The Bacterial Dissimilation of Naphthalene

Data are presented indicating that the major pathway for the oxidation of naphthalene by a strain of Pseudomonas occurs via salicylic acid, which is further oxidized through catechol to β-ketoadipic acid. On the basis of growth, simultaneous adaptation, and cell-free extract experiments, the following compounds are regarded as unlikely intermediates in naphthalene dissimilation: 1,4-naphthoquinone, α-naphthol, β-naphthol, 1,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 1,5-dihydroxynaphthaIene, phenol, trans-o-hydroxycinnamic acid, and phthalic acid. Evidence was found that a second pathway of naphthalene oxidation produces 1,2-naphthoquinone. 1,2-Dihydroxynaphthalene was found to be non-enzymatically converted to 1,2-naphthoquinone. The 1,2-naphthoquinone was not further metabolized and was found to be responsible for the characteristic brown to reddish orange color of the culture medium. Omission of FeCl 2 and MgSO 4 from the basal medium prevented the formation of salicylic acid but did not interfere with the production of 1,2-naphthoquinone.