FIG. 2.

Production of alpha-hemolysin on 2.5% rabbit blood agar in COL and its isogenic mutants. (A) Two microliters each of supernatant from an overnight culture was placed on rabbit blood agar plates for 24 h at 37°C. wt, wild type. (B) One percent rabbit erythrocytes were mixed with culture supernatants in equal proportions, and the mixture was incubated at 37°C for 1 h in microtiter wells. The highest dilution giving rise to visibly detectable lysis was defined as the hemolytic titer.