The colloidal nature of complex fluids enhances bacterial motility
The colloidal nature of complex fluids enhances bacterial motility
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DOI：
10.1038/s41586-022-04509-3
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发表时间：
2022-03-31
期刊：
影响因子：
64.8
通讯作者：
Cheng, Xiang
中科院分区：
文献类型：
--
作者：
Kamdar, Shashank;Shin, Seunghwan;Cheng, Xiang
人类微生物组、海洋和土壤生态系统中微生物的自然栖息地充满了胶体和大分子。这种环境表现出非牛顿流动特性，极大地影响微生物的运动（1-5）。虽然简单牛顿流体中游动鞭毛细菌的低雷诺数流体动力学已经得到了很好的发展（6-9），但我们对复杂非牛顿流体中细菌运动性的理解还不太成熟（10，11）。即使经过六十年的研究，关于聚合物溶液中细菌运动增强的性质和起源的基本问题仍在争论中（12-）（23）。在这里，我们表明，稀释胶体悬浮液中的鞭毛细菌显示出与稀释聚合物溶液中的鞭毛细菌在数量上相似的运动行为，特别是普遍的颗粒大小依赖性运动增强高达80%，伴随着对细菌摆动的强烈抑制（18）（，）（24）。由于胶体的硬球性质，其大小和体积分数在实验中各不相同，我们的结果揭示了复杂流体中细菌运动增强的长期争议，并表明聚合物动力学可能不是捕获现象的必要条件（12-）（23）。一个物理模型，结合胶体性质的复杂流体定量解释细菌摆动动力学和流动性增强胶体和聚合物流体。我们的研究结果有助于理解复杂流体中细菌的运动行为，这与广泛的微生物过程和复杂环境中的工程细菌游泳有关（26，27）。
The natural habitats of microorganisms in the human microbiome, ocean and soil ecosystems are full of colloids and macromolecules. Such environments exhibit non-Newtonian flow properties, drastically affecting the locomotion of microorganisms(1-5). Although the low-Reynolds-number hydrodynamics of swimming flagellated bacteria in simple Newtonian fluids has been well developed(6-9), our understanding of bacterial motility in complex non-Newtonian fluids is less mature(10,11). Even after six decades of research, fundamental questions about the nature and origin of bacterial motility enhancement in polymer solutions are still under debate(12-)(23). Here we show that flagellated bacteria in dilute colloidal suspensions display quantitatively similar motile behaviours to those in dilute polymer solutions, in particular a universal particle-size-dependent motility enhancement up to 80% accompanied by a strong suppression of bacterial wobbling(18)(,)(24). By virtue of the hard-sphere nature of colloids, whose size and volume fraction we vary across experiments, our results shed light on the long-standing controversy over bacterial motility enhancement in complex fluids and suggest that polymer dynamics may not be essential for capturing the phenomenon(12-)(23). A physical model that incorporates the colloidal nature of complex fluids quantitatively explains bacterial wobbling dynamics and mobility enhancement in both colloidal and polymeric fluids. Our findings contribute to the understanding of motile behaviours of bacteria in complex fluids, which are relevant for a wide range of microbiological processes' and for engineering bacterial swimming in complex environments(26,27).