POTENTIAL FOR CARBOXYLATION-DEHYDROXYLATION OF PHENOLIC-COMPOUNDS BY A METHANOGENIC CONSORTIUM

An anaerobic consortium that carboxylated and dehydroxylated phenol to benzoate, and 2-cresol to 3-methylbenzoic acid, under methanogenic co nditions was studied. Phenol induced this transformation activity. Add ition of 4-hydroxypyridine or an increase in the concentration of prot eose peptone to 0. 5 % (w/v) delayed the transformation. Phenol enhanc ed the rate of transformation of 2-cresol whereas 2-cresol delayed the transformation of phenol. Phenols with ortho-substitutions (chloro-, fluoro-, bromo-, hydroxyl-, amino-, or carboxyl-) were transformed to meta-substituted benzoic acids. However, meta- and para-substituted ph enols (cresols, fluorophenols, and chlorophenols) were not transformed . Phenol was most rapidly metabolized, followed by catechol, 2-cresol, 2-fluorophenol, 2-aminophenol, 2-chlorophenol, 2-hydroxybenzoic acid, and 2-bromophenol. The consortium O-demethylated anisole to phenol an d 2-methoxyphenol to catechol, and oxidized 2-hydroxybenzyl alcohol to 2-hydroxybenzoic acid. Aniline, 2-ethylphenol, 2-hydroxypyridine, 2-a cetamidophenol, 2,6-dimethylphenol, 2-phenylphenol, and 1-naphthol wer e not metabolized.