Laccase is essential for lignin degradation by the white-rot fungus Pycnoporus cinnabarinus

The white-rot fungus, Pycnoporus cinnabarinus, provides an excellent model organism to elucidate the controversial role of laccase in lignin degradation, P, cinnabarinus produces laccase in one isoform as the predominant phenoloxidase in ligninolytic cultures, and neither LiP nor MnP are secreted, Yet, P, cinnabarinus degrades lignin very efficiently, In the present work, we show that laccase-less mutants of P, cinnabarinus were greatly reduced in their ability to metabolize C-14 ring-labeled DHP, However, (CO2)-C-14 evolution in these mutant cultures could be restored to levels comparable to those of the mild-type cultures by addition of purified P, cinnabarinus laccase, This clearly indicates that laccase is absolutely essential for Lignin degradation by P, cinnabarinus. (C) 1997 Federation of European Biochemical Societies.