FIG 3.

Loss of manL affects pH homeostasis by changing AD gene expression. (A to C) pH measurements of stationary-phase cultures (20 h) in TY (A and B) or BHI (C) medium were recorded for strains SK36 (MMZ1612), manL, manLComp, arcA, and manL arcA. For BHI cultures, 0, 1, or 5 mM arginine was added to the medium before cultivation. Data were obtained from three biological replicates. (D) RT-qPCR was performed to measure the expression of the arcA gene in exponential-phase cultures prepared in TY containing glucose (Glc) or lactose (Lac) or in BHI. The abundance of arcA mRNA was calculated relative to an internal control (gyrA). Three biological replicates were included for each sample, and the results are their averages and standard deviations (error bars). Asterisks represent statistical significance calculated using a two-way analysis of variance (ANOVA) followed by a Tukey test (**, P < 0.01; ***, P < 0.001; ****, P < 0.0001).