FIG 9.
The ybbA gene is specific for enterobactin and is not required for bacillibactin to promote sporulation gene expression. The fluorescence intensity of besA, ybbA, or wild-type (WT) B. subtilis PsspB-yfp microcolony lawns in response to 10 μM bacillibactin was quantified, and the corresponding fluorescence images of the lawns (false-colored green) are shown at the top. There was no significant difference in sporulation gene expression on wild-type or ybbA microcolony lawns with bacillibactin. In contrast, sporulation gene expression was significantly decreased on besA microcolony lawns (n = 3). Error bars represent standard deviations. *, P < 0.05; ns, not significant.