Figure 4. The C. perfringens agrB locus regulates PFO production.

A and B) Hemoglobin (Hb) release assay. Culture supernatants obtained, at the indicated time point, from strain 13 (S13), S13 pfoA-null mutant (S13ΔpfoA), CPJV501 (ΔagrB), CPJVp1 (ΔagrB/P1), CPJVp2 (ΔagrB/P2) or CPJVp3 (ΔagrB/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.