Far-infrared irradiation-induced injuries to Escherichia coli at below thelethal temperature

Escherichia coli in phosphate-buffered saline irradiated with far-infrared (FIR) energy was injured and killed even under the condition where the bulk temperature of the suspension was maintained below the lethal temperature. Using four kinds of antibiotics (penicillin G, chloramphenicol, nalidixic acid and rifampicin), we investigated the Fin irradiation-induced damage to E. coli on the basis of the sensitivity changes to the antibiotics. FIR ir radiation increased the organism's sensitivity to rifampicin both below and above the lethal temperature. The increase in sensitivity to chloramphenic ol was observed only when FIR irradiation occurred above the lethal tempera ture. These results suggest that the mechanism of FIR irradiation-induced d eath in E. coli differs according to whether the radiation exposure occurs above or below the lethal temperature.