A novel toluene-3-monooxygenase pathway cloned from Pseudomonas pickettii PKO1

J Bacteriol. 1994 Jun;176(12):3749-56. doi: 10.1128/jb.176.12.3749-3756.1994.


Plasmid pRO1957, which contains a 26.5-kb fragment from the chromosome of Pseudomonas pickettii PKO1, allows P. aeruginosa PAO1 to grow on toluene or benzene as a sole carbon and energy source. A subclone of pRO1957, designated pRO1966, when present in P. aeruginosa PAO1 grown in lactate-toluene medium, accumulates m-cresol in the medium, indicating that m-cresol is an intermediate of toluene catabolism. Moreover, incubation of such cells in the presence of 18O2 followed by gas chromatography-mass spectrometry analysis of m-cresol extracts showed that the oxygen in m-cresol was derived from molecular oxygen. Accordingly, this suggests that toluene-3-monooxygenation is the first step in the degradative pathway. Toluene-3-monooxygenase activity is positively regulated from a locus designated tbuT. Induction of the toluene-3-monooxygenase is mediated by either toluene, benzene, ethylbenzene, or m-cresol. Moreover, toluene-3-monooxygenase activity induced by these effectors also metabolizes benzene and ethylbenzene to phenol and 3-ethylphenol, respectively, and also after induction, o-xylene, m-xylene, and p-xylene are metabolized to 3,4-dimethylphenol, 2,4-dimethylphenol, and 2,5-dimethylphenol, respectively, although the xylene substrates are not effectors. Styrene and phenylacetylene are transformed into more polar products.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biodegradation, Environmental
  • Cloning, Molecular
  • Cresols / metabolism
  • Enzyme Induction
  • Gene Expression Regulation, Bacterial
  • Genes, Bacterial / genetics*
  • Genes, Regulator
  • Models, Biological
  • Oxygenases / genetics*
  • Oxygenases / metabolism
  • Pseudomonas / enzymology
  • Pseudomonas / genetics*
  • Pseudomonas / metabolism
  • Restriction Mapping
  • Substrate Specificity
  • Toluene / metabolism*


  • Cresols
  • Toluene
  • Oxygenases
  • toluene-3-monooxygenase
  • cresol