Strains lacking YggX and GshA display distinct sensitivity to H₂O₂ and superoxide. Strains DM10000 (wild type; diamonds), DM9673 (yggX; circles), DM9680 (gshA; triangles), and DM9720 (yggX gshA; squares) were tested for sensitivity toward H₂O₂ and superoxide. In each case, the data points represent the average results from triplicate cultures. (A) Cells were grown at 37°C with shaking to an OD₆₅₀ of 0.3 in minimal glucose medium containing 100 nM thiamine and 0.2% Casamino Acids with (gray) or without (black) 2 mM deferoxamine. At the indicated times after exposure to 8 mM H₂O₂, cells were diluted 1:10 into minimal NCE medium containing 1,300 U/ml catalase and then dilution plated onto LB medium. (B) Cells were grown at 37°C with shaking in minimal glucose medium containing 100 nM thiamine and indicated concentrations of Paraquat (PQ). The OD₆₅₀ after 24 h of growth was recorded and standardized to the growth achieved with no Paraquat to give a percent final growth yield.

The expression of entB is affected by the presence of deferoxamine differently in strains lacking YggX and GshA. Cells containing an entB::lacZ gene fusion, DM7879 (wild type; diamonds) and DM7880 (yggX and gshA mutant; squares), were grown in Chelex resin-treated LB growth medium with added trace minerals, 10 μM FeCl₃, and the indicated concentration of deferoxamine to an OD₆₅₀ of 0.4 before being harvested and assayed for β-galactosidase activity. Error bars show variations in results from triplicate cultures.

Cells lacking YggX and GshA are unable to grow in minimal succinate medium. The indicated strains were grown at 37°C with shaking in minimal succinate medium containing 100 nM thiamine with the addition of 50 μM FeCl₃. Growth is reported as the specific growth rate (μ) and was calculated by the equation ln(X/X₀)/T, where X is A₆₅₀, X₀ is A₆₅₀ at time zero, and T is time (in hours). Bars represent errors from triplicate cultures. No growth was seen for the fur mutant strain.