A fluid-dynamic interpretation of the asymmetric motion of singly flagellated bacteria swimming close to a boundary
A fluid-dynamic interpretation of the asymmetric motion of singly flagellated bacteria swimming close to a boundary
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DOI：
10.1529/biophysj.105.067553
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发表时间：
2005-12-01
影响因子：
3.4
通讯作者：
Magariyama, Y
中科院分区：
文献类型：
--
作者：
Goto, T;Nakata, K;Magariyama, Y
单胶凝细菌，溶藻弧菌，通过改变其鞭毛的旋转方向向前和向后移动。人们观察到这种细菌几乎精确地沿着先前的路径回溯，并以之字形游动。然而，在存在边界的情况下，运动会发生显著的变化，变成更接近圆形轨迹的东西。此外，当细胞靠近墙壁游泳时，向前和向后的速度明显不同。这项研究详细介绍了细菌在刚性边界附近运动的边界元模型和使用该模型进行的数值分析的结果。结果表明，细菌的运动受俯仰角(即边界与游动方向的夹角)的影响明显，相对于细菌的俯仰，向前运动比向后运动更稳定。根据这些结果，建立了一组图表表示，解释了观察到的前进和后退运动之间在轨迹和速度上的不对称。对于向前运动，平行于边界移动的细胞将保持这一轨迹。然而，对于向后运动，产生的轨迹取决于细菌是接近还是离开边界。鞭毛和边界之间的流体动力相互作用随着细胞方向的不同而变化，并导致所产生的轨迹的特殊性。
The singly agellated bacterium, Vibrio alginolyticus, moves forward and backward by alternating the rotational direction of its flagellum. The bacterium has been observed retracing a previous path almost exactly and swimming in a zigzag pattern. In the presence of a boundary, however, the motion changes significantly, to something closer to a circular trajectory. Additionally, when the cell swims close to a wall, the forward and backward speeds differ noticeably. This study details a boundary element model for the motion of a bacterium swimming near a rigid boundary and the results of numerical analyses conducted using this model. The results reveal that bacterium motion is apparently influenced by pitch angle, i.e., the angle between the boundary and the swimming direction, and that forward motion is more stable than backward motion with respect to pitching of the bacterium. From these results, a set of diagrammatic representations have been created that explain the observed asymmetry in trajectory and speed between the forward and backward motions. For forward motion, a cell moving parallel to the boundary will maintain this trajectory. However, for backward motion, the resulting trajectory depends upon whether the bacterium is approaching or departing the boundary. Fluid-dynamic interactions between the flagellum and the boundary vary with cell orientation and cause peculiarities in the resulting trajectories.