In all cells, DNA replication and cell division are temporally coordinated to maintain a one-to-one relationship between genome and cell duplication. Cell cycle regulation in bacteria is subject to additional stringency because division cycles can be as short as 20 min, thus cells must replicate and segregate a full genome equivalent within this timeframe. To date no mechanism has been identified in E. coli to link replication and division. Pioneering work by the Helmstetter lab indicated that the bacterial cell cycle might be controlled solely by the frequency and timing of replication initiation. This idea stemmed from synchronized cell experiments, which showed that in E. coli B/r strains the periods of DNA replication and septum development were relatively constant (~40 and 20 min, respectively) with the remainder of the cell cycle defined as a flexible pre-initiation “B” period . It was hypothesized that cell division was triggered by an unknown event occurring at the end of the replication period, presumably replication of an essential cell division gene . Supporting this view, replication termination and cell division occur at the same cell location , and there is even some sharing of machinery between the two processes .