Figure 2: Effect of external CaCl2 or EGTA on the ability of B. subtilis to maintain cytosolic Ca2+ levels. B. subtilis cells were grown and treated under the same conditions for the proteomic analysis (Materials and Methdos). Cells expressing aequorin were grown to mid-logarithmic phase and treated with two concentrations of CaCl2 (5 mM and 10 mM) or EGTA (0.5 mM and 1.0 mM) for 15 min at 35°C. Treated cells (0.1 ml) were loaded onto a 96-well plate and read in a luminometer each second. CaCl2 (1mM) or EGTA (1 mM) was injected at the times indicated by the arrow. At the end of the experiment 0.05 ml of 4%NP40, 100 mM CaCl2 was injected to discharge the remaining aequorin. Untreated cells containing the apoaequorin plasmid were used as control. A) [Ca2+]i values of cells treated with CaCl2, 5m M (blue) and 10 mM (red), Control cells (green). B) [Ca2+]i values of cells treated with EGTA, 0.5 mM (blue) and 1.0 mM (red), 845 Control cells (green).