TIMING AND GENETIC-REGULATION OF COMMITMENT TO SPORULATION IN BACILLUS-SUBTILIS

Sporulation in Bacillus subtilis is a simple developmental system invo lving the differentiation of two cell types called the prespore and th e mother cell. The process is induced by nutrient deprivation and culm inates with the formation of a mature spore, which is released by lysi s of the mother cell. We have studied commitment to sporulation with s everal different assays. The results indicate that commitment occurs s oon after the formation of the asymmetrically positioned division sept um that separates the prespore and the mother cell. This is earlier th an the previously postulated point of commitment, prespore engulfment by the mother cell. Commitment coincides approximately with activation of the early prespore- and mother-cell-specific sigma factors, sigma( E) and sigma(F).