Three series of samples were prepared from
Mycobacterium smegmatis Jucho and stored at-20C; (a)
35S-labeled cells in 10% glycerol (intracellular irradiation with incorporated
35S); (b) non-radioactive cells in 10% glycerol containing 10μc/ml
35S (extracellar irradiation with
35S); and (c) non-radioactive cells in 10% glycerol (control). Viable numbers and mutation frequency to isoniazid resistance were determined until the 84th day storage period. Conclusions from the above experiments are as follows:
(1) Bacterial cells maintained their viability up to 84 days of storage, when frozen in 10% glycerol containing no radioisotope.
(2) Bacterial cells irradiated with extracellular
35S maintained their viability or decreased their viable numbers only slightly even after 84 days of irradiation period.
(3) Bacterial cells with incorporated
35S lost their viability at a faster rate. It is suggested that this effect is due to the transmutation of
35S to
35Cl in bacterial protein molecules.
(4) As far as the observation from the technique of the present study with some experimental errors was concerned, no significant increase in mutation frequency could be detected in both the samples irradiated with incorporated
35S and with extracellular
35S.
抄録全体を表示