After 20 h incubation of cells at 37°C (16 h incubation prior to the addition of resazurin and further incubation for 4 h), the blue color shows no growth, whereas the pink wells represent growing cells (B = MOPS minimal media as sterility control, U = untreated cells). Numbers refer to concentrations or exposure as indicated. (A) The EtBr MIC shows a ≈64-fold increase in sensitivity when the TolC pump is knocked out. (B) UV irradiation MIC shows a ≈32-fold increase in sensitivity to UV with the uvrA knockout. (C) 4-NQO MIC shows a 30-µM MIC for the compound, which decreased eightfold in the uvrA knockout, confirming the compound to be a substrate for NER. (D) ATBC MIC, the MIC is > 125 µM for both strains used, indicating ATBC is nontoxic. The experiments were performed in triplicate on three independent days. No appreciable difference was identified among the replicates. A black and white version of this figure has been placed in the Supplementary material for improved visual accessibility (Supplementary Figure S1).