Figure 1.

The C. heterostrophus Δnps6 Strain Is Hypersensitive to the Superoxide Generator KO₂ and to Iron Depletion.

(A) Hypersensitivity of C. heterostrophus Δnps6 strains to KO₂. Five-day-old cultures of wild-type (top row) and Δnps6 (bottom row) strains of C. heterostrophus. Growth of the Δnps6 strain is completely inhibited on MM supplemented with 12 mM KO₂ (bottom row, middle), whereas the wild type is still able to grow on MM with 24 mM KO₂ (top row, right).

(B) Hypersensitivity of C. heterostrophus Δnps6 strains to the iron chelator 2DP. Five-day-old cultures of wild-type (top row) and Δnps6 (bottom row) strains of C. heterostrophus. Growth of the Δnps6 strain is completely inhibited on MM supplemented with 150 μM 2DP (bottom row, middle), whereas the wild type still grows under the same conditions.

(C) Hypersensitivity of the C. heterostrophus Δnps6 strain to the iron chelator BPS. Average colony diameters of wild-type and Δnps6 strains of C. heterostrophus grown on MM or MM supplemented with 100 μM BPS for 5 d. Error bars indicate 95% confidence intervals. A statistically significant difference (P < 0.01) in growth was observed on MM with BPS between the wild-type and C. heterostrophus Δnps6 strains. Note that there was no difference in their growth on MM.