Degradation of 2-chlorophenol and 3-chlorobenzoate by Rhodococcus opacus 1cp

Variants of strain Rhodococcus opacus Icp that were capable of utilizing 2- chlorophenol and 3-chlorobenzoate as sole sources of carbon and energy were obtained through multiple subcultures of this strain in liquid medium cont aining these xenobiotics. Unlike 4-chlorophenol and 2,4-dichlorophenol, whi ch are utilized by Rh. opacus Icp via the 4-chlorocatechol branch of a modi fied ortho-cleavage pathway, 2-chlorophenol and 3-chlorobenzoate were utili zed via the 3-chlorocatechol branch. Among the products of degradation of 2 -chlorophenol and 3-chlorobenzoate, 3-chlorocatechol and 2-chloromuconate w ere identified. Two 2-chlorocatechol 1,2-dioxygenases, the key enzymes of t he modified ortho-cleavage pathway, were isolated, purified, and characteri zed. Both enzymes were able to cleave 3- and 4-chlorocatechol; their activi ties toward 3-chlorocatechol were higher than the activity of the respectiv e enzyme isolated from cells grown on 4-chlorophenol. The enzymes were homo dimers, with a molecular weight of subunits of 29 kDa.