TRANSGLYCOSYLATION OF EXTRACELLULAR β-GLUCOSIDASE OF TRICHODERMA PSEUDOKONINGI1 S38 AND ITS FUNCTION IN REGULATION OF CELLULASE BIOSYNTHESIS

摘要

Two β-glucosidase (βG) components, βG1 and βG2, purified from extracellular culture filtrate of Trichodenna pseudokoningii S38 by chroma-tography techniques, showed transglycosylation activity, the character of which was previously believed to belong to the membrane-bound βG. βG1 also hydrolyzed cellobiose (and other β-linked disaccharides) to produce glucose, and could hydrolyze p-nitrophenyl-β-D-glucoside (PNPG). However, the activity of hydrolysis of disaccharides and PNPG of βG2 was lower than that of βG1, but it had higher trans-glycosylation activity, showing different substrate specificities. The trans-cosylation products originating from cellobiose by βGs, such as all of the other β-linked disaccharides and even cellotriose, weredetermined by HPLC. Among them, gentiobiose was believed to be the most effective inducer of cellulose biosynthesis in this strains. The induction ability of a certain disaccharide had a relationship with its amount in the traction mixture which was controlled by the dual activities of βG, hydrolysis and transglycosylation.