| Abstract: | α-Amylase (EC 3.2.1.1) was excreted by Calvatia gigantea in liquid growth media containing different sources of starch. Among the factors affecting enzyme production in shake flasks were the type and the concentration of starch and the nitrogen source supplied. Optimum cultural conditions for maximum enzyme production were: soluble starch concentration, 5%; inoculum size, 3.75 × 105 conidia per ml; 5-day cultivation time at 28 to 30°C. The observed maximum yield of 81.3 U of saccharifying enzyme activity per ml of growth medium was the highest ever reported in the literature for submerged cultures. Partially purified enzyme functioned optimally at pH 4.5 to 5.5 and 53 to 58°C. The activation energy of enzymic hydrolysis of starch in the range of 20 to 40°C was 8,125 cal/mol (ca. 3.41 × 104 J). The apparent Km value of the enzyme at 25°C was 7.68 × 10−4 g/ml. Some of the properties of the enzyme under investigation were similar to those of α-amylases excreted from molds producing large amounts of the enzyme. |
