Bacterial proteases: production, isolation and utilization in animal nutrition

Under conditions of submerged fermentation of Bacillus licheniformis strain L-3 in 15-L MBR-Schulzer bioreactor, the maximum production of proteolytic enzymes was achieved in the nutrient medium which contained 1% milk powder, 0.3% yeast autolysate, 0.5% corn starch and malt (20 ml per 100 ml of the medium). The preparation obtained of extracellular alkaline bacterial Ser-protease of the subtilisin type is characterized by optimum pH 9.8-10.2 good up to a temperature stability (65 degrees C) and has molecular weight cca of 26 kDa. The use of chemical mutagens (HNO2, 5-bromouracil) has enabled to select new strains (L-3N and L-3U) whose protease activity is 1.8-2.2 times higher as compared to the original Bacillus licheniformis strain L-3. The addition of these enzymes to the fodder has a positive effect on the retention of nitrogen substances.