Cloning, Expression and Biochemical Characterization of the Recombinant α-amylase from Bacillus subtilis YX48

Background: Amylase used in the market is mostly medium-temperature enzyme or high-temperature enzyme and has poor enzyme activity under low-temperature environment. Acid α-amylase can be used to develop digestion additives in the pharmaceutical and healthcare industries. The amino acid sequence and structural differences among α-amylases obtained from various organisms are high enough to confer interesting biochemical diversity to the enzymes. However, low- temperature (0-50°C) amylase, with an optimum temperature and heat sensitivity, has a greater potential value than medium (50-80°C) and high (80-110°C) temperature amylases. Methodology: The gene amy48 from encoding extracellular α-amylase in Bacillus subtilis YX48 was successfully cloned into the pET30a (+) vector and expressed in Escherichia coli BL21 (DE3) for biochemical characterization. Results and Conclusion: The molecular weight of α-amylase was 75 kDa. The activity of α-amylase was not affected by Ca²⁺, and Amy48 had the best activity at pH 5.0 and 37°C. AMY48 has high stability over a narrow pH and temperature range (5.0-8.0 and 30-45°C). Amylase activity was strongly inhibited by Zn²⁺, Mn²⁺, Cu²⁺, and Fe²⁺ ions, but Na+, K+, and Co²⁺ ions stimulate its activity slightly. The purified enzyme showed gradually reduced activity in the presence of detergents. However, it was remarkably stable against EDTA and urea.