Figure 6.

Other modes of bacterial cell division. (A) Subsequent generations of the spherical S. aureus divide in a plane orthogonal to the two previous generations. Although cell wall synthesis was speculated to occur only during septum synthesis, new evidence suggests that circumferential cell wall synthesis also occurs in this organism. Subsequent to cell division, the septum-derived cell wall material (red) contributes to less than half of the newly formed daughter cell. The division plane of the next generation lies orthogonal to that of the preceding generation. (B) Top: The marine gammaproteobacterium Candidatus Thiosymbion oneisti attaches via one pole to the surface (brown lines) of the nematode Laxus oneistus. This bacterium grows wider along the short axis prior to FtsZ (purple) assembly, which occurs at mid-cell parallel to the long axis of the cell, presumably to permit both daughter cells to remain adhered to the host. Bottom: In another gammaproteobacterial relative of this organism (yet to be named), that lives on the surface of a different nematode Robbea hypermnestra, FtsZ localizes closer to the host-proximal pole and trigger septum formation. Subsequently, several fragmented FtsZ foci continue to mediate septum synthesis towards the distal pole. The factors involved in the regulation of longitudinal division remains to be elucidated.