Optical Force Measurements Illuminate Dynamics of Escherichia coli in Viscous Media

Armstrong, Declan; Nieminen, Timo A.; Favre‐Bulle, Itia A.; Stilgoe, Alexander B.; Lenton, Isaac C. D.; Schembri, Mark A.; Rubinsztein‐Dunlop, Halina

doi:10.3389/fphy.2020.575732

Cited by 4 publications

(2 citation statements)

References 25 publications

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“…(1). Although models predict a viscosity dependence, recent studies have found that F is independent of viscosity ( Armstrong et al, 2020 ). This equation of motion yields a terminal velocity of…”

Section: Introductionmentioning

confidence: 99%

Quantification of Motility in Bacillus subtilis at Temperatures Up to 84°C Using a Submersible Volumetric Microscope and Automated Tracking

et al. 2022

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We describe a system for high-temperature investigations of bacterial motility using a digital holographic microscope completely submerged in heated water. Temperatures above 90°C could be achieved, with a constant 5°C offset between the sample temperature and the surrounding water bath. Using this system, we observed active motility in Bacillus subtilis up to 66°C. As temperatures rose, most cells became immobilized on the surface, but a fraction of cells remained highly motile at distances of >100 μm above the surface. Suspended non-motile cells showed Brownian motion that scaled consistently with temperature and viscosity. A novel open-source automated tracking package was used to obtain 2D tracks of motile cells and quantify motility parameters, showing that swimming speed increased with temperature until ∼40°C, then plateaued. These findings are consistent with the observed heterogeneity of B. subtilis populations, and represent the highest reported temperature for swimming in this species. This technique is a simple, low-cost method for quantifying motility at high temperatures and could be useful for investigation of many different cell types, including thermophilic archaea.

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Section: Introductionmentioning

confidence: 99%

Quantification of Motility in Bacillus subtilis at Temperatures Up to 84°C Using a Submersible Volumetric Microscope and Automated Tracking

et al. 2022

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“…We show, in an experiment, that single descents can be used to calibrate the optical trap where large trap strengths restrict the performance of equilibrium measurements as they are in a regime where the signal is too close to the detection noise floor. This type of calibration is ideal for multiple and dynamic optical traps to rapidly determine the swimming forces of optically driven micromachines, active matter, and cells on the two micron size scale [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Signal-to-Noise and Fast Calibration of Optical Tweezers Using Single Trapping Events

2021

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The trap stiffness us the key property in using optical tweezers as a force transducer. Force reconstruction via maximum-likelihood-estimator analysis (FORMA) determines the optical trap stiffness based on estimation of the particle velocity from statistical trajectories. Using a modification of this technique, we determine the trap stiffness for a two micron particle within 2 ms to a precision of ∼10% using camera measurements at 10 kfps with the contribution of pixel noise to the signal being larger the level Brownian motion. This is done by observing a particle fall into an optical trap once at a high stiffness. This type of calibration is attractive, as it avoids the use of a nanopositioning stage, which makes it ideal for systems of large numbers of particles, e.g., micro-fluidics or active matter systems.

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Direct measurement of self-diffusiophoretic force generated by active colloids of different patch coverage using optical tweezers

Raj,

Roy,

Kumar

et al. 2025

Journal of Colloid and Interface Science

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Optical Force Measurements Illuminate Dynamics of Escherichia coli in Viscous Media

Cited by 4 publications

References 25 publications

Quantification of Motility in Bacillus subtilis at Temperatures Up to 84°C Using a Submersible Volumetric Microscope and Automated Tracking

Quantification of Motility in Bacillus subtilis at Temperatures Up to 84°C Using a Submersible Volumetric Microscope and Automated Tracking

Enhanced Signal-to-Noise and Fast Calibration of Optical Tweezers Using Single Trapping Events

Direct measurement of self-diffusiophoretic force generated by active colloids of different patch coverage using optical tweezers

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