Cultivation parameters and growth conditions of the recombinant cells in the 5-L bioreactor.

<p>A: The cultivation parameters; B: The control cells carrying the empty pUC18 vector; C: The recombinant P_T7-CHb; D: The recombinant P_vgh-CHb. <i>E. coli</i> cells carrying blank vectors were used as the controls. Seed cells of the recombinants were inoculated at a 1:100 ratio into LB medium containing 50 mg/ml ampicillin for P_vgh-CHb and 20 mg/mL tetracycline for P_T7-CHb. For recombinant P_T7-CHb, 0.05 mM IPTG was added into the medium to induce CHb expression. The culture temperature was kept at 37 ∞C, and the pH value of the medium was kept at pH 6.8 with 200 mM NaOH titration. Before inoculation, LB liquid was injected into sterile air for 30 min, and then the dissolved oxygen (DO) of the medium was set as 100%. The error bars indicated the standard deviation generated from three replicates data. * indicates the significant differecne (P<0.05) at 18 h time point calculated by one-way ANOVA analysis.