Figure 3.

Evolutionary rescue of Escherichia coli and Klebsiella pneumoniae after differing exposure times and at different temperatures. The big dots represent the evolutionary rescue presented as the mean cell density in colony forming units (cfu)/mL of formed transconjugants after the exposure to either ampicillin (50 µg/mL) or cephalothin (50 µg/mL) and the introduction of a rescuing strain harboring beta-lactamase resistance gene against these antibiotics in conjugative plasmid pEC13. The small dots represent individual data points per treatment. For reference, the number of transconjugants in the absence of antibiotics was measured at the 1 h time point. Statistical analysis and standard deviations are presented in Table S1. Letters indicate the results from Tukey’s “Honest Significant Difference” test. Groups indicated by the same letter do not differ significantly. Different exposure times to antibiotics were tested for (A) Escherichia coli and (B) Klebsiella pneumoniae. (C) The effect of temperature (37, 22 or 4 °C) on the evolutionary rescue of E. coli was measured after 16 h exposure to ampicillin and cephalothin.