FIG. 6.

(A) Concentration of GABA_e (mM) exported following the resuspension of the cells of an overnight culture of L. monocytogenes 10403S grown in 20 ml BHI in a similar volume of various mixes of BHI with DM (plus 10 mM Glu) and BHI with water (plus 10 mM Glu) at pH 3.5 supplemented with 10 μg ml⁻¹ chloramphenicol. Values are means of experiments performed in triplicate. Error bars represent standard deviation (n = 3). (B) Concentration of GABA_i (mM) accumulated in the cells of an overnight culture of L. monocytogenes 10403S grown in 20 ml BHI following its resuspension in a similar volume of various mixes of BHI with DM (plus 10 mM Glu) and BHI with sterile water (plus 10 mM Glu) at pH 3.5 supplemented with 10 μg ml⁻¹ chloramphenicol. The concentration of intracellular GABA represents amounts of GABA released by cells contained in 20 ml of culture following their resuspension in 0.5 ml of water and boiling for 10 min. Values are means of experiments performed in triplicate. Error bars represent standard deviation (n = 3). (C) Concentration of GABA_e following the transfer of cells contained in a culture of L. monocytogenes 10403S grown overnight in DM or BHI to an equivalent volume of acidified DM or BHI (pH 3.5) containing 10 μg ml⁻¹ chloramphenicol. Following the transfer of cells in the acidified medium, they remained at low pH for 45 min. Values are means of experiments performed in triplicate. Error bars represent standard deviation (n = 3). (D) Concentration of GABA_i following the transfer of cells contained in a culture of L. monocytogenes 10403S grown overnight in DM or BHI to an equivalent volume of DM or BHI (pH 3.5). Cells remained at low pH for 45 min. Values are means of experiments performed in triplicate. Error bars represent standard deviation (n = 3).