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

Abstract

An alkalophilic bacterial strain was isolated from the soil sample of Assam, North-East India. This strain was found capable of growing and producing α-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 α-amylase from this bacterium. From this strain, a major extracellular α-amylase of ∼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 α-amylases purified from thermostable bacteria. The purified enzyme showed optimum activity at pH 10.0 and 80 °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 α-amylase as a high maltose-forming enzyme. The future application of this enzyme in food and detergent industries is highly promising.