A 3D Motile Rod-Shaped Monotrichous Bacterial Model

Abstract

We introduce a 3D model for a motile rod-shaped bacterial cell with a single polar flagellum which is based on the configuration of a monotrichous type of bacteria such as Pseudomonas aeruginosa. The structure of the model bacterial cell consists of a cylindrical body together with the flagellar forces produced by the rotation of a helical flagellum. The rod-shaped cell body is composed of a set of immersed boundary points and elastic links. The helical flagellum is assumed to be rigid and modeled as a set of discrete points along the helical flagellum and flagellar hook. A set of flagellar forces are applied along this helical curve as the flagellum rotates. An additional set of torque balance forces are applied on the cell body to induce counter-rotation of the body and provide torque balance. The three dimensional Navier-Stokes equations for incompressible fluid are used to described the fluid dynamics of the coupled fluid-microorganism system using Peskin's immersed boundary method. A study of numerical convergence is presented along with simulations of a single cell and the interaction of two model cells.

Swimming Behavior of Pseudomonas aeruginosa Studied by Holographic 3D Tracking

“…Theoretical simulations for the motility of monotrichous, rod-shaped bacteria predict nearly linear helical trajectories for both, forward and backward swimming [50]. For other microorganisms moving at low Reynolds numbers helical motion is known to be the default trajectory [48], [49], [51].…”

A general formulation of Bead Models applied to flexible fibers and active filaments at low Reynolds number

“…Many of the flagellate microorganisms such as spermatozoa, bacteria or artificial microdevices use spiral swimming to propel through viscous fluid. Propulsion with rotating rigid or flexible filaments has been thoroughly investigated in the past years ( [86,36,87,56,24,88,77]). In this section we illustrate the versatility of the proposed model by investigating the effect of the Sperm number and the eccentricity of the swimming gait on the swimming speed of C. Elegans.…”

Modeling polymorphic transformation of rotating bacterial flagella in a viscous fluid

“…A similar approach is to use regularized stokeslets [34,35], which yields a similar result to slender-body theory for rigid helices [36] but can be extended to elastic filaments [34]. Recent studies have used full three-dimensional numerical computations of the Navier–Stokes equations in an immersed boundary framework to capture the two-way fluid-structure interaction between the filament and the aqueous environment [37,38]. In particular, Lim and Peskin [38] incorporated the Kirchhoff rod theory to describe the flagellar dynamics of a pair of monostable helical filaments interacting with the surrounding viscous fluid.…”