FIG 2.

Disruption of the opp and app operons results in an increase in sporulation frequencies. (A) Sporulation frequency (CFU ml⁻¹ ethanol-resistant spores) of 630Δerm, MC296 (opp), MC301 (app), and MC307 (opp app) grown in 70:30 sporulation medium at T₂₄. (B) Percentage of phase-bright spores assessed by phase-contrast microscopy. (C) Percentage of cells that have a polar septum or partially/completely engulfed forespores, assessed by fluorescence microscopy using the membrane-specific dye FM4-64. (D) Representative growth curve of 630Δerm, MC296 (opp), MC301 (app), and MC307 (opp app) grown in 70:30 sporulation medium. The means and standard errors of the means for spore counts of at least two biological replicates are shown. *, P ≤ 0.05 by two-tailed Student's t test.