Molecular analysis of Bacillus velezensis KB 2216, purification and biochemical characterization of alpha-amylase.

Alpha-amylase producing strain KB 2216 was identified as Bacillus velezensis. The growth pattern showed that 72 h is the optimum incubation period of amylase production, which is a stationary period for the strain. By the purification process, maximum alpha-amylase activity was achieved up to 418.25 U/mL at 72 h of incubation, which was purified with 4.74 folds, 4230.32 U/mg specific activity, with 31.35% yield. The strain was found to produce an oligomeric alpha-amylase, namely Amy3. Amy3 was a trimeric macromolecule of 195 kDa with 62, 64, and 66 kDa subunits, as revealed by zymogram and SDS PAGE analyses. Amy3 was highly active at 55 °C and pH 5.5. It had shown the highest stability at pH 5.0-5.5 and between 0 ̊C and 4 ̊C. It did not require any metal cofactors, but it was inhibited by Ag

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Declaration of competing interest The authors declare that they have no conflict of interest.