Fig. 3From: Cell factory for γ-aminobutyric acid (GABA) production using Bifidobacterium adolescentis Response surface plot (A, D) and contour plot (B, E) to examine the effect of substrate concentration and initial culture pH on GABA yield. A–C B. adolescentis JCM 1275/pKKT427::POri-gadBC. D–F B. adolescentis JCM 1275/pKKT427::Pgap-gadBC. C, F gadB and gadC expression at different initial culture pH levels. Values are presented as the means ± SDBack to article page