Effects of ftsB , ftsC , mtsA , and htsA inactivation on 55Fe3+ ferrichrome uptake. Wild-type and mutant strains were grown to OD600 of 0.4 in 10 ml of THY and THY/spectinomycin, respectively. The bacterial pellets were washed with 1.0 ml of THY and incubated with 0.16 μM 55Fe3+ ferrichrome 1.0 ml of THY at room temperature for 1 h. A triplet of 0.2 ml samples were taken from each mixture, and bacteria were pelleted and washed twice with 0.4 ml of THY. 55Fe3+ radioactivity associated with the bacteria was measured. Presented are the mean values ± SD of 55Fe3+ radioactivity associated with the bacteria in a representative of three experiments.