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Summary of Research Projects (Supports in 2003
Fiscal Year)
| Subjects |
Study on the Motion of Spirochete Whose Swimming Speed Increases with
Viscosity |
| Representative researcher |
National Food Research Institute Yukio MAGARIYAMA |
| It is known that the swimming speed of spirochete increases with the viscosity. Such phenomena cannot be observed in the macroscopic world. Traditional theories have predicted that the swimming speed of a bacterial cell monotonously decreases with the viscosity. I have previously proposed a hypothesis that the motion efficiency increases with the viscosity because of a quasi-rigid network formed by the polymer molecules (skating-bacteria hypothesis). This hypothesis has successfully explained the motion property of externally flagellated bacteria in viscous environments. I consider that the skating-bacteria hypothesis is also valid for the motion of spirochete. Simultaneous measurement of the swimming speeds and rotation rates of spirochete cells is required for experimental examination of the hypothesis. I developed two-directional-illuminated dark-field microscopy (2DDM). The image of a spirochete cell obtained by 2DDM was colored with green or red depending on the direction of its cell segment. That image allowed me to determine the center and rotational phase of the cell. In other words, I could simultaneously determine the swimming speed and rotation rate of a spirochete cell from the 2DDM movie. The preliminary result using Brachyspira pilosicoli suggested the validity of the hypothesis. |
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