Cooperation occurs at all scales in the natural world, from the cooperative binding of ligands on
the molecular scale, to the coordinated migration of animals across continents. To understand
the key principles and mechanisms underlying cooperative behaviours, researchers tend to
focus on understanding a small selection of model organisms. In this talk, we will look through a
mathematician’s lens at one of the most well-studied model organisms in biology—the multiflagellated bacterium Escherichia coli.
First, we will introduce the basic features of swimming at the microscopic scale, both biological
(the flagellum) and mathematical (the Stokes equations). Then, we will describe two recent
theoretical developments on the cooperative dynamics of bacterial flagella: an
elastohydrodynamic mechanism that enables independent bacterial flagella to coordinate their
rotation, and a load-sharing mechanism through which multiple flagellar motors split the
burden of torque generation in a swimming bacterium. These results are built on a foundation of
classical asymptotic approaches (e.g., multiple-scale analysis) and prominent mathematical
models (e.g., Adler’s equation) that will be familiar to mathematicians working in many areas of
applied mathematics.