Microbial degradation of fomesafen and detoxification of fomesafen-contaminated soil by the newly isolated strain Bacillus sp FE-1 via a proposed biochemical degradation pathway

Fomesafen is a long residual herbicide and poses a potential risk to environmental safety, leading to an increasing need to find eco-friendly and cost-effective techniques to remediate fomesafen-contaminated soils. In this article, a novel strain of Bacillus sp., FE-1 was isolated from paddy field soil. This strain was found to degrade fomesafen both in liquid medium and in soil. >82.9% of fomesafen, at concentrations of 0.5, 1 and 10 mg L-1, was degraded by Bacillus sp. FE-1 in liquid medium within 14 h. The optimal pH and temperature for degradation were 7.0 and 35 degrees C, respectively. Soil samples inoculated with strain FE-1 showed significantly increased rates of fomesafen degradation. Two metabolites of fomesafen degradation were detected and identified as amino-fomesafen and 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-amino-benzoic acid. This is the first report of a novel fomesafen biodegradation pathway involving the reduction of a nitro group followed by the hydrolysis of an amide bond. The excellent remediation capability of the isolate FE-1 to detoxify fomesafen-contaminated soil was shown by bio-assay of the sensitive aftercrop corn. The results indicate that Bacillus sp. FE-1 has potential for use in the bioremediation of fomesafen-contaminated soil. (c) 2017 Elsevier B.V. All rights reserved.