Temperate Phages of Streptomyces venezuelae: Lysogeny and Host Specificity Shown by Phages SV1 and SV2

SUMMARY: The generalized transducing phage SV1 of Streptomyces venezuelae lysogenizes its host with low efficiency and is therefore temperate. Phage SV2 is also temperate in S. venezuelae, which it lysogenizes more efficiently than SV1. Prophage SV2 is the first example of a u.v.-inducible prophage in Streptomyces. Stable double lysogens able to produce both SV1 and SV2 and insensitive to each phage have been isolated. The relative efficiencies of plating of SV1 and SV2 on four different strains of S. venezuelae indicate that, between them, these strains have four different host specificities. The molecular basis of each host specificity remains to be determined.