Purification and characterisation of a highly thermostable extracellular protease from Bacillus thermantarcticus, strain M1

A high thermostable extracellular protease was purified to homogeneity and characterised from Bacillus thermantarcticus, strain M1. The molecular mass was about 42 kDa. Almost total inhibition of protease by phenyl methyl sulphonylfluoride (PMSF), suggested that the enzyme belonged to the serine protease family. The enzyme was active and stable in a broad range of pH with an optimum at pH 7.0. The protease showed the highest activity at 70 degrees C and was stable for 24 h at 70 degrees C, with an increase of the enzymatic activity of about 4 times, in the presence of CaCl2. The protease retained about 50% activity after 3 h of incubation in the presence of CaCl2 with various commercial detergents. Purified protease was found to be stable, for one week, in presence of DMSO, methanol, ethanol, acetonitrile, isopropanol.