Purification and characterization of an extracellular thermotolerant alkaliphilic serine protease secreted from newly isolated Bacillus sp. DEM07 from a hot spring in Dehloran, Iran

Abstract The current study examines a thermotolerant alkaliphilic serine protease from newly isolated Bacillus sp . DEM07, which was purified with a 20% total protein yield and 14.28 fold purification. The molecular weight of the enzyme was estimated to be 27.5 kDa. The K m and V max values of the purified enzyme were found to be 0.06 mg/ml and 1.25 μmol/min, respectively. The enzyme maintained activity and stability over the 30–55 °C temperature range exhibiting its optimum activity at 50 °C. Furthermore, high activity and stability were found over a wide range of pH from 4 to 11 with a supreme at pH 10. CTAB, TritonX-100, SDS, and H 2 O 2 significantly enhanced the protease activity by 300, 266, 136, and 158%, respectively. The protease was inhibited by PMSF, suggesting that it can be a serine protease. Acetone and DMSO appeared as the most potent, increasing protease activity up to 216 and 105%, respectively. The enzyme retained more than 70% of its initial activity in the other organic solvents. DEM07 protease was capable of proteolyzing various substrates, suggesting broad substrate specificity. Considering these properties, the enzyme could be applied as a novel potent protease in industrial and biotechnological processes.