Formation of Associated Oxidative Stress in Cells of Escherichia coli Exposed to Different Environmental Stressors

Abstract

The impact of stress factors such as ethanol, acetic acid, and sodium chloride caused the accumulation of hydrogen peroxide in Escherichia coli cells and activation of the gene expression of the OxyR regulon. The development of oxidative stress depended on the nature and intensity of the impact of the stress factor. The determination of changes in cell susceptibility to external influences in the presence of the antioxidant thiourea, which neutralizes reactive oxygen species, demonstrated their involvement in the action of osmotic and acid stress. When the antioxidant was introduced, there was a slowdown in the death rate of cells subjected to lethal stress (decrease in CFU in culture to <0.01% of the initial amount) and a decrease in cell viability in the absence of activation of expression of antioxidant genes under conditions of less intense exposure (decrease in CFU to 10–0.01%). It can be assumed that, depending on the intensity of stress, reactive oxygen species can act either as a damaging agent or as a signal for the launch of protective mechanisms. Cells cultured under microaerobic conditions were more resistant to heat and more sensitive to the effects of acetic acid than cells grown under more intensive aeration.