Wu-Zhang Bohan, Zhang Peixin, Baillou Renaud, Lindner Anke, Clement Eric, Gompper Gerhard, Fedosov Dmitry A
Theoretical Physics of Living Matter, Institute for Advanced Simulation, Forschungszentrum Jülich, Jülich 52425, Germany.
Laboratoire PMMH-ESPCI, UMR 7636 CNRS-PSL-Research University, Sorbonne Université, Université Paris Cité, Paris 75005, France.
J R Soc Interface. 2025 Jun;22(227):20250035. doi: 10.1098/rsif.2025.0035. Epub 2025 Jun 18.
The huge variety of microorganisms motivates fundamental studies of their behaviour with the possibility to construct artificial mimics. A prominent example is the bacterium, which employs several helical flagella to exhibit a motility pattern that alternates between run (directional swimming) and tumble (change in swimming direction) phases. We establish a detailed model, coupled to fluid flow described by the dissipative particle dynamics method, and investigate its run-and-tumble behaviour. Different characteristics, including body geometry, flagella bending rigidity, the number of flagella and their arrangement at the body, are considered. Experiments are also performed to directly compare with the model. Interestingly, in both simulations and experiments, the swimming velocity is nearly independent of the number of flagella. The rigidity of a hook (the short part of a flagellum that connects it directly to the motor), polymorphic transformation (spontaneous change in flagella helicity) of flagella and their arrangement at the body surface strongly influence the run-and-tumble behaviour. Mesoscale hydrodynamics simulations with the developed model help us better understand physical mechanisms that govern dynamics, yielding the run-and-tumble behaviour that compares well with experimental observations. This model can further be used to explore the behaviour of and other peritrichous bacteria in more complex realistic environments.
微生物种类繁多，这激发了对其行为进行基础研究的兴趣，并有可能构建人工模拟物。一个突出的例子是细菌，它利用几根螺旋状鞭毛展现出一种在游动（定向游泳）和翻滚（游泳方向改变）阶段之间交替的运动模式。我们建立了一个详细的模型，该模型与用耗散粒子动力学方法描述的流体流动相耦合，并研究其游动和翻滚行为。我们考虑了不同的特征，包括菌体几何形状、鞭毛弯曲刚度、鞭毛数量及其在菌体上的排列方式。还进行了实验以直接与模型进行比较。有趣的是，在模拟和实验中，游泳速度几乎与鞭毛数量无关。钩（鞭毛直接连接到马达的短部分）的刚度、鞭毛的多态转变（鞭毛螺旋度的自发变化）及其在菌体表面的排列方式强烈影响游动和翻滚行为。使用所开发模型进行的介观流体动力学模拟有助于我们更好地理解控制动力学的物理机制，产生与实验观察结果吻合良好的游动和翻滚行为。该模型可进一步用于探索在更复杂现实环境中周毛菌和其他细菌的行为。
