Purification and characterization of a novel and versatile α-amylase from thermophilic<i>Anoxybacillus</i>sp. YIM 342

Abstract

An extracellular thermophilic α-amylase (1, 4-α-d-glucanohydrolase, EC 3.2.1.l) from Anoxybacillus sp. YIM 342 was partially purified by ultrafiltration followed by ammonium sulfate fractionation and dialysis. This procedure was followed by a single purification step using gel filtration chromatography to give a 10.41% yield, 1912.2 U/mg specific activity, and 32-fold purification enrichment. The molecular mass of the purified α-amylase was determined to be 68 kDa using sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The optimum temperature and pH of the α-amylase activity were 80°C and 9.0, respectively. Furthermore, the high hydrolysis rate toward amylose and amylopectin suggested the enzyme has significant potential for applications in starch degradation. The Km and Vmax of the amylase toward soluble starch was 4.18 mg/mL and 7.48 µmol/min/mg, respectively. This enzyme hydrolyzes soluble starch to glucose, maltose, and maltotriose, indicating that the amylase represents a promising candidate for applications in the biofuel industry.