Before revision:  We find strong evidence of power-law stress-stiffening in the E. coli cell wall, with an exponent of 1.07 \pm 0.25 , such that the wall is significantly stiffer in live cells (E  MPa\pm \pm  ) than in unpressurized saculli .
After revision:  We find strong evidence of power-law stress-stiffening in the E. coli cell wall, with an exponent of 1.07 \pm 0.25 , such that the wall is significantly stiffer in live cells (E  MPa\pm 8 MPa and 49\pm ) than in unpressurized saculli .