Membrane Damage and Its Repair in the Thermophilic Bacterium, Thermus Thermophilus HB-8 Exposed to u.v. Radiation and ⁶⁰Co γ-rays

Summary

When exposed to either u.v. radiation or ⁶⁰Co γ-rays, the thermophilic bacterium, Thermus thermophilus HB-8, which can grow at 49–85°C, lost its ability to take up extracellular K⁺ in a dose-dependent manner. However, the loss was reduced by incubation at 37°C after exposure to u.v. radiation or γ-rays. Cell survival after exposure to ⁶⁰Co γ-rays, as measured by colony formation, was increased by incubation at 37°C after exposure, whereas cell survival after u.v. radiation was not. These results, therefore, indicate that the loss of ability of cells to take up K⁺ after u.v. radiation was not due to cell death but some damage to the membrane itself, and that the membrane damage can be repaired. Lipid peroxidation is not responsible for the membrane damage, because HB-8 cells do not contain unsaturated fatty acids in their membranes.

• ultraviolet
• membrane
• thermophilic bacterium
• repair
• potassium ions