A NOVEL TOLUENE-3-MONOOXYGENASE PATHWAY CLONED FROM PSEUDOMONAS-PICKETTII-PKO1

Plasmid pRO1957, which contains a 26.5-kb fragment from the chromosome of Pseudomonas pickettii PKO1, allows P. aeruginosa PAO1 to grow on t oluene or benzene as a sole carbon and energy source. A subclone of pR O1957, designated pRO1966, when present in P. aeruginosa PAO1 grown in lactate-toluene medium, accumulates m-cresol in the medium, indicatin g that m-cresol is an intermediate of toluene catabolism. Moreover, in cubation of such cells in the presence of O-18(2), followed by gas chr omatography-mass spectrometry analysis of m-cresol extracts showed tha t the oxygen in m-cresol was derived from molecular oxygen. Accordingl y, this suggests that toluene-3-monooxygenation is the first step in t he degradative pathway Toluene-3-monooxygenase activity is positively regulated from a locus designated tbuT. Induction of the toluene-3-mon ooxygenase is mediated by either toluene, benzene, ethylbenzene, or m- cresol. Moreover, toluene-3-monooxygenase activity induced by these ef fecters also metabolizes benzene and ethylbenzene to phenol and 3-ethy lphenol, respectively, and also after induction, o-xylene, m-xylene, a nd p-xylene are metabolized to 3,4-dimethylphenol, 2,4-dimethytphenol, and 2,5-dimethylphenol, respectively, although the xylene substrates are not effecters. Styrene and phenylacetylene are transformed into mo re polar products.