Quantification of putative virulence factor activities of C. perfringens strains derived from cattle, sheep and chickens. The lines represent the mean with the standard error of the means. (A) The alpha toxin activity in the supernatant of anaerobically grown C. perfringens strains was determined by measuring the lecithinase activity in an egg yolk agar well diffusion assay. (B) The perfringolysin O activity in the supernatant of anaerobically grown C. perfringens strains was determined by measuring the hemolysis of horse erythrocytes. The PFO titer is the reciprocal of the last dilution which showed complete hemolysis. Each difference in titer of one unit represents a twofold difference in perfringolysin O activity. (C) The mucinolytic activity of C. perfringens strains was assayed by adding cultures of strains to wells in TSA-mucin plates and quantification of zones of mucin lysis (in mm). (D) The potential to degrade the extracellular matrix was examined by measuring the breakdown of fluorescent labeled gelatin by supernatant of anaerobically grown C. perfringens strains. RLU = relative light units.