FIG. 4.

Genetic requirements for growth stimulation by enterobactin. Filter disks (inset) containing enterobactin were added to iron starvation minimal medium (FS-MM) plates containing EDDHA to impose Fe limitation. White brackets indicate the extent of observed growth stimulation. A thin bracket indicates weak growth. For growth in liquid culture, the indicated strains were grown in FS-MM in triplicate, and the final cell density (OD₆₀₀) was measured. The results shown are mean ± the standard deviation.