乳糖诱导葡萄球菌肠毒素A基因在大肠杆菌中的表达

以乳糖作为诱导剂代替传统方法中的IPTG,分别从菌龄、诱导剂浓度、诱导时间及诱导剂的添加方式等方面,对乳糖诱导金黄色葡萄球菌肠毒素A(staphylococcal enterotoxins A,SEA)基因在大肠杆菌BL21(DE3)中的表达进行了研究。结果表明,重组大肠杆菌表达SEA的优化条件为:在对数生长期(OD600约为0.6),一次性添加终浓度为0.5 mmol/L的乳糖诱导6 h。目标蛋白的表达量占菌体总蛋白质的36.9%,略低于以IPTG为诱导剂时38.1%的表达量。乳糖价格仅为IPTG的1%左右,因此,在SEA的大规模制备中,使用乳糖作为诱导剂可以大大节约成本。

Lactose-Induced Expression of Staphylococcus aureus Enterotoxin A in Escherichia coli BL21(DE3)

Expression of staphylococcus aureus enterotoxin A in Escherichia coli BL21(DE3) using lactose as inducer instead of IPTG was investigated.Effect of inducing conditions,including cell age of recombinant,concentration of lactose,inducing time and adding model of the lactose on the expression level were detaited studied and analyzed.The optimal inducing conditions listed as followed: 0.5 mmol/L(final concentration) lactose by one-time method at the mid-phase of cell growth(OD600=0.6) and then cultured bacteria at 37 ℃,180 r/min for 6 h.The yield of recombinant staphylococcal enterotoxin A induced by lactose was about 36.9% of the total cell solution protein.It was just a little below of that induced by IPTG(38.1%).The price of lactose is only 1% of that of IPTG.All of these suggested that the lactose is available to be effective inducer with lower cost in the process of large-scale production of recombinant protein.