Deoxyribonucleic acid degradation in Bacillus subtilis during exposure to actinomycin D.

At high concentrations (10 mug/ml), actinomycin D inhibited deoxyribonucleic acid (DNA) synthesis in Bacillus subtilis. Inhibition occurred quickly (in less than 1 min) and was complete. In strain 23 thy his, inhibition of DNA synthesis by actinomycin D was followed by partial degradation of one of the two daughter strands to acid-soluble products. Degradation began at the replication point and proceeded over a distance equal to about 12% of a chromosome in length. Actinomycin D played some essential part in degradation, since exposure of the cells to other treatments or agents which inhibit growth did not lead to the above result.