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Direct measurement of cell wall stress-stiffening and turgor pressure in live bacterial cells

By Yi Deng, Mingzhai Sun and Joshua W. Shaevitz


We study intact and bulging Escherichia coli cells using atomic force microscopy to separate the contributions of the cell wall and turgor pressure to the overall cell stiffness. We find strong evidence of power-law stress-stiffening in the E. coli cell wall, with an exponent of 1.22 \pm 0.12, such that the wall is significantly stiffer in intact cells (E = 23 \pm 8 MPa and 49 \pm 20 MPa in the axial and circumferential directions) than in unpressurized sacculi. These measurements also indicate that the turgor pressure in living cells E. coli is 29 \pm 3 kPa.Comment: Main Text: 4 pages, 4 figures. Supplemental Materials: 9 page

Topics: Physics - Biological Physics, Quantitative Biology - Biomolecules
Year: 2011
DOI identifier: 10.1103/PhysRevLett.107.158101
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