Isolation and Partial Characterization of an Extracellular Branched d-Glucan from Monilinia fructigena

Abstract

Summary: Rapidly growing liquid shake cultures of Monilinia fructigena secreted a polysaccharide which caused an increase in the viscosity of the nutrient liquor. Glucose/malt medium supported most rapid growth and greatest polysaccharide accumulation. Acetone precipitation and dialysis resulted in preparations which were essentially ash and nitrogen free. Gel chromatography indicated that the polysaccharide was polydisperse over the mol. wt range 80000 to 5000. Molecular size was positively correlated with viscosity and inversely correlated with aqueous solubility. Carbohydrate analyses by paper and gas-liquid chromatography indicated that glucose accounted for > 90% of the sugar residues present. Mannose and galactose were also detected. Charged groups were absent. Periodate oxidation revealed that the main linkage was 1 → 4, with a low proportion of 1 → 2 linkages. The degree of branching varied between every fifth and every tenth residue. Linkages of 1 → 3 type were virtually absent. Interaction with concanavalin A indicated the presence of non-reducing terminal α-d-glucopyranosyl or α-d-mannopyranosyl residues.