Fluid mechanics of swimming bacteria with multiple flagella

Kanehl, Philipp; Ishikawa, Takuji

doi:10.1103/physreve.89.042704

Cited by 34 publications

(27 citation statements)

References 20 publications

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“…Our results indicate that while both cell shape and flagellum number independently affect swimming speed, flagellum number contributes to a larger alteration in speed as compared with changing cell shape. Recent modeling studies of bacteria with different numbers of peritrichous flagella predict that swimming speed increases logarithmically with increased flagellation (Kanehl and Ishikawa, ). While we assumed a linear model based on our experimental observations, a logarithmic dependence gives comparable results, predicting an increase of ∼ 26% when comparing bacteria with four versus three flagella, and supports our observations that swimming speed correlates with flagellum number.…”

Section: Discussionmentioning

confidence: 99%

Helicobacter pylori strains vary cell shape and flagellum number to maintain robust motility in viscous environments

Martínez

Hardcastle

Wang

et al. 2015

Molecular Microbiology

147

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Summary The helical shape of the human stomach pathogen Helicobacter pylori has been suggested to provide mechanical advantage for penetrating the viscous stomach mucus layer. Using single-cell tracking and quantitative morphology analysis we document marked variation in cell body helical parameters and flagellum number among H. pylori strains leading to distinct and broad speed distributions in broth and viscous gastric mucin media. These distributions reflect both temporal variation in swimming speed and morphologic variation within the population. Isogenic mutants with straight-rod morphology showed 7–21% reduction in speed and a lower fraction of motile bacteria. Mutational perturbation of flagellum number revealed a 19% increase in speed with 4 vs. 3 median flagellum number. Resistive force theory modeling incorporating variation of both cell shape and flagellum number predicts qualitative speed differences of 10–30% among strains. However, quantitative comparisons suggest RFT underestimates the influence of cell body shape on speed for helical shaped bacteria.

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Section: Discussionmentioning

confidence: 99%

Helicobacter pylori strains vary cell shape and flagellum number to maintain robust motility in viscous environments

Martínez

Hardcastle

Wang

et al. 2015

Molecular Microbiology

147

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“…We then consider the situation where the cell body is stuck on the wall, a configuration where all characteristics of the experiments are precisely known. Boundary element methods have long been used to study problems in bacteria locomotion including flagellar propulsion [23], interaction between two swimming bacteria [24], bacterial behaviour and entrapment close to surfaces [25,26], and locomotion using multiple flagella [27]. Similarly, slender-body theory has been used to address problems in bacterial swimming such as bacterial polymorphism and optimal propulsion [28] and microscale pumping by bacteria near walls [29].…”

Section: Introductionmentioning

confidence: 99%

Computing the motor torque ofEscherichia coli

Das

Lauga

2018

Soft Matter

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The rotary motor of bacteria is a natural nano-technological marvel that enables cell locomotion by powering the rotation of semi-rigid helical flagellar filaments in fluid environments. It is well known that the motor operates essentially at constant torque in counter-clockwise direction but past work have reported a large range of values of this torque. Focusing on Escherichia coli cells that are swimming and cells that are stuck on a glass surface for which all geometrical and environmental parameters are known (N. C. Darnton et al., J. Bacteriol., 2007, 189, 1756-1764), we use two validated numerical methods to compute the value of the motor torque consistent with experiments. Specifically, we use (and compare) a numerical method based on the boundary integral representation of Stokes flow and also develop a hybrid method combining boundary element and slender body theory to model the cell body and flagellar filament, respectively. Using measured rotation speed of the motor, our computations predict a value of the motor torque in the range 440 pN nm to 829 pN nm, depending critically on the distance between the flagellar filaments and the nearby surface.

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“…A variety of computational methods have been developed to tackle it including slender-body theory [12][13][14], boundary elements to implement boundary integral formulations [15], the immersed boundary method [16,17], regularised flow singularities [18] and particlebased methods [19,20].…”

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confidence: 99%

Hydrodynamic interactions between nearby slender filaments

Man

Koens

Lauga

2016

EPL

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Cellular biology abound with filaments interacting through fluids, from intracellular microtubules, to rotating flagella and beating cilia. While previous work has demonstrated the complexity of capturing nonlocal hydrodynamic interactions between moving filaments, the problem remains difficult theoretically. We show here that when filaments are closer to each other than their relevant length scale, the integration of hydrodynamic interactions can be approximately carried out analytically. This leads to a set of simplified local equations, illustrated on a simple model of two interacting filaments, which can be used to tackle theoretically a range of problems in biology and physics.While one tends to think of biological cells as stubby, their environment is in fact rich with filamentous structures. Inside cells, polymeric filaments of microtubules, actin, and intermediate filaments fill the eukaryotic cytoplasm [1] and provide it with its mechanical structure [2]. Outside cells, the motion of flagella and cilia allows cells to generate propulsive forces [3][4][5] and induces flows critical to human health [6,7].In all cases, these biological filaments are immersed in a viscous fluid in which they move at low Reynolds number, be it due to their polymerisation, to fluctuations and thermal forces, or to the action of molecular motors [8]. At low Reynolds number, the flows induced locally by the motion of filaments relative to a background fluid have a slow spatial decay as ∼ 1/r [9,10]. In situations where filaments are close to each other, we thus expect nonlocal hydrodynamic interactions to be important [11].Integrating long-ranged hydrodynamic interactions between filaments has long been recognised as a challenging problem, and one where the theoretical approach has consisted of either full numerical simulations or very simplified analysis. A variety of computational methods have been developed to tackle it including slender-body theory [12][13][14], boundary elements to implement boundary integral formulations [15], the immersed boundary method [16,17], regularised flow singularities [18] and particlebased methods [19,20].While these computational approaches allow to address complex geometries and dynamics, the difficulty of integrating long-range hydrodynamic interactions has prevented analytical approaches from providing insight beyond simplified setups. The two most common approaches in biophysics consist in replacing the dynamics in three dimensions by a two-dimensional problem for which the analysis may be easier to carry out [21,22], or by focusing on far-field hydrodynamic interactions and ignoring the geometrical details of near-field hydrodynamics, a popular approach to study synchronisation of flagella and cilia [23][24][25][26][27][28][29] Fig. 6. In each event, the head became the tail (at least once). For an angle change of 0°, the cell exhibited successive reversals; this was rare. For an angle change of 180°, the cell backed up without changing the orientation of its long axis (the head became th...

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Fluid mechanics of swimming bacteria with multiple flagella

Cited by 34 publications

References 20 publications

Helicobacter pylori strains vary cell shape and flagellum number to maintain robust motility in viscous environments

Helicobacter pylori strains vary cell shape and flagellum number to maintain robust motility in viscous environments

Computing the motor torque ofEscherichia coli

Hydrodynamic interactions between nearby slender filaments

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