Purification and characterization of an extracellular thermostable alkaline α-amylase from the moderately halophilic bacterium, Bacillus persicus

Today a large number of bacterial amylases are available commercially in industry. The goal of the present study was purification and biochemical characterization of an extracellular thermostable alkaline α-amylase from the novel moderately halophilic, Bacillus persicus from the Aran-Bidgol, Iran.
Purification of enzyme, was carried out by acetone precipitation, ultrafiltration and Q-Sepharose cation exchange chromatography.
The purified native enzyme showed a molecular mass of 53 kDa composed of a monomer by SDS–PAGE. The optimum pH, temperature and NaCl concentration were 10, 45 ∘C and 0.85 M respectively. It retained 50% of activity at 1.25 M NaCl and about 73% of activity at highly alkaline pH of 10.5, therefore it was a moderately halophilic and also can activate by divalent metal ions especially Ca2 and Mg2. The apparent values of Km and Vmax were obtained 1.053 mg/ml and 356μ/min respectively.
In the present study we report the purification and characterization of a moderately halophilic α-amylase from a newly isolated Bacillus persicus. The purified enzyme shows interesting properties useful for industrial and biotechnological applications. The molecular cloning and structural studies of this α-amylase are in progress in our laboratory.