Microbial biodegradation of butachlor pollution (obsolete pesticide Machete 60% EC)

Abstract

The chloroacetamide herbicide butachlor is a widely used herbicide that has caused environmental pollution in many areas. The degradation mechanism of butachlor and bioremediation of butachlor contaminated-sites by bioaugmentation is of great concern. In this study, the novel strain Catellibacterium caeni sp. nov DCA-1 T was found to degrade 81.2% of 50 mg l -1 butachlor in 84 h, and efficiently degrade butachlor in a relatively broad range of temperatures from 15 to 35 ??C and initial pH values from 6.0 to 9.0. Five metabolites produced during butachlor degradation by strain DCA-1 T were identified based on gas chromatography-mass spectrometry, and a different degradation pathway of butachlor was proposed. The removal of butachlor by bioaugmentation of strain DCA-1 T in three different soils was also studied. The inoculation of DCA-1 T cells significantly accelerated the degradation of butachlor in both sterile and non-sterile soils, with 57.2%-90.4% of 50 mg kg -1 butachlor removed in 5 days compared to 5.4%-36% in the controls. The removal rate of butachlor in the sterile red soil (pH 4.8) inoculated with strain DCA-1 T was lower than that in the sterile fluvo-aquic soil (pH 6.3) and high sandy soil (pH 8.2), showing that soil type significantly affected the butachlor degradation. This study highlights an important potential use of strain DCA-1 T for the cleanup of chloroacetamide herbicides contaminated-sites and presents a different degradation pathway of butachlor in a pure culture. ?? 2012 Elsevier Ltd.