School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
Davidson School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
Phys Rev E. 2019 Dec;100(6-1):062605. doi: 10.1103/PhysRevE.100.062605.
Near an interface, the distribution of swimming microorganisms such as bacteria is distinguished from inert colloidal particles because of the interfacial hydrodynamics induced by swimming. In this work, we use nontumbling flagellated bacteria, Escherichia coli, to study cell distribution near gas and liquid interfaces and compare it to the case of a solid wall. For low-viscosity ratios such as gas interfaces, we observe a stronger cell accumulation compared to that near liquid and solid surfaces. This contradicts known theoretical predictions. Therefore, we develop a model based on Brownian dynamics, including hydrodynamic effects and short-range physiochemical interactions between bacteria and interfaces. This model explains our experimental findings and can predict cell distribution near clean and surfactant-contaminated interfaces. By considering higher order singularities, this study helps explain bacteria orientation, trajectories, and cell density.
在界面附近，由于游泳引起的界面流体动力学，游动微生物（如细菌）的分布与惰性胶体颗粒明显不同。在这项工作中，我们使用非翻滚鞭毛细菌大肠杆菌来研究气体和液体界面附近的细胞分布，并将其与固体壁面的情况进行比较。对于低黏度比（如气体界面），与液体和固体表面相比，我们观察到细胞的积累更强烈。这与已知的理论预测相矛盾。因此，我们基于布朗动力学开发了一个模型，包括细菌与界面之间的流体动力效应和短程物理化学相互作用。该模型解释了我们的实验结果，并可以预测清洁和表面活性剂污染界面附近的细胞分布。通过考虑更高阶奇点，这项研究有助于解释细菌的取向、轨迹和细胞密度。
