Biophysics of Microbial Locomotion

Eppur si muove-the work of Galileo Galilei marked the beginning of the quantitative study of motion for scope-observable entities. Extending this physics-based perspective to the microscope-observable microbial world has uncovered principles of motion that diverge sharply from our everyday intuition, revealing physics as being essential to understanding microbial motility. In this review, we explore the fundamental physical principles that enable and constrain the motility strategies evolved by diverse microorganisms, with a focus on prokaryotes, to enable propulsion in fluids and along surfaces. We examine how microbial motility functions in complex, heterogeneous environments, and we provide a brief evolutionary perspective on microbial motility by highlighting its costs and benefits. In summary, we show how including a physical approach in the study of microbial motility both unveils general solutions and specific adaptations and enables a better understanding of a world for which our intuition is not trained.