg的土壤中投加降解菌后,小麦的出苗率、株高、根长及鲜重均明显高于未投加降解菌的对照组(P<0.05).

A chlorimuron-ethyl-degrading strain(LCY-4),which was isolated from the sewage sludge of a sewage treatment tank in the Jiangsu Hormone Research Institute,was identified as Rhodotorula mucilaginosa based on morphological characteristics and 26S rDNA sequence analysis.The results of these studies showed that the strain exhibited a chlorimuron-ethyl degradation rate of 87.33%at the end of a 5-d incubation period in mineral salt medium with 100mg/L chlorimuron-ethyl under the optimal degradation conditions(2.5%inoculum size,28°C and pH 6.0).The optimal degradation conditions of strain LCY-4 in chlorimuron-ethyl-contaminated soil(containing 10mg/kg chlorimuron-ethyl)were a 2.5%inoculum size,25°C,pH 6.0 and a 30%soil water content.In these experiments,a chlorimuron-ethyl degradation rate of 90.74%was observed at the end of a 30-d incubation period.Soil remediation experiments showed that the application of the chlorimuron-ethyl-degrading strain LCY-4 could alleviate the phytotoxicity of chlorimuron-ethyl on wheat seedlings.In chlorimuron-ethyl-contaminated soil with 10mg/kg chlorimuron-ethyl,the rate of seed emergence,plant height,root length and fresh weight in the treatment group with the addition of LCY-4 were higher than those in the control group without the addition of LCY-4(P<0.05).