Applications of a high maltose forming, thermo-stable alpha-amylase from an extremely alkalophilic Bacillus licheniformis strain AS08E in food and laundry detergent industries

An alkalophilic bacterial strain was isolated from the soil sample of Assam, North-East India. This strain was found capable of growing and producing alpha-amylase at extremely alkaline pH (12.5). By molecular characterization, this bacterium was identified as Bacillus licheniformis strain AS08E. Statistical optimization of media components resulted in 3-fold increase in the production of alpha-amylase from this bacterium. From this strain, a major extracellular alpha-amylase of similar to 55 kDa was purified to homogeneity with a 14.5-fold increase in its specific activity. The N-terminal sequence of this enzyme showed extensive identity with alpha-amylases purified from thermostable bacteria. The purified enzyme showed optimum activity at pH 10.0 and 80 degrees C, and demonstrated stability toward various surfactants, organic solvents, and commercial laundry detergents. The spectroflurometric analysis suggests that the enzyme has a strong binding affinity toward soluble starch. TLC analysis of starch degradation product displays this alpha-amylase as a high maltose-forming enzyme. The future application of this enzyme in food and detergent industries is highly promising. (C) 2013 Elsevier B.V. All rights reserved.