Figure 6. Transconjugants experience a growth deficit immediately after conjugation.

(A) Generation times (in minutes) of E.coli Bw27783 with or without plasmid R388. Results represent the average and standard deviation of 12 experiments. (B)Scheme showing the experimental design to test the effect of plasmid conjugation in early transconjugants. Donor and recipient cells were grown in LB broth in the presence of selective antibiotics and mixed in 1∶1 conjugations on LB-Agar. Conjugation was allowed to take place for 30 minutes and cells were resuspended in fresh LB. Plate counting was used to determine de number of donors (D) recipients (R) and transconjugants (Tc). (C) Results of the competition experiments between D, R and Tc cells. (Left panel) Absolute numbers (cells/ml) of each species along the time course of the experiment. Each data point was measured by triplicate. (Right panel) Proportion of plasmid containing cells that are transconjugants along the time course of the experiment. Since plasmid R388 does not conjugate in liquid media, all variations in the relative proportions of Tc cells to D and R cells must be due to differences in growth. Results show a decrease in the relative abundance of Tc cells compared to D cells, that recovers after t = 90 minutes. The lower bars indicate the apparent generation times for each cell type calculated from data shown on the left panel.