Chromosome Replication in Salmonella typhimurium

The replication of theSalmonella typhimurium chromosome was studied. As withE. coli 15T− , replication was sequential. After amino acid starvation, replication proceeded from a unique and heritable region of the chromosome. 5-Bromouracil, when substituted for thymine, did not disturb the sequence of replication nor did it initiate extra replication cycles. By labeling the origin and the terminus of the chromosome with3 H- and14 C-thymine, respectively, it was possible to determine that the rate of chain elongation decreases as the growth rate decreases. No gap in the replication cycle could be observed.