Systematic pathway engineering of Corynebacterium glutamicum S9114 for L-ornithine production.

Background: L-Ornithine is a non-protein amino acid with extensive applications in medicine and the food industry. Currently, L-ornithine production is based on microbial fermentation, and few microbes are used for producing L-ornithine owing to unsatisfactory production titer.

Results: In this study, Corynebacterium glutamicum S9114, a high glutamate-producing strain, was developed for L-ornithine production by pathway engineering. First, argF was deleted to block L-ornithine to citrulline conversion. To improve L-ornithine production, ncgl1221 encoding glutamate transporter, argR encoding arginine repressor, and putP encoding proline transporter were disrupted. This base strain was further engineered by attenuating oxoglutarate dehydrogenase to increase L-ornithine production. Plasmid-based overexpression of argCJBD operon and lysine/arginine transport protein LysE was tested to strengthen L-ornithine synthesis and transportation. This resulted in efficient L-ornithine production at a titer of 18.4 g/L.

Conclusions: These results demonstrate the potential of Corynebacterium glutamicum S9114 for efficient L-ornithine production and provide new targets for strain development.