用乳糖作为诱导剂进行重组蛋白的表达

目的研究用乳糖替代IPTG作为诱导剂进行重组蛋白的表达。方法以表达SARS刺突蛋白片段的工程菌BL21(DE3)/S为模型菌株,采用葡萄糖、甘油作为碳源,不同浓度的乳糖和异乳糖作为诱导剂,在摇瓶中进行表达实验。在40L发酵罐中进行验证。结果在摇瓶实验中,乳糖浓度大于0.5mmol/L即可以很好地诱导目的蛋白的表达,表达量与IPTG诱导时相当;葡萄糖的存在可以抑制乳糖,但不能抑制异乳糖的诱导作用;使用甘油作为碳源,既不抑制乳糖,也不抑制异乳糖的诱导作用。在发酵罐实验中,诱导初始阶段葡糖糖的存在抑制乳糖的诱导作用。结论在以乳糖操纵子为调控手段的工程菌表达系统中,可以使用乳糖作为诱导剂,诱导阶段应采用非葡萄糖碳源。

Expression of Recombinant Gene in E. coli Using Lactose as Inducer

Objective To study the factor influencing the fermentation of recombinant E.coli strain using lactose as an inducer instead of IPTG.Methods Incubate the recombinant E.coli BL21(DE3)/S strain expressing the spike protein of SARS virus in spinner,using glucose and glycerol as carbon source and the lactose and isolactose at various concentrations as inducers.Verify the test result by the fermentation in a 40 L fermentor.Results In spinner,the lactose at a concentration of more than 0.5 mmol/L induced the expression of target protein,and the expression level was equivalent to that induced by IPTG.Glucose could inhibit the induction of lactose but could not inhibit the induction of isolactose.However,the glycerol as carbon source showed no inhibitory effect on the induction of lactose or isolactose.In fermentor,the existence of glucose at early stage inhibited the induction of lactose.Conclusion In the expression system of recombinant bacterial strain using lactose operon,lactose may be used as an inducer.However,non-glucose carbon source shall be used at the stage of induction.