Quinones as terminal electron acceptors for anaerobic microbial oxidation of phenolic compounds.

The capacity of anaerobic granular sludge for oxidizing phenol and p-cresol under anaerobic conditions was studied. Phenol and p-cresol were completely converted to methane when bicarbonate was the only terminal electron acceptor available. When the humic model compound, anthraquinone-2,6-disulfonate, was included as an alternative electron acceptor in the cultures, the oxidation of the phenolic compounds was coupled to the reduction of the model humic compound to its corresponding hydroquinone, anthrahydroquinone-2,6-disulfonate. These results demonstrate for the first time that the anaerobic degradation of phenolic compounds can be coupled to the reduction of quinones as terminal electron acceptor.