CONSTRUCTION OF A NOVEL POLYCHLORINATED BIPHENYL-DEGRADING BACTERIUM - UTILIZATION OF 3,4'-DICHLOROBIPHENYL BY PSEUDOMONAS ACIDOVORANS M3GY

Pseudomonas acidovorans M3GY is a recombinant bacterium with the novel capacity to utilize a biphenyl congener chlorinated on both rings, 3, 4'-dichlorobiphenyl (3,4'-DCBP), as a sole carbon and energy source. S train M3GY was constructed with a continuous amalgamated culture appar atus (L. Krockel and D. D. Focht, Appl. Environ. Microbiol. 53:2470-24 75, 1987) with P. acidovorans CC1(19), a chloroacetate and biphenyl de grader, and Pseudomonas sp. strain CB15(1), a biphenyl and 3-chloroben zoate degrader. Genetic and phenotypic data showed the recipient paren tal strain to be P. acidovorans CC1 and the donor parental strain to b e Pseudomonas sp. strain CB15. In growth experiments with 3,4'-DCBP as a sole source of carbon, cultures of strain M3GY increased in absorba nce from 0.07 to 0.39 in 29 days while reaching a protein concentratio n of 58 mu g ml(-1) and 67% substrate dehalogenation. 4-Chlorobenzoate was identified from culture supernatants of strain M3GY by gas chroma tography-infrared spectrometry-mass spectrometry; this would be consis tent with the oxidation of the m-chlorinated ring through the standard biphenyl pathway. 4-Chlorobenzoate was converted to 4-chlorocatechol, which was metabolized through the meta-fission pathway. The construct ion of P. acidovorans M3GY, with the novel capability to utilize 3,4'- DCBP, thus involves the complete use of meta-fission pathways for sequ ential rupture of the biphenyl and chlorobenzoate rings.