Related Experiment Video
Updated: Aug 12, 2026

Preparation, Imaging, and Quantification of Bacterial Surface Motility Assays
Published on: April 7, 2015
Swarming motility in undomesticated Bacillus subtilis
Daniel B Kearns1, Richard Losick
1Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
Abstract:
Swarming motility was identified and characterized in an undomesticated strain of Bacillus subtilis. Rapid surface migration was preceded by a cell density-dependent lag period, which could be eliminated if actively swarming cells were used as the inoculum. The leading edge of the swarm was characterized by multicellular rafts of highly flagellated cells. Flagellum biosynthesis and surfactant production were required for swarming. Swarming was not found in any of several standard laboratory strains. Laboratory strains are characteristically unable to produce surfactant, but such a strain remained unable to swarm even when surfactant was provided by extracellular complementation. We conclude that robust swarming is a feature of undomesticated B. subtilis and that this behaviour has been lost or attenuated in laboratory strains through the accumulation of multiple genetic defects.
Related Concept Videos
Intracellular Movement of Viruses and Bacteria
Flagella and Motility in Bacteria
Fimbriae, Pili, and Axial Filaments
Chemotaxis in E. coli
Bacterial Phylum Tenericutes
Colonisation of Pathogens

