Bacterial flagella are nanomachines that drive bacteria motility and taxis in response to environmental changes. Whether flagella are permanent cell structures and, if not, the circumstances and timing of their production and loss during the bacterial life cycle remain poorly understood. Here we used the single polar flagellum of Vibrio alginolyticus as our model and implementing in vivo fluorescence imaging revealed that the percentage of flagellated bacteria (PFB) in a population varies substantially across different growth phases. In the early‐exponential phase, the PFB increases rapidly through the widespread production of flagella. In the mid‐exponential phase, the PFB peaks at around 76% and the partitioning of flagella between the daughter cells are 1:1 and strictly at the old poles. After entering the stationary phase, the PFB starts to decline, mainly because daughter cells stop making new flagella after cell division. Interestingly, we observed that bacteria can actively abandon flagella after prolonged stationary culturing, though cell division has long been suspended. Further experimental investigations confirmed that flagella were ejected in V. alginolyticus, starting from breakage in the rod. Our results highlight the dynamic production and loss of flagella during the bacterial life cycle.

中文翻译：

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活细胞荧光成像显示细菌鞭毛的动态产生和损失。

细菌鞭毛是纳米机器，可响应环境变化而驱动细菌运动和滑行。鞭毛是否是永久性细胞结构，如果不是，则在细菌生命周期中其产生和丧失的情况和时机仍然知之甚少。在这里，我们使用了溶藻弧菌的单极鞭毛作为我们的模型并进行体内荧光成像显示，种群中鞭毛细菌（PFB）的百分比在不同的生长期之间存在很大差异。在早期的指数阶段，PFB通过鞭毛的大量繁殖而迅速增加。在指数中期，PFB的峰值约为76％，子代细胞之间的鞭毛分配为1：1，严格在旧极。进入稳定期后，PFB开始下降，主要是因为子细胞在细胞分裂后不再产生新鞭毛。有趣的是，我们观察到，尽管长期以来细胞分裂一直处于暂停状态，但是经过长时间的固定培养，细菌可以主动放弃鞭毛。进一步的实验研究证实鞭毛被弹射出V. alginolyticus，从杆断裂开始。我们的结果突出了细菌生命周期中鞭毛的动态产生和损失。