Slowdown of surface diffusion during early stages of bacterial colonization

Vourc’h, Thomas; Peerhossaini, Hassan; Léopoldès, J.; Méjean, Annick; Chauvat, F.; Cassier‐Chauvat, Corinne

doi:10.1103/physreve.97.032407

Cited by 11 publications

(35 citation statements)

References 35 publications

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“…Once the bacteria (in suspension) have been placed in the measurement cell, they are let free to sediment on the lower surface of the cell and diffuse for two hours, so that their diffusion coefficient reaches a plateau value, as is explained in [11]. Then, light intensity is increased for one hour and we record the changes in the motility that occurs after this perturbation.…”

Section: Resultsmentioning

confidence: 99%

“…The obtained observation cell is then turned over so that we observe the displacement of the bacteria on the glass coverslip, and placed on the stage of an inverted optical microscope coupled to a CCD camera. Detailed description of the experimental set-up and procedures are given in [11].…”

Section: Experimental Conditionsmentioning

confidence: 99%

“…Experiments start by setting the light intensity at I0 for two hours so that the bacteria reach their motility plateau [11]. The intensity is then increased to the higher value for one hour, which defines a step.…”

Section: Control Of Isotropic Lightmentioning

confidence: 99%

“…We have previously described the diffusion coefficient of Synechocystis bacteria in terms of intermittency by the formula [11]:…”

Section: Evolution Of the Diffusion Coefficientmentioning

confidence: 99%

“…This is a unicellular prokaryote, whose genome has been completely determined [8], and which is a typical microorganism for the investigation of photosynthesis [9]. We have previously characterized the intermittent motility of these bacteria, based on the alternation of "run" periods during which they move, and "tumble" periods which consist of localized motion [10,11]. We have also studied the effects of hydrodynamic stress on the growth of Synechocystis sp.…”

Section: Introductionmentioning

confidence: 99%

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Light Control of the Diffusion Coefficient of Active Fluids

Vourc’h

Léopoldès

Peerhossaini

2020

Journal of Fluids Engineering

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Active fluids refer to the fluids that contain self-propelled particles such as bacteria or micro-algae, whose properties differ fundamentally from the passive fluids. Such particles often exhibit an intermittent motion, with high-motility "run" periods broken by low-motility "tumble" periods. The average motion can be modified with external stresses, such as nutrient or light gradients, leading to a directed movement called chemotaxis and phototaxis, respectively. Using cyanobacterium Synechocystis sp.PCC 6803, a model micro-organism to study photosynthesis, we track the bacterial response to light stimuli, under isotropic and non-isotropic (directed) conditions. In particular, we investigate how the intermittent motility is influenced by illumination. We find that just after a rise in light intensity, the probability to be in the run state increases. This feature vanishes after a typical characteristic time of about 1 hour, when initial probability is recovered. Our results are well described by a mathematical model based on the linear response theory. When the perturbation is anisotropic, we observe a collective motion toward the light source (phototaxis). We show that the bias emerges due to more frequent runs in the direction of the light, whereas the run durations are longer whatever the direction.

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Section: Resultsmentioning

confidence: 99%

Section: Experimental Conditionsmentioning

confidence: 99%

Section: Control Of Isotropic Lightmentioning

confidence: 99%

“…We have previously described the diffusion coefficient of Synechocystis bacteria in terms of intermittency by the formula [11]:…”

Section: Evolution Of the Diffusion Coefficientmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Light Control of the Diffusion Coefficient of Active Fluids

Vourc’h

Léopoldès

Peerhossaini

2020

Journal of Fluids Engineering

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Growth and pigment production of Synechocystis sp. PCC 6803 under shear stress

et al. 2022

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Cyanobacteria, such as Synechocystis, have recently become attractive hosts for sustainable production of biofuels and bio‐fixation of CO2 due to their genetic tractability and relatively fast growth. Cultivation of cyanobacteria requires shear stress, which is generated by mixing and air bubbling. In the present work, the impact of shear stress caused by stirring and air bubbling on the growth and pigment production of Synechocystis sp. PCC 6803 is investigated. For this purpose, agitated and airlift bubble column photobioreactors were used. The results showed that the growth and yield production were improved by mixing the culture system. However, there is a limit to this improvement: In the case of air bubbling, increasing shear stress (by rising air bubbling flow rate) to more than 185 mPa did not show any significant growth enhancement, while increasing the shear stress from 40 to 185 mPa improved the yield production up to 85%. At the optimal stirring rate, the yield production in the stirred photobioreactors increased by about 60% as compared to that of unstirred culture. The measurements of chlorophylla and carotenoid showed a strong correlation between biomass production and total pigment content. The highest level of cellular pigment (pigment per cell) was detected at the early stages of culture growth when cells were preparing for the rapid exponential growth phase.

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Genomics of cyanobacteria: New insights and lessons for shaping our future—A follow-up of volume 65: Genomics of cyanobacteria

Chauvat

Cassier‐Chauvat

2021

Advances in Botanical Research

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Cyanobacteria, the only known photosynthetic prokaryotes, are ancient organisms regarded as the producers of the Earth's oxygenic atmosphere and the ancestors of plant chloroplasts. Contemporary cyanobacteria have evolved as widely-diverse organisms in colonizing most aquatic and soil biotopes, where they face various environmental challenges and competition or symbiosis with other organisms. Cyanobacteria exhibit a wide morphological diversity (unicellular/multicellular, cylindrical/spherical shapes) and many species differentiate specialized cells for growth and survival under adverse conditions. They convert captured solar energy at high efficiencies, to fix an enormous amount of carbon from CO 2 into a huge biomass that sustains a large part of the food chain, and they tolerate high CO 2 content in gas streams. They also synthesize a vast array of biologically active metabolites with great interests for human health and industries. Hence, they are viewed as promising "low-cost" cell factories for the carbon-neutral production of chemicals, thanks to their simple nutritional requirements, their metabolic robustness and plasticity, and the powerful genetics of some model strains.In 2013 when ABR vol 65 entitled "Genomics of Cyanobacteria" was published, approximately 70 cyanobacteria had their genomes fully or partially sequenced. Since then, the number has increased up to about 2000 (https:// genome.jgi.doe.gov/portal/), genome editing studies using CRISPR/Cas have been reported in several model cyanobacteria (Gale et al., 2019; ☆

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Slowdown of surface diffusion during early stages of bacterial colonization

Cited by 11 publications

References 35 publications

Light Control of the Diffusion Coefficient of Active Fluids

Light Control of the Diffusion Coefficient of Active Fluids

Growth and pigment production of Synechocystis sp. PCC 6803 under shear stress

Genomics of cyanobacteria: New insights and lessons for shaping our future—A follow-up of volume 65: Genomics of cyanobacteria

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