The long-range goal of this project is to understand the mechanism whereby the bacterial cell localizes the site of cell division and to define the subsequent changes in organization of the cell envelope that result in formation of the division septum at this site. A combination of genetic, electron microscopic and membrane isolation techniques will be used to study events that precede visible ingrowth of the septum. An attempt will be made to identify genes responsible for progression through the early stages of differentiation at division sites, to describe the biogenesis of pre-septation structures by studying synchronized cells and appropriate cello division mutants, and to define the relationship of these structures to other division-related events.