Starch Hydrolyzing Enzymes: Alpha-Amylase

Starch hydrolyzing enzymes comprise of 30% of worldwide enzyme consumption and are the second most important commercial enzymes with 25% of world enzyme market share. Among them α-amylase is the most important starch hydrolytic enzyme and has diverse applications in starch processing, baking, automatic dishwashing detergents, textile desizing, medicine, pulp and paper, and brewing industry. However, requirements for each industry are very specific, mainly concerning with pH, oxidative stability, chelator resistance, and temperature behavior. Thus, a single enzyme cannot fulfill all the industrial demands and therefore, there is a constant demand for the search for novel enzyme having better thermostability, broad pH working range, surfactant stable and raw starch digesting properties to suit various industrial applications.

Nature harbors several novel microorganisms which may produce novel enzymes suitable for industrial applications. Thus, an effort was made to isolate strains capable of producing high-titer of industrially important amylases, which could retain their activity and stability under various industrial conditions by screening the soil sample of Assam, India. Subsequently, the taxonomic identification of isolated strains was done by polyphasic approach, and then the culture conditions of such potent bacteria were optimized for maximizing their α-amylase production. Thereafter, efforts were also made to isolate, purify and biochemically characterize the α-amylase(s) from promising microbial strains, and also to search for the possible industrial applications of such purified enzymes. Successively, the gene for promising α-amylase was cloned and expressed in E. coli to produce commercially acceptable yields.

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...spectively after six hours of incubation at 60°C. It also formed deep holes and erodes the smooth surface of all the tested starch granules, indicating its usefulness in starch processing industries. The bread supplementation studies with the AmyBS-I and commercial α-amylase (Himedia) showed that the AmyBS-I supplemented bread had better bread amelioration quality as compared to control and commercial enzyme supplemented ones. The partially purified α-amylase from B. subtilis strain AS01a was also used for immobilization studies on magnetic nanoparticles (MNP) and it was found that with the immobilization of resulted in ~ 26-fold increase in specific activity was observed as compared to the free enzymes. The continuous starch hydrolysis experiment by MNP bound enzyme showed that there was significant increase in starch hydrolysis as compared to free unbound enzymes.