Single Step Purification of Novel Thermostable and Chelator Resistant Amylase from Bacillus Licheniformis RM44 by Affinity Chromatography

Bacillus licheniformis RM44 was isolated from hot spring near Karachi and screened for the production of extracellular amylase Amy RM44. Amy RM44 was purified to homogeneity on a single step by affinity chromatography using insoluble corn starch. The molecular weight of Amy RM44 was estimated to be 66 kDa by SDS–PAGE and zymographic analysis. Nine fold purification was achieved with the specific activity of 870 U/mg that provides the total yield of the enzyme up to 31%. Studies on purified AmyRM44 characterization revealed that the optimum temperature of enzyme was 100 ºC. Amy RM44 was proved to be highly thermostable as it retained 50% activity after 2 h at 100 ºC. Amy RM44 was stable over wide range of pH with optimum activity at pH 5. Enzyme activity was not significantly inhibited by SDS and EDTA. Amy RM44 also exhibited its activity towards various carbohydrates such as dextrin, pullulan, α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.