Ligninolytic enzymes of the white rot fungus Panus tigrinus

The enzymes of the white rot fungus Panus tigrinus, synthesized during solid-state fermentation on straw, were purified and characterized. The enzymes are Mn-dependent peroxidase (MnP) (EC 1.11.1.-) and laccase (benzenediol:oxygen oxidoreductase; EC 1.10.3.2). The lignin peroxidase (Lip) (EC 1.11.1.-) activity was not detected at any stage during cultivation. The Mr of MnP was 43,000, and that of laccase 64,000. Isoelectric focusing resolved both preparations into two isoenzymes. The pI values are 3.2 (minor) and 2.95 (major component) for MnP and 3.0 (major) and 2.9 (minor component) for laccase. Conditions for the optimum activity of MnP and laccase were specified, and the effect of both enzymes on native lignin and lignin model compounds studied. The results suggest that lignin degradation by Panus involves the action of Mnp and laccase, but not Lip. Antibodies against Lip and laccase, obtained from the fungus Phlebia radiata, reacted with the ligninolytic complex of P. tigrinus, thus indicating that the ligninolytic enzymes of these two white rot fungi are interrelated.