2-Chlorobenzoic acid and 2,5-dichlorobenzoic acid metabolism by crude extracts of Pseudomonas sp CPE2 strain

Crude extracts of Pseudomonas sp. CPE2 strain, which is capable of growing on 2-chlorobenzoic acid (2-CBA) and 2,5-dichlorobenzoic acid (2,5-dCBA) in the absence of other carbon sources, were found to be capable of bioconverting 2-CBA and 2,5-dCBA to catechol and 4-chlorocatechol, respectively, by a reaction requiring molecular oxygen and exogenous NADH. Extracts obtained from 2-CBA-grown cells in the presence of 2-CBA and from 2,5-dCBA-grown cells in the presence of 2,5-dCBA were found to have activities similarly influenced by the assay parameters pH, temperature, and by concentration of oxygen, protein, Fe2+ FAD and NADH in the assay medium. In addition, the activity of the two crude extracts in the presence of 2-CBA or 2,5-dCBA was described by very similar Michaelis-Menten kinetic parameters. These observations led to the speculation that a unique broad-spectrum chlorobenzoate 1,2-dioxygenase catalyses the 2-CBA and 2,5-dCBA metabolism both in 2-CBA- and 2,5-dCBA-grown CPE2 cells.