ADAPTATION OF COMAMONAS-TESTOSTERONI TA441 TO UTILIZE PHENOL - ORGANIZATION AND REGULATION OF THE GENES INVOLVED IN PHENOL DEGRADATION

Comamonas testosteroni TA441 was not able to grow on phenol as a sole carbon and energy source, but it gained the ability to utilize phenol after a 2-3-week incubation in a medium containing phenol. Phenol hydr oxylase (PH) and catechol 2,3-dioxygenase (C230) were highly induced b y phenol in the adapted strain designated as strain P1, suggesting tha t phenol was degraded via the meta-pathway. Gene clusters for phenol d egradation were isolated from both strains TA441 and P1. The structura l genes encoding multicomponent PH and C230 (aphKLMNOPQB), and a regul atory gene of the NtrC family (aphR), were located in a divergent tran scriptional organization, The cloned aphKLMNOPQB genes from either str ain TA441 or strain P1 produced active PH and C230 enzymes in strain T A441. No difference was found between the strains in the sequences of aphR and the intergenic promoter region of aphK and aphR, However, the transcriptional activities of the aphK and aphR promoters were higher in strain P1 than in strain TA441. The aphK-promoter activity was not observed in aphR mutant strains and these strains could not grow on p henol. The aphR mutant of strain P1 was able to grow on phenol after t ransformation with a recombinant aphR gene but strain TA441 was not, s uggesting that the expression of the aph genes is silenced by an unide ntified repressor in strain TA441 and that this repressor is modified in strain P1.