Purification and some properties of a thermostable alpha-amylase from Bacillus apiarius CBML 152

A thermostable alpha-amylase was purified from Bacillus apiarius CBML 152 by ethanol precipitation, starchamylase complex formation and by ion-exchange chromatography using DEAE-cellulose at pH 8.6, eluted with 0.2 to 0.3 M NaCl in the starting buffer (0.5 M tris-HCl, pH 8.6). The purified enzyme was homogeneous in polyacrylamide gel electrophoresis. The molecular weight of the enzyme was found to be about 65,000 dalton by gel electrophoresis in the presence of SDS. Characteristically the enzyme was an acidic protein, highly pH stable and thermostable, retaining 100% activity after being exposed to 60 degrees C for 1 hr and to pH 6.0-9.0 for 48 hr. Some divalent cations, as Ca2+, Fe2+, Mn2+ and Zn2+, stimulated the enzyme activity at different molar concentrations.