Deformation of the envelope of a spherical Gram-negative bacterium during the atomic force microscopic measurements

A theoretical approach for the description of the deformation of the envelo pe of a spherical Gram-negative bacteria is presented. It is shown that the force-displacement relation taken on top of bacteria is accurately approxi mated by a linear dependence. The bacterial rigidity is shown to be control led mainly by its turgor pressure, while the lateral rigidity of the bacter ial wall determines the distance from the tip at which the displacement van ishes.