METHOD FOR SYNTHESIS OF GALACTOOLIGOSACCHARIDE USING THERMUS CALDOPHILUS GK24β-GLYCOSIDASE AND HIGH-LEVEL EXPRESSION SYSTEM OF RECOMBINANT THERMUS CALDOPHILUS GK24β-GLYCOSIDASE USED IN THE SAME METHOD

摘要

PURPOSE: A method for synthesis of galactooligosaccharide using Thermus caldophilus GK24 β-glycosidase and a high-level expression system of recombinant Thermus caldophilus GK24 β-glycosidase used in the same method are provided, thereby conducting the synthesis at high temperature to improve galactooligosaccharide rate and percentage and inhibit other microorganism contamination. CONSTITUTION: A method for synthesis of galactooligosaccharide comprises reacting Thermus caldophilus GK24 β-glycosidase with lactose or beta-binding saccharides as a substrate under conditions of 30 to 50%(wt/vol) of lactose, reaction temperature of 70 to 90 deg. C and pH 5.0 to 6.0. A recombinant plasmid pTTGL contains the Thermus caldophilus GK24 β-glycosidase gene. A transformed Escherichia coli W3110/pTTGL(KCCM 10414) is produced by transforming with the recombinant plasmid pTTGL.