BIODEGRADATION OF 2,4-DICHLOROPHENOL THROUGH A DISTAL META-FISSION PATHWAY

Alcaligenes eutrophus JMP222, a derivative of A. eutrophus JMP134 whic h has lost plasmid pJP4 (encoding the tfd genes for the ortho fission pathway), was induced for the meta fission pathway when grown on o-cre sol. Resting cell suspensions, grown on o-cresol, oxidized 2,4-dichlor ophenol (2,4-DCP), a degradation product of 2,4-dichlorophenoxyacetic acid, to 3,5-dichlorocatechol. Further degradation of 3,5-dichlorocate chol was observed by the production of a yellow ring fission product w ith liberation of chloride. Oxidation of 2,4-DCP (305 mu M) in 47 hs r esulted in 69% dehalogenation through this pathway, The ring fission p roduct was characterized as 2-hydroxy-3,5-dichloro-6-oxo-hexa-2,4-dien oic acid by gas chromatography-mass spectrometry and gas chromatograph y-Fourier transform infrared spectroscopy. These data indicate that 2, 4-DCP is degraded through a distal meta ring fission pathway, in contr ast to either a suicidal proximal fission or the standard ortho fissio n pathway.