The <i>C. perfringens agr</i>B locus regulates PFO production.

<p>A and B) Hemoglobin (Hb) release assay. Culture supernatants obtained, at the indicated time point, from strain 13 (S13), S13 <i>pfo</i>A-null mutant (S13Δ<i>pfo</i>A), CPJV501 (Δ<i>agr</i>B), CPJVp1 (Δ<i>agr</i>B/P1), CPJVp2 (Δ<i>agr</i>B/P2) or CPJVp3 (Δ<i>agr</i>B/P3), were incubated (1∶1) with a 1% suspension of horse red blood cells for 30 min at 37°C. Non-inoculated TGY or 0.1% saponin (Saponin) was included as negative or positive control, respectively. PFO-induced Hb release was detected by obtaining the absorbance at 570 (A₅₇₀). C) For each time point, the OD₆₀₀ of the cultures is shown. For all panels, error bars represent the standard error of the mean calculated using data from three independent experiments.