FIG 2.

Iterative optimization of PhoB-dependent reporter performance. A representative of the best promoters from the first set of semirandomized variants (pEW6AQ) (numbered 4 in Fig. 1B) was compared to an optimal variant (pJLS1088) generated after constraining additional positions, as indicated in Fig. 1C. Reporters were evaluated in the ES114 and ΔphoB strains and were grown in minimal medium amended with high or low concentrations of PO₄. The promoterless parent vector pJLS27 (labeled “None”) is included to show the background. Fluorescence values were taken at an OD₅₉₅ of 1.0, and error bars indicate standard deviations (n = 3). Data show results from one representative experiment of three performed.