The effect of iron limitation on the growth of wild-type and <i>pfsR</i> deletion mutant cells.

<p>A, Growth of the wild type (wt, open circles) and the <i>pfsR</i> deletion mutant (pfsR, closed circles) under iron-limiting conditions. Growth was determined by measuring the optical density at 730 nm (OD₇₃₀). B, Growth of the <i>pfsR</i> deletion mutant in the presence of increasing concentrations (0 µM, open circles; 10 µM, closed circles; 25 µM, open squares; 50 µM, closed squares; 100 µM, open triangles) of the iron chelator 2,2′-dipyridyl. C, Wild-type and <i>pfsR</i> deletion mutant cell cultures under iron-limiting conditions. At the exponential growth phase (OD₇₃₀ of 0.6 to 0.8), wild-type and <i>pfsR</i> deletion mutant cells were diluted to OD₇₃₀ of 0.2, incubated in iron-free BG-11 medium, and treated with 10 µM (A and C) or various concentrations (B) of 2,2′-dipyridyl (dipyridyl) for the indicated periods of time. The data are means of three biological replicates with error bars indicating the standard deviations (SD).