Rotation of a swimming bacterium. Negative
of a digital darkfield exposure, observation
time 1 sec, bar = 5 µm.
The rotation of a swimming bacterium can be visualized photographically by long-term exposure. On the photograph the bacterium rotates 15 times within 1 second. This is 900 times per minute. The flagellum (which is here not visible) turns about three times faster (2700 times per minute).