[Role of the antioxidant system in response of Escherichia coli bacteria to cold stress].

The response of aerobically grown Escherichia coli cells to the cold shock induced by the rapid lowering of growth temperature from 37 to 20 degrees C was found to be basically the same as the oxidative stress response. The enhanced sensitivity of cells deficient in two superoxide dismutases, Mn-SOD and Fe-SOD, and the increased expression of the Mn-SOD gene, sodA, in response to cold stress were interpreted as both oxidative and cold stresses are due to a rise in the intracellular level of superoxide anion. The long-term cultivation of E. coli at 20 degrees C was also accompanied by the typical oxidative stress response reactions--an enhanced expression of the Mn-SOD and catalase HPI genes and a decrease in the intracellular level of reduced glutathione (GSH) and in the GSH/GSSG ratio.