Fig. 2

Acid production assay. Wild-type UA159, ptxA ⁻ strain, ptxB ⁻ strain, ptxAB ⁻ strain, CptxA ⁻ strain, CptxB ⁻ strain and CptxAB ⁻ strain were incubated in BHI or TVL medium for 24 h (a) and 48 h (b) anaerobically. The pH measurements of the media were performed before and after the incubation, and are presented as ΔpH. A significant difference is indicated by *P < 0.05, **P < 0.01 compared to UA159. The results presented here are the average of three independent experiments performed in triplicate