Detection of motility and putative synthesis of flagellar proteins in Salmonella pullorum cultures.

Salmonella pullorum is a host-adapted pathogen of poultry previously thought to be nonmotile and nonflagellated. We discovered that motility can be induced in this organism under special medium conditions, and this motility was observed in 39 of 44 S. pullorum isolates tested. The migration appeared to occur only on the medium surface and not within the medium itself, indicating that swimming may not be responsible for this event. Agar concentration, carbohydrate concentration and type, and temperature of incubation all affected the motility. Flagellar stains and transmission electron micrographs of the motile S. pullorum culture showed long fibrous appendages resembling flagella extending from the cells, but these appendages were thinner and less numerous than the flagella observed on Salmonella enteritidis. Antisera to G flagellar antigens reacted strongly with the induced-motility S. pullorum culture, indicating that G epitopes were expressed on these cells. These results indicate that, contrary to the paradigm which held that S. pullorum is nonmotile and nonflagellated, motility can be induced in S. pullorum and that the organism appears to have the capacity to produce flagella.