Anaerobic Biodegradation of Monoaromatic Compounds

Toluic acids degradation was studied undermethanogenic and sulfate-reducing conditions. Alltoluic acid isomers were degraded undersulfate-reducing conditions, with m-toluatedegradation occurring at the fastest rate. Benzoate,isophthalate, and m-carboxybenzylsuccinate weredetected in m-toluate-degrading enrichments,suggesting a fumarate addition mechanism form-toluate degraation. The metabolism of benzoate by Syntrophusaciditrophicus in coculture with hydrogen-usingmicroorganisms was studied. Cyclohexane carboxylate,cyclohex-1-ene carboxylate, pimelate, and glutaratetransiently accumulated during growth with benzoate.S. aciditrophicus also metabolized benzoate in pureculture in the absence of hydrogen-utilizing partnersor terminal-electron acceptors. A novel protocol was developed to determinewhether the degradation of toluene undersulfate-reducing conditions depends on interspecieshydrogen transfer. Although the outcome of theexperiments failed to support the tested hypothesis,the protocol will be useful to determine the role ofinterspecies hydrogen transfer in the degradation ofdifferent compounds in environmental samples.