Figure 1

Fold-induction of SOS response in SOS-R2 strains over-expressing candidate nitroreductases upon challenge with CB1954 or nitro-CBI-DEI. Mid-exponential phase cultures of each SOS-R2 sfiA:lacZ reporter strain, either over-expressing a candidate nitroreductase from the expression vector pUCX or containing an empty pUCX plasmid control, were incubated for 3 h in the presence of A. 5 μM nitro-CBI-DEI or B. 20 μM CB1954, after which relative induction of the SOS response in each strain was measured by β-galactosidase assay as previously described [8]. Data are the mean Miller units from three independent experiments, each performed in duplicate; and error bars are ± 1 standard deviation. The black dotted line indicates the basal SOS activity in the empty plasmid control. *** indicates p < 0.001 by one-way ANOVA with Dunnett comparison of test to control.