Measurement of the interconnected turgor pressure and envelope elasticity of live bacterial cells

Zhang, Huanxin; Wang, Huabin; Wilksch, Jonathan J.; Strugnell, Richard A.; Gee, Michelle L.; Feng, Xi‐Qiao

doi:10.1039/d0sm02075c

Cited by 9 publications

(22 citation statements)

References 44 publications

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“…Our result also provides new insights about the indentation stiffness of long, thin cylindrical shells. Cylinder indentation was previously studied in the zero-pressure limit [15] and the membrane limit which incorporated the effects of pressure-related stresses while ignoring elastic stiffness [13,30]. We connect these disparate regimes by exploiting a separation of pressure scales which arises for thin cylinders, which allowed us to calculate the indentation stiffness of cylindrical shells over a wide range of pressures (III G and FIG.…”

Section: Discussionmentioning

confidence: 99%

Indentation responses of pressurized ellipsoidal and cylindrical elastic shells: Insights from shallow-shell theory

Sun,

Paulose

2021

Preprint

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Pressurized elastic shells are ubiquitous in nature and technology, from the outer walls of yeast and bacterial cells to artificial pressure vessels. Indentation measurements simultaneously probe the internal pressure and elastic properties of thin shells, and serve as a useful tool for strength testing and for inferring internal biological functions of living cells. We study the effects of geometry and pressure-induced stress on the indentation stiffness of ellipsoidal and cylindrical elastic shells using shallow-shell theory. We show that the linear indentation response reduces to a single integral with two dimensionless parameters that encode the asphericity and internal pressure. This integral can be numerically evaluated in all regimes and is used to generate compact analytical expressions for the indentation stiffness in various regimes of technological and biological importance. Our results provide theoretical support for previous scaling and numerical results describing the stiffness of ellipsoids, reveal a new pressure scale that dictates the large-pressure response, and give new insights to the linear indentation response of pressurized cylinders.

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Section: Discussionmentioning

confidence: 99%

Indentation responses of pressurized ellipsoidal and cylindrical elastic shells: Insights from shallow-shell theory

Sun,

Paulose

2021

Preprint

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“…Resistor and a cross-sectional area of 0.8 µm 2 [34]; S. saprophyticus is a spherical microorganism that has a diameter of 1 µm [35]. The average doubling times for K. pneumoniae and S. saprophyticus in our microfluidic devices at 37 • C are 55 min.…”

Section: Microfluidicmentioning

confidence: 99%

“…Two microorganisms, Klebsiella pneumoniae (ATCC 13883) and Staphylococcus saprophyticus (ATCC 15305), are purchased from American Type Culture Collection (ATCC, Rockville, MD). K. pneumoniae is a Gramnegative, non-motile, rod-shaped bacterium that has a length of 2 − 3 µm and a cross-sectional area of 0.8 µm 2 [34]. S. saprophyticus is a Gram-positive, non-motile, spherical bacterium that has a diameter of 1 µm [35].…”

Section: Bacteria Preparationmentioning

confidence: 99%

“…The bacterium is modeled as a hollow cylinder with length l cyl = 2 µm, radius r cyl = 500 nm and wall thickness t = 26 nm, with two semi-spheres of the same radius and thickness attached to both ends, as shown in Fig. 12(a) [34]. The cell wall is modeled as a linear elastic material with Young's modulus E = 49 MPa, Poisson's ratio ν = 0.16, and density ρ b = 1, 100 kg/m 3 [34,85,86].…”

Section: Temperature Increase Due To Joule Heatingmentioning

confidence: 99%

“…The cell wall is modeled as a linear elastic material with Young's modulus E = 49 MPa, Poisson's ratio ν = 0.16, and density ρ b = 1, 100 kg/m 3 [34,85,86]. The inside of the bacterium is modeled as water under turgor pressure (p T = 29 kPa) [34]. The bacterium is surrounded by a sphere of water under atmospheric pressure.…”

Section: Temperature Increase Due To Joule Heatingmentioning

confidence: 99%

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Measurement of the Low-Frequency Charge Noise of Bacteria

Yang,

Gress,

Ekinci

2022

Preprint

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Bacteria meticulously regulate their intracellular ion concentrations and create ionic concentration gradients across the bacterial membrane. These ionic concentration gradients provide free energy for many cellular processes and are maintained by transmembrane transport. Given the physical dimensions of a bacterium and the stochasticity in transmembrane transport, intracellular ion concentrations and hence the charge state of a bacterium are bound to fluctuate. Here, we investigate the charge noise of 100s of non-motile bacteria by combining electrical measurement techniques from condensed matter physics with microfluidics. In our experiments, bacteria in a microchannel generate charge density fluctuations in the embedding electrolyte due to random influx and efflux of ions. Detected as electrical resistance noise, these charge density fluctuations display a power spectral density proportional to 1/f 2 for frequencies 0.05 Hz ≤ f ≤ 1 Hz. Fits to a simple noise model suggest that the steady-state charge of a bacterium fluctuates by ±1.30 × 10 6 e (e ≈ 1.60 × 10 −19 C), indicating that bacterial ion homeostasis is highly dynamic and dominated by strong charge noise. The rms charge noise can then be used to estimate the fluctuations in the membrane potential; however, the estimates are unreliable due to our limited understanding of the intracellular concentration gradients.

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Mechanical–electrochemical coupling theory of bacterial cells

Zhang

Wang

Gao

et al. 2022

International Journal of Solids and Structures

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Measurement of the interconnected turgor pressure and envelope elasticity of live bacterial cells

Abstract: Turgor pressure and envelope elasticity of bacterial cells are two mechanical parameters that play a dominant role in cellular deformation, division and motility. However, a clear understanding of these two...

Cited by 9 publications

References 44 publications

Indentation responses of pressurized ellipsoidal and cylindrical elastic shells: Insights from shallow-shell theory

Indentation responses of pressurized ellipsoidal and cylindrical elastic shells: Insights from shallow-shell theory

Measurement of the Low-Frequency Charge Noise of Bacteria

Mechanical–electrochemical coupling theory of bacterial cells

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