Production, Purification and Characterization of Extracellular α-Amylase from Mutant Strain Aspergillus Oryzae MSPP

Aspergillus oryzae is well known species and it has an important role in the fermentation of oriental food products and in industrial application as a producer of hydrolytic enzymes. An extracellular α-amy¬lase enzyme from mutant strain A. oryzae MSPP was purified to electrophoretic homogeneity by a simple procedure including ammonium sulfate precipitation, anion-exchange chromatography and Sephadex gel filtration. All purification steps were checked by PAGE. The molecular mass of the purified α-аmylase was estimated to be 52 kDa. The enzyme had a pH optimum at 4.7 and was stable in the range of pH 4.7 to 10. The optimal temperature for the highest α-amylase activity was measured at 50˚C. Half-life of the enzyme was 30 min at 50˚C. Stability of the purified enzyme mainly depended on the presence or absence of soluble starch in the reaction mixture. Michaelis constant (Km) for soluble starch as a substrate was estimated to be 5 mg/ml.