Laccase-Producing White-Rot Fungus Lacking Lignin Peroxidase and Manganese Peroxidase

This paper presents an overview of phenoloxidases involved in lignin degradation with a particular focus on laccase. To investigate the role of laccase in lignin degradation, Pycnoporus cinnabarinus was identified as an excellent organisms for further study. It produces only one isoelectric form of laccase and yet degrades lignin fast and extensively. We report here on the purification and characterization of the P. cinnabarinus laccase. Laccases are generally considered to have a too low redox potential to attack non-phenolic lignin substrates. This is also true for the laccase from P. cinnabarinus . However, to make up for this deficiency, P. cinnabarinus was found to produce a redox mediator, 3-hydroxy anthranilic acid (3-HAA). Laccase plus the redox mediator, was demonstrated to degrade a non-phenolic lignin model dimer.