Albane Thery

Twisting and buckling in bacteria: from individual to collective effects

Our picture of bacterial motility relies on model organisms such as E. coli, often ignoring the diverse morphology of bacteria. In this talk, I will discuss how attempting to apply the classical helical flagellum-motor-body framework to the motile oral pathogen Selenonomas sputigena, in collaboration with the UPenn Dental School, instead led us to new questions relating bacterial architecture and motility. “Why do these bacteria have a helical shape?” and “Why are their flagella implanted to the side”? I will present the elasto-hydrodynamic model we are using to study the coupling between body shape and flagellar position, including regimes where buckling and large deformations of the flagellum occur.
Large mechanical deformations—such as twisting and knot formation—also arise at the collective scale. I will show how similar modelling approaches can inform our understanding of filamentous cyanobacterial gliding motility at the colony scale, and the formation of macroscopic structures.
By highlighting the role of large deformations in bacterial behaviour, I hope to discuss the limitations of analytical approaches and large-scale simulations for microbial cell mechanics models.