Hydrolysis of yeast cell-wall glucan by extracellular (1→3)- β-glucanases from Aspergillus niger

Abstract

An enzyme preparation containing (1→3)- β-glucanase activity was prepared from a cultivation medium of industrial production of citric acid by Aspergillus niger using chromatography on Sephadex G-50. The preparation was used for enzyme hydrolysis of insoluble yeast cell-wall glucans into water-soluble fragments. Low-molecular-weight fragments (<10,000 daltons) were removed from high-molecular-weight water-soluble glucan fragments by gel filtration. The molecular weight of the high-molecular-weight fragments was in the range from 30,000 to 80,000 daltons as determined by gel chromatography. A change of length of glucan fragments was observed during the course of hydrolysis. It was probably due to transglycosylation reactions. 13C-NMR spectral analysis of the original glucan and the products of the hydrolysis indicated that only fragments with (1→6)- β-configuration were removed from the original glucan by this procedure. The importance of (1→6)- β-fragments for the compact structure of the original glucan is also discussed.