Additional file 6: Figure S5. Response surface and contour plots depicting γ-aminobutyric acid (GABA) yield, with addition of pyridoxal 5′-phosphate (PLP) by B. adolescentis recombinants, B. adolescentis JCM 1275/pKKT427::POri-gadBC (A, B) and B. adolescentis JCM 1275/pKKT427::Pgap-gadBC (D, E). The interaction between the initial culture pH and substrate concentration of monosodium glutamate (MSG) (mM) following addition of the co-factor PLP is shown.