Effect of Deuterium on the Expression of Inducible Genes in Escherichia coli

It has been shown for the first time that preliminary incubation of bacteria in a medium containing deuterium oxide (D2O) at concentrations of 2.5 to 10% leads to an increase in recA expression induced by hydrogen peroxide at concentrations of 2.2–8.8 mmol/L. The induction of recA in deuterated and non-deuterated (control) cultures was compared using a biosensor based on the E. coli strain K12 MG1655 (pRecA-lux), where luminescence occurs as a result of recA promoter activation in response to DNA damage caused by H2O2. The most effective D2O concentrations were 5.0 and 7.5%. To explain the phenomenon, expression of the catalase gene was studied in deuterated and non-deuterated cultures of E. coli K12 MG1655 (pKatG-lux) biosensor. The luminescence of this biosensor results from activation of the katG promoter in response to an increase in the concentration of H2O2 in the cell. It was found that D2O downregulated katG expression, which can lead to H2O2 accumulation, and, as a consequence, to an increase in the level of DNA damage as seen by an increase in recA expression.