These experiments were conducted to investigate the conditions of the acid protease production by Rhizopus oryzae and the characteristics of crude enzyme. The results obtained were as follows:
1. The optimum culture time and the optimum amount of added water to the wheat bran medium were about 48 hrs and 80∼120%, respectively.
2. The addition of (NH₄)_6Mo_7O_(24), (NH₄)₂SO₄, NH₄NO₃, casein, and albumin, respectively, as nitrogen sources to the wheat bran medium was effective. Of these, the optimum concentrations cf addition of (NH₄)_6Mo_7O_(24), and casein which were the mast effective were 0.1% and 1.0%, respectively.
3. The addition of glucose, galactose, maltose, lactose, and soluble starch, respectively, as carbon sources to the wheat bran medium was effective. Of these, the optimum concentration of addition of glucose, which was the most effective was. 3.0%.
4. The addition of KH₂PO₄, as a phosphate salt to the wheat bran medium was effective. The optimum concentration of addition of KH₂PO₄ was 0.3%.
5. The optimum pH for the enzyme action was 2.4, the optimum temperature about 40℃, and the stable pH range 2.0∼5.0. The enzyme was stable below 40℃.
6. The enzyme activity increased rapidly for 10 minutes after addition, but thereafter it increased slowly.
7. The enzyme activity increased rapidly to 2 ㎖ of addition, but nearly did not increase at the amounts greater than 2㎖.
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