Abstract
3-Phenoxybenzoic acid (3-PBA) is of great environmental concern with regards to endocrine disrupting activity and widespread occurrence in water and soil, yet little is known about microbial degradation in contaminated regions. We report here that a new bacterial strain isolated from soil, designated DG-02, was shown to degrade 95.6% of 50 mg·L−1 3-PBA within 72 h in mineral salt medium (MSM). Strain DG-02 was identified as Bacillus sp. based on the morphology, physio-biochemical tests and 16S rRNA sequence. The optimum conditions for 3-PBA degradation were determined to be 30.9°C and pH 7.7 using response surface methodology (RSM). The isolate converted 3-PBA to produce 3-(2-methoxyphenoxy) benzoic acid, protocatechuate, phenol, and 3,4-dihydroxy phenol, and subsequently transformed these compounds with a q max, K s and K i of 0.8615 h−1, 626.7842 mg·L−1 and 6.7586 mg·L−1, respectively. A novel microbial metabolic pathway for 3-PBA was proposed on the basis of these metabolites. Inoculation of strain DG-02 resulted in a higher degradation rate on 3-PBA than that observed in the non-inoculated soil. Moreover, the degradation process followed the first-order kinetics, and the half-life (t 1/2) for 3-PBA was greatly reduced as compared to the non-inoculated control. This study highlights an important potential application of strain DG-02 for the in situ bioremediation of 3-PBA contaminated environments.
Highlights
3-Phenoxybenzoic acid (3-PBA) is of great environmental concern with regards to endocrine disrupting activity and widespread occurrence in water and soil, yet little is known about microbial degradation in contaminated regions
Strain DG-02 belongs to the Bacillus group of bacteria based on the morphology, physiobiochemical characteristics, and 16S rRNA gene analysis
It has been suggested that the accumulated 3-PBA, which has antimicrobial property, prevents the proliferation of pyrethroid-degrading microorganisms [22,32]
Summary
3-Phenoxybenzoic acid (3-PBA) is of great environmental concern with regards to endocrine disrupting activity and widespread occurrence in water and soil, yet little is known about microbial degradation in contaminated regions. 3-Phenoxybenzoic acid (3-PBA) is a common primary metabolite of the synthetic pyrethroid insecticides (SPs) that have been extensively used in agriculture and urban areas because of their high efficiency and low mammalian toxicity [1]. It is the important chemical raw material widely used in the manufacture of SPs and dyes [2]. To the best of our knowledge, the microbial metabolic pathway of 3-PBA has not been investigated so far and remains unclear
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