A: Southern blotting of genomic DNA from H pylori 250 and its flgK mutant digested with HindIII. The probes used were specific for the flgK gene, chloramphenicol resistance (Cm) gene and λ DNA. Lane W, wild-type strain; lane M, mutant; λ HindIII marker used as a molecular size standard; B: Western blotting of anti-r-FlgK polyclonal antibodies to confirm the phenotype of flgK isogenic mutant (absence of 67 kDa band). Lane W, wild-type strain. Lane M, mutant. Low molecular weight protein markers.