FIG. 2.
(A) Appearance of wild-type (wt) bacteria, the Δiap mutant, the iap+ revertant, and the rough (RIII) strain in phase-contrast microscopy. (B and C) Scanning electron microscopy (B) and transmission electron microscopy (C) images of the wt, Δiap, and iap+ strains. Pictures of the bacteria were taken in the exponential-growth phase (exp), in the stationary phase (stat), after overnight culture, and after 36 h of growth. Arrows indicate remarkable sites of abnormal cell division, where bacterial filaments seem to break; arrowheads indicate unusual flat poles present in the Δiap mutant. In panel C, the differences in the mode of septum formation among the three strains are clearly visible.