Feng Jingjing, Zhang Zexin, Wen Xiaodong, Xue Jianfeng, He Yan
Department of Chemistry, Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Tsinghua University, Beijing 100084, China.
State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China; Centre for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University, Suzhou 215006, China.
iScience. 2019 Dec 20;22:123-132. doi: 10.1016/j.isci.2019.11.012. Epub 2019 Nov 8.
Flagellated bacteria move collectively in a swirling pattern on agar surfaces immersed in a thin layer of viscous "swarm fluid," but the role of this fluid in mediating the cooperation of the bacterial population is not well understood. Herein, we use gold nanorods (AuNRs) as single particle tracers to explore the spatiotemporal structure of the swarm fluid. Individual AuNRs are moving in a plane of ∼2 μm above swarms, traveling for long distances in high speed without interferences from bacterial movements. The particles are lifted and transported by collective mixing of small vortices around bacteria during localized clustering and de-clustering of motile cells. Their motions fit the Lévy walk model, revealing efficient fluidic flows above the swarms. These flows provide obstacle-free highways for long-range material transportations, allow swarming bacteria to perform population-level communications, and imply the essential role of the fluid phase on the emergence of large-scale synergy.
在浸没于一层薄薄的粘性“群体流体”中的琼脂表面上，有鞭毛的细菌以漩涡模式集体移动，但这种流体在介导细菌群体合作中所起的作用尚未得到充分理解。在此，我们使用金纳米棒（AuNRs）作为单粒子示踪剂来探索群体流体的时空结构。单个金纳米棒在群体上方约2微米的平面内移动，高速长距离行进且不受细菌运动的干扰。在运动细胞局部聚集和解聚过程中，粒子通过细菌周围小漩涡的集体混合而被提升和运输。它们的运动符合列维行走模型，揭示了群体上方高效的流体流动。这些流动为远程物质运输提供了无障碍通道，使群体细菌能够进行群体水平的通讯，并暗示了液相在大规模协同作用出现中的重要作用。
