Medium Optimization for the Protease Production by Bacillus licheniformis Isolated from Cheongkookjang.

摘要

Medium Optimization for the Protease Production by Bacillus licheniformis Isolated from Cheongkookjang. Yoon, Ki-Hong* and Hye Young Shin. Department of Food Science & Biotechnology, Woosong University, Daejeon 300-718, Korea - Bacillus licheniformis fermenting soybean product with highest score in consumer acceptance had been isolated from homemade Cheongkookjang. In order to develop the medium composition, effects of ingredients including nitrogen sources, carbon sources, metal ions and phosphate were examined for protease production of the isolate. Potato starch increased the protease productivity, while glucose repressed it. Yeast extract was the most effective nitrogen source for enzyme production. The calcium was found to increase protease activity slightly while cell growth and enzyme production was completely inhibited by divalent ions such as Zn2+, Cu2+ and Co2+. The maximum protease productivity was reached approximately 800 unit/mL in the optimized medium consisting of potato starch (1.5%), yeast extract (1.5%), CaCl2 (0.7%), K2HPO4 (0.03%) and KH2PO4 (0.03%). The protease activity of culture filtrate was gradually decreased after incubation for 28 h.