Dynamics of Bacterial Swarming
Dynamics of Bacterial Swarming
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DOI：
10.1016/j.bpj.2010.01.053
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发表时间：
2010-05-19
影响因子：
3.4
通讯作者：
Berg, Howard C.
中科院分区：
文献类型：
--
作者：
Darnton, Nicholas C.;Turner, Linda;Berg, Howard C.
当会游泳的营养细菌在琼脂表面的富含介质中生长时，它们会变得多核，拉长，合成大量的鞭毛，产生润湿剂，并以协调的方式在表面移动：它们成群结队地移动。我们研究了成群的大肠杆菌的运动，将单个细胞的运动与它们在游泳时的运动进行了比较。蜂群细胞的速度与整体游泳速度相当，但分布非常广泛。它们的速度和方向在短距离(几个晶胞长度)上是相关的，但这种相关性不是各向同性的。我们观察到在许多蜂群系统中明显的漩涡，可能是由于关联成群的细胞之间日益持久的相关性所致。在游泳中看到的正常的游动-翻滚行为在很大程度上被抑制了，相反，细胞通过邻居的随机推挤不断地重新定位，在十分之几秒内随机调整方向。在蜂群的边缘，细胞通常会暂停，然后游回蜂群的中心或沿其边缘游回。细胞之间的局部排列是许多群集理论的必要条件，它是通过细胞体碰撞和/或短程流体动力相互作用来完成的。
When vegetative bacteria that can swim are grown in a rich medium on an agar surface, they become multinucleate, elongate, synthesize large numbers of flagella, produce wetting agents, and move across the surface in coordinated packs: they swarm. We examined the motion of swarming Escherichia coli, comparing the motion of individual cells to their motion during swimming. Swarming cells' speeds are comparable to bulk swimming speeds, but very broadly distributed. Their speeds and orientations are correlated over a short distance (several cell lengths), but this correlation is not isotropic. We observe the swirling that is conspicuous in many swarming systems, probably due to increasingly long-lived correlations among cells that associate into groups. The normal run-tumble behavior seen in swimming chemotaxis is largely suppressed, instead, cells are continually reoriented by random jostling by their neighbors, randomizing their directions in a few tenths of a second. At the edge of the swarm, cells often pause, then swim back toward the center of the swarm or along its edge. Local alignment among cells, a necessary condition of many flocking theories, is accomplished by cell body collisions and/or short-range hydrodynamic interactions.