THE BACTERIAL OXIDATION OF AROMATIC COMPOUNDS III

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Abstract
Dried cells of Pseudomonas fluorescens grown on mandelate, benzoate or phenol oxidize catechol with an oxygen uptake of one mole per mole of substrate, an R.Q. of zero and an acid formation of 2 equivalents per mole of substrate. At the end of the oxidation, the production of one mole of [beta]-ketoacid per mole of catechol oxidized can be shown by catalytic decarboxylation with aniline citrate. The product of this oxidation has been isolated and identified as [beta][beta] -ketoadipic acid. Dried cells of P. fluorescens grown on p-hydroxybenzoate carry out a similar oxidation of protocatechuic acid, with the formation of equimolar amts. of carbon dioxide and [beta] -ketoadipic acid. Although both types of dried cells can oxidize hydroxyhydroquinone, the reaction is nonenzymatic, and does not result in the formation of [beta]-ketoadipic acid. The implications of these findings in the light of earlier work on the oxidation of aromatic substrates by P. fluorescens are discussed, and a unified reaction scheme is presented. Special problems in the analysis of expts. on adaptive patterns that may arise when initially distinct oxidative metabolic pathways merge in a common intermediate are presented and analyzed.
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