Secretory expression and enzymatic properties of a maltooligosaccharide-forming amylase

• 1、Food Science and Technology School, Jiangnan University, Wuxi 214122
• 2、Food safety and nutrition Collaborative Innovation Center, Jiangnan University, Wuxi 214122

Abstract： Firstly, a novel maltooligosaccharide-forming amylase was cloned from Bacillus stearothermophilus STB04 and expressed in B. subtilis WB600.The best fermentation conditions for recombinant amylase was determined preliminarily；then the recombinant amylase was purified and its properties were measured. Finally the product synthesis of this enzyme was analysed preliminarily. The results showed that the optimized culture conditions were as follows: The B. subtilis cells were cultured in TB medium at 30oC for 36 h. The amylase displayed an optimum at 45oC and pH 6.5, and was stable at 35oC and pH 3.0~11.0. The enzyme could be partly inhibited by the presence of some heavy metal ions especially Fe3+ and Sn2+, and EDTA could also restrain its activity. It was able to hydrolyze various starch, maltodextrin, and cellulose, and maltodextrin was hydrolyzed most rapidly. At the condition of 45oC and pH 6.5, the amylase primarily produced maltotriose, maltotetraose and maltopentaose as the initial maltooligosaccharide products.

Keywords： Maltooligosaccharide Maltooligosaccharide-forming amylase Secretory expression Characterization Product synthesis