Fig. 2.

V. fischeri ES114 produces a siderophore that inhibits V. harveyi growth. A. Schematic of the V. fischeri ES114 aerobactin biosynthetic operon. The arrows depict the locations of five independent transposon insertions identified in the screen. B. V. harveyi growth in minimal marine medium supplemented with 10% (v/v) culture fluids from WT V. fischeri ES114 or the indicated V. fischeri ES114 mutant strain. In the case of the no addition control, 10% (v/v) minimal marine medium was added. C. CAS assay quantitation of siderophore present in culture fluids collected from WT V. fischeri ES114, the indicated mutant V. fischeri ES114 strains, or V. fischeri MJ11. D. V. harveyi growth in minimal marine medium supplemented with 10% (v/v) culture fluids prepared from WT V. fischeri ES114. The indicated concentrations of ferrous (Fe²⁺, no siderophore required) sulfate were added simultaneously to the cell-free culture fluids. In the case of the no addition control, 10% (v/v) minimal marine medium was added. In B, C, and D, error bars represent standard deviations for three biological replicates. Unpaired two-tailed t tests were performed comparing the treated conditions to the no addition control (B), mutants to WT (C), and iron-treated samples to the untreated (0 μM) control sample (D). P values: ns ≥ 0.05, * < 0.05, *** < 0.001, **** < 0.0001.