重组β-环糊精葡萄糖基转移酶生产偶合糖的工艺优化

Optimization of maltooligosyl fructofuranosidesproduction by recombinant β-cyclodextrin glycosyltransferase

摘要:

偶合糖为一种可代替蔗糖的新型甜味剂，因其具有着色性能良好、保水性能优良、抗龋齿等优点，在食品、医药等领域具有良好的应用前景。本研究旨在找到廉价且易获得的供受体，并利用环状芽孢杆菌Bacilluscirculans 251来源的环糊精转移酶 (β-CGTase) 生产偶合糖，并优化确定制备偶合糖工艺。以蔗糖为受体，分别从加酶量、淀粉种类、温度、pH、供受比、异淀粉酶复配等因素对β-CGTase制备偶合糖工艺进行了优化。采用105 g/L马铃薯淀粉、95 g/L蔗糖为底物，向反应体系中添加13.5 U/g固定化β-CGTase和45.0 U/g异淀粉酶，在pH 5.5、40 ℃条件下反应21 h偶合糖产率达到88.4%。本研究创新性使用异淀粉酶协同β-CGTase制备偶合糖，该方法在产率和成本上均具有明显优势，为酶法制备偶合糖的工业化应用进一步奠定了理论和实验基础。

关键词:偶合糖，环糊精葡萄糖基转移酶，固定化，异淀粉酶，响应面

Abstract:

Coupling sugar is a kind of new sweetener which can substitute sucrose. It has a good application prospect in food, medicine and other fields because of its good coloration, water retention and anti caries. The purpose of this study was to find cheap and easily available donor and acceptor, and to optimize the preparation process of coupling sugar by using β-cyclodextrin glycosyltransferase from Bacilluscirculans 251. Using sucrose as acceptor, the factors of preparing coupling sugar was optimized, including enzyme dosage, starch types, temperature, pH, ratio of starch/sucrose, and cooperation of isoamylase and β-CGTase. When 105 g/L potato starch and 95 g/L sucrose was used as substrates, the yield of coupling sugar reached 88.4%, which was catalyzed by 13.5 U/g immobilized β-CGTase and 45.0 U/g isoamylase under the conditions of pH 5.5 and 40 °C for 21 h. In this study, isoamylase and β-CGTase were used to prepare coupling sugar innovatively. This method had obvious advantages in yield and cost, which laid both theoretical and experimental foundation for the industrial enzymatic preparation of coupling sugars.

Key words:coupling sugar, maltooligosyl fructofuranosides, immobilized enzyme, isoamylase, response surface