Direct measurement of cell wall stress stiffening and turgor pressure in live bacterial cells. Author Yi Deng, Mingzhai Sun, Joshua Shaevitz Publication Year 2011 Type Journal Article Abstract 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±0.12, such that the wall is significantly stiffer in intact cells (E=23±8 MPa and 49±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±3 kPa. Keywords Escherichia coli, Models, Biological, Computer Simulation, Microscopy, Atomic Force, Stress, Mechanical, Microbial Viability, Cell Wall, Pressure, Rheology Journal Phys Rev Lett Volume 107 Issue 15 Pages 158101 Date Published 10/2011 Alternate Journal Phys. Rev. Lett. Google ScholarBibTeXEndNote X3 XML