Studies on the Origin of Bacterial Viruses

Abstract

Analyses of small samples containing a few cells each show that lysogenicB, raegatherium produces phage particles in groups of from 10 to 1000 depending on the megatkerium strain and the culture medium.These groups probably correspond to the number of particles produced by a single cell. The proportion of such phage-producing cells varies from <1 X 10 -1° to about 1 X 10 m depending on the megatherium strain and the culture medium.If a culture produces two types of phage, the different types usually appear in separate samples. If mixed samples occur, the number of such samples is about what would be expected for the probability that two separate groups would appear in one sample. This result indicates that the appearance of a distinct phage type is the result of a change in the hactedal cell rather than a change in a phage particle, since in the latter case a mixture of the two types would result. II. The Effect of Ultraviolet Light on the Incidence of Phage-Producing and of Terramycin-Resistant Cells in Various B. raegatherium Cultures ABSTRACTLow intensity of ultraviolet light increases the proportion of both phage-producing cells and of terramycin-resistant mutants. The increase in phage-producing cells is greater than the increase in terramycin-resistant cells.