Production of α-Amylase by Bacillus subtilis QM3 and its Enzymatic Properties

Abstract

Alpha-amylase is a starch hydrolyzing enzyme which has many industrial applications. In this study, Bacillus subtilis QM3 has ability to produce α-amylase. Identification was done by iodine test, based on the clear zone around the sample in starch agar plates. Alpha-amylase activity was measured using 3,5-dinitrosalicylic acid (DNS). The result showed B. subtilis QM3 can produce α-amylase and activity of α-amylase was 50.58 IU/mL. The study on enzymatic properties was found: the optimum temperature is 70°C, and its stability is high at 30°C - 70°C. The optimum pH is 6.0, and the stability is high under the condition of pH was 6.0 - 7.0. Ca2+, Na+, K+ and Mg2+ promoted the activity of alpha-amylase, and their relative enzyme activities were 130.1%, 118.1%, 115.9% and 110.4% respectively. Fe2+, Zn2+, Cu2+, Mn2+ and EDTA inhibited the activity of alpha-amylase. The relative enzyme activities were 86.1% 77.8%, 67.4%, 64.2% and 48.4% respectively.