FIG 8.
Multiple siderophores promote sporulation gene expression in B. subtilis. The fluorescence intensity of wild-type B. subtilis PsspB-yfp microcolony lawns in response to 10 μM ferrichrome, 10 μM ferrioxamine E, or 10 μM bacillibactin or the corresponding solvent for each compound was quantified; representative fluorescence images of the B. subtilis microcolony lawns (false-colored green) are shown at the top. All three siderophores (ferrichrome, ferrioxamine E, and bacillibactin) significantly promoted sporulation gene expression (n ≥ 3). Error bars represent standard deviations. *, P < 0.05; **, P < 0.000005.