Production of the Protease Enzyme from Bacillus cereus Bacteria Isolated from Some Cooked Foods and Determining the Factors Affecting the Production of the Enzyme

Abstract

15 samples of cooked food (cooked potatoes) were collected from different places and conditions in order to isolate bacteria that produce the protease enzyme. The samples were grown after diluting them on a medium (nutrient agar, mannitol salt agar, skim milk agar, nutrient broth, and mannitol egg yolk polymyxin agar), then cultural tests were conducted (shape, size, color, and edge of the colonies), microscopic tests (response to Gram stain), and biochemical tests (catalase, oxidase, indole, methyl red, voges-proskuer, citrate, urease test, kilgers iron Agar), and all isolates were diagnosed in the VITEK2 diagnostic device, where the approved isolation and diagnosis results showed that (6) isolates belong to the genus Bacillus cereus. These isolates were subjected to primary and secondary screening processes to obtain the most efficient isolate for producing the protease enzyme. It turned out that the isolate bearing the number (1) is the most efficient isolate, as it has given enzymatic activity to the crude enzyme. 11.23 units/ml, specific efficacy 1.20 units/mg, and protein concentration 9.32 mg/ml.