Maria Tătulea-Codrean (Clare College, University of Cambridge) – Cooperative dynamics of bacterial flagella: harnessing multi-scale modelling in biological fluid mechanics

Abstract

Cooperation arises at all scales in the natural world, from the cooperative binding of receptors at the supramolecular scale to the migration of animals across continents. In this talk, we will construct and solve simple mathematical models to understand the mechanisms driving cooperative behaviours at the microscopic scale—namely, cooperative propulsion and spontaneous synchronization. The subject of these models is the bacterium Escherichia coli—one of the best studied model organisms in biology—and the slender helical appendages (flagella) that E. coli uses for propulsion. First, we will show that the hydrodynamic interactions between the flagella, coupled with the limited capacity for torque generation of the bacterial flagellar motor, lead to unexpected trends in the swimming speed of multiflagellated bacteria [1]. Next, we will propose and analyse an elastohydrodynamic mechanism that enables rotating flagella to spontaneously synchronize their phases without the involvement of a central pattern generator [2]. In both studies, we combine numerical and asymptotic techniques with pertinent information about the features of E. coli bacteria to gain new biophysical insights. If time allows, we will conclude by drawing analogies between the elastohydrodynamic mechanism for synchronization and another recently developed model based on load-dependent actuation with distributed time delay [3].

References:

[1] M. Tătulea-Codrean and E. Lauga (2024) Physical mechanism reveals bacterial slowdown above a critical number of flagella. J. R. Soc. Interface, 21:20240283.

[2] M. Tătulea-Codrean and E. Lauga (2022) Elastohydrodynamic synchronization of rotating bacterial flagella. Phys. Rev. Lett., 128:208101.

[3] N. Diederen and M. Tătulea-Codrean (2025) Hydrodynamic synchronization of rotating flagella with load-dependent actuation. In preparation.