LOSS OF THE TOL META-CLEAVAGE PATHWAY FUNCTIONS OF PSEUDOMONAS-PUTIDA STRAIN PAW1 (PWWO) DURING GROWTH ON TOLUENE

A derivative of Pseudomonas putida strain PaW1 bearing the TOL plasmid pWWO was isolated from a culture which has grown unlimited on toluene. In contrast to the parent strain PaW1, the derivative, strain CG220, is unable to grow with xylenes and toluates, while toluene and benzoate served as substrates. Strain CG220 had a remarkable growth advantage against the wild type when grown with toluene. Biochemical analysis showed that in strain CG220 toluene was metabolised through the TOL plasmid upper pathway to benzoate and the latter to amphibolic intermediates by the chromosomal encoded ortho-cleavage pathway. No activities of the TOL plasmid encoded toluate dioxygenase and catechol 2,3-dioxygenase were detectable in strain CG220. No reversion of strain CG220 to growth with xylenes or toluates was observed. Hybridisation experiments with TOL plasmid-derived gene probes and oligonucleotides revealed that genes xy/Y to xy/G were absent, while xy/X and xy/K were still present.