Purification and characterization of a novel thermostable and acid stable α-amylase from bacillus Sp. Iranian S1

This study describes the purification and biochemical characterization of a novel thermostable and acidic pH stable α -amylase from Bacillus sp.Iranian S1 which isolated from the desert soil (Gandom-e- Beryan in Lut desert, Iran). Maximum enzyme production was in exponential phase with activity 2.93 U ml-1 at 50°C and pH 5. The enzyme was purified by isopropanol sedimentation, ion-exchange chromatography on DEAE cellulose DE-52 and gel filtration on Sephadex G-100. The purification procedure performed for α-amylase enzyme achieved about 98.9-fold purification with 25% yield and specific activity 375.9 U mg-1 of protein. The molecular weight of purified a-amylase was estimated around 70 KDa by SDS-PAGE and it was stable in a wide range of temperature and pH between 30°C- 110°C and 3-9, respectively. Assayed with soluble starch as substrate, the enzyme displayed optimal activity at 90°C and pH 5. The purified a-amylase was acid- and thermo-stable with novel properties making it suitable for many industrial purposes.