Biodegradation of fenoxaprop-P-ethyl (FE) by Acinetobacter sp. strain DL-2 and cloning of FE hydrolase gene afeH

Fenoxaprop-P-ethyl (FE) is widely used as a post-emergence aryloxyphenoxy propionate (AOPP) herbicide in agriculture. An efficient FE-degrading strain DL-2 was isolated from the enrichment culture and identified as Acinetobacter sp. and the metabolite fenoxaprop acid (FA) was identified by HPLC/MS analysis. The strain DL-2 could also degrade a wide range of other AOPP herbicides. A novel FE hydrolase esterase gene afeH was cloned from strain DL-2 and functionally expressed in Escherichia coli BL21(DE3). The specific activities of recombinant AfeH was 216.39 U mg−1 for FE with Km and Vmax values of 0.82 μM and 7.94 μmol min−1 mg−1. AfeH could also hydrolyze various AOPP herbicides, p-nitrophenyl esters and triglycerides. The optimal pH and temperature for recombinant AfeH were 9.0 and 50 °C, respectively; the enzyme was activated by Co2+ and inhibited by Ca2+, Zn2+, Ba2+. AfeH was inhibited strongly by phenylmethylsulfonyl and SDS and weakly by dimethyl sulfoxide.