The Salmonella typhimurium flgM gene, which encodes a negative regulator of flagella synthesis and is involved in virulence, is present and functional in other Salmonella species.

FlgM inhibits the flagella-specific sigma factor FliA and is involved in the mouse-virulence of Salmonella typhimurium. In recent experiments, we observed that: (i) a flgM gene that could function to negatively regulate flagella synthesis was present in a variety of salmonellae; and (ii) the flgM gene derived from Salmonella species that are not normally virulent in mice could complement the S. typhimurium flgM mutant for virulence. Our results suggest that a functional flgM has been retained in most, and perhaps all, Salmonella species, regardless of the motility or virulence phenotype of the strain.