Abstract
1. Bacteria having somatic antigen (8), 20 are lysogenic strains, among which both S. kentucky and S. corvallis produce two phages, Plt 20 and Psc. Each of S. emek and S. albany produces only one phage same as Plt 20. Pit 20, a particle with a diameter of 7080mμ, has the ability to make a round and turbid plaque having a diameter of 23 millimeters and to add somatic antigen 20 to a recipient bacterial cell. On the other hand, Psc whose diameter is 100110mμ can make a clear plaque with a diameter of about 1 millimeter and it is not able to govern the production of somatic antigen 20. Besides, these two phages have significant differences in antigenicity and the grade of resistance to heat and phenol, and a little difference also in behavior in various pH ranges. They are both temperate phages and lead to lyse or lysogenize S-51 and S-55 which possess somatic antigen 6, 8. Somatic antigen of a recipient bacterial cell infected with Plt 20 is converted from 6, 8 to 6, 8 20 and at the same time lysogenization of the recipient is observed. Especially, S-51 becomes a doubly lysogenic strain as a result of double infections with these two phages. Plt 20 segregates a mutant phage Plc 20 with a rate of 1/500 which is different from the parent phage only in the morphology of plaque but not different in size and other characteristics.
2. pit 20 and its mutant phage Plc 20 are able to transduce streptomycin resistance and sugar fermentation ability from one strain to another with the frequency of 10-6 to 10-7. It is clear also in this experiment that only one character is transduced into one bacterial cell at a time and that the transduced character continues to be transmitted to the pedigrees with genetic stability. Moreover, it was shown that sometimes a transduction phenomenon occurs which does not accompany lysogenization and antigenic transformation. No transduction phenomenon can be observed with respect to Psc which is not concerned with the production of somatic antigen 20.
