Study on isolation and identification of acidic α-amylase producing strain and enzymatic properties

An acidic α-amylase producing strain was screened through screening medium supplemented with starch by the method of hydrolysis halo, and the amylase activity of the fermentation broth was 123U/mL. The stain was identified as Bacillus lincheniformis by morphology observation, physiological and biochemical tests and 16S rDNA sequence analysis, and was named as Bacillus lincheniformis BW-2. The enzymatic properties of the amylase were also investigated. The optimum pH and temperature of the amylase was 4.5 and 70℃, respectively. It also showed excellent thermostability and pH stability. The amylase activity was activated by Ca2+and Mg2+, whereas, it was inhibited by Mn2+and Cu2+. Meanwhile, these inhibitors PMSF and DTT had little effect on the enzyme activity. The molecular weight and structure of the amylase from BW-2 maybe was different from the known thermostable amylase by PAGE analysis. BW-2 was an acidic amylase producing strain which showed research and development potential.