Eur. Phys. J. E (2022) 45: 34
https://doi.org/10.1140/epje/s10189-022-00188-0

Regular Article - Living Systems

A physical mechanism underlying the torque generation of the bacterial flagellar motor

Department of Physics, National TsingHua University, Hsinchu, Taiwan, Republic of China

^a ycchou@phys.nthu.edu.tw

Received: 26 January 2022
Accepted: 25 March 2022
Published online: 11 April 2022

Abstract

This study proposes a physical mechanism underlying the torque generation of a bacterial flagellar motor (BFM), in which the torque for the rotation of the rotor can be generated from impulsive forces resulting from collisions between the randomly moving stator and rotor. The torque required for the rotation of the rotor may be generated through two coexisting mechanisms: mechanism (A), in which the stator collides with the rotor, whose rotation axis fluctuates asymmetrically, generating a torque in the direction of the rod, and mechanism (B), in which physical collisions between the stator and the asymmetric and generate the torque in the direction of the rod. Mechanism (A) might be related the bidirectional rotation and the tumbling of the motion of the cell. Mechanism (B) might be related to occurrence of the steps in the time traces of the rotational angle, backward stepping or switching of the rotational direction, and the knee-shaped – relation. The above-mentioned characteristics of the rotation of BFM are reproduced in a model device designed to confirm the applicability of the proposed concept to real BFM. Moreover, a prediction of the disappearance of the knee-shaped – relation of the actual BFM at a high temperature is proposed.