Figure 4

β-galactosidase activities of the recombinant strains producing the BvgS variants. The β-galactosidase activities of the ptx: lacZ fusion were measured as a function of increasing concentrations of nicotinate or MgSO₄. The basal (non-modulated) activities of the three variants tested were not significantly different (P > 0.1) from that of wild type (WT) BvgS. The BPSMΔbvgS and BPSMΔbvgA variants had hardly detectable levels of β-galactosidase activities in all conditions, and therefore they were not included in the figure. In each panel, one and two asterisks represent significantly different activities (with P < 0.05 and P < 0.01, respectively) than that of the same non-modulated BvgS variant.