PMC

Determination of the swimming motility of strains 3072/96 (black), C227–11φcu (shaded) and Sakai (grey) on MMS soft agar plates with and without lamb’s lettuce extract. Significant differences regarding the motility of the strains are indicated with *** (p < 0.001)

Biofilm formation of the respective strains grown in M9 minimal medium (grey) and in lamb’s lettuce medium (black). Significant differences between the strains and growth conditions are marked with * (p < 0.05), ** (p < 0.01), and *** (p < 0.001)

Growth of different E. coli strains. E. coli O157:H7 strain Sakai (squares), O157:H⁻ strain 3072/96 (circles) and O104:H4 strain C227–11φcu (triangles) were grown in lamb’s lettuce medium (a), and M9 minimal medium supplemented with 0.4% glucose (b) at room temperature and 180 rpm

Differential gene expression of flagellar biosynthesis associated genes. Flagellar genes of the three strains were grouped into classes I to III according to Kalir et al. []. Log₂ fold-changes are shown for the different genes of the three classes for each strain with upregulated genes in red, downregulated genes in green and genes not differentially expressed (n. d. e.) in yellow

Analysis of differentially expressed genes and gene sets of the shared genome. a Principal component analysis plot of normalized expression values for the shared genome of the three different E. coli strains. The PCA-plot was calculated with the DESeq2 package, using TPM normalized gene counts (with the respective strain-specific gene lengths) for the shared genome []. Differences between the growth conditions in lamb’s lettuce medium are depicted as dots, and in M9 minimal medium as triangles. E. coli O157:H7 strain Sakai is shown in blue, E. coli O157:H⁻ strain 3072/96 in green, and E. coli O104:H4 strain C227–11φcu in red. b Venn diagram of differentially regulated shared genes shown for all three strains. Up- and downregulated genes resulted from transcriptional patterns of cells grown in lamb’s lettuce medium compared to cells grown in M9 minimal medium. Differentially regulated genes are shown in circles, intersections show overlapping genes of two or three strains. E. coli O157:H7 strain Sakai is marked in blue, E. coli O157:H⁻ strain 3072/96 in green and E. coli O104:H4 strain C227–11φcu in red. c Gene set enrichment analysis showing selected up- and downregulated gene sets derived from transcriptomic analyses of E. coli O157:H⁻ strain 3072/96 (black), E. coli O104:H4 strain C227–11φcu (shaded), and E. coli O157:H7 strain Sakai (grey) after growth in lamb’s lettuce medium and M9 minimal medium