PDF(Pubmed)
Abstract：
Surface-associated bacterial communities flourish in nature and in the body of animal hosts with abundant macromolecular polymers. It is unclear how the endowed viscoelasticity of polymeric fluids influences bacterial motile behavior in such environments. Here, we combined experiment and theory to study near-surface swimming of flagellated bacteria in viscoelastic polymer fluids. In contrast to the swimming behavior in Newtonian fluids, we discovered that cells swim in less curved trajectories and display reduced near-surface accumulation. Using a theoretical analysis of the non-Newtonian hydrodynamic forces, we demonstrated the existence of a generic lift force acting on a rotating filament near a rigid surface, which arises from the elastic tension generated along curved flow streamlines. This viscoelastic lift force weakens the hydrodynamic interaction between flagellated swimmers and solid surfaces and contributes to a decrease in surface accumulation. Our findings reveal previously unrecognized facets of bacterial transport and surface exploration in polymer-rich environments that are pertinent to diverse microbial processes and may inform the design of artificial microswimmers capable of navigating through complex geometries.
摘要：
表面相关的细菌群落在自然界和动物宿主体内蓬勃发展，具有丰富的大分子聚合物。尚不清楚聚合物流体的赋予粘弹性如何影响此类环境中的细菌活动行为。这里,我们将实验和理论相结合，研究了鞭毛细菌在粘弹性聚合物流体中的近表面游动。与牛顿流体中的游泳行为相反，我们发现细胞在较少弯曲的轨迹中游动，并显示出减少的近地表积累。通过对非牛顿流体动力的理论分析，我们证明了作用在刚性表面附近的旋转细丝上的通用升力的存在，这是由沿弯曲流动流线产生的弹性张力引起的。这种粘弹性升力削弱了鞭毛游泳者与固体表面之间的水动力相互作用，并有助于减少表面积累。我们的发现揭示了在富含聚合物的环境中细菌运输和表面探索的先前未被识别的方面，这些方面与多种微生物过程有关，并且可能为能够通过复杂几何形状导航的人工微型游泳者的设计提供信息。
