FIG. 2.

EM sections of CpgA-depleted cells throughout the growth phase. Strain 168 (A) and strain BFS2823 (B to D), both grown in E-medium without IPTG, are shown. EM sections (samples were fixed with 2.5% glutaraldehyde in cacodylate buffer and stained with 1% uranyl acetate, and ultrathin sections were contrasted with lead acetate) were prepared as described previously (26) and are shown at different stages of the growth phase. (A) Mid-exponential phase, OD = 0.4; (B) OD = 0.4; (C) OD = 0.8; (D) stationary phase. In contrast to strain 168, a variety of misshapen cells with some abnormal division planes are visible throughout the growth phase with depleted cells. BFS2823 with IPTG or a derivative of BFS2823, ectopically expressing cpgA from a xyl promoter, produces largely normal cells (data not shown).