Inactivation and mutations in Mycobacterium avium by decay of incorporated radioactive phosphorus.

NACTIVATION of bacteria and bacteriophages by decay of incorporated radio‘active phosphorus (P”) has been reported by STENT and FUERST (1955), FUERST and STENT (1956), STRAUSS, VAHARU, FRICKEY and MATHESON (1956), TESSMAN, TESSMAN and STENT (1957), MCFALL, PARDEE and STENT (1958), and KAUDEWITZ, VIELMETTER and FRIEDRICH-FREKSA ( 1958). These authors have suggested that the P32 disintegrations which occur in the bacterial deoxyribonucleic acid (DNA) may be mainly responsible for the inactivation of the cell. Working with an avirulent strain of Mycobacterium avium, the present author (TSUKAMURA 1960a) has stated that the mutagenic effect of radioactive isotopes is not always parallel with the radioactivity and that radioactive phosphorus, which can incorporate into the DNA, can exhibit a significant mutagenic effect, while radioactive sulfur, which cannot incorporate into the DNA, can exhibit no significant mutagenic effect. These results have indicated that the mutagenic effect is affected by the intracellular localization of the isotope. The present paper concerns relationship between the intracellular distribution of P32 and the inactivation and mutations induced by the presence of P32. The results have revealed that inactivation and mutations in this organisms are produced rather by the decay of incorporated radioactive phosphorus (change of P32 into S”) rather than by the beta-ray irradiation.