Flexibility of bacterial flagella in external shear results in complex swimming trajectories.
Flexibility of bacterial flagella in external shear results in complex swimming trajectories.
复制标题
细菌鞭毛在外部剪切力下的灵活性导致复杂的游动轨迹。
DOI：
10.1098/rsif.2014.0904
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Aranson,IS
中科院分区：
文献类型：
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作者：
Tournus,M;Kirshtein,A;Berlyand,LV;Aranson,IS
许多细菌在游动运动中使用旋转螺旋鞭毛。在寻找食物或迁移到一个新的栖息地时，细菌偶尔会解开它们的鞭毛丝并翻滚，导致方向的突然改变。柔性鞭毛也可以容易地通过外部剪切流变形，导致复杂的细菌轨迹。在这里，我们研究了鞭毛的灵活性的影响，在两个基本的剪切流的细菌导航：平面剪切和Poiffille流实现在长通道。基于细长体弹性动力学理论和数值分析，我们发现了自推进、弹性和剪切诱导的鞭毛弯曲相互作用所产生的各种非平凡效应。我们表明，在平面剪切流的细菌执行周期性运动，而在Poietille流，他们向中心的通道或收敛到一个极限环迁移。我们还发现，即使是少量的随机重定向也会引起细菌的强烈反应，导致整体非周期性轨迹。我们的发现证实了鞭毛灵活性的敏感作用，并为细菌在复杂剪切流中的导航提供了新的线索。
Many bacteria use rotating helical flagella in swimming motility. In the search for food or migration towards a new habitat, bacteria occasionally unbundle their flagellar filaments and tumble, leading to an abrupt change in direction. Flexible flagella can also be easily deformed by external shear flow, leading to complex bacterial trajectories. Here, we examine the effects of flagella flexibility on the navigation of bacteria in two fundamental shear flows: planar shear and Poiseuille flow realized in long channels. On the basis of slender body elastodynamics and numerical analysis, we discovered a variety of non-trivial effects stemming from the interplay of self-propulsion, elasticity and shear-induced flagellar bending. We show that in planar shear flow the bacteria execute periodic motion, whereas in Poiseuille flow, they migrate towards the centre of the channel or converge towards a limit cycle. We also find that even a small amount of random reorientation can induce a strong response of bacteria, leading to overall non-periodic trajectories. Our findings exemplify the sensitive role of flagellar flexibility and shed new light on the navigation of bacteria in complex shear flows.