Figure 4.

DNA fragmentation in nucleoids from E. coli strain TG1 exposed to CIP in different culture times. The growth curve of the bacteria, evaluated by monitoring turbidity at OD₆₀₀, is presented above. The distribution of the frequencies of the diffusion widths of DNA fragments from the nucleoids were categorized into the five classes 0 to IV described in Table 1 and Fig. 2. Aliquots from a batch culture were removed at 3 h (exponentially growing phase) and at 7, 9, and 23 h (stationary phase), incubated with 1 μg/ml CIP for 0 (i.e., technical processing time of 8 min) (medium) and 5 min (below), and then processed to determine the DNA fragmentation.