Abstractα-Amylases from a huge number of sources have been isolated and characterised but very few of them meet the demands of the industries. The industrial processes take place under conditions hostile to biocatalysts thus increasing the industrial demand for a highly stable enzyme in good titre level. Improved understanding of biomolecular aspects of α-amylases has led to the advanced understanding of their catalytic nature. Enzymes with high stability are obtained from extremophiles. Extensive studies have demonstrated the importance of regulating expression and catalytic efficiency of nonextremophiles through genetic engineering, directed evolution and chemical modifications. The inability to culture most microorganisms in the environment by standard methods has also led to the focus on the development of metagenomics for getting improved biocatalytic functions. The present review aims to compile the studies reported by researchers in manipulating nonextremophiles and improving stability through directed evolution, metagenomics and protein engineering.

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