α-toxin and perfringolysin O activity in culture supernatants of isogenic strains.

<p>Mid-exponential phase culture supernatants from the wild-type strain (WT), a <i>ccp</i> mutant carrying the vector plasmid pJIR750, M(v), and the <i>ccp</i> mutant carrying the <i>ccp⁺</i> complementation plasmid pJIR3680, M(<i>ccp⁺</i>), were either concentrated 5-fold or used undiluted to assay for α-toxin (<b>A</b>) or perfringolysin O activity (<b>B</b>), respectively (n = 3). Error bars represent S.E.M.