Purification and characterization of heat-tolerant protease produced by Bacillus polyfermenticus SCD

A protease produced by Bacillus polyfermenticus SCD was purified and characterized as a new detergent material. The protease was purified from supernatant produced by B. polyfermenticus SCD, by ammonium sulfate precipitation, ion-exchange chromatography on a DEAE-Sephadex A-50, and finally gel filtration chromatography on Sephadex G-50. The molecular mass of this enzyme was 44 kDa based on SDS-PAGE. The optimum temperature and pH were 50°C and pH 8.0. The ranges of its stability to the pH and temperature were 7.0 to 9.0 and under 40°C, respectively. The enzyme was highly stable in the presence of the surfactants like Triton X-100 (0.1%), showing a 2-fold increase in its proteolytic activity. However, the enzyme was slightly inhibited by the chelating agent EDTA (1 mM). The enzyme has a maximum activity at 50°C and the activity can be increased by surfactants such as Triton X-100 and Tween 80.