抄録
Quantitative analysis on the interactions between prophage and superinfecting phages has offered a possible way to approach to the problem of prophage conditions in lysogenic cells and has brought many important knowledges.
The present paper deals with the prophage substitution phenomenon in a temperate phageinfected lysogenic bacteria. Growing lysogenic cells of BI (δ) strain were superinfected with another temperate phage, beta strain, which is serologically unrelated to the carried phage, delta. When the superinfection was carried with a high multiplicity of infection (more than 10 beta particles per bacterium) it was found that about 99.7 per cent of them were killed and only about 0.1 per cent can form survival colonies. The phage produciable fraction of them were about 0.1 per cent for beta and only about 10-4 of the beta-infected BI (δ) cells can produce delta phage.
The survival colonies were, then, tested for their lysogenicity and it was discovered that in about 20-30 per cent of the survival colonies prophage substitution by the infecting beta phage occurred. No double lysogenic colonies which produce both phage types, beta and delta, however, were found in 351 colonies tested. This will suggest that beta and delta are mutually exclusive in lysogenization process.
According to these results some discussions were made around the intracellular prophage conditions.
