Biophysics-archive of Growth and Shape Control in Bacteria

Synopsis

In bacteria, the reproducible and robust construction of the cell wall is essential for mechanical integrity and viability under osmotic stress. Antibiotics that disrupt cell wall construction ultimately lead to discontinuous mechanical failure of the cell. Our work explores the biophysics of cell growth and death, as a guide to understanding mechanisms that disrupt mechanical properties of the cell. We use high resolution time-lapse microscopy of the cell wall and computational image processing to characterize the dynamics of growth and morphological regulation. Analysis of cell-surface fluorescence indicates that the cytoskeleton is present at sites of active growth and that depolymerization of the cytoskeleton causes homogeneous, unstructured growth and eventual cell death by rupture. When combined with cell-shape analysis, our data strongly suggest that dynamic localization of the bacterial cytoskeleton is part of a curvature sensing and growth feedback mechanism that orchestrates heterogeneous growth to maintain cell shape and regulate mechanical stress. Insights from classical mechanics and the detailed structure of the cell wall are used to develop a testable theory of mechanical cell death and point toward genes of interest that may be implicated in such mechanisms of cell death.