Abstract

The surface distribution of flagella in peritrichous bacterial cells has been traditionally assumed to be random. Recently, the presence of a regular grid-like pattern of basal bodies has been suggested. Experimentally, the manipulation of the anchoring points of flagella in the cell membrane is difficult, and thus, elucidation of the consequences of a particular pattern on bacterial locomotion is challenging. We analyze the bundle formation process and swimming properties of Bacillus subtilis-like cells considering random, helical, and ring-like arrangements of flagella by means of mesoscale hydrodynamics simulations. Helical and ring patterns preferentially yield configurations with a single bundle, whereas configurations with no clear bundles are most likely for random anchoring. For any type of pattern, there is an almost equally low probability to form V-shaped bundle configurations with at least two bundles. Variation of the flagellum length yields a clear preference for a single major bundle in helical and ring patterns as soon as the flagellum length exceeds the body length. The average swimming speed of cells with a single or two bundles is rather similar, and approximately \(50\%\) larger than that of cells of other types of flagellar organization. Considering the various anchoring patterns, rings yield the smallest average swimming speed independent of the type of bundle, followed by helical arrangements, and largest speeds are observed for random anchoring. Hence, a regular pattern provides no advantage in terms of swimming speed compared to random anchoring of flagella, but yields more likely single-bundle configurations.

Graphic abstract

中文翻译：

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细长周毛细菌中的鞭毛排列：束形成和游泳特性

摘要

传统上认为周毛细菌细胞中鞭毛的表面分布是随机的。最近，有人提出存在规则的网格状基体图案。在实验上，操纵细胞膜中鞭毛的锚定点是很困难的，因此，阐明特定模式对细菌运动的影响具有挑战性。我们通过中尺度流体动力学模拟，分析了枯草芽孢杆菌样细胞的束形成过程和游泳特性，考虑了鞭毛的随机、螺旋和环状排列。螺旋和环形图案优先产生具有单束的构型，而没有清晰束的构型最有可能用于随机锚定。对于任何类型的图案，形成具有至少两个束的V形束配置的概率几乎同样低。一旦鞭毛长度超过身体长度，鞭毛长度的变化就会明显偏爱螺旋形和环形图案中的单个主束。具有单束或两束细胞的平均游泳速度相当相似，并且比其他类型鞭毛组织的细胞大约大\(50\%\) 。考虑到各种锚定模式，环产生最小的平均游泳速度，与束的类型无关，其次是螺旋布置，并且观察到随机锚定的最大速度。因此，与鞭毛的随机锚定相比，规则模式在游泳速度方面没有优势，但产生更可能的单束配置。

图文摘要