[DNA content in Escherichia coli mutants resistant to rifampicin and nalidixic acid]

DNA content was studied in Escherichia coli strains resistant to rifampicin and nalidixic acid. When the strain resistant to the acid was grown in the M-9 medium with glucose, it was found to contain 14.6 X 10(-15) to 17.8 X 10(-15) g of DNA per cell, the rifampicin-resistant strain contained 10.2 X 10(-15) to 34.8 X 10(-15) g of DNA per cell, and the parent sensitive strain contained 7.5 X 10(-15) to 9,2 X 10(-15) g of DNA per cell under the identical conditions. The morphology and certain physiological characteristics of the mutants were also modified.