Characterization and application of a detergent-stable alkaline α-amylase from Bacillus subtilis strain AS-S01a

A strain AS-S01a, capable of producing high-titer alkaline alpha-amylase, was isolated from a soil sample of Assam, India and was taxonomically identified as Bacillus subtilis strain AS-S01a. Optimized alpha-amylase yield by response surface method (RSM) was obtained as 799.0 U with a specific activity of 201.0 U/mg in a process control bioreactor. A 21.0 kDa alkaline alpha-amylase purified from this strain showed optimum activity at 55 degrees C and pH 9.0, and it produced high molecular weight oligosaccharides including small amount of glucose from starch as the end product. The K-m and V-max values for this enzyme towards starch were determined as 1.9 mg/ml and 198.21 mu mol/min/mg, respectively. The purified alpha-amylase retained its activity in presence of oxidant, surfactants, EDTA and various commercial laundry detergents, thus advocating its suitability for various industrial applications. (C) 2011 Elsevier B.V. All rights reserved.