Department of Science, Payame Noor University
Department of Chemical and Petroleum Engineering, Sharif University of Technology
Biochemical and Bioenvironmental Research Center, Sharif University of Technology
The production of protease by Bacillus licheniformis BBRC 100053 was studied. The most appropriate medium for the growth and protease production is composed of: lactose 1%, yeast extract 0.5%, peptone 0.5%, KH2PO4 0.1%, MgSO4.7H2O 0.02%. Enzyme production corresponded with growth and reached a maximums level (589 U/ml) during the stationary phase at 35°C, pH equivalent to 10 and with 150 rpm after 73 hours. Protease activity was highest at pH 8 and 45°C. The best carbon sources are respectively lactose and maltose and the best nitrogen source is peptone. The protease was highly active and stable from pH 7.0 to 11.0 with an optimum at pH 7-8. Thermo stability of the enzyme was considered in the presence and absence of 2mM CaCl2. Enzyme is non stable at temperatures higher than 50°C while the thermal stability was enhanced in the presence of Ca2+. The enzyme retained 15 and 8% of its initial activity after heating for 60min at 60°C in the presence and absence of 2mM CaCl2, respectively and retained 7 and 3% of at 70°C in the presence and absence of 2mM CaCl2. .