TOM, A NEW AROMATIC DEGRADATIVE PLASMID FROM BURKHOLDERIA (PSEUDOMONAS) CEPACIA G4

Burkholderia (Pseudomonas) cepacia PR1(23) has been shown to constitut ively express a toluene catabolic pathway distinguished by a unique to luene ortho-monooxygenase (Tom). This strain has also been shown to co ntain two extrachromosomal elements of <70 and >100 kb. A derivative s train cured of the largest plasmid, PR1(23) Cure, was unable to grow o n phenol or toluene as the sole source of carbon and energy, which req uires expression of the Tom pathway. Transfer of the larger plasmid fr om strain G4 (the parent strain inducible for Tom) enabled PR1(23) Cur e to grow on toluene or phenol via inducible Tom pathway expression, C onjugal transfer of TOM(23c) from PR1(23) to an antibiotic-resistant d erivative of PR1(23) Cure enabled the transconjugant to grow with eith er phenol or toluene as the sole source of carbon and energy through c onstitutive expression of the Tom pathway. A cloned 11.2-kb EcoRI rest riction fragment of TOM(23c) resulted in the expression of both Tom an d catechol 2,3-dioxygenase in Escherichia coli, as evidenced by its ab ility to oxidize trichloroethylene, toluene, m-cresol, o-cresol, pheno l, and catechol. The largest resident plasmid of PR1 was identified as the source of these genes by DNA hybridization, These results indicat e that the genes which encode Tom and catechol 2,3-dioxygenase are loc ated on TOM, an approximately 108-kb degradative plasmid of B. cepacia G4.