一株路德维希肠杆菌的筛选及其对3-苯氧基苯甲酸的降解特性分析

Screening and characterization of a 3-phenoxybenzoic acid degrading Enterobacter ludwigii

摘要:

[目的]3-苯氧基苯甲酸（3-phenoxybenzoic acid，3-PBA）的消除是解决拟除虫菊酯类农药污染的关键，目的是从受拟除虫菊酯类农药污染植物根系土壤中分离出3-PBA高效降解菌株。[方法]采用富集驯化、筛选纯化方法，以3-PBA为唯一碳源、能源筛选3-PBA降解菌株；菌株鉴定采用形态、生理生化和16S rRNA序列分析法；并研究其生长降解动力学特性，最后采用Box-Behnken响应面分析确定最佳降解条件。[结果]从川北地区大豆根系土壤中筛选得到1株高效降解菌BPBA031，经鉴定为路德维希肠杆菌（Enterobacter ludwigii）；该菌株耐3-PBA浓度达1600 mg/L，其生长降解过程分别符合Logistic生长动力学（μ_m=0.09149 h^-1，X_m=1.1145）和一级降解动力学模型（k=0.02085，t_1/2=33.24 h）；对3-PBA降解的最适条件为34-37、3-PBA浓度25-200 mg/L和pH 7.5-8.5；在35.19、30.0 mg/L 3-PBA和pH 7.58条件下，该菌株48 h对3-PBA的降解率达83.75%。[结论]路德维希肠杆菌BPBA031是1株高效3-PBA降解菌，可作为生物修复受3-PBA或拟除虫菊酯类农药污染环境的潜在菌株资源。

Abstract:

[Objective] Elimination of 3-phenoxybenzoic acid (3-PBA) is the key to solve the pyrethroid pesticides contamination environment. The aim of this study was to isolate efficient 3-PBA-degrading strains from the plant rhizosphere contaminated by pyrethroid pesticides. [Methods] 3-PBA-degrading strains was screened by using enrichment domestication, isolating and purification methods with 3-PBA used as the sole carbon source. Then the effcient 3-PBA-degrading strain was identified by morphological, physio-biochemical tests and 16S rRNA sequence analysis, and its growth and degradation kinetics and degradation characteristics were studied. Moreover, the degradation conditions were optimized by the Box-Behnken response surface analysis. [Results] A novel 3-PBA-degrading strain BPBA031 isolated from the soybean rhizosphere in northern Sichuan Province was classified into Enterobacter ludwigii, which could be resistant to high concentration of 3-PBA (1600 mg/L). The growth of strain BPBA031 and 3-PBA degradation respectively followed the logistic growth kinetic model (μ_m=0.09149 h^-1, X_m=1.1145) and first-order degradation kinetic model (k=0.02085, t_1/2=33.24 h). The optimum conditions for 3-PBA degradation were culture temprature of 34-37 , 3-PBA concentration of 30.0 mg/L and initial pH 7.58 after 48 h of incubation. [Conclusion] Enterobacter ludwigii BPBA031, a highly effcient 3-PBA-degrading strain, can be used as a potential strain resource for bioremediation of environment polluted by 3-PBA or pyrethroid pesticides.