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

Abstract

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.