The production of extracellular endo-α-mannanase by the mushroom Volvariella volvacea

Seven species of mushrooms were screened for yeast mannan hydrolysing enzyme. Low enzyme activity was identified in the culture filtrate of Volvariella volvacea, growing in starch–KNO3 medium under submerged conditions. Mannan (yeast) as a carbon source was found to stimulate enzyme production but not to support appreciable growth of the mushroom. Better enzyme production was achieved by developing a suitable fermentation medium containing mixed carbon sources (starch and mannan) and a suitable nitrogen source in proper concentrations. Some of the factors affecting liberation of reducing groups from yeast mannan by the culture filtrate enzyme were studied. Low molecular weight oligosaccharides, liberated from yeast mannan by the action of the enzyme, were isolated and identified as mannooligosaccharides. No mannose could be identified to be present in the enzymatic hydrolysate of mannan. Endo-α-mannase activity for this mushroom enzyme was suggested.