Ghosh Udita U, Ali Hessein, Ghosh Ranajay, Kumar Aloke
Department of Mechanical Engineering, Indian Institute of Science, Bangalore, India.
Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816, USA.
J Colloid Interface Sci. 2021 Jul 15;594:265-278. doi: 10.1016/j.jcis.2021.02.102. Epub 2021 Mar 9.
Bacteria can thrive in biofilms, which are intricately organized communities with cells encased in a self-secreted matrix of extracellular polymeric substances (EPS). Imposed hydrodynamic stresses can transform this active colloidal dispersion of bacteria and EPS into slender thread-like entities called streamers. In this perspective article, the reader is introduced to the world of such deformable 'bacteria-EPS' composites that are a subclass of the generic flow-induced colloidal structures. While bacterial streamers have been shown to form in a variety of hydrodynamic conditions (turbulent and creeping flows), its abiotic analogues have only been demonstrated in low Reynolds number (Re < 1) particle-laden polymeric flows. Streamers are relevant to a variety of situations ranging from natural formations in caves and river beds to clogging of biomedical devices and filtration membranes. A critical review of the relevant biophysical aspects of streamer formation phenomena and unique attributes of its material behavior are distilled to unveil five grand scientific challenges. The coupling between colloidal hydrodynamics, device geometry and streamer formation are highlighted.
细菌能够在生物膜中茁壮成长，生物膜是一种结构复杂的群落，其细胞被包裹在由细胞外聚合物（EPS）自分泌形成的基质中。施加的流体动力应力可将这种由细菌和EPS组成的活性胶体分散体转变为称为拖尾丝的细长丝状实体。在这篇观点文章中，读者将进入这样一个可变形的“细菌-EPS”复合材料的世界，它们是一般流动诱导胶体结构的一个子类。虽然已证明细菌拖尾丝可在各种流体动力条件下（湍流和蠕动流）形成，但其非生物类似物仅在低雷诺数（Re < 1）的含颗粒聚合物流中得到证实。拖尾丝与从洞穴和河床中的自然形成到生物医学设备和过滤膜堵塞等各种情况相关。对拖尾丝形成现象的相关生物物理方面及其材料行为的独特属性进行了批判性综述，以揭示五个重大科学挑战。突出了胶体流体动力学、设备几何形状与拖尾丝形成之间的耦合关系。
