Synergistic Effects of Cellobiose Dehydrogenase, Cellulases, and .BETA.-Glucosidase from Irpex lacteus in the Degradation of Various Types of Cellulose.

Synergistic effects in the degradation of bacterial cellulose (BC), Avicel and H3PO4-swollen Avicel (HA) by cellobiose dehydrogenase (CDH) and ?A-1, 4-glucanases from Irpex lacteus including exo-cellulase (Ex-1), endo-cellulase (En-1) and ?A-glucosidase were investigated. CDH effectively promoted both the degradation of celluloses by Ex-1 and synergism of Ex-1 and En-1 but moderately the degradation by En-1. Kinetic studies indicated that CDH enhances cellulose degradation by Ex-1 more effectively than ?A-glucosidase does by preventing product inhibition. The enhancement in the cellulose-degrading capability of cellulases by synergistically acting with CDH was significant and independent of the crystallinity of substrate while the synergistic effect of Ex-1 and En-1 by themselves was limited when substrates were at low crystallinity. Despite the large amount of cellobiose consumed by CDH in the presence of electron acceptors, the cellulolytic enzyme system from 1. lacteus effectively degraded different cellulose sources and continued producing sufficient glucose for the cell.