Alkaline protease production by bacillus licheniformis LBA 46 in a bench reactor: effect of temperature and agitation

The production of protease from Bacillus licheniformis LBA 46 was studied in a 6 L reactor using the experimental design tool. The higher protease production was obtained in the exponential phase of growth reaching maximum activity (similar to 3,000 U/mL) after 48 h of fermentation at 30 degrees C and 300 rpm in a culture medium made of agroindustrial by-products. In the thermostability study, the semi-purified enzyme retained about 78% of the initial activity after 120 min at 50 degrees C. The protease was purified 3.33 times by ammonium sulfate precipitation and DEAE-Sepharose column chromatography and had a molecular mass estimated at 40 kDa by SDS-PAGE. The purified protease showed optimum activity at 50 and 60 degrees C, optimal activity in pH 8.5 and stability in the range between pH 5-10 after 24 h of incubation at 4 degrees C, presenting more than 86% of the initial activity.36261562