Arabinanase, Galactanase and Mannanase Activity of Koji Molds

Abstract

In the previous paper, the enzymatic properties of xylanase produced by koji molds cultured on steamed wheat bran was reported. In this paper, the enzymatic properties of arabinanase, galactanase, and mannanase produced by the koji molds are investigated. The results obtained were as follows: (1) The best conditions to determine the enzymatic activity of koji molds were to incubate the mixture of the enzyme and substrates including arabinan from beet pulp, arabinogalactan from soybean meal, or galactomannan from soybean hull in a buffer solution of pH 4.5 for 60 minutes at 40°C. (2) Arabinanase and galactanase were stable at pH 4.0-9.0 and pH 4.0-8.0, respectively, whereas mannanase was unstable above pH 6.5. In respect to that stability, arabinanase and galactanase were stable below 45°C, whereas mannanase was unstable above 30°C. (3) The koji molds isolated from tane-koji for Shoyu manufacture showed high-level activity of the three hemicellulases. (4) High activity of the three hemicellulases was obtained in the old colonies of deep color of brown or brown-green and of short stokes. (5) Relatively high correlations were seen between arabinase activity and galactanase (1% of risk), neutral protease (1% of risk) and alkaline protease (5% of risk).