[Oxidation characteristics of the aromatic acids formed in DDT breakdown by a Pseudomonas aeruginosa culture].

The purpose of this work was to study the process of oxidation of aromatic acids (benzoic, salicylic and phenylacetic acids) produced as the result of DDT degradation by Pseudomonas aeruginosa 640x. The cultural broth was analysed by thin-layer chromatography, chromato-mass spectrometry and the enzymes of aromatic acid oxidation were investigated. Benzoate was shown to be oxidized via p-hydroxybenzoic acid, protocatechuic acid and its ortho degradation. Phenylacetate, the principal of DDT degradation, was hydroxylated by the culture with simultaneous migration of the two-carbon fragment and decomposition of the resultant homogentisic acid. Salicylic acid was not oxidized by the culture; it was accumulated in the medium. Analysis of the enzymes involved in the oxidation of the aromatic cycle has shown that the culture lacks salicylate hydroxylase, metapyrocatechase and gentisate 1,2-dioxygenase. Instead, it manifested the activities of the enzymes catalysing ortho cleavage of the cycle, namely, pyrocatechase and protocatechoate 3 : 4 dioxygenase, as well as homogentisate oxygenase.