Expression of Recombinant Human Superoxide Dismutase Gene in Escherichia coli Induced by Lactose

The possibility of using lactose as an inducer to substitute IPTG in the fermentation of rhCu/Zn-SOD in E.coli BL21(DE3) was investigated. The growth of E.coli and the expression of the recombinant protein were compared after induction by lactose or IPTG. The influences of concentrations of lactose and metal ions and induction temperatures on the expression of the recombinant protein were examined. Finally the recombinant E.coli was cultured in a 5 L fermentor. The maximum enzyme activity of rhCu/Zn-SOD reached 1810 U per ml fermentation broth. The results suggested that rhCu/Zn-SOD could be expressed in E.coli with lactose as a substitute inducer and the maximum enzyme activity was about 89% of that with IPTG.