Figure 1

Laboratory evolution using single-gene deletion strains as ancestors. (a) The method of laboratory evolution by serial dilution. Every 24 hours, cells from the well with the highest drug concentration that exhibited an OD₆₂₀ > 0.1 were transferred to fresh medium with the drug gradient. (b) Design of the experiment. We used 173 deletion strains of transcription factors as the ancestor strains for laboratory evolution in three different antibiotics. (c,d) Examples of the time courses of IC₅₀ during laboratory evolution. The IC₅₀ time courses of (c) the ΔsoxS strain under Cefixime and (d) the ΔmraZ strain under Ciprofloxacin (blue lines) are presented with those of the wild-type strain BW25113 (without gene deletion - yellow lines). The time courses of 8 and 40 replicates are shown for the deletion strains and BW25113, respectively.