Common induction and regulation of biphenyl, xylene/toluene, and salicylate catabolism in Pseudomonas paucimobilis

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Abstract
P. paucimobilis strain Q1 capable of utilizing biphenyl was isolated from soil. This strain grew on substituted biphenyls and on salicylate, xylene or toluene or both (xylene/toluene), and substituted benzoates. Evidence is presented that the catabolism of biphenyl, xylene/toluene and salicylate is regulated by a common unit in this strain. The catabolism of biphenyl, xylene/toluene and salicylate is interrelated, since benzoate and toluate are common metabolic intermediates of biphenyl and xylene/toluene and salicylate is produced from 2-hydroxybiphenyl (o-phenylphenol). All the oxidative enzymes of the biphenyl, xylene/toluene and salicylate degradative pathways were induced when the cells were grown on biphenyl, xylene/toluene or salicylate. P. paucimobilis Q1 cells showed induction of the meta-cleavage enzymes of 2,3-dihydroxybiphenyl and catechol. Biphenyl-negative derivatives of strain Q1 were simultaneously rendered xylene/toluene and salicylate negative; reversion to the biphenyl-positive character of such derivatives invariably led to a xylene/toluene- and salicylate-positive phenotype. Growth of P. paucimobilis Q1 cells with benzoate as sole C source allowed the induction of only the ortho pathway enzymes, suggesting that biphenyl, xylene/toluene or salicylate specifically induced the meta pathway enzymes for the oxidative degradation of these compounds.