The Control of Normal DNA Replication In Bacteria

In liquid cultures of bacteria balanced growth is readily obtained, and, at a given temperature, the growth rate can be varied over a wide range by changing the composition of the medium. Since the average chemical constitution of the cells remains unaltered during balanced growth, each cell component must double in number between successive divisions. In particular, the DNA complement which makes up the bacterial genome must replicate once, and once only, in a time interval which can be varied from about 20 minutes to several hours (at 37°). In the growing cell this might be achieved by adjusting the actual rate of DNA synthesis in such a way that exactly one round of replication would be completed between cell divisions. In terms of known control mechanisms this adjustment might be effected, e.g., by fixing the intracellular concentrations of the deoxy-nucleoside-triphosphates at appropriate levels through inhibition and repression...