Identification of cell wall subunits in bacillus subtilis and analysis of their segregation during growth.

Continuous as well as pulse-labeling and chase experiments with Bacillus subtilis demonstrated that the cell wall (both peptidoglycan and teichoic acid) is composed of a limited number of blocks which, once completed, segregate during subsequent growth without undergoing any mixing with newly synthesized blocks. This observation suggests that new wall material is inserted in a limited number of zones. Previously reported observations which suggested diffuse intercalation of new wall material are reinterpreted on the basis of our results. Experiments performed on different media showed that the number of segregation units per unit of cell length and thus the density of insertion zones increases with medium richness. This finding suggests analogies between the regulation of cell wall and DNA synthesis.