Complementation of ΔfliC mutants. (A) Transmission electron micrographs of strains containing either pES196 (fliC+) or the vector alone (pMTL84151). 1, 630Δerm/pES196; 2, ΔfliC 383/pES196; 3, ΔfliC 88/pES196; 4, 630Δerm/pMTL84151; 5, ΔfliC 383/pMTL84151; 6, ΔfliC 88/pMTL84151. Flagella are indicated by arrows. (B) Motility stab assay for strains containing either the fliC complementing plasmid (pES196) or the vector alone (pMTL84151). The strain genotype is indicated above each tube, with the presence of each plasmid shown at the top of each set of tubes. Only wild-type strains (630Δerm) containing a chromosomally carried fliC gene showed penetration of the medium.