Degradation of methoxylated benzoic acids by a Nocardia from a lignin-rich environment: significance to lignin degradation and effect of chloro substituents

Appl Microbiol. 1973 Aug;26(2):176-84.

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

  • Benzoates / metabolism*
  • Biodegradation, Environmental
  • Cell-Free System
  • Chemical Phenomena
  • Chemistry
  • Chromatography, Gas
  • Chromatography, Thin Layer
  • Hydrocarbons, Chlorinated / metabolism*
  • Hydroxylation
  • Lignin / metabolism*
  • Nocardia / enzymology
  • Nocardia / metabolism*
  • Oxygen Consumption
  • Oxygenases / metabolism
  • Sewage
  • Spectrophotometry, Infrared
  • Spectrophotometry, Ultraviolet
  • Water Microbiology*

Substances

  • Benzoates
  • Hydrocarbons, Chlorinated
  • Sewage
  • Lignin
  • Oxygenases