Abstract:Two bacterial strains, Pseudomonas sp. CO-1 and CO-44, capable of degrading 4-chlorophenol, were isolated from coking wastewater collected from Shaoguan, Guangdong, South of China. The optimum conditions for 4-chlorophenol degradation by these two strains were pH 6.0~8.0 and temperatures 35~40℃. The degradation rate of 4-chlorophenol was negatively related with the initial concentration of 4-chlorophenol in mineral salt medium. Both strains could degrade phenol and cresols, strain CO-1 also could degrade 1-naphthyl phenol and naphthalene. Approximately 300mg/L phenol and 100mg/L cresols in coking wastewater as well as 100mg/L 4-chlorophenol supplemented were completely degraded within 42 hours at 2% inoculum rate. Phenol hydroxylase gene were detected from both two strains, in addition to catechol 1,2-dioxygenase gene and catechol 2,3-dioxygenase gene were detected from strain CO-1 and CO-44 respectively.