地衣芽胞杆菌麦芽糖α-淀粉酶产麦芽糖特性研究

Studying on the Maltogenicα-amylase Property of the Production of Maltose fromBacillus licheniformis

为了开发新的生产麦芽糖浆的淀粉酶,在大肠杆菌中表达了一个地衣芽胞杆菌(Bacillus licheniformis)麦芽糖α-淀粉酶,并对该酶产麦芽糖的特性进行研究。结果显示,重组酶分子大小为65kDa,以淀粉为底物的最适温度为45℃,最适pH值为6.5。以浓度为20%的可溶性淀粉为底物,加入106U/g淀粉的地衣芽胞杆菌麦芽糖α-淀粉酶,反应48h,采用HPLC检测产物,产物中只有葡萄糖和麦芽糖,其中麦芽糖含量为52.21%,还原糖得率为72.1%;当加入1U/g淀粉的普鲁兰酶协同作用进行反应时,产物中麦芽糖的含量增加到57.16%,还原糖得率增加到92.5%。该酶在麦芽糖浆的工业生产上有较大的潜在应用价值。

A maltogenic a-amylase from Bacillus licheniformis is cloned and expressed in E. coll. Enzymatic property and the production of maltose were studied for generating new am- ylase for maltose syrup. The recombinant enzyme molecular size was 65 kDa. The optimal ac- tivity for soluble starch hydrolysis was obtained at 60℃ and pH 6. 6. The HPLC results showed that the hydrolysis products of 20% soluble starch by adding 106 U recombinant en- zymes per gram starch for 48 hours were glucose and maltose and 52.21% of hydrolysates are maltose. The conversion rate was about 72.1%. Along with pullulanase （1U/g starch）, the content of maltose reached 57. 16% with 92.5% the conversion rate. The recombinant enzyme shows the great potential value in the production of maltose syrup industry.