Regulation of Chromosome Replication in Bacillus subtilis: Effects of Amino Acid Starvation in Strain 168

Amino acid starvation allows limited synthesis of deoxyribonucleic acid (DNA) in Bacillus subtilis strain W23. DNA synthesis increased by about 30% after leucine starvation and by about 60% after histidine starvation. Genetic analysis on the DNA synthesized after amino acid starvation showed that all genetic markers examined have replicated, regardless of which amino acid was starved for. Initially, all markers replicated equally, but upon further replication, the thr cysB and the argA to lys regions replicated ahead of their neighboring, proximal regions. This could indicate that preferred stopping sites exist in these regions or additional sites from which replication can originate reside there. The results suggest that chromosome replication continues from those sites where it had stopped during amino acid starvation.