Structural investigation of cell wall polysaccharides extracted from wild Finnish mushroom Craterellus tubaeformis (Funnel Chanterelle)

Abstract

Craterellus tubaeformis (Funnel Chanterelle) is among the most abundant wild mushrooms in Finland. Three polysaccharide fractions were sequentially extracted from the fruiting bodies of C. tubaeformis, using hot water, 2% and 25% KOH solutions, respectively, and purified. The monomer composition, molecular weight, and chemical structure were determined using chromatographic and spectroscopic methods. Thermogravimetric analysis was performed as well. The hot water extract consisted mainly of high-molecular weight -> 2,6)-alpha-Man-(1 -> and -> 6)-alpha-Gal-(1 -> chains, covalently bound to proteins. The alkali extracts consisted of acidic -> 6)-beta-Glc-(1 ->, with branches of short -> 3)-beta-Glc-(1 -> chains or single beta-Glc residues. The use of alkali influenced the glycosidic linkages, molecular mass and thermal stability of the polysaccharide fractions. The use of KOH 2% increased the amount of low molecular weight polysaccharides, resulting in bimodal molecular weight distributions, with little impact on the thermal stability. Conversely, extraction with KOH 25% provided low molecular weight polysaccharides with substantially reduced thermal stability.