Figure 4. Chromosomal association with FQ persistence eliminated in HR mutants.

(A) Representative DNA histogram of a stationary-phase population of MG1655 ΔrecA stained with 5 μg/mL Hoechst 33342. The small peak (arrow) that is less fluorescent than the 1Chr peak was not culturable after sorting and has been previously described as cells without nucleoids³⁵. (B) When sorted and treated with 5 μg/mL LEVO, the association between chromosomal content and persistence was eliminated in a MG1655 ΔrecA mutant (n = 3). (C) Representative DNA histogram of a stationary-phase population of MG1655 ΔrecB stained with 5 μg/mL Hoechst 33342. (D) No association between chromosomal content and persistence was observed in a MG1655 ΔrecB mutant treated with 5 μg/mL LEVO (n = 3). Raw CFU/mL values and additional controls can be found in Figure S4. 1Chr and 2Chr indicate chromosome number as determined by experiments presented in Figure 2. Representative gating strategies are indicated by a and b. Error bars portray ± SEM. All replicates were independent biological replicates. No statistical significance was achieved as determined using a one-way ANOVA (ΔrecA: F(2,6) = 0.15, p = 0.86; ΔrecB: F(2,6) = 0.38, p = 0.70).