Purification and biochemical characterization of a thermostable alpha-amylase from Bacillus cereus

Considerable economic importance and wide range of applications of thermo-stable amylases in various industries has significantly increased the demand for amylase production with optimal stability properties. Natural bacterial flora of hot springs can be used as new sources for α- amylase production due to high tolerance to heat and stability in different pH ranges. In this study, Ghinarjeh hyperthermal hot spring was studied to identify the bacterial species that have amylase activity. Bacterial clones producing amylase were identified based on biochemical characteristics and molecular methods. In the next step, the growth conditions of isolated bacteria and amylase production were optimized. Finally, after extraction and purification of α- amylase enzyme from isolated clones, biochemical characteristics were evaluated. The results showed that isolated bacterial clone is a member of the genus Bacillus, and also indicated that the purified enzyme is a thermostable, and calcium-independent amylase enzyme. The purified amylase showed maximum activity at pH˷ 8, however the enzyme is active and stable in a broad range of acidic and alkaline pH (3.5- 10). The enzyme has maximum hydrolysis activity at 80°C and 80% of this activity remains at 50-70°C. According to this study, this bacterial strain can be suitable and promising source for production of high performance, thermostable amylase in order to use at industrial level.