Based on the study of enzyme production from recombinant strain E.coli BL21 (DE3)/pET-24a-palI fermented in shake flasks,and the effect of different induction concentrations of lactose used in 3 liter fermentor on its production were investigated.Results showed that the activity in the supernatant of shake flasks and 3 liter fermentor (under 0.4 g/(L · h) lactose induction) was 253.1 and 654 U/mL,respectively.Furthermore,the reaction conditions for isomaltulose production by sucrose isomerase were optimized in this study.The optimized conditions were as follows:400 g/L sucrose,pH 6.5,20 U sucrose isomerase per gram sucrose,8 h of incubation at 30 ℃.Under the optimized conditions,the maximal yields of isomaltulose could reach 87.9％.%对重组菌株E.coli BL21(DE3)/pET-24a-palI摇瓶发酵产酶进行研究,探讨了3L发酵罐中不同乳糖诱导浓度对菌体高密度发酵产酶的影响.结果表明,摇瓶发酵得到胞外上清酶活253.1 U/mL,3L发酵罐高密度发酵时,在0.4 g/(L·h)乳糖诱导浓度下,发酵上清酶活可达到最大值654 U/mL.对重组蔗糖异构酶转化蔗糖生成异麦芽酮糖的酶转化条件进行了优化,结果表明,当底物浓度为400 g/L,反应初始pH6.5,温度30℃,加酶量20 U/g蔗糖,转化时间8h,异麦芽酮糖可以达到最大转化率87.9％.
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