Fig. 2.

Impact of sarA on the alpha-toxin phenotype of post-exponential-phase cultures. (A) Alpha-toxin production was assessed by Western blotting of supernatants from post-exponential-phase cultures (OD₅₆₀ of 3.0) and quantified by using Image J. Results are shown for the wild-type strains (black) and their isogenic sarA mutants (gray) relative to the signal observed with 50 ng of a purified alpha-toxin standard. Results are shown as the average ± standard deviation from three independent experiments. (B) Results of Western blots using supernatants from post-exponential-phase (solid bars [data from panel A]) and stationary-phase supernatants (cross-hatched bars [data from Fig. 1]) supernatants were replotted to illustrate the impact of mutating sarA on growth-phase-dependent changes in the alpha-toxin phenotype in different strains of S. aureus.