Probing spiroplasma's cytoskeletal motility mechanism through hydrodynamic modelling and experiment.

Abstract

Nearly all swimming bacteria have evolved to utilize external, helical, rotating appendages called flagella to achieve motility. These flagella are anchored into a cell wall which provides a structural rigidity during the swimming process. Contrary to this, a unique helical bacterium called spiroplasma has neither a cell wall nor flagella, yet still swims in water. Instead, this bacterium utilizes a set of actively deformable cytoskeletal filaments, internal to the cell, which allow for swimming motility. These filaments force the cell's bilayer membrane to deform, however, the interaction between the membrane and these filaments is unclear. Using this information, we have created an algorithm to handle this motility using the regularized stokeslet method which accurately describes spiroplasma's motion and used microscopy at varying viscosities to prove this description. We describe how our simulations found unique features of spiroplasma's motility and what this means for the interaction between spiroplasma's cytoskeleton and membrane.