Extended Data Fig. 5: Comparison of ftsZ mutant cellular phenotypes in log and stationary phases.
The differing functions of FtsZ1 and FtsZ2 were also apparent when cultures of the knock-out, complementation and overexpression strains were compared in mid-log and stationary phases. Phase-contrast images (left) and Coulter cytometry distributions (right) of the wild-type and overexpression strains (a) and the indicated ftsZ knockout and complementation strains b, c, all grown in Hv-Cab with the indicated concentration of Trp and sampled at mid-log and stationary phases. The data shown are representative of at least two independent experiments. Scale bars, 5 μm. Compared to mid-log cells, all the strains except the strains without a copy of ftsZ2, tended towards the wild-type size (smaller) and regular plate morphology in stationary phase. The ΔftsZ2 strains were somewhat smaller in stationary phase, but maintained greatly enlarged giant plate and elongated cells, suggesting a poor recovery as cell growth slows in stationary phase. These findings suggest that FtsZ2 confers a partial ability to divide and recover more normal cell sizes as the cell growth rate slows in stationary phase, whereas cells without FtsZ2 have a much stronger block to division that is maintained even as cells slow or stop growth in stationary phase.
