Repeated, Selection-Driven Genome Reduction of Accessory Genes in Experimental Populations
(A) Schematic view of engineered deletion mutants. Each arc represents the deleted region in the mutant ET1 (dark blue), ET2 (green), ET3 (brown) and ET4 (grey). (B) Reaction norms of fitness for deletion mutants and wild type in 4 selective environments: M, S, MS, M/S, and each half-environment of M/S (M→S and S→M). (C) Transition time from S to M. (D) Fitness cost at stationary phase estimated as the fitness drop from hour 28 to hour 48. (E–G) Succinate-grown cultures with the following treatments: E, ampicillin (12.5 µg/mL); F, arsenate (30 mM); G, 36°C. Relative growth rate or final OD600 (optical density) was calculated as the ratio of with and without treatment. Error bars represent 95% confidence intervals and significant differences from wild-type are indicated by *(P<0.05).