异源果聚糖蔗糖酶在乳酸乳球菌中的分泌表达

Secretory expression of heterologous levansucrase in L.lactis NZ9000

为了实现果聚糖蔗糖酶简便有效的纯化,文章将来源于解淀粉芽孢杆菌的基因sacB添加组氨酸标签后与信号肽基因usp45融合形成基因片段usp45-sacB,然后插入质粒pNZ8048中,导入乳酸乳球菌(L.lactis)NZ9000构建重组菌株L.lactis(pNZ8048-usp45-sacB)。通过电泳验证纯化蛋白的分子量为51 kDa,符合预期大小,确定果聚糖蔗糖酶成功表达。为了进一步提高果聚糖蔗糖酶的产量,该研究对诱导时间和诱导剂的质量浓度进行优化,得出最优的表达条件为:诱导时间48 h,诱导剂nisin质量浓度2μg/L。

In this study,in order to realize the simple and effective purification of levansucrase,the gene sacB from Bacillus amyloliquefaciens was added with histidine label and fused with the signal peptide gene usp45 to form the gene fragment usp45-sacB,then it was inserted into the plasmid pNZ8048 and introduced into L.lactis NZ9000 to construct the recombinant strain L.lactis(pNZ8048-usp45-sacB).It is verified by electrophoresis that the size of the purified protein is 51 kDa,which is in line with the expected size,and it is confirmed that the levansucrase is successfully expressed.In order to further improve the yield of levansucrase,the induction time and the concentration of inducer were optimized.The best expression conditions are as follows:the induction time is 48 h and the concentration of inducer nisin is 2μg/L.