Purification and characterization of neutral protease from Bacillus substilis UBT7 isolated from Terasi, Indonesian fermented fish

Neutral protease producing bacterium Bacillus substilis UBT7 strain isolated from Terasi, an Indonesian fermented fish grew in shake flask and fermenter, and produced protease at 37 °C, pH 7 for 24 hour. After three purification steps, the enzyme was successfully purified. This neutral protease had an apparent molecular mass of 32 kDa as estimated by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The enzyme was active optimum on 50 °C. This indicated that the enzyme was slightly thermozyme. The stability was decreased on 40 °C. The enzyme was optimum in pH 7. The enzyme was somehow enhanced with Fe²⁺ and K²⁺ metal ionsbut not by the addition of Ni²⁺.