摘要
右旋糖酐蔗糖酶是一种以蔗糖为底物,催化转移D-葡萄糖基生成α-葡聚糖或低聚糖的葡萄糖基转移酶。对肠膜明串珠菌的产酶发酵条件进行了优化,通过正交实验得出该菌的最优产酶条件为蔗糖5 g/100 mL、牛肉膏2 g/100 mL、酵母膏1.25 g/100 mL、pH7.0。采用多级中空纤维超滤膜对粗酶液进行浓缩,使粗酶液酶活由2.31 U/mL提高到了8.78 U/mL,为酶法定向合成右旋糖酐奠定基础。
The dextransucrase is a kind of glucosyltransferases that can catalyze the transfer of D-glucopyranosyl units by synthesizing sucrose to α-glucans or oligosaccharides.In this paper,the optimum fermentation conditions of dextransucrase-producing Leuconostoc mesenteroides were researched.Results were concluded that the optimum fermentation conditions were as follows: sucrose concentration was 5 g/100 mL,beef extract concentration was 2 g/100 mL,yeast concentration was 1.25 g/100 mL,pH value was 7.0.Meanwhile,the crude enzyme liquid was concentrated by the multistage hollow fiber ultrafiltration membrane and the crude enzyme liquid enzyme activity increased from 2.31 U/mL to 8.78 U/mL,which laid the foundation for the stereospecific synthesis of dextran.
引文
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