Optimizing of nutrient media for Penicillium candidum 5-1 to increase the biosynthesis of casein-specific protease

Abstract

This study aimed to optimize the nutrient media of the protease-producing strain Penicillium candidum 5-1,
the strain was isolated from spoiled dairy products. The nutrient medium closest to the natural substrate was
selected. Accordingly, the percentage composition of lactose, casein, and potassium dihydrogen phosphate was
determined. Optimal conditions for deep cultivation, including temperature, pH, and cultivation time, were
established. The results showed that by optimizing the components of the nutrient media and determining the
optimal conditions, the protease activity of the strain increased approximately by 50% (0.37 U/MG).
The effect of the enzyme preparation on milk showed that the protease preparation curdles the milk instead
of coagulating. This fact indicates the presence of a different type of protease, which is synthesized in nutrient media close to
natural conditions, this enzyme may be a peripheral, auxiliary (minor) component, and requires further research.