Recombinant Escherichia coli Strains with Inducible Campylobacter jejuni Single Domain Hemoglobin CHb Expression Exhibited Improved Cell Growth in Bioreactor Culture
Fig 4
Growth curves of the recombinants PT7-CHb and Pvgh-CHb and the corresponding empty vector controls in anaerobic capped bottles.
A: The recombinant PT7-CHb; B: The recombinant Pvgh-CHb. LB medium containing 50 mg/ml ampicillin for Pvgh-CHb and 20 mg/mL tetracycline for PT7-CHb was deaerated with an ultrasonic cleaner for 20 min. E. coli cells carrying the blank vector were used as controls. Seed cells of the recombinants were inoculated into the 500-mL volume capped bottle filled with 400-mL LB medium at a ratio of 1/50 and cultured at 37 ∞C in a thermostatic rotator (eccentric distance = 20 mm) with 200 rpm agitation rate. For recombinant PT7-CHb, 0.05 mM IPTG was added to the medium to induce CHb expression. The optical density (OD600) of the cells were measured every 2 h. The error bars indicated the standard deviation generated from three replicates data. * indicates the significant differecne (P<0.05) at 20 h time point calculated by one-way ANOVA analysis.