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bioRxiv · 10.1101/2024.09.29.615714

Bacterial motility patterns adapt smoothly in response to spatial confinement and disorder

Zhang, H.·Wetherington, M. T.·Ko, H.·FitzGerald, C. E.·Nirody, J. A.
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Abstract

In unconfined environments, bacterial motility patterns are an explicit expression of the internal states of the cell. Bacteria operating a run-and-tumble behavioral program swim forward when in a run state, and are stalled in place when in a reorienting tumble state. However, in natural environments, motility dynamics often represent a convolution of bacterial behavior and environmental constraints. Recent investigations showed that Escherichia coli swimming through highly confined porous media exhibit extended periods of trapping punctuated by forward hops, a seemingly drastic restructuring of run-and-tumble behavior. We introduce a microfluidic device to systematically explore bacterial movement in a range of spatially structured environments, bridging the extremes of unconfined and highly confined conditions. We observe that trajectories reflecting unconstrained expression of run-and-tumble behavior and those reflecting hop-and-trap dynamics coexist in all structured environments considered, with ensemble dynamics transitioning smoothly between these two extremes. We present a unifying swim-and-stall framework to characterize this continuum of observed motility patterns and demonstrate that bacteria employing a consistent set of behavioral rules can present motility patterns that smoothly transition between the two extremes. Our results indicate that the control program underlying run-and-tumble motility is robust to changes in the environment, allowing flagellated bacteria to navigate and adapt to a diverse range of complex, dynamic habitats using the same set of behavioral rules.

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Zhang, H., Wetherington, M. T., Ko, H., FitzGerald, C. E., Nirody, J. A.. 2024-09-30. Bacterial motility patterns adapt smoothly in response to spatial confinement and disorder. https://doi.org/10.1101/2024.09.29.615714

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