Enzymatic delignification by laccase-natural mediator systems supplemented with xylanase

Laccase-mediator systems have been applied to delignify lignocellulose in paper and pulp industries. Due to the high cost and potential toxicity of artificial mediators, naturally derived compounds, such as lignin-derived products, have attracted much attention as redox mediators. In this study, natural aromatic compounds (e.g., vanillic acid, vanillin, syringaldehyde, syringic acid, 4-hydroxybenzoic acid) were used as mediators for laccase-catalyzed delignification. The effects of xylanase on laccase-natural mediator systems and subsequent lignin removal were also studied. The proposed new laccase-mediator systems with or without xylanase supplementation would overcome the problems with traditional systems, such as laccase-HBT and laccase-ABTS. Such novel oxidative enzymatic systems would contribute to the industrial application of laccase in biorefineries.