A new mode of swimming in singly flagellated
            <i>Pseudomonas aeruginosa</i>

Tian, Maojin; Wu, Zhengyu; Zhang, Rongjing; Yuan, Junhua

doi:10.1073/pnas.2120508119

“…Other bacterial species have been observed to wrap their extracellular (unsheathed) flagella around themselves (Alirezaeizanjani et al, 2020; Cohen et al, 2020; Constantino et al, 2018; Hintsche et al, 2017; Kühn et al, 2017; Tian et al, 2022). This behavior, which Shewanella putrefaciens uses to burrow back out of a tight spot when stuck, is triggered by a mechanical instability in the flagellum that buckles it when the cell can no longer move to alleviate the torque of flagellar rotation (Kühn et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Dynamic structural adaptations enable the endobiotic predation ofbdellovibrio bacteriovorus

Kaplan

¹

,

Chang

²

,

Oikonomou

³

et al. 2022

Preprint

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Bdellovibrio bacteriovorusis an endobiotic microbial predator that offers promise as a living antibiotic for its ability to kill Gram-negative bacteria, including human pathogens. Even after six decades of study, fundamental details of its predation cycle remain mysterious. Here, we used cryo-electron tomography to comprehensively image the lifecycle ofB. bacteriovorusat nanometer-scale resolution. In addition to providing the first high-resolution images of predation in a native (hydrated, unstained) state, we also discover several surprising features of the process, including novel macromolecular complexes involved in prey attachment/invasion and a flexible portal structure lining a hole in the prey peptidoglycan that tightly seals the prey outer membrane around the predator during entry. Unexpectedly, we find thatB. bacteriovorusdoes not shed its flagellum during invasion, but rather resorbs it into its periplasm for degradation. Finally, following replication and division in the bdelloplast, we observe a transient and extensive ribosomal lattice on the condensedB. bacteriovorusnucleoid.Graphical abstract

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“…Bacterial motility in our simulations is modeled as a classic run-and-tumble algorithm with a uniform turn angle distribution to minimize bias to the computational results due to parameter choice. However, P. aeruginosa motility differs and follows a “run-reverse” or “run-reverse-pause” pattern with a different turn angle distribution ( 41 ). We strategically tested the influence of different turn angle distributions on the resulting colonization efficiency of the experimental twin geometry and found that the trend of reduced colonization efficiency as a function of the settling velocity and higher colonization efficiency by the chemotactic cells remains unchanged ( Supplementary Fig.…”

Section: Discussionmentioning

confidence: 99%

Porous marine snow differentially benefits chemotactic, motile, and nonmotile bacteria

Borer

¹

,

Zhang

²

,

Baker

³

et al. 2022

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Particulate organic carbon settling through the marine water column is a key process that regulates global climate by sequestering atmospheric carbon. The initial colonization of marine particles by heterotrophic bacteria represents the first step in recycling this carbon back to inorganic constituents—setting the magnitude of vertical carbon transport to the abyss. Here, we demonstrate experimentally using millifluidic devices that although bacterial motility is essential for effective colonization of a particle leaking organic nutrients into the water column, chemotaxis specifically benefits at intermediate and higher settling velocities to navigate the particle boundary layer during the brief window of opportunity provided by a passing particle. We develop an individual-based model that simulates the encounter and attachment of bacterial cells with leaking marine particles to systematically evaluate the role of different parameters associated with bacterial run-and-tumble motility. We further use this model to explore the role of particle microstructure on the colonization efficiency of bacteria with different motility traits. We find that the porous microstructure facilitates additional colonization by chemotactic and motile bacteria, and fundamentally alters the way non-motile cells interact with particles due to streamlines intersecting with the particle surface.

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“…Bacterial motility in our simulations is modelled as a classic run-and-tumble algorithm with a uniform turn angle distribution to minimize bias to the computational results due to parameter choice. However, P. aeruginosa motility differs and follows a “run-reverse” or “run-reverse-pause” pattern with a different turn angle distribution 45 . We strategically tested the influence of different turn angle distributions on the resulting colonization efficiency of the experimental twin geometry and found that the trend of reduced colonization efficiency as a function of the settling velocity and higher colonization efficiency by the chemotactic cells remains unchanged (SI Fig.…”

Section: Discussionmentioning

confidence: 99%

Porous marine snow differentially benefits chemotactic, motile, and non-motile bacteria

Borer

¹

,

Zhang

²

,

Baker

³

et al. 2022

Preprint

View full text Add to dashboard Cite

Particulate organic carbon settling through the marine water column is a key process that regulates global climate by sequestering atmospheric carbon. The initial colonization of marine particles by heterotrophic bacteria represents the first step in recycling this carbon back to inorganic constituents – setting the magnitude of vertical carbon transport to the abyss. Here, we demonstrate experimentally that bacterial motility is required for particle colonization and chemotaxis specifically benefits at higher settling velocities. We further explore the role of particle microstructure on the colonization efficiency of bacteria with different motility traits. We highlight that non-motile cells benefit disproportionally from the porous microstructure and are relatively enriched in the particle wake due to the efficient particle colonization of chemotactic and motile cells. Our results imply that although the chemotactic and motile bacteria benefit from the high nutrient availability when colonizing the particles, scavenging of these cells benefits the often oligotrophic, non-motile cells common among the planktonic community.Significance statementBacteria in the ocean rely on ephemeral nutrient patches from sinking marine particles, but attaching to these structures is challenging as particle settling rates often exceed bacterial swimming velocities and the numerically dominant marine bacteria are non-motile – posing an interesting paradox about the prominence of particle foraging. Here, we quantify the importance of chemotaxis and motility for the efficient colonization of marine particles and find that although chemotaxis provides a clear advantage, motility is the basic requirement for particle colonization. We expand this analysis to consider highly heterogeneous particle structures and find a disproportionate benefit for non-motile cells by facilitating a direct encounter with the particle surface and enriching non-motile microbes in the nutrient-rich particle plume.

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A new mode of swimming in singly flagellated Pseudomonas aeruginosa

Cited by 24 publications

References 35 publications

Dynamic structural adaptations enable the endobiotic predation ofbdellovibrio bacteriovorus

Dynamic structural adaptations enable the endobiotic predation ofbdellovibrio bacteriovorus

Porous marine snow differentially benefits chemotactic, motile, and nonmotile bacteria

Porous marine snow differentially benefits chemotactic, motile, and non-motile bacteria

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