抄録
The decimal reduction dose of γ-ray on freeze-dried clean Escherichia coli cells and Bacillus subtilis spores was about 7×104 rad and it was about three times higher than that on E. coli cells suspened in saline. E. coli cells contained in Takadiastase or trypsin powder showed quite the same susceptibility to γ-irradiation as they were present cleanly. These enzyme activities were not impaired at all even at the dose of 2×105 rad. When these enzyme powders containing E. coli cells were stored under varied atmospheric relative humidity, the deleterious effect of γ-ray on bacterial cells was highly enhanced in those samples stored under more than 80.5% relative humidities. The additions of excipients, such as glucose and lactose, and of a protectant, L-cysteine, to the bacteria-containing dry enzyme powder did not show any sign of either enhancement or retardation of γ-ray action on enzyme and bacteria. Based on these observations, the utilizability of radiosterilization on biological medicaments is discussed.
