Fig 9.

Hb iron utilization assays. Nonpolar deletion mutants were constructed in C. diphtheriae 1737 and assessed for their ability to use Hb as the sole iron source for growth in low-iron mPGT medium. Cultures were grown overnight at 37°C, and cell density was measured by A₆₀₀. Results are the means from three independent experiments ± standard deviations. The growth difference between the wt and the chtB-htaB double mutant (*) was significant at a P value of <0.05.