FIG. 5.

Growth deficiency of ΔfslE mutant under iron limitation. (A) Growth on iron-replete and iron-deficient agar plates. Cultures of Schu S4 and GR211 in iron-replete CDM were washed in che-CDM−Fe and resuspended to an optical density of 1.0. Tenfold serial dilutions were made in che-CDM−Fe and spotted on an iron-replete or iron-limiting agar plate. Growth was assessed after 3 days on the rich plate and 4 days on the iron-limiting plate. (B) Growth in liquid culture. Washed cells were inoculated into iron-replete (high Fe³⁺) or iron-limiting (low Fe³⁺) che-CDM and growth followed over a period of 56 h. Cultures were grown in triplicate, and the means and standard deviations of one representative experiment are shown in the growth plot. (C) Complementation of ΔfslE mutant in trans. GR211 cells transformed with either control vector pFNLTP6gro-GFP or the fslE⁺ plasmid pGIR469 were washed and inoculated into iron-replete (hi Fe³⁺) or iron-limiting (lo Fe³⁺) che-CDM. The growth of cultures in duplicate was monitored over 48 h, and the results at the 48-h time point are shown for one representative experiment.