FIG. 2.

Xenosiderophore-stimulated growth of wild-type (WT) gonococcal strain FA19 compared to growth of isogenic mutants lacking putative TonB-dependent transporters. Strains were grown in CDM containing 2.5 μM bovine transferrin, supplemented with either 7.5 μM human transferrin (positive control), 10 μM enterobactin, or 10 μM salmochelin S2. Each time point represents the mean and standard deviation of results from three independent experiments. The strains used in this assay were FA19 (wild type), MCV925 (tdfF), MCV926 (tdfG), MCV927 (tdfH), and MCV928 (tdfJ).