title: Degradation of methoxylated benzoic acids by a Nocardia from a lignin-rich environment: significance to lignin degradation and effect of chloro substituents.
abstract: Strain A81 of Nocardia corallina hydroxylates or demethylates p-anisic acid to p-hydroxybenzoic acid and isovanillic acid. It demethylates veratric acid to a mixture of vanillic and isovanillic acids. These are both demethylated to protocatechuic acid, which undergoes ring cleavage to afford beta-carboxy-cis-cis-muconic acid. The intermediacy of protocatechuic acid in the catabolic pathway of veratric acid was confirmed by blocking ring cleavage with an additional substituent in the ring: 5-chlorovanillic acid was demethylated to 5-chloro-protocatechuic acid, which accumulated. Chloro substituents in the ring of other methoxylated benzoic acids also arrested their normal metabolism by the Nocardia: an ortho-chloro substituent thwarted both demethylation and ring-opening. ortho-Hydroxylation of p-methoxybenzoic acid to isovanillic acid was unaffected by a chlorine ortho to the methoxyl group. Washed whole cells of veratric acid-grown N. corallina A81 produced no detected structural changes in an isolated lignin. The implications of this observation are discussed.
mesh_terms: D001565:Benzoates / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002474:Cell-Free System; D055598:Chemical Phenomena; D002621:Chemistry; D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D006843:Hydrocarbons, Chlorinated / Q000378:metabolism*; D006900:Hydroxylation; D008031:Lignin / Q000378:metabolism*; D009615:Nocardia / Q000201:enzymology / Q000378:metabolism*; D010101:Oxygen Consumption; D010105:Oxygenases / Q000378:metabolism; D012722:Sewage; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D014871:Water Microbiology
chemical_list: D001565:Benzoates; D006843:Hydrocarbons, Chlorinated; D012722:Sewage; D008031:Lignin; D010105:Oxygenases