title: Anaerobic biodegradation ofPara-cresol under three reducing conditions.
abstract: The anaerobic degradation ofp-cresol was studied with one sediment source under three reducing conditions-denitrifying, sulfidogenic, and methanogenic. Loss ofp-cresol (1 mM) in all the anaerobic systems took initially 3 to 4 weeks. In acclimated culturesp-cresol was degraded in less than a week.p-Cresol was completely metabolized under denitrifying, sulfidogenic, and methanogenic conditions, with formation of nitrogen gas, loss of sulfate, and formation of methane and carbon dioxide, respectively.p-Cresol metabolism proceeded throughp-hydroxybenzal-dehyde andp-hydroxybenzoate under denitrifying and methanogenic conditions. These compounds were rapidly degraded in cultures acclimated top-cresol under all three reducing conditions. These results suggest that the initial pathway ofp-cresol degradation is the same under denitryfying, sulfidogenic, and methanogenic conditions and proceeds via oxidation of the methyl substituent top-hydroxybenzaldehyde andp-hydroxybenzoate. The initial rate ofp-hydroxybenzaldehyde degradation was high in both the unacclimated cultures and in the cultures acclimated top-cresol, suggesting that this step is nonspecific. Benzoate was additionally detected as a metabolite followingp-hydroxybenzoate in the methanogenic cultures, but not in the denitrifying or sulfidogenic cultures. The degradation pathway therefore may diverge afterp-hydroxybenzoate formation depending on which electron acceptor is available.
authors.affiliation: Department of Microbiology, New York University Medical Center, 10016, New York, New York, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Häggblom
authors.forename: M D
authors.initials: MD
authors.lastname: Rivera
authors.forename: I D
authors.initials: ID
authors.lastname: Bossert
authors.forename: J E
authors.initials: JE
authors.lastname: Rogers
authors.forename: L Y
authors.initials: LY
authors.lastname: Young