Figure 1.

Experimental setup. (A) mutS E. coli lines were grown on agar plates for a total of 39 days or ∼1650 generations assuming a generation time of 34 min (Figure S2 in File S1). (B) After 3 days of growth, ∼100 million bacteria are sampled on the edge of the colony, diluted in 1 μl LB medium, and ∼10⁶ bacteria are deposited at the center of a new agar plate for a new 3-day growth cycle. This transfer should thus not impose any substantial bottleneck for the cells sampled on the edge of the colony that we are interested in following through time. This procedure was repeated 12 times for a total of 39 days of evolution for each line. (C) The expansion on several plates aims to mimic a continuous expansion. WGS, whole-genome sequencing.