The infection of Escherichia coli with lambda 22 phage and the establishment of lysogeny.

SUMMARY Infection of Escherichia coli by phage λ22 in 0.02M-Sr(NO3)2, CaCl2 or MnSO4 occurred as readily as in 0.02M-MgSO4. The response of bacteria infected in the presence of Sr2-, Ca2+ and Mg2+ was predominantly lysogenic, but infection in 0.02 M-Mg2+ gave a higher lysogenic response (90%) than with the other cations tested. With Mn2+ in optimal conditions, at least 25% of the infected bacteria always gave the lytic response. When the newly infected bacteria were transferred to a growth medium, a period of about 40 min. had to elapse before the prophage could be detected by zygotic induction by mating with a non-lysogenic F - organism. A period of about 100 min. was required before all the bacteria giving the lysogenic response could be induced by ultraviolet radiation.