Degradation of diclofop-methyl by pure cultures of bacteria isolated from Manitoban soils

Abstract

Pure cultures of Chryseomonas luteola and Sphingomonas paucimobilis isolated from Manitoban soils were able to utilize diclofop-methyl (methyl-2-[4-(2,4-dichlorophenoxy)phenoxy]propanoate) as the sole source of carbon and energy. An actively growing culture of C. luteola completely degraded 1.5 μg diclofop-methyl∙mL−1to diclofop acid and 4-(2,4-dichlorophenoxy)phenol within 71 h, as determined by gas chromatographic analysis. The accumulation of these metabolites in the growth medium resulted in the cessation of growth, indicating the organism's inability to degrade phenoxyphenol in the presence of diclofop acid. Sphingomonas paucimobilis mineralized 1.5 μg diclofop-methyl∙mL−1to diclofop acid within 54 h. A biphasic growth pattern indicated that this organism was capable of degrading diclofop acid to 4-(2,4-dichlorophenoxy)phenol and 2,4-dichlorophenol and (or) phenol. Neither of the organisms was able to utilize 2,4 -dichlorophenol as the sole source of carbon and energy.Key words: diclofop-methyl, biodegradation, herbicide.