FIGURE 5: DMB impairs proton motive force in S. Typhimurium. Cells were grown in NCE minimal medium supplemented with succinate (30 mM) and acetate (0.5 mM) to an OD₆₀₀ of ∼0.5 and added nucleobases or CCCP as indicated; cultures were incubated for 15 min at 37°C with shaking. Cells were stained with EtBr, cultures were irradiated with 530-nm light, and fluorescence emitted at 600 nm was monitored over 4 min. The rate of EtBr accumulation is expressed as relative fluorescence units/s. Results are provided as the mean from three biological replicates, with each experiment containing technical triplicates. Error bars denote the standard deviation of three biological replicates. A paired Student's t test was performed compared to the no treatment control to determine statistical significance; ns, not significant. Abbreviations: DMB, 5,6-dimethylbenzimidazole; 5-Me-Bza, 5-methylbenzimidazole; Ade, adenine; CCCP, carbonyl cyanide m-chlorophenolhydrazone.