Degradation of phenanthrene by mutant naphthalene-degrading Pseudomonas putida strains

Five naphthalene- and salicylate-utilizing Pseudomonas putida strains culti vated for a long time on phenanthrene produced mutants capable of growing o n this substrate and 1-hydroxy-2-naphthoate as the sole sources of carbon a nd energy. The mutants catabolize phenanthrene with the formation of 1-hydr oxy-2-naphthoate, 2-hydroxy-1-naphthoate, salicylate, and catechol. The lat ter products are further metabolized by the meta- and ortho-cleavage pathwa ys. In all five mutants, naphthalene and phenanthrene are utilized with the involvement of plasmid-born genes. The acquired ability of naphthalene-deg rading strains to grow on phenanthrene is explained by the fact that the in ducible character of the synthesis of naphthalene dioxygenase, the key enzy me of naphthalene and phenanthrene degradation, becomes constitutive.