Study On The Fermentation And The Characterization Of A High Alkaline Protease

The fermentation medium and the conditions of a high yield strain producing high alkaline protease were studied, the purification and the characterization of the alkaline protease were also studied. The main contents and the results of the study were as follows:1. The main components of the medium were substituted one by one, and all of the producers' goods were homemade. The optimum medium were consist of: cotton seed meal 3%, yeast extract 1.75%, maltrin (DE 30%) 10%, Nacitrate 0.3%,CaCl20.3%, K2HPO4l%.2. The optimum fermentation conditions were confirmed: seed age 12h, inoculum volume 2%, a 250ml flask containing 50ml medium, 200r/min, 34 C, and the highest enzyme activity was 33985u/ml after cultivated 54h. The experiment was also scaled up in the 7L fermentor. Controlling the fermented broth pH value over 7.0 by the feeding process, the alkaline protease activity was about 36579u/ml of the crude enzyme liquor.3. The alkaline protease was purified using ammonium sulphate precipitation and ion exchange chromatography. The specific activity was 18620.20u/mg, 27.54% of the alkaline protease was recovered with 5.23-fold purification.4. The optimum pH and temperature toward the hydrolysis of casein were pH 10-11 and 40~60 C. The alkaline protease was stable at pH 7~12 and about 80% of the initial enzymatic activity was retained after a 120min incubation period at pH 10.5 and 45 C.