Role of thiol redox systems in Escherichia coli response to thermal and antibiotic stresses

摘要

Isogenic knockout mutants of Escherichia coli deficient in components of the glutathione and thioredoxin redox systems and growing at various temperatures (20-46A degrees C) exhibited considerable differences in growth rate and survival, as well as in expression of the antioxidant genes. In the parental strain E. coli BW25113 (wt) treated with ciprofloxacin, ampicillin, or streptomycin, dependence of survival on growth temperature was a V-shaped curve with the maximum sensitivity within the range corresponding to high growth rates (40-44A degrees C). Significant inverse correlation was observed between log CFU at different temperatures and specific growth rate prior to antibiotic addition. This applied to most of the mutants, which exhibited higher resistance to the three antibiotics tested at nonoptimal temperatures (20 and 46A degrees C) than at 37 and 40A degrees C. No correlation was found between resistance to stress and antibiotics and expression of the antioxidant genes. The role of global regulators ppGpp and sigma(s) in E. coli resistance to antibiotics and nonoptimal temperatures was shown.