4-Hydroxybenzoic Acid Secreted from Trametes versicolor Catalyzes the Oxidation of a Nonphenolic β-O-4 Lignin Model Dimer as Laccase Mediator

Abstract

To detect natural laccase mediator, the extracellular culture fluid of Trametes versicolor laccase production medium was fractionated using degradation of anthracene which can not be degraded with laccase alone. As a result, 4-hydroxybenzoic acid (HBA) was isolated from the culture fluid, and it was clear that HBA acted as a natural mediator and the degradation efficiency of anthracene by laccase greatly increased. The laccaseHBA system could also oxidized the nonphenolic β-O-4 lignin model dimer to pruduce the Cα-oxidation, βether cleavage and aromatic ring cleavage products. The oxidation mechanisms of the laccase-HBA system are very similar to those for lignin peroxidase and laccase-1-hydroxybenzotriazol (HBT) system.