FIG. 5.

Effects of Mg²⁺ and other ions on yadA expression. (A) The alkaline phosphatase activity of strain YP28 (yadA-phoA) was determined in exponential phase at 37°C at increasing concentrations of Mg²⁺ (0 to 20 mM) with or without 20 mM Na oxalate (NaOx). Strain YP1 (inv-phoA) was used as a control grown in increasing concentrations of Mg²⁺ (0 to 20 mM) with 20 mM Na oxalate. (B) The alkaline phosphatase activity of YP28 (yadA-phoA) was determined in exponential-phase cultures grown at 37°C in the presence of the divalent cations indicated. Each value represents the average ± the standard deviation of three different experiments performed in triplicate. (C) The alkaline phosphatase activity of YP28 (yadA-phoA) was determined in exponential-phase cells at 37°C after the addition of 20 mM MgCl₂. Strain YP1 (inv-phoA) was used as a control.