Initial steps in the degradation of 3,4-dimethylbenzoic acid by Pseudomonas putida strain DMB

Pseudomonas putida strain DMB capable of growing on 3,4-dimethylbenzoic acid as the only C and energy source was isolated by enrichment techniques. It does not utilize for growth or cooxidize the other dimethylbenzoate isomers tested. 3,4-Dimethylsalicylic acid, 3,4-dimethylphenol and 3,4-dimethylcatechol were isolated and identified by nuclear magnetic resonance and mass spectra in the reaction mixture of P. putida washed cells. The detection of the two first metabolites suggests that the initial step in the degradation of 3,4-dimethylbenzoic acid is the formation of 3,4-dimethylcyclohexa-3,5-diene-1,2-diol-1-carboxylic acid which underwent an acid-catalyzed dehydration yielding 3,4-dimethylsalicylic acid and 3,4-dimethylphenol. Further degradation proceeds through 3,4-dimethylcatechol via the meta pathway.