Abstract:

The strain PS03 isolated from oil and preserved in our laboratory, which was a special bioactive strain belonging to the family of Penicillium sp., was solid-state cultured in a triangular flask to produce amylase in this work. The effects of medium composition and culture conditions on the production of amylase were examined. PS03 cultured in the medium consisting of 30.04% wheat bran, 3.70% soybean meal powder, 3.70% rise hull and 55.56% distilled water gave the highest amylase production. The optimal culture conditions were determined through single factor experiments to be: initial medium pH 3; the amount of the inoculated seed (containing108 conidia/mL), 1.85%; culture temperature, 28 ℃; and culture time, 96 h. In addition, the crude enzyme solution obtained under the above conditions was sampled to determine optimal pH and temperature for the reaction of this enzyme. The amylase from PS03 showed high activity in a pH range between 2.0 and 10.0. The relationship between enzyme activity and pH was a double peak-shaped curve. The highest peak of enzyme activity was observed at pH 3, with 100% relative activity, and the peak of enzyme activity appearing at pH 9 was lower, indicating a relative activity of 84.98%. The optimal reaction temperature of this enzyme was 60 ℃, and the relative activity at 90 ℃ was 39.06%. It can be concluded through this study that the amylase produced by PS03 is a special acidic middle-temperature amylase having good tolerance to strong alkaline and acidic conditions as well as high temperature.

Key words: strain PS0312, Penicillium sp., solid fermentation, amylase