Enantioselective Catabolism of the Two Enantiomers of the Phenoxyalkanoic Acid Herbicide Dichlorprop by sp. DBS4.

Dichlorprop [()-2-(2,4-dichlorophenoxy)propanoic acid; DCPP], an important phenoxyalkanoic acid herbicide (PAAH), is extensively used in the form of racemic mixtures (-DCPP), and the environmental fates of both DCPP enantiomers [()-DCPP and ()-DCPP] mediated by microorganisms are of great concern. In this study, a bacterial strain sp. DBS4 was isolated from contaminated soil and was capable of utilizing both ()-DCPP and ()-DCPP as the sole carbon source for growth. Strain DBS4 preferentially catabolized ()-DCPP as compared to ()-DCPP. The optimal conditions for -DCPP degradation by strain DBS4 were 30 °C and pH 7.0. In addition to -DCPP, other PAAHs such as ()-2-(4-chloro-2-methylphenoxy)propanoic acid, 2,4-dichlorophenoxyacetic acid, 4-chloro-2-methylphenoxyacetic acid, and 2,4-dichlorophenoxyacetic acid butyl ester could also be catabolized by strain DBS4. Bioremediation of -DCPP-contaminated soil by inoculation of strain DBS4 exhibited an effective removal of both ()-DCPP and ()-DCPP from the soil. Due to its broad substrate spectrum, strain DBS4 showed great potential in the bioremediation of PAAH-contaminated sites.