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 envelope of a spherical Gram-negative bacteria is presented. It is shown that the force-displacement relation taken on top of bacteria is accurately approximated by a linear dependence. The bacterial rigidity is shown to be controlled mainly by its turgor pressure, while the lateral rigidity of the bacterial wall determines the distance from the tip at which the displacement vanishes.