Flagellin is the subunit protein which polymerizes to form the filaments of bacterial flagella. Xenorhabdus strains undergo spontaneous variations involving a large number of phenotypes. Phase 1 variants were motile, whereas phase 2 variants were non-flagellated cells which did not synthesize flagellin. Effectively, the fliC gene is not transcribed in phase 2 variants. Belongs to the bacterial flagellin family.