Species name： Escherichia coli
Harvard UniversityDepartment of Molecular and Cellular BiologyHarvard Biological Labs Howard C. Berg
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. They diffuse locally but are not perturbed by the swarming cells, which shows that the surface of the swarm is stationary. We think it is covered by a surfactant monolayer pinned at its edges. The smoke particles were about 0.2 µm in diameter. The cells were about 1 µm in diameter by 5 µm long.
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).
(2014.03.11)