Antani Jyot D, Theroux Austen, Emonet Thierry, Turner Paul E
Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA.
Center for Phage Biology & Therapy, Yale University, New Haven, CT 06520, USA.
bioRxiv. 2025 May 10:2025.05.06.652435. doi: 10.1101/2025.05.06.652435.
Bacteria often rapidly evolve resistance to bacteriophages (phages) by mutating or suppressing the phage-receptors, the factors that phages first target to initiate infection. Flagellotropic phages infect bacteria by initially binding to the flagellum. Since motility is an important fitness factor that allows bacteria to efficiently explore their environment, losing flagellar function to evade infection by flagellotropic phages represents a crucial trade-off. In this study, we investigated the evolutionary responses of when exposed to the flagellotropic phage . Using an experimental evolution approach, cells were repeatedly subjected to environments rich in phage but selective for motility. Unlike traditional well-mixed cultures, we employed swim-plate assays to simulate spatial confinement and promote motility. Whole genome sequencing of evolved populations revealed early emergence of non-motile, -resistant mutants with mutations disrupting motility-related genes. Motile mutants emerged in later passages, possessing mutations in the flagellin gene . Swim-plate assays showed a diverse range of motility among these mutants, with some displaying slower, and others faster, expansion speeds compared to the ancestral strain. Single-cell tracking experiments indicated an increased tumble bias in -resistant mutants, suggesting an adaptive response involving altered flagellar rotation. Our findings demonstrate that motility can undergo trade-offs and trade-ups with phage resistance, shedding light on the complex evolutionary dynamics between motile bacteria and flagellotropic phages.
细菌常常通过突变或抑制噬菌体受体（噬菌体首先靶向以启动感染的因子）来迅速进化出对噬菌体的抗性。嗜鞭毛噬菌体最初通过与鞭毛结合来感染细菌。由于运动性是一种重要的适应性因素，它使细菌能够有效地探索其环境，因此为了逃避嗜鞭毛噬菌体的感染而丧失鞭毛功能代表了一种关键的权衡。在本研究中，我们调查了[细菌名称]暴露于嗜鞭毛噬菌体[噬菌体名称]时的进化反应。使用实验进化方法，[细菌名称]细胞反复暴露于富含噬菌体[噬菌体名称]但对运动性有选择性的环境中。与传统的充分混合培养不同，我们采用泳板试验来模拟空间限制并促进运动性。对进化群体的全基因组测序揭示了非运动性、抗噬菌体突变体的早期出现，这些突变体的突变破坏了与运动性相关的基因。运动性突变体在后期传代中出现，其鞭毛蛋白基因[基因名称]发生了突变。泳板试验显示这些突变体之间存在多种运动性，与祖先菌株相比，一些突变体的扩展速度较慢，而另一些则较快。单细胞追踪实验表明，抗噬菌体突变体的翻滚偏向增加，这表明涉及鞭毛旋转改变的适应性反应。我们的研究结果表明，运动性可以与噬菌体抗性进行权衡和权衡，揭示了运动性细菌与嗜鞭毛噬菌体之间复杂的进化动态。
