麦芽四糖淀粉酶可水解淀粉或麦芽糊精生成麦芽四糖,在食品领域有着广泛应用。为降低生产成本,对前期构建的生产麦芽四糖淀粉酶的重组枯草芽孢杆菌进行发酵优化。通过对培养基的氮源和碳源进行优化,以5%的接种量,在33 ℃、200 r/min条件下发酵48 h,发现以25 g/L豆粕粉和25 g/L工业蛋白胨为氮源,5 g/L甘油为碳源时,重组酶酶活力最高可达236 U/mL。利用发酵所得重组麦芽四糖淀粉酶制备麦芽四糖并进行酶反应条件优化,使用高效液相色谱检测产物含量。发现当酶转化反应温度为50 ℃,反应pH为7.0,加酶量为30 U/g底物,底物麦芽糊精的质量浓度为250 g/L时,反应12 h,麦芽四糖转化率可达73.2%,为降低生产成本和工业制备麦芽四糖提供了理论依据。
Maltotetraose amylase hydrolyzes starch or maltodextrin to form maltotetraose. In order to reduce costs, the fermentation condition of previously constructed recombinant Bacillus subtilis that produces maltotetraose amylase was optimized by optimizing the nitrogen and carbon sources of the medium. It was found that when the medium contained 25 g/L soybean meal, 25 g/L industrial peptone, and 5 g/L glycerol, fermented at 33 ℃ and 200 r/min for 48 h and at a seeding rate of 5%, the activity of fermented maltotetraose amylase was up to 236 U/mL. Furthermore, maltotetraose was prepared with the enzyme and the reaction condition was optimized, and the products were detected by HPLC. The results showed that when the reaction temperature was 50 ℃, the reaction pH was 7.0, the amount of enzyme was 30 U/g substrate, the concentration of substrate (maltodextrin) was 250 g/L, and reacted for 12 h, the conversion rate of maltotetraose reached 73.2%. This study provides a theoretical basis for reducing production costs and preparing maltotetraose at an industrial scale.
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