Entrapment of pusher and puller bacteria near a solid surface

Wu, Kuan; Hsiao, Yi Teng; Woon, Wei Yen

doi:10.1103/physreve.98.052407

Cited by 15 publications

(20 citation statements)

References 31 publications

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“…This provides support for a deterministic departure mechanism, such as the combination of cell rotation and flagellar contact proposed by refs. 21 and 24, rather than the entrapment and noise-mediated release observed for other swimmer geometries (48).…”

Section: Near-surface Interactions and Scatteringmentioning

confidence: 84%

Hopping trajectories due to long-range interactions determine surface accumulation of microalgae

Buchner

Muller

Mehmood

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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The accumulation of motile cells at solid interfaces increases the rate of surface encounters and the likelihood of surface attachment, leading to surface colonization and biofilm formation. The cell density distribution in the vicinity of a physical boundary is influenced by the interactions between the microswimmers and their physical environment, including hydrodynamic and steric interactions, as well as by stochastic effects. Disentangling the contributions of these effects remains an experimental challenge. Here, we use a custom-made four-camera view microscope to track a population of motile puller-type Chlamydomonas reinhardtii in a relatively unconstrained three-dimensional (3D) domain. Our experiments yield an extensive sample of 3D trajectories including cell-surface encounters with a planar wall, from which we extract a full description of the dynamics and the stochasticity of swimming cells. We use this large data sample and combine it with Monte Carlo simulations to determine the link between the dynamics at the single-cell level and the cell density. Our experiments demonstrate that the near-wall scattering is bimodal, corresponding to steric and hydrodynamic effects. We find, however, that this near-wall dynamics has little influence on the cell accumulation at the surface. On the other hand, we present evidence of a cell-induced surface-directed rotation leading to a vertical orbiting behavior and hopping trajectories, consistent with long-range hydrodynamic effects. We identify this long-range effect to be at the origin of the significant surface accumulation of cells.

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Section: Near-surface Interactions and Scatteringmentioning

confidence: 84%

Hopping trajectories due to long-range interactions determine surface accumulation of microalgae

Buchner

Muller

Mehmood

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…Such a comparison must distinguish between "pusher" and "puller" type microbes. Since "pusher" type microbes hydrodynamically attracted to solid surfaces, the searching process for exit holes may be enhanced because of efficient surface-mediated searching, while "puller" type microbes may exhibit longer search times since they are hydrodynamically repelled from solid surfaces (58)(59)(60). Therefore, compared to "pusher" type microbes, the transport of "puller" type microbes in porous media is expected to be inhibited.…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of transport enhancement for self-propelled nanoswimmers in a porous matrix

Greydanus

Schwartz

2021

Proc. Natl. Acad. Sci. U.S.A.

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Micro/nanoswimmers convert diverse energy sources into directional movement, demonstrating significant promise for biomedical and environmental applications, many of which involve complex, tortuous, or crowded environments. Here, we investigated the transport behavior of self-propelled catalytic Janus particles in a complex interconnected porous void space, where the rate-determining step involves the escape from a cavity and translocation through holes to adjacent cavities. Surprisingly, self-propelled nanoswimmers escaped from cavities more than 20× faster than passive (Brownian) particles, despite the fact that the mobility of nanoswimmers was less than 2× greater than that of passive particles in unconfined bulk liquid. Combining experimental measurements, Monte Carlo simulations, and theoretical calculations, we found that the escape of nanoswimmers was enhanced by nuanced secondary effects of self-propulsion which were amplified in confined environments. In particular, active escape was facilitated by anomalously rapid confined short-time mobility, highly efficient surface-mediated searching for holes, and the effective abolition of entropic and/or electrostatic barriers at the exit hole regions by propulsion forces. The latter mechanism converted the escape process from barrier-limited to search-limited. These findings provide general and important insights into micro/nanoswimmer mobility in complex environments.

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“…Though the squirmer was first developed as a model to understand ciliary propulsion, it is now widely used to study other types of microswimmers broadly classified as pullers and pushers [6,36]. While pullers have an extensile force dipole, resulting, e.g., from the front part of the body, pushers have a contractile force dipole stemming, e.g., from the rear part of the body [7].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics of chiral squirmers

Burada,

Maity,

Jülicher

2021

Preprint

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Many microorganisms take a chiral path while swimming in an ambient fluid. In this paper, we study the combined behavior of two chiral swimmers using the well-known squirmer model taking into account chiral asymmetries. In contrast to the simple squirmer model, which has an axisymmetric distribution of slip velocity, the chiral squirmer has additional asymmetries in the surface slip, which contribute to both translations and rotations of the motion. As a result, swimming trajectories can become helical and chiral asymmetries arise in the flow patterns. We study the swimming trajectories of a pair of chiral squirmers that interact hydrodynamically. This interaction can lead to attraction and repulsion, and in some cases even to bounded states where the swimmers continue to periodically orbit around a common average trajectory. Such bound states are a signature of the chiral nature of the swimmers. Our study could be relevant to the collective movements of ciliated microorganisms.

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Entrapment of pusher and puller bacteria near a solid surface

Cited by 15 publications

References 31 publications

Hopping trajectories due to long-range interactions determine surface accumulation of microalgae

Hopping trajectories due to long-range interactions determine surface accumulation of microalgae

Mechanisms of transport enhancement for self-propelled nanoswimmers in a porous matrix

Hydrodynamics of chiral squirmers

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