Effect of organic solvents on the expression of stress response genes in Escherichia coli

Effect of methanol and dimethyl sulfoxide on the expression of E. coli genes involved in responses to various adverse conditions was studied using lacZ gene fusions. It was found that 5% dimethyl sulfoxide increases the expression of sodA, fpr, rmf, and cadA, decreases the expression of mar, ompF, rpoS, and ldcC and does not affect the expression of soxS, micF, nfo, oxyR, and katG. Of the above genes, an increase in the expression of soxS, sodA, fpr, katG, and rmf and a decrease in the expression of ldcC, mar, and ompF were observed with the addition of 5% methanol. The elevated levels of antioxidant genes' expression (soxS, sodA, fpr, and katG) during the first stages of exposure to solvents may indicate the formation of oxidative stress in bacterial cells. The 2-fold reduction in the expression of genes encoding tran-scriptional regulators, which control general stress response (rpoS) and multiple antibiotic resistance (mar), in the presence of dimethyl sulfoxide may be regarded as one of the reasons of its antibacterial activity.