Fig. 3: Experimental evolution of pOXA-48_transconjugants depends on plasmid structure and plasmid-induced fitness cost.
Experimental evolution was performed by 28-day passages of transconjugants from the three ST38 E. coli strains in LB or in M9 minimal medium. For evolution of the transconjugants, meropenem was added every day (MEM/day) or every three days (MEM/3 days) in cultures at subinhibitory concentration. For each condition five lineages were evolved in parallel. a Evolution of the relative doubling time of ST38_1 pOXA-48_1, pOXA-48_2 or pOXA-48_3 transconjugant populations in the presence of meropenem at subinhibitory concentration and of the parental strain. b Evolution of the relative doubling time from ST38_2 and ST38_3 pOXA-48_1 transconjugants in the presence of meropenem at subinhibitory concentration. c Evolution of the relative doubling time of ST38_2 pOXA-48_1 transconjugants in M9 medium in the presence of meropenem at subinhibitory concentration. For (a), (b) and (c), doubling times were determined during exponential growth phase in the absence of meropenem. The relative doubling time was calculated as the ratio of the doubling time to one of the evolved plasmid-free lineages collected on the same day. Boxplots show median, box bounds 25th and 75th quartiles, whisker bounds minimum and maximum excluding outliers and outliers are values > 1.5 × interquartile range. For a, b and c, the results are from five independent evolved lineages. Normal distribution of data was assessed with Shapiro-Wilk normality test. Statistical analysis was performed with pairwise two sample two-sided t-test and p-values (Source Data) were FDR-adjusted. ns: no significant difference; ***p < 0.001, ****p < 0.0001. a: p = 3.51e-19, p = 1.7e-04 (from left to right); c: p = 8.17e-10. Source data are provided as a Source Data File.
