Species name： Escherichia coli
Harvard UniversityDepartment of Molecular and Cellular BiologyHarvard Biological Labs Howard C. Berg
When grown on 0.45% Eiken agar in rich medium, cells of E. coli elongate, produce more flagella, and move over the surface of the agar in a coordinated manner. The chemotaxis system in not thought to be required. As you will see in the movies, taken at 30 degrees C, the cells swirl about in rafts or packs. At the edge of the swarm they form a monolayer. At the very edge, cells are nearly stationary. Farther back, closer to the point of inoculation, cells pile up in multilayers and are very active. The videos were made in bright-phase contrast. Smoke particles on the top surface near the swarm edge were visualized in dark field by adding a fiber-optic illuminator oriented about 10 degrees from horizontal.
Zhang, R., Turner, L. and Berg, H.C. The upper surface of an Escherichia coli swarm is stationary. PNAS 107: 288-290 (2010).
Turner, L., Zhang, R., Darnton, N., and Berg, H.C. Visualization of flagella during bacterial swarming. J. Bacteriol. 192, 3259-3267 (2010).
(2014.03.12)