Bacterial dimensions sensitively regulate surface diffusivity and residence time

TL;DR

This study shows how bacterial size variations significantly influence their surface residence time and diffusivity, revealing sensitive regulation of bacterial motility strategies.

Contribution

It uncovers the linear relationship between bacterial dimensions and surface residence time, and predicts how size affects optimal tumble bias and surface diffusivity.

Findings

Logarithm of surface residence time linearly relates to bacterial size.

Small size variations cause large changes in residence time.

Optimal tumble bias and diffusivity depend strongly on bacterial dimensions.

Abstract

Run-and-tumble is a common but vital strategy that bacteria employ to explore environment suffused with boundaries, as well as to escape from entrapment. In this study we reveal how this strategy and the resulting dynamical behavior can be sensitively regulated by bacterial dimensions. Our results demonstrate that the logarithm of the surface residence time for bacteria with constant tumble bias is linearly related to a dimensionless parameter of bacterial intrinsic size characteristics, where a small variation in bacterial dimensions, which is natural in a suspension, reproduces well the experimentally observed large variation in bacterial residence time. Furthermore, our results predict that the optimal tumble bias corresponding to the maximum surface diffusivity depends strongly on bacterial dimensions, where the same small variation in bacterial dimensions gives rise to a strongly diversified optimal tumble bias and an order of magnitude change in surface diffusivity.