抄録
The kinetics of phage induction in some lysogenic strains of E. coli and Shigella was investigated by means of ultraviolet light (UV) irradiation. The main evidence to be noticed is the following.
(1) The kinetics of β phage induction in A34 (β, γ) was observed to be a kind of two-hit phenomenon, whereas that in an artificial lysogenic Shigella, strain KA (βL), single-hit phenomenon. The radiosensitivity of both lysogenic strains with respect to β phage induction was nearly equal each other.
(2) Under suitable UV dose, more than 80 per cent of the bacteria irradiated were induced with both two lysogenic strains.
(3) The number of β prophage in KA (βL) and A34 (β, γ) was estimated to be about 2 and 3-4 per bacterium, respectively.
(4) The descending portion of the induction curves is composed of two different parts, each of which is distinguished by its inclination, suggesting that the inactivation of phage production in overirradiated cells occurs by at least two different mechanisms.
(5) The UV sensitivity of bacteria tested as to phage induction and colony forming ability was markedly depend upon the physiological state of bacteria, for instance, inanition of the bacterial cells or growth phase of the culture, at the time of irradiation.
