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

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.

Key words:Enterobacter Ludwigii;biodegradation;3-phenoxybenzoic acid;degradation characteristics