Ligninolytic Activities of the Biopulping Fungus Ceriporiopsis Subvermispora in Solid State Cultures, 1997 Biological Sciences Symposium Proceedings

Lignin peroxidases are generally considered the primary catalysts for the fungal cleavage of nonphenolic lignin structures. However, some white-rot fungi, such as Ceriporiopsis subvermispora, efficiently degrade nonphenolic lignin without expressing any detectable lignin peroxidase activity. Since C. subvermispora is a likely candidate for the biological pretreatment of wood chips (biopulping) on an industrial scale, a deeper knowledge of its ligninolytic system is desirable. To study the mechanism of lignin depolymerization by C. subvermispora, cellulose block cultures of the fungus were given a polymeric lignin model compound in which the P-O-4-linked substructure of lignin is covalently attached to polyethylene glycol. The C!, sidechain carbon of the model was labeled with 14C to enable the detection of structural changes following fungal attack. Chromatographic and mass spectrometric methods were used to identify the products. The new models proved to be valuable tools to elucidate the major ligninolytic reactions of C. subvermisporu. Q-C,, and C,-Gary1 cleavage were shown to be major pathways of lignin model cleavage in this fungus despite its evident lack of lignin peroxidase.