昆虫病原细菌Cip蛋白基因工程菌发酵条件的优化

ptimization of Expression Conditions of Recombinant Crystalline Inclusion Protein of Entomopathogenic Bacterium in Escherichia coli

昆虫病原发光杆菌属(Photorhabdus)细菌产生的2种胞内晶体蛋白CipA和CipB已在大肠杆菌原核表达系统中进行稳定表达,为进一步提高该蛋白在大肠杆菌中的表达水平,确定工程菌摇瓶培养的最适条件,研究了多种无机离子、装液量、培养基初始pH值、诱导前添加葡萄糖等因素对工程菌摇瓶发酵的影响。结果显示,在发酵培养基中添加10 mmoL/L Mg2+和15 mmoL/LPO43-,调节初始pH值至7.2,装液量为25mL(250mL摇瓶),诱导前添加10g/L葡萄糖时,Cip蛋白的表达量可明显提高,发酵条件优化后CipA和CipB的表达量达到了39%和41%。

Two types of intracellular crystalline inclusion proteins produced by Photorhabdus bacteria,CipA and CipB,were expressed in protocaryotic expression system previously.To improve the expression level of the two proteins and determine the optimal expression conditions,the effects of inorganic ions,liquid volume,initial pH value,addition of glucose before induction and other factors were studied on shake flask fermentation of engineered bacteria.The result showed that when 25 mL recombinant bacteria were cultured in 250 mL LB medium（pH 7.2） with 10 mmoL/L Mg2＋ and 15 mmoL/L PO3-_4,and 10 g/L glucose was added before induction,both of CipA and CipB could be highly expressed,up to 39% and 41% of the total bacterial proteins,respectively.