Metabolic Engineering of Corynebacterium Glutamicum for Making Cell Factory for Ornithine Biosynthesis

L-Ornithine is non-essential amino acid which has versatile applications. Here, we metabolically engineered Corynebacterium glutamicum ATCC 13032 strain for overproduction of L-ornithine. Firstly, the proB and argF genes were knocked out to block the conversion of L-ornithine to citrulline and block the competitive flux, respectively. Next, the argF gene encoding the protein which repress the L-arginine operon was knocked out to increase the ornithine production. The engineered strain produced 230 mg/L of L-ornithine from glucose as carbon source in flask cultivation. This strain was further enhanced by overexpression of the argCJBD genes from arginine overproducer C. glutamicum ATCC 21831 strain using expression plasmid resulting 7.19 g/L of L-ornithine production. To make enough NADPH pool, the carbon flux was changed to the pentose phosphate pathway. For redirection of flux, the pgi and zwf genes were overexpressed by changing the start codons and replacing the native promoter of tkt operon with strong sod promoter. The final strain YW06 (pSY223) went through the fed-batch cultivation and produced 51.5 g/L of L-ornithine after 40 h with the productivity of 1.29 g/L/h. This results represents the possibility of producing L-ornithine efficiently with C. glutamicum strains. [This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries from the Ministry of Science, ICT and Future Planning (MSIP) through the National Research Foundation (NRF) of Korea (NRF-2012M1A2A2026556 and NRF-2012M1A2A2026557).]