Effect of Free Radicals and Cultivation Media on Radiation Sensitivities ofEscherichia coli and Related Bacteria
2000 Volume 35 Issue 1-2 Pages 1-6
Details
2000 Volume 35 Issue 1-2 Pages 1-6
Effects of gamma-irradiation on some strains of Escherichia coli, Salmonella enteritidis and Staphylococcus aureuswere investigated in the presence of N2, N2O and O2and with the hydroxyl radical (OH) scavengers glycerol, polyethylene glycol and formate. Injured cell membrane of bacteria was detected using with MacConkey agar forE.. coliandS. enteritidisand 7% NaC1 Triptic soy agar forSt. aureusinstead of Tryptic soy agar for recovery medium. From this study, addition of glycerol significantly reduced the sensitivity in all of strains, and cell membrane was not injured significantly except in radiation sensitive strainE.. coliA4-1. When superoxide radicals (O2-) were generated during irradiation in the presence of formate, injured cell membrane increased significantly in all of strains. However, molecular oxygen (O2) and OH radicals also had some effects on the damage of cell membrane. These results suggest that most radiation induced cell lethality was responsible to the cooperative effects of intracellular OH radicals and O2on DNA with lessor effect of damage on cell membrane by O2-radicals, O2and OH radicals. On the radiation sensitive strain of E.. coli, cell lethality occurred significantly by the injury of cell membrane compared with other strains.
