Isolation of soil thermophilic strains of actinomycetes for the production of α-amylase

Two thermophilic strains of actinomycetes, KS-52 and KS-60, were induced to produce alpha-amylase. alpha-Amylase activity was determined on solid medium supplemented with starch. The detection was based on the formation of clear or transparent zones around colonies. The size of transparent zone was found to be proportional to the amount of alpha-amylase enzyme produced by the strains. Extraction of alpha-amylase was done in liquid medium. The assay was observed by measuring the release of reducing sugar (RS) by 3,5-dinitrosalicylic acid (DNS) method and expressed in International Units (IU). The thermophilic strains were further tested for their ability to produce alpha-amylase enzyme by growing them on two different substrates - soluble starch (1%) and corn starch (1%). Optimization of the alpha-amylase production activity was achieved through variations of parameters including pH, incubation period, temperature, and carbon sources.