Enhanced l-ornithine production by systematic manipulation of l-ornithine metabolism in engineered Corynebacterium glutamicum S9114.

l-Ornithine is a non-protein amino acid with extensive applications in medicine and the food industry. Currently, l-ornithine is produced by microbial fermentation; however, this process needs to be further improved in terms of l-ornithine productivity and cost reduction. In this study, overexpression of LysE was observed to increase l-ornithine production in engineered Corynebacterium glutamicum S9114. To overcome the drawbacks of using a plasmid to express LysE, Ptac, a strong promoter, was inserted in the upstream region of lysE on the chromosome. This strain was further engineered by attenuating the expression of ncgl2228 and proB, and enhancing the expression of gdh and argCJBD. Combination of those targets resulted in l-ornithine production at a titer of 25 g/L, which was 63.4% higher than that produced by the original strain (15.3 g/L). These results demonstrated the positive effects of overexpressing LysE on l-ornithine production and provided novel targets for developing l-ornithine-producing C. glutamicum strains.