Figure 2

Time course of extracellular GABA production by C. glutamicum strains GAD ∆ pknG , C. glutamicum GAD, and C. glutamicum W. The three strains were cultured separately in 20 mL of GP2 medium containing 50 g L⁻¹ glucose and 25 μg mL⁻¹ kanamycin using a 200-mL shaker flask. Fermentation was performed at 30°C for 96 hours at 120 rpm. A: Extracellular GABA concentrations (circles) and glucose consumption (diamonds) of C. glutamicum strains GAD ∆pknG (closed symbols) and GAD (open symbols) were monitored. GABA (squares) and glucose consumption (dotted line) of strain W were monitored as controls. B: The OD₆₀₀ values of C. glutamicum strains GAD ∆pknG (closed triangles) and GAD (open triangles) were monitored throughout the fermentation. Data are expressed as the mean and standard error from three independent experiments.