乳酸杆菌pPG质粒表达系统理想表达条件的探索

Exploration of optimal expression conditions in Lactobacillus casei with pPG vector

对乳酸杆菌pPG质粒表达系统理想表达条件进行了探索。以干酪乳杆菌Lactobacillus casei 393为宿主菌,β-葡萄糖苷酸酶(gusA)基因作为表达的报告基因,根据干酪乳杆菌的生长特性对细胞表面表达载体pPG表达过程中各个关键因素的影响进行了探索。得出最佳表达条件:将其培养于质量浓度为1%乳糖,初始pH值在6.0～6.5之间的MRS培养基中,30～32℃,静止培养至A590OD达0.5,培养时间约8 h,表达效率最高,外源蛋白的表达量可占菌体总蛋白的14%。

The expression conditions of plasmid pPG have been explored, Escherichia coli β-Glucuronidase （gusA） gene was used as a reporter gene for analyzing expression conditions of pPG .mediating surface-anchored expression in Lactobacillus casei 393. According to the growth character of Lactobacillus casei, we have explored each critical fictor which influences the expression of pPG. The expression level of gusA could achieve 14.0% of the whole cell proteins When the recombinant L.casei393 was incubated in basal MRS medium ofpH between 6,0 and 6,5, supplemented with 1% lactose, at 30℃ or 32 ℃, without shaking, to the absorbance of A590OD reaching about 0.510, about 8h. Exploring each critical fictor of affecting gusA＇s expression provides the basis for expressing Other active protein （peptide）.