FIG. 3.

Effect of added siderophores on growth of B. cepacia K56-2 and K56orbA::tp. (A) Comparison of growth rates in medium containing 10 μg of either ornibactins, pyochelin, or SA/ml. K56-2, solid lines; K56orbaA::tp, dashed lines. (B) Ability of the orbA gene in trans to complement the growth of K56orbA::tp in the presence of 10 μg of ornibactins/ml. Optical densities of the cultures were determined at selected intervals. Values are means ± standard deviations of triplicate assays. These experiments were repeated twice with similar results.