ABSTRACT
In order to obtain high yield of the HrpNEcc protein with a lower total cost,fermentation and lactose induction conditions for recombinant E.coli BL21(DE3)/pET30a(+)hrpN Ecc were optimized in flasks and the recombinant E.coli was fermentated in 7L fermenter.The optimized incoulum concentration was 5% and the optimized nutrient medium was TB medium.The HrpNEcc protein yield reached 417.60mg/L by adding 3g/L exogenous inducer lactose in the growth prophase of log-phase for the recombinant E.coli.The HrpNEcc protein yield was higher 36.73% than that of the case of no any inducer,and was higher 16.85% than that of the case of adding IPTG.The wet weight of cell pellet of the recombinant E.coli reached 57.24g/L after fermentation in 7L fermenter,the HrpNEcc protein reached 3.29g/L,about 50.2% of total cellular protein.