FIG. 4.

Quantification of newly synthesized phage DNA after induction. Strain 8325-4φ13 was treated with different concentrations (one-quarter the MIC, one-half the MIC, or the MIC) of either ciprofloxacin (Cipro.; gray columns) or trimethoprim (Trim.; black columns) or was left untreated (control). The newly formed attP sites were calculated by quantitative real-time PCR in reference to the total amount of bacterial DNA represented by the chromosomal gene gyrase (number of copies attP/copy of gyr). Values from two separate DNA isolations and two independent PCRs each were used to calculate the mean amount of attP sites (±standard errors of the mean).