Galactose can be an inducer for production of therapeutic proteins by auto-induction using E. coli BL21 strains

► Protein production by auto-induction was higher than IPTG induction in a modified LB medium. ► Galactose mediated auto-induction was identified by medium analysis and spiking induction experiments. ► Escherichia coli BL21 cultures induced by galactose can saturate at considerably higher density than those induced by IPTG. ► Galactose was not consumed by E. coli BL21. ► Auto-induced fed-batch fermentation was demonstrated for effective protein production at 400-L scale.