DEMETHYLATION OF THE LIGNIN MODEL DIMER 1-(3',4'-DIMETHOXYPHENYL)-2-(ORTHO-METHOXYPHENOXY)-PROPANE-1,3-DIOL BY THE WHITE-ROT FUNGUS PHLEBIA-TREMELLOSA

Phlebia tremellosa dealkylates nonphenolic beta-O-4-linked lignin model dimers; the phenolic products are oxidized by laccase. There is no evidence of alpha,beta-cleavage as catalyzed by lignin peroxidase in some other white rot fungi. Methanol is the product of demethylation of 1-(3',4'-dimethoxyphenyl)-2-(o-methoxyphenoxy)-propane-1,3-diol, and the demethylation reaction can be assayed by the release of radioactive CH3OH from the 4'-(O-CH3)-C-14 labelled compound. In older cultures, the methanol is metabolized to CO2. Demethylation is stimulated by oxygen and blocked by several common metabolic inhibitors. Both the mycelium and the extracellular medium are required for demethylation.