In this study, to obtain higher agmatine yields using the previously developed E. coli strain AUX4 (JM109 ΔspeC ΔspeF ΔspeB ΔargR), the genes encoding glutamate dehydrogenase (gdhA), glutamine synthetase (glnA), phosphoenolpyruvate carboxylase (ppc), aspartate aminotransferase (aspC), transhydrogenase (pntAB), and biosynthetic arginine decarboxylase (speA) were sequentially overexpressed by replacing their native promoters with the heterologous strong trp, core-trc, or 5Ptacs promoters to generate the plasmid-free E. coli strain AUX11. The fermentation results obtained using a 3-L bioreactor showed that AUX11 produced 2.93 g L-1 agmatine with the yield of 0.29 g agmatine g-1 glucose in the batch fermentation, and the fed-batch fermentation of AUX11 allowed the production of 40.43 g L-1 agmatine with the productivity of 1.26 g L-1 h-1 agmatine. The results showed that the engineered E. coli strain AUX11 can be used for the industrial fermentative production of agmatine.
Keywords: agmatine production; batch and fed-batch fermentation; gene overexpression; promoter substitution.