The wiggling trajectories of bacteria
The wiggling trajectories of bacteria
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DOI：
10.1017/jfm.2012.217
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发表时间：
2012-08-25
影响因子：
3.7
通讯作者：
Fu, Henry C.
中科院分区：
文献类型：
--
作者：
Hyon, Yunkyong;Marcos;Fu, Henry C.
许多可移动的细菌显示出与螺旋游泳路径相对应的摆动轨迹。摆动轨迹是鞭毛相对于细胞体偏离轴向而使细胞摆动的结果。摆动轨迹的空间范围由游动速度和鞭毛扭矩控制，从而导致细胞体的旋转。我们使用正则化的斯托克斯莱特方法来研究鞭毛束产生的摆动轨迹，鞭毛束可以相对于富鞭毛细菌的细胞体在许多位置和方向形成。将鞭毛束建模为相对于细胞体具有固定位置和方向的刚性螺旋，我们表明摆动轨迹取决于鞭毛束相对于细胞体的位置和方向。我们观察和量化了枯草芽孢杆菌的螺旋摆动轨迹，它显示出广泛的轨迹节距和半径，许多节距大于4微米。对于这种细菌，我们发现相对于细胞体具有固定方向的鞭毛束不太可能产生节距大于4微米的摆动轨迹。基于扭矩平衡的估计表明，这种对节距的限制是鞭毛束施加的大扭矩的结果。另一方面，具有固定取向的多个刚性束，与最近实验观察到的类似，能够产生具有大节距的摆动轨迹。
Many motile bacteria display wiggling trajectories, which correspond to helical swimming paths. Wiggling trajectories result from flagella pushing off-axis relative to the cell body and making the cell wobble. The spatial extent of wiggling trajectories is controlled by the swimming velocity and flagellar torque, which leads to rotation of the cell body. We employ the method of regularized stokeslets to investigate the wiggling trajectories produced by flagellar bundles, which can form at many locations and orientations relative to the cell body for peritrichously flagellated bacteria. Modelling the bundle as a rigid helix with fixed position and orientation relative to the cell body, we show that the wiggling trajectory depends on the position and orientation of the flagellar bundle relative to the cell body. We observe and quantify the helical wiggling trajectories of Bacillus subtilis, which show a wide range of trajectory pitches and radii, many with pitch larger than 4 mu m. For this bacterium, we show that flagellar bundles with fixed orientation relative to the cell body are unlikely to produce wiggling trajectories with pitch larger than 4 mu m. An estimate based on torque balance shows that this constraint on pitch is a result of the large torque exerted by the flagellar bundle. On the other hand, multiple rigid bundles with fixed orientation, similar to those recently observed experimentally, are able to produce wiggling trajectories with large pitches.