The nucleic acid content of Escherichia coli strains B and B/r

The differences in the DNA and RNA content of cells of Escherichia coli strain B and its radio-resistant mutant, strain B/r, in the logarithmic phase of growth are not statistically significant. In the stationary phase, cells of strain B/r contain more DNA than those of strain B, but the difference is barely significant; the RNA content of the B/r cells is significantly higher. The differing radiosensitivities of the two strains cannot be correlated with differences in their content of nucleic acids.