Production and characterization of a thermophilic and extremely halotolerant alpha-amylase isolated from Anoxybacillus gonensis AT23

Thermophilic alpha-amylase can be used in different industries such as starch processing and detergents. This study was performed to isolate alpha-amylase-producing bacteria and characterization of the enzyme.
After sample collection from Gorooh hot spring in Kerman province, Iran, thermophilic alpha-amylase- producing bacteria were isolated using the starch-agar medium. 16S rDNA sequencing was used to identify the bacterial strain. Characterization of the thermophilic alpha-amylase was performed in the presence of various factors such as pH, temperature, metal ions, chemical compounds, and organic solvents. Also, kinetic parameters of the enzyme were determined in different concentrations of starch.
Anoxybacillus gonensis AT23 was identified as the best thermophilic alpha-amylase- producing strain. The alpha-amylase enzyme showed the optimal activity at pH 5 to 6. Sevenfold increase in the enzyme activity was observed in the presence of NaCl (3M). Mn2 and Zn2 increased the enzyme activity about 95% and 31%, respectively. Kinetic parameters including Km and Vmax were estimated about 1.657 mg/ml and 0.0059 mg/ml/min, respectively. Also, enzyme activity was also improved about 2 folds in the presence of organic solvents including n-butanol and 10% cyclohexane.
Our results indicated that AT23 alpha-amylase is a halophile and organic solvent-tolerant enzyme. Therefore, it can be used in different industries.