Figure 3.

Effect of the gene cassettes array content. (a) Effect of cassettes network size. MG1656 strains containing plasmidic integrons, varying only by the number of gene cassettes (GC) they carried (plasmids 5, 18 and 20; Table 1), were placed in competition with the MG1656 λatt::gfp+pZA2 strain (Supplementary Figure S3B). For each condition (1, 2 or 4 gene cassettes), control plasmids with neither intI1 nor cassette expression (plasmids 10, 19 and 24; Supplementary Table S1) were used to evaluate the inherent cost of carrying this plasmid size (light gray). (b) Influence of the nature of the gene cassettes. Competition experiments were performed between the MG1656 λatt::gfp+pZA2 strain and MG1656 strains carrying plasmids with a one-cassette integron (plasmids 20–23; Table 1) (Supplementary Figure S3C). The cassette was aadA1, catB9, aac(6′)-Ib or dfrA15. Plasmid 24 was used as a control to evaluate the carriage cost of this plasmid size.