An Overview of Microbial α-amylase and Recent Biotechnological Developments

The α-amylase is one of the most promising commercial enzymes with tremendous applications in various industries. Microbial α-amylase shares almost 25-30% of the enzyme market due to its catalytic function in several industries, including sugar, detergent, paper, textile, pharmaceutical industries, etc. The α-amylase hydrolyzes glycosidic linkages of structural components of starch, resulting in maltose, glucose, and high fructose syrups. Starch, the second most abundant organic substance on the Earth, is a readily available, low-cost renewable substrate mainly used in biorefinery and food industries. Amylases are ubiquitous in nature due to their involvement in carbohydrate metabolism. The α-amylases of microbial origin have technical advantages as compared to animal and plant origin. Considering physicochemical properties, bacterial α-amylases are most diverse. However, for industrial purposes, these properties of the biocatalyst, either individually or in a combination, are required to modify through genetic and protein engineering according to the targeted process. The review presents an overview of the current findings of microbial sourced α- amylases, commercial applications, market trends in relevant industries, and achieved improvements in thermostability, catalytic function, pH tolerance, substrate, and product specificities through recombinant DNA technology and protein engineering.