Torque generation in the bacterial flagellar motor

Synopsis

The bacterial flagellar motor (BFM) drives swimming in a wide variety of bacterial species, making it crucial for several fundamental biological processes, including chemotaxis and community formation. Here, we put forward a model for the BFM's fundamental torque-generation mechanism, and show that our results can reproduce recent experiments from motors with a single torque-generator (stator). We extend our model to accommodate motors with multiple engaged stators and predict that the maximum speed of the BFM is not universal, as currently believed, but rather increases as additional torque-generators are recruited. We show that this assumption is consistent with current experimental evidence and consolidate our predictions with arguments that a processive motor must have a high duty ratio at high loads.