Biodegradation of fenoxaprop-ethyl by an enriched consortium and its proposed metabolic pathway

Fenoxaprop-ethyl (FE) is widely used as a post-emergence aryloxyphenoxy propionate (AOPP) herbicide in agriculture. Microbial metabolism is the main mechanism responsible for FEdegradation in natural soil; however, the microbial FE-degradation mechanism remains unclear. The FE-degrading consortium W1 was isolated by enrichment using FE polluted soil. FE (0.5 mM) was completely degraded by consortium W1 at 30 degrees C and pH7 after 7days of incubation. Consortium W1 demonstrated the ability to degrade FE stably under a wide range of pH and temperature conditions. Four intermediate metabolites, fenoxaprop acid (FA), 6-chloro-2,3-dihydrobenzoxazol-2-one (CDHB), 2-amino-5-chlorophenol (2A5CP), and 2-(4-hydroxyphenoxy)-propionic acid (HPP), were detected and identified using liquid chromatography-mass spectrometry analysis. The community structure of W1 was analyzed using RFLP. The main strains of the consortium shared high similarity at the 16S rRNA gene level with Pigmentiphaga daeguensis and Pseudoxanthomonas sp. Pigmentiphaga sp. strain DL-8, which degrades CDHB and HPP, and Acinetobacter sp. strain DL-2, which transforms FE to FA, were isolated from the consortium. Finally, for the first time, a possible biochemical pathway for the degradation of FE is proposed. (C) 2014 Elsevier Ltd. All rights reserved.