Microbial oxidation of naphthalene. I. Factors concerning salicylate accumulation.

Little information has been contributed to the mechanisms of biological degradation of polycyclic hydrocarbons. The oxidation of naphthalene has received the most attention. Strawinski and Stone (1943, 1954) reported the isolation of substantial amounts of salicylic acid ("most" of the 2.9 mg per ml medium of ether extractable product) from the breakdown of naphthalene by Pseudomonas aeruginosa. Salicylic acid has been verified as an intermediate in naphthalene oxidation by Treccani (1953), Walker and Wiltshire (1953), and Murphy and Stone (1955). These latter systems were not entirely satisfactory for intermediary studies. Either the intermediate compound (salicylate) was recovered in small amounts; i.e., 23 mg from 2 L culture medium (Walker and Wiltshire, 1953), 0.6 mg per ml medium (Murphy and Stone, 1955), or the organism employed was incapable of growth when subcultured continuously in medium containing naphthalene as sole carbon source (Murphy, 1953; Murphy and Stone, 1955). The present study was undertaken in order to isolate a naphthalene-oxidizing system which would be useful for investigating the mechanism of oxidation of polycyclic hydrocarbons. A procedure for isolating such a system and certain physiological factors concerned with the accumulation of the intermediate product, salicylic acid, are described.