Cell division of the Escherichia coli lon- mutant

Summary Escherichia coli lon^-cells were subjected to treatments which produced a decrease in the DNA/mass ratio of the cell. Thymine starvation, a shift-up from minimal medium to rich medium, and exposure to BUdR each caused greater inhibition of cell division in lon^-cells than in lon⁺cells. DNA metabolism was found to be the same in both lon⁺and lon^-cells during these treatments. The results are consistent with the hypothesis that the lon^-defect leads to inhibition of cell division under conditions which produce a decreased DNA/mass ratio.