[Comparative characters of the transducing virulent streptococcal phages A25 and CA1]

The properties of two virulent streptococcal bacteriophages and their DNAs have been studied. Both phage A25 and phage CA1 generated the generalized transduction of chromosomal and plasmid markers among group A streptococci. Phage CA1 differs from the morphologically and serologically related and well-known transducing phage A25 by the efficiency of transduction, the duration of the latent period of reproduction, buoyant density in CsCl and by the lytic spectrum. Phage CA1 also was active against the lysogens resistant to phage A25. Phage genomes are presented as the linear permutated DNA molecules with molecular mass of 23 megadaltons having terminal repetitions of different size. These data have been obtained as a result of homoduplex analysis of the DNAs. A non-homologous fragment 29% of the molecular length of the phage genomes has been revealed by heteroduplex analysis of phage DNAs. This fragment seems to be responsible for the differences in biological properties of the phages. Phage A25 is heterogenous in buoyant density and molecular length of its DNA.