Transduction of bacteriophage resistance in Streptococcus pyogenes with coinfection lysates of the virulent phage A25ts1-2 and a temperate bacteriophage 2511

Abstract

Two new mutants of Streptococcus pyogenes designated KS107 and KS136 were shown to allow adsorption of a virulent bacteriophage KV1, but replication of viral DNA did not occur in these mutants. The novel observation was made that coinfection of donor ceils with phages A25ts1-2 and 2511 enhanced transduction of phage resistance and of antibiotic resistance. Mixed donor lysates did not give enhanced transduction. Antiserum to A25ts1-2 blocked transduction, suggesting that the presence of 2511 promoted packaging of chromosomal DNA into A25ts1-2 particles. Phage 2511 was isolated by induction of a clinical strain, but it behaved as a lytic phage in laboratory strains. Phage KV1 was isolated from sewage and was found to be closely related to A25ts1-2, whereas 2511 was clearly different. The phage resistance gene of KS107 was not linked to any of three antibiotic resistance genes by cotransduction tests.