A Ca-independent α-amylase that is active and stable at low pH from the Bacillus sp KR-8104

Bacillus sp. KR-8104 was selected from a set of 18 bacteria strains isolated from soil samples and screened for production of amylase. The maximum productivity obtained at pH 5-6 and 60-65 h after cultivation in production medium. New extracellular Ca-independent alpha-amylase was highly purified using ion exchange and hydrophobic interaction chromatography, which showed a single band with an apparent molecular weight of 59 kDa by SDS-PAGE. This enzyme is active in a wide pH range with its maximum activity at low pH values (4.0-6.0) and has the 90% of its maximum activity at pH 3.5. The alpha-amylase is optimally active at 75-80 degrees C. The presence or absence of Ca2+ and EDTA did not affect enzyme activity and thermal stability. (c) 2005 Elsevier Inc. All rights reserved.