Isolation and Characterization of Fenoxaprop-p-ethyl-Degrading Bacteria Strain Acinetobacter sp.T-1 and Its Degrading Characteristics

Fenoxaprop-p-ethyl(FE) is a postemergence applied aryloxyphenoxy propionate(AOPP) herbicide used for the control of annual and perennial weeds in crops and it caused severely environmental pollution for its widely used in agriculture.Bioremediation is an effective and economic method to treat the environment that has been polluted by FE.So researchers paid much attention in this area.In the present study,a bacterial strain T-1 capable of degrading FE was isolated from the soil which was contaminated by FE for a long time.Strain T-1 was preliminarily identified as Acinetobacter sp.based on its physiological and biochemical characters and 16S rRNA gene sequence analysis.Strain T-1 could utilize FE as the sole carbon source for growth,and degrade 95% of 50 mg·L-1 FE within 5 days.The optimal temperature of FE degradation by strain T-1 was 37 ℃,and stain T-1 could degrade over 85% of 50 mg·L-1 FE within pH5~11.Inoculum size and concentration of substrate had a significant effect on the degradation of FE by strain T-1.And the degradation rate could increase with the increasing of the inoculum size,while the increase in the concentration of the substrate would inhibit the degradation of FE.The ion Ni2+ could inhibit the strain to degrade FE slightly,and other metal ions had no effect on the degradation of FE by strain T-1 in the experimental range.One major metabolite fenoxaprop acid(FA) was identified by LC-MS during the degradation of FE and this showed that the metabolic pathway of strain T-1 degrading FE was the cleavage of ester bonds to form FA and ethanol.