Unraveling bacterial strategies for spatial exploration is crucial for understanding the complexity in the organization of life. Bacterial motility determines the spatio-temporal structure of microbial communities, controls infection spreading and the microbiota organization in guts or in soils. Most theoretical approaches for modeling bacterial transport rely on their run-and-tumble motion. For Escherichia coli, the run time distribution was reported to follow a Poisson process with a single characteristic time related to the rotational switching of the flagellar motors. However, direct measurements on flagellar motors show heavy-tailed distributions of rotation times stemming from the intrinsic noise in the chemotactic mechanism. Currently, there is no direct experimental evidence that the stochasticity in the chemotactic machinery affect the macroscopic motility of bacteria. In stark contrast with the accepted vision of run-and-tumble, here we report a large behavioral variability of wild-type , revealed in their three-dimensional trajectories. At short observation times, a large distribution of run times is measured on a population and attributed to the slow fluctuations of a signaling protein triggering the flagellar motor reversal. Over long times, individual bacteria undergo significant changes in motility. We demonstrate that such a large distribution of run times introduces measurement biases in most practical situations. Our results reconcile the notorious conundrum between run time observations and motor switching statistics. We finally propose that statistical modeling of transport properties, currently undertaken in the emerging framework of active matter studies, should be reconsidered under the scope of this large variability of motility features.

中文翻译：

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E的3D空间探索。大肠杆菌回肠运动时间变异

阐明细菌的空间探索策略对于理解生命组织的复杂性至关重要。细菌运动性决定了微生物群落的时空结构，控制了肠道或土壤中感染的扩散和微生物群的组织。对细菌运输进行建模的大多数理论方法都依赖于它们的运转运动。对于大肠杆菌，运行时间分布据报道遵循泊松过程，具有与鞭毛马达的旋转切换相关的单个特征时间。然而，直接测量鞭毛马达显示出旋转时间的重尾分布是由于趋化机理中的固有噪声引起的。目前，没有直接的实验证据表明趋化机制中的随机性会影响细菌的宏观运动。与人们普遍认为的“奔跑”和“奔跑”的观点形成鲜明对比的是，在这里我们报道了野生动物在其三维运动轨迹中表现出的巨大的行为变异性。在较短的观察时间上，可以在种群上测量到较大的运行时间分布，这归因于触发鞭毛运动逆转的信号蛋白的缓慢波动。长期以来，单个细菌的蠕动发生重大变化。我们证明，如此大的运行时间分布会在大多数实际情况下引入测量偏差。我们的结果调和了运行时间观察和电动机开关统计之间臭名昭著的难题。