Effect of overexpression of genes encoding enzymes in the upstream pathway of glutamate biosynthesis on l-ornithine production in C. glutamicum ΔAP. OD₆₀₀ (white bars); l-ornithine concentration (black bars). Cells were cultured in the fermentation medium 25 μg ml⁻¹ Kan and 0.5 mM IPTG at 30 °C for 72 h. Data are mean ± SD for three replicates