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

Abstract

Two β-glucosidase (βG) components, βG1 and βG2, purified from extracellular culture filtrate of Trichoderma pseudokoningii S38 by chromatography 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 transglycosylation activity, showing different substrate specificities. The transcosylation products originating from cellobiose by βGs, such as all of the other β-linked disaccharides and even cellotriose, were determined 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.