Figure 6

ICDH-Coumarin induces swarming initiation and represses biofilm formation by modulating extracellular Fe³⁺ availability and RssAB signaling.

(a) Migration radius of WT, ΔrssBA, Δpvc, and ΔrssBA-pvc strains on LB swarming plates supplemented with ICDH-Coumarin (0–300 μM). (b) Quantified RssAB signaling of WT and Δpvc carrying pEGFP-RssBA::Gm during swarming progression (2–8 hr) on LB swarming plates containing arabinose (0.1%) and ICDH-Coumarin (0–300 μM) is shown. (c) Migration radius of WT and Δpvc on LB swarming plates supplemented with or without Fe³⁺ (100 μM) and ICDH-Coumarin (300 μM). (d) Biofilm of WT and Δpvc in LB condition supplemented with or without Fe³⁺ (100 μM) and ICDH-Coumarin (300 μM) was determined by monitoring absorbance at 630 nm. The results shown represent means ± SEM from three independent experiments (n = 3). One-way ANOVA with * and ** represent P values < 0.05 and <0.01 compared to LB group; ^# represents P-value < 0.05 compared to ICDH-Coumarin group.