Cytochemical localization of cellulases in decayed and nondecayed wood

Summary Enzyme assay showed that the commercial cellulase from Trichoderma reesei degraded several polysaccharide substrates; highest activity was on xylan. Transmission electron micrographs showed that the T. reesei cellulase degraded nondecayed wood extensively; the attack always progressed from the point of contact into the cell wall. Cytochemically prepared wood that had been decayed by Poria placenta showed uniform distribution of electron-dense particles throughout the walls; the same results were observed with added T. reesei cellulase. In wood decayed by Ganoderma applanatum without or with added T. reesei cellulase, the progress of degradation was similar to that in nondecayed wood. Negatively stained T. reesei cellulase had 3–7 nm diameter for the smallest particles; the smallest diamaters of electron-dense particles in wood ranged from 3–7 nm. This suggests that the electron-dense particles probably are cellulase molecules.