Isolation and Identification of a Di-(2-Ethylhexyl) Phthalate-Degrading Bacterium and Its Role in the Bioremediation of a Contaminated Soil

Di-(2-ethylhexyl) phthalate (DEEP) is a high-molecular-weight phthalate ester (PAE) that has been widely used in the manufacture of polyvinylchloride and contributes to environmental pollution. The objectives of the present study were to isolate a DEEP degrader that can utilize DEEP as a carbon source and to investigate its capacity to biodegrade DEEP in both liquid culture and soil. A bacterial strain WJ4 was isolated from an intensively managed vegetable soil, which was contaminated with PAEs. The strain WJ4 was affiliated to the genus Rhodococcus and was able to remove DEEP from soil effectively. A period of only 7 d was required to degrade about 96.4% of DEEP (200 mg L-1) in the liquid culture, and more than 55% of DEEP (1.0 g kg(-1)) in the artificially contaminated soil was removed within 21 d. Furthermore, Rhodococcus sp. strain WJ4 had a strong ability to degrade DEEP without additional nutrients in liquid minimal medium culture and DEEP-contaminated soil and to degrade the homologue of DEEP in both liquid culture and soil. Strain WJ4 represents a novel tool for removing PAEs from contaminated soils and it may have great potential for application in the remediation of environmental pollution by PAEs.