Studying the Mechanism of Dioxidine Genotoxicity Using Lux Biosensors of Escherichia coli

The ability of the antibacterial agent dioxidine to generate the superoxide anion radical in E. coli cells, induce an SOS response, or cause DNA fragmentation or death of bacteria, as well as the effect of antioxidants on the processes listed, were studied using E. coli luminescent biosensors. Dioxidine induced the SOS response in the pColD-lux biosensor in concentrations typical for the most efficient induction of luminescence in a pSoxS-lux biosensor, the intensity of which depends on the amount of superoxide in the cell. Dioxidine in concentrations of more than 0.001 mol/L caused a decrease in the survival of bacterial cells, which is accompanied by the degradation of their DNA (as demonstrated by electrophoretic analysis). DNA degradation increased with an increase in the dioxidine concentration and decreased in the presence of the antioxidants glutathione and acetylcysteine. Antioxidants weakened the induction of the SOS response by dioxidine, as well as generation of superoxide radicals. Likely mechanisms of the formation of the hydroxyl radical during the reduction of the dioxidine NO group by bacterial reductases are discussed.