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

Abstract

I57Rapidly 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 I + 4, with a low proportion of I + 2 linkages. The degree of branching varied between every fifth and every tenth residue. Linkages of I + 3 type were virtually absent. Interaction with concanavalin A indicated the presence of non-reducing terminal a-D-glucopyranosyl or a-D-mannopyranosyl residues.

Exocellular glucan production by Acremonium diospyri

“…Although they are predominantly (1-3)-/3 and (1-6)-/3 linked glucans [4], other linkage types have been detected. For example, (1-4)-fl linkages have been reported in glucans from both Monilinia fructicola [5] and M. fructigena [2]. The latter also contained (1-2)-/3 linkages.…”

“…Many fungi produce polysaccharides which are freely dispersed in the medium, as in Claviceps fusiformis [1], Monilinia fructigena [2] and Botrytis cinerea [3]. Although they are predominantly (1-3)-/3 and (1-6)-/3 linked glucans [4], other linkage types have been detected.…”

Reserve Carbohydrates of Algae, Fungi, and Lichens

“…Appreciable accumulation of a glucan by Moniliniafructigena has been reported by ARCHER et al (1977). The viscous polysaccharide, which also contains a small quantity of mannose residues, has not been rigorously characterized.…”

X‐ray diffraction results from the extracellular fungal glucan secreted by Monilinia fructigena

“…This yielded a polydisperse polysaccharide (Fraction I of [3]) of an7 5 300 daltons, exhibiting high viscosity and poor water solubility. This material consists almost entirely of glucose residues joined by predominantly 1 + 4 glucosidic linkages and exhibits a degree of branching involving on average every fifq glucose unit [3] . At present, however, there is no evidence to suggest that such branching occurs in a regular manner.…”

“…A suitable preparation was isolated from glucosemalt extract cultures by acetone precipitation [3] . It was purified by redissolving in warm water and two further precipitations with 50% (v/v) acetone.…”