Origin of rigid bacterial "giant flagella" ("giant whips", riesenzopfe)

Abstract

Development of "giant flagella" in microcultures of Proteus vulgaris occurred by an aggregation of flagella from motionless cells in a microcolony. Regular free flagellar aggregations very similar to those of the Proteus also were encountered in microcultures of a peritrichous Bacillus species, but were seen in but one of a very large number of microcultures of a monotrichous Escherichia coli strain. Observation of actively motile cells in wet mounts and of stained preparations of the three species with dark phase contrast, Nomarski differential interference, dark-field, and brightfield optics led to an hypothesis concerning the life history which accepts the flagellum as being flexible in the functional state. After an active period extending through more than one generation, the flagellum becomes rigid and apparently is ejected from the cell as a complete unit, including what appears to be a bulbous basal body.