FIG. 1.

Verification of superoxide-sensitive phenotype. ISS1 transposon mutants that displayed an initial MV-sensitive phenotype were further verified by spotting of 7.5 μl from a 10-fold dilution series, with a starting optical density (A₆₀₀) of 2.0 made in 0.85% NaCl, onto THY agar plates containing 5 mM MV (THY+MV). As a control, cultures were also spotted on plain THY agar plates with no additions (THY). Experiments were repeated at least three times, and the relevant areas of the representative plates are shown. UA159 is the wild-type strain, while IBS921, IBS922, and IBS923 are independent MV-sensitive mutants.