Surviving Escherichia coli in Good Shape: The Many Faces of Bacillary Bacteria

One characteristic defining a bacterial species is its cell shape (van Leeuwenhoek, 1684). Our work deals with simple symmetrical shapes that can be defined by the ratio between two dimensions, length L and diameter 2R. There are two such possible forms, an approximation to a prolate (including a sphere, where L/ 2R =1) and a cylinder (the length of which equals L-2R > 0) with hemispherical polar caps. Cells of the latter (bacilli) are often transformed into spheroids (cocci), such as upon entrance to the stationary phase (in gram negative species) or sporulation (in gram positives). The most familiar rod-shaped bacterium, which can easily become sphere-like, is Escherichia coli. Being the species of preference in the investigations conducted during the last 3 decades in our respective laboratories, it is the focus of this Chapter. The general laws derived are valid for other bacterial species and seem universal, albeit with slight modifications.