Fig. 4.

LuxT, YebK, Fre, and GlpK are activators of siderophore production in V. fischeri ES114. A. CAS assay quantitation of siderophore levels in culture fluids collected from the indicated V. fischeri ES114 strains. B. V. harveyi growth after 16 h in minimal marine medium supplemented with 10% (v/v) culture fluids prepared from the indicated V. fischeri ES114 strains. In the case of the no addition control, 10% (v/v) sterile minimal marine medium was added. C. Relative fluorescence values (mVenus/OD₆₀₀) of the indicated V. fischeri ES114 strains carrying an iucA’-mVenus transcriptional reporter on a plasmid. Values represent relative fluorescence when OD₆₀₀ = 0.4 for each sample. D. As in C, except that the strains harbor a translational iucA’-’mVenus reporter. In all panels, error bars represent standard deviations of three biological replicates. Unpaired two-tailed t tests were performed comparing mutants to WT (A, B, C, and D). P values: ns ≥ 0.05, *** < 0.001, **** < 0.0001.