2種のファージを産生する溶原性大腸菌A34株のファージ誘発に関する実験

Abstract

The auther described recently on the lysogenic Escherichia coli A34 that has perpetuated the capacity producing two phages, serologically unrelated (designated β and γ, respectively), in a same cell.In this paper, was given some basic data of induction of A34 by ultra violet treatment and some conditions concerning the occurence of induction.The bacterial suspension was treated with different doses of ultra violet light, and the induction and inactivation curve of A34 (β) complex was plotted in Fig. 1. It may be interpreted that the induction depends on the dose of ultra violet light but not on the intensity. Maximal induction rate would only reach to about 50 to 70 per cent of treated cells. These comparatively low maximal iuduction rates suggest the counteraction between the curves of induction and inactivation, caused by different mechanisms.Furthermore, the fact that the curve of induction and inactivation of A34 (γ) complex (Fig. 2) is different in shape from that of A34 (β) complex, showed that both induction sensitivity and inactivation are specific for those two kinds of phages.The phage liberation pari passu in broth was demonstrated. Under these conditions, the latent period was estimated about 80 minutes and burst sizes about 700 for β and 250 for γ (Fig. 4). Corresponding to the end of latest period, significant fall in bacterial turbidity was observed (Fig. 5). Thus it may be fairly asserted that in lysogenic bacterial culture, phages are liberated in the same manner as that of virulent phage-bacteria system.In addition, the auther determined whether both kinds of phages are simultaneously induced or not in a same cell; experiments of single cell distribution and those utilizing the mixed indicator have been done several times, which led to the conclusion that both phages could be independently induced in the same cell. From the above results, it may well be concluded that phage production is due to local effects on prophage, rather than the cellular modification of bacteria caused by ultra violet light.In conclusion, contrary to Bertani's opinion, at least the production of each phage after the ultra violet treatment was not mutually exclusive.