Fig. 4

ErEurope is consistently immotile due to loss of motility operons. a No genes from the four motility operons of E. rectale [25] are detected in ErEurope strains, and only a very small fraction of non-ErEurope genomes are lacking some or all of these genes (Additional file 1: Fig. S18). Asterisks denote cultured isolate genomes. b Differentially abundant, non-operon potentially motility-associated KOs between ErEurope and the remaining subspecies. csrA was added despite being present in the flgM/csrA operon because it can be found elsewhere in some E. rectale genomes as well. We annotated genes using eggNOG-mapper [26] and only KOs of the E. rectale reference genome annotated by KEGG [27] are considered. Potentially motility-associated KOs were defined as being part of at least one of the following KEGG pathways: quorum sensing, bacterial chemotaxis, flagellar assembly, and two-component system. p values were calculated using a two-sided Wilcoxon test and corrected for multiple testing at 5% FDR using the Benjamini-Hochberg method. c Core gene sequence and flgB/fliA operon sequence genetic clustering for all motile strains (those belonging to either ErAfrica, ErEurasia or ErAsia). d In vitro motility characterization via phase-contrast microscopy of six E. rectale isolates (“Materials and methods”). Asterisk marks strain L2–21, which is the only immotile ErEurasia strain, presumably as a consequence of the specific lack of the flgB/fliA motility operon we found in its genomes