SUMMARY: Of thirty coagulase-positive staphylococci, twenty-seven proved to be lysogenic. Free phage was found in filtrates of 4-5 hr. broth cultures of the lysogenic strains. The phages from six of these strains were examined by estimation of the amounts occurring in filtrates, for serology and for their range of lytic reactions with indicator strains. A number of strains were found which carried as many as five distinct bacteriophages. Probable phage mutations were also demonstrated. Interference effects due to lysogenicity were not a marked feature of the strains investigated.

It is assumed that the free phage released by the lysogenic strains is responsible for infection of sensitive indicator strains. The approximate proportion of lysogenic cells capable of releasing phage has been determined for three strains; it varied for the three strains and according to the indicator strains used, ranging from 1/3 cells inoculated to 1/30,000 cells inoculated. The mechanism of the release is probably due to multiplication of the phage in a number of lysogenic cells with consequent lysis of the cells and release of the phage.

Lysogenicity appeared to be a permanent feature of these strains. Every cell was apparently carrying phage and treatment with heat, with specific antibacteriophage serum, or by growth in broth containing sodium citrate did not make the cells non-lysogenic. For such strains, apart from an extracellular release of phage from a few cells in each culture, there is postulated an intracellular transference of phage to each daughter cell at cell division.


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