(a) Wild-type (preTA+), deletion (ΔpreTA), complemented (preTA++), and empty vector E. coli BW25113 strains were assayed for residual 5-FU using disk diffusion (0–48 hours incubation) and LC-QTOF/MS (48 hours). Complementation and empty vector were on the ΔpreTA background. (b) Wild-type, single gene deletion (ΔpreT, ΔpreA) and operon deletion (ΔpreTA) strains of E. coli BW25113 were assayed for conversion of 5-FU to DHFU by LC-MS/MS. Open circles represent individual values, filled circles represent means [n=3; *p-value<0.05; 5-FU: 52 hr, p=0.041; DHFU: 30 hr, p=0.011; 45 hr, p=0.004; 52 hr, p=0.009, 2-way ANOVA with Tukey’s correction relative to baseline of the same analyte]. (c) 5-FU MIC determination of the E. coli strains shown in panel a and Fig. 1d in minimal (M9MM) media. Values are normalized to the growth control (no 5-FU) with darker colors indicating growth inhibition. Sterile media is shown in the final row.