METABOLISM OF NAPHTHALENE, 1-NAPHTHOL, INDENE, AND INDOLE BY RHODOCOCCUS SP STRAIN NCIMB-12038

The regulation of naphthalene and 1-naphthol metabolism in a Rhodococc us sp. (NCIMB 12038) has been investigated. The microorganism utilizes separate pathways for the degradation of these compounds, and they ar e regulated independently, Naphthalene metabolism was inducible, but n ot by salicylate, and 1-naphthol metabolism, although constitutive, wa s also repressed during growth on salicylate. The biochemistry of naph thalene degradation in this strain was otherwise identical to that fou nd in Pseudomonas putida, with salicylate as a central metabolite and naphthalene initially being oxidized via a naphthalene dioxygenase enz yme to cis-(1R,2S)-1,2-dihydroxy-1,2-dihydronaphtalene (naphthalene ci s-diol). A dioxygenase enzyme was not expressed under growth condition s which facilitate 1-naphthol degradation, However, biotransformations with indene as a substrate suggested that a monooxygenase enzyme may be involved in the degradation of this compound, Indole was transforme d to indigo by both naphthalene-grown NCIMB 12038 and by cells grown i n the absence of an inducer, Therefore, the presence of a naphthalene dioxygenase enzyme activity was not necessary for this reaction. Thus, the biotransformation of indole to indigo may be facilitated by anoth er type of enzyme (possibly a monooxygenase) in this organism.