Effects of ftsB and ftsC inactivation on 55Fe3+ ferrichrome uptake under growth conditions. (A) Uptake for 30 min. 55Fe3+ ferrichrome (0.16 μM) was added into cultures of the wild-type and mutant strains at 37°C in THY and THY supplemented with spectinomycin, respectively, when OD600 was 0.3. A triplet of 1 ml samples were taken from each culture 30 min later, and bacteria were immediately pelleted and washed twice with 0.4 ml of THY. Presented are the mean values ± SD of 55Fe3+ radioactivity associated with the bacteria. (B) Uptake for 3 h. 55Fe3+ ferrichrome (0.16 μM) was added into the wild-type and mutant cultures at 37°C when OD600 was 0.2, and, 3 h later, the samples were processed as in panel A for determination of 55Fe3+ radioactivity.