Degradation of alkyl-substituted benzenes and their photo-oxidation products by a marine mixed bacterial population

Oxidation of alkyl-substituted benzenes by a marine mixed bacterial population showed no accumulation of phenyl acetic and phenyl acrylic acids, although more than 90 % of the substrates were converted to microbial cells and carbon dioxide. Photo-oxidation products were also used by bacteria to form assimilable intermediates. These reactions with mixed population constitute an interesting example of favourable interaction between bacterial degradation and photo-oxidation and can explain the disappearance of compounds listed as recalcitrant substrates. Key intermediates have been identified by gas chromatography and mass spectrometry. A mechanism based on their chemical structure is proposed for the degradation of alkyl-substituted benzenes containing side chains with odd and even numbers of carbon atoms.