Engineering <i>Corynebacterium glutamicum</i> for the Production of 5-Aminolevulinic Acid under Microaerobic Conditions Guided by a Genome-Scale Metabolic Network

5-Aminolevulinic acid (5-ALA) has been widely used in modern agriculture and therapy as a biostimulant, feed nutrient, and photodynamic drug. Although metabolic engineering strategies have been employed to increase the yield of 5-ALA in <i>Corynebacterium glutamicum</i>, the production of 5-ALA under microaerobic conditions has not been studied. In this paper, we developed, for the first time, overproducing-5-ALA <i>Corynebacterium glutamicum</i> strains under microaerobic conditions, guided by a genome-scale metabolic network model. The engineered strain for the C4 pathway synthesis of 5-ALA was constructed based on the <i>Corynebacterium glutamicum</i> genome-scale metabolic network model <i>i</i>CW773 under different oxygen environmental conditions. The fusion of the key enzymes SucCD and HemA effectively opened the substrate channel and improved the biosynthesis of 5-ALA. Further selection of 5-ALA synthetases alleviated the inhibitory effect of heme, which further improved the titer of 5-ALA. Combinatorial optimization of the <i>lpd</i>, <i>coaA</i>, and <i>ppc</i> genes was employed to enhance the supply of the precursor succinyl-CoA. Finally, a 3.8 g/L 5-ALA titer was achieved in a 5-L bioreactor at 8% dissolved oxygen. This study provides a reference for the synthesis of 5-ALA or other high value-added chemicals with succinyl-CoA as the precursor under microaerobic conditions.