[论文解读] Ecological memory of hydrodynamic cues shapes growth and migration of motile microorganisms

Narges Kakavand, Anupam Sengupta|arXiv (Cornell University)|Feb 27, 2026

Micro and Nano Robotics被引用 0

一句话总结

这项研究在运动性浮游植物中展示了生态记忆，表明先前的流体动力暴露在各生长阶段重塑了Heterosigma akashiwo 的生长与游动特征，且效应依暴露时机与顺序而异。

ABSTRACT

Microorganisms live in inherently dynamic environments where fluctuations in biotic and abiotic factors shape their behaviour, physiology, and fitness. The concept of ecological memory: the lasting imprint of prior environmental cues, suggests that past exposures can exert prolonged effects on microbial growth, resilience, and phenotypic expressions. For motile microbes in aquatic ecosystems, environmental variability is mediated by fluid motion, which may engender a form of hydrodynamic memory, whereby prior exposure to specific spatio-temporal cues influence future growth and migratory behaviour. Yet, the emergence of such flow-induced memory, or its long-term consequences for trait evolution and population dynamics, remain unexplored. We integrate millifluidic flow control, high-resolution cell tracking, and tunable hydrodynamic cues to quantify growth and migration of Heterosigma akashiwo, a model microbe, across growth stages. Using two complementary perturbation scenarios: standard (flow after static conditions) and reverse (flow before static growth), we test how the temporal structure of forcing shapes multigenerational responses. This combinatorial design disentangles exposure history from its duration, and reveals how prior flow modulates sensitivity, generating legacy effects. Compared with static controls, repeated hydrodynamic exposure alters doubling time, carrying capacity, gravitactic stability, and swimming speed distributions; shifting growth phase progression and tolerance to subsequent perturbations. These results establish a mechanistic framework for flow-induced memory in motile microbes, revealing how past fluidic cues shape future growth and migration. Our study advances predictive understanding of motile microbes in natural and engineered hydrodynamic systems experiencing increasing variability under global environmental changes.

研究动机与目标

• 受到动态水环境中生态记忆以及流体动力作为记忆诱发线索在运动微生物中的作用所驱动。
• 量化不同时间点的水动力暴露如何影响两株Heterosigma akashiwo 的生长动力学与运动性。
• 确定暴露史及其持续时间是否在适应度与行为上产生持久的跨代效应。

提出的方法

• 使用轨道震动器的毫升流控以施加可调的水动力条件（大约110 rpm）。
• 两种扰动方案：标准（静态 -> 扰动）和反向（扰动 -> 静态），以将暴露史与当前条件分离。
• 通过对数生长拟合来量化生长，获得特定生长率（倍增时间）和承载容量。
• 通过垂直游动速度、游动方向分布（风玫瑰图）和从ω(θ)的正弦拟合得到的重力定向再取向时间(tau_r)来表征运动性。
• 在生长阶段（早期指数阶段、中期指数、早期稳态、中期稳态）跟踪两株H. akashiwo（HA452 与 HA3107）。
• 在扰动与静态条件下进行多时延的生长指标与运动描述符的统计比较。

Figure 1 : Tracking ecological memory in motile microorganisms. (A)–(D): Standard scenario (static $\rightarrow$ shaker): microbial growth initially under static condition (red hue), followed by hydrodynamic perturbations (blue hue). (A) 0-hour: cells transferred to the shaker immediately post-inocu

实验结果

研究问题

• RQ1 扰动相对于生长阶段的时序如何影响H. akashiwo 的生长速率与承载容量？
• RQ2 先前的水动力暴露是否会诱发持久的（记忆）效应于运动性与 gravitactic 稳定性，在回到静态条件时这些效应是否仍然存在？
• RQ3 是否存在对水动力历史及其持续时间的株系特异性敏感差异？
• RQ4 反向暴露（扰动后静态条件）与持续扰动相比，如何改变随后的生长与运动性？

主要发现

• 水动力历史显著重塑生长动力学，相对于静态对照，双倍增期和承载容量会因扰动时机而异。
• 早期及持续暴露对两株均加速生长，而中期指数扰动会降低生物量产出并可能减慢增长。
• 后期扰动（后期稳态）对生长指标的影响较小，但可能影响生存动态；时序决定适应度结果。
• HA3107 在指数生长期暴扰下显示出比HA452更强的负面效应，表明株系特异性脆弱性。
• 反向扰动实验显示持久效应：早期释放保留生长速率但生物量略有损失，而晚期释放则加剧生长速率与承载容量的下降。
• 水动力历史也重新编程了运动性，扰动细胞相较静态对照表现出更低的垂直速度与方向稳定性改变（再取向时间增大），尤其在0小时延迟情形下。

Figure 2 : Quantifying swimming and reorientation dynamics of motile microbes. Raw (A) and binarized (B) images of swimming cells; insets present magnified view. (C) Swimming trajectories; inset presents zoom-in views of a selection of trajectories. (D) Trajectories visualized in the milifluidic cha