Comparison of two beta-glucosidases for the enzymatic synthesis of beta-(1-6)-beta-(1-3)-gluco-oligosaccharides.

A domain of epiglucan was synthesized by beta-glucosidases. Two beta-glucosidases, an extracellular beta-glucosidase derived from Sclerotinia sclerotiorum grown on xylose, and a commercial lyophilized preparation of beta-glucosidase from Aspergillus niger, were used to synthesize gluco-oligosaccharides from cellobiose and, specially, beta-(1-6) branched beta-(1-3) gluco-oligosaccharides, corresponding to the structure of epiglucan. Gentiobiose, cellotriose, cellotetraose, beta-Glc-(1-3)-beta-Glc-(1-4)-Glc, beta-Glc-(1-6)-beta-Glc-(1-4)-Glc and beta-Glc-(1-6)-beta-Glc-(1-3)-Glc were synthesized from cellobiose by both enzymes. The latter compound was preferentially synthesized by the beta-glycosidase from Sclerotinia sclerotiorum. Under the best conditions, only 7 g l(-1) of beta-Glc-(1-6)-beta-Glc-(1-3)-Glc was synthesized by the beta-glycosidase from Aspergillus niger compared to 20 g l(-1) synthesized with beta-glycosidase from Sclerotinia sclerotiorum.