APPLICATION OF PSEUDOMONAS-PUTIDA PGG 786 CONTAINING P-450 CYTOCHROME MONOOXYGENASE FOR REMOVAL OF TRACE NAPHTHALENE CONCENTRATIONS

This study explores the potential for a bacterial monooxygenase to remove polynuclear aromatic hydrocarbons from aqueous solutions at high rates. This is part of a larger effort to test the versatility of the cytochrome P-450cam monooxygenase enzyme system for detoxification of industrial process wastewaters that contain trace quantities of hazardous compounds like PAHs or halocarbons. The intracellular concentration of P-450cam in washed, resting cell suspensions of Pseudomonoas putida PpG 786 that were cultured on camphor was measured by adapting a spectrophotometric method used to measure P-450 concentration in extracts of mammalian tissues. Naphthalene removal in the suspensions was measured as a function of incubation time, biomass concentration, starting naphthalene concentration (3-180-mu-mol/L) and in the presence of known P-450 inhibitors. Involvement of the P-450cam system in the measured naphthalene disappearance was established by showing that while significant naphthalene removal occurred in camphor-grown biomass, no disappearance was observed in glutamate-grown biomass and that removal was turned off in the presence of the P-450 inhibitor metyrapone. The half-life of naphthalene removal for a 1 ppm solution (7.8 mu-M) was about 18 h. The fraction of naphthalene removed descreased rapidly as initial naphthalene concentration increased, and essentially no naphthalene was removed when the starting concentration exceeded 189-mu-mol/L (23 ppm).