Fig. 2. Batch fermentation profiles of the E. coli DGB303 strain under three different conditions.
(A) Batch fermentation profiles at pH 7.0 with 2 g/l succinic acid, (B) pH 5.0 after IPTG induction with 2 g/l succinic acid, and (C) pH 5.0 after IPTG induction with 4 g/l succinic acid. Except for pH values and succinic acid concentrations, all batch fermentations were conducted in a 1.8 L MR medium with 20 g/l glucose, 10 g/l ammonium sulfate, and 5 g/l yeast extract for 24 h. The black arrow represents induction timing for gene expression. Symbols: filled circle (●), optical density (OD600); filled square (■), glucose concentration; filled triangle (▲), succinic acid concentration; open circle (○), GABA concentration; open diamond (◇), acetate concentration; open triangle (△), lactate concentration; open squares (□), glutamate concentration.