Induction conditions that promote the effect of glycerol on recombinant protein production in Escherichia coli

Proinsulin was expressed by <i>Escherichia coli</i> SHuffle T7 with pET system in minimal medium containing glucose (Glu medium), glucose and glycerol (GluGly medium) or glycerol (Gly medium). With 100 μM IPTG, proinsulin production did not increase with glycerol. In contrast, proinsulin production per medium volume in GluGly and Gly media was approximately 3∼4-fold higher than in Glu medium with 10 μM IPTG. mRNA expression of target protein was higher in GluGly versus Glu medium, indicating that proinsulin production was enhanced by the release of glucose-induced catabolite inhibition. Although proinsulin production did not differ between GluGly and Gly media at 25 h, substrate was consumed quickly in GluGly medium with 1.55±0.12 times higher proinsulin production at 15 h. Productivity, considering the production period, was highest in the GluGly medium. This study shows a mixture of glucose and glycerol is valuable for protein production in <i>E. coli</i> with low IPTG concentrations.