The complete sequence of the double-stranded DNA genome of a serotype-converting temperate bacteriophage, ST64T, was determined. The 40,679-bp genomic sequence of ST64T has an overall GC content of 47.5% and was reminiscent of a number of lambdoid phages, in particular, P22. Inferred proteins of ST64T which exhibited a high degree of sequence similarity to P22 proteins (>90%) included the functional serotype conversion cassette, integrase, excisionase, Abc1, Abc2, early antitermination (gp24), NinD, NinH, NinZ, packaging (gp3 and gp2), head (with the exception of gp26, gp7, gp20, and gp16), and tail proteins. The putative immunity genes were highly related to those of Salmonella enterica serotype Typhimurium phage L, whereas the lysis genes were almost identical to those of S. enterica serovar Typhimurium PS3.

The complete sequence of the double-stranded DNA genome of a serotype-converting temperate bacteriophage, ST64T, was determined. The 40,679-bp genomic sequence of ST64T has an overall GC content of 47.5% and was reminiscent of a number of lambdoid phages, in particular, P22. Inferred proteins of ST64T which exhibited a high degree of sequence similarity to P22 proteins (>90%) included the functional serotype conversion cassette, integrase, excisionase, Abc1, Abc2, early antitermination (gp24), NinD, NinH, NinZ, packaging (gp3 and gp2), head (with the exception of gp26, gp7, gp20, and gp16), and tail proteins. The putative immunity genes were highly related to those of Salmonella enterica serotype Typhimurium phage L, whereas the lysis genes were almost identical to those of S. enterica serovar Typhimurium PS3.

Temperate coliphages were recovered from sewage, mammalian feces, and lysogenic strains of Escherichia coli. A total of 32 phages of independent origin were divided into six groups by applying the criteria of host range, antigenic homology, and the ultraviolet inducibility of the prophage. The demonstration of genetic interactions in some cases has confirmed the classification scheme. Nine phages were assigned to the P2 family and 19 to the lambda family. The remaining four isolates may represent some novel phylogenetic types. Phages recovered from the lysogenic strains of E. coli were all found to be P2 related, whereas a majority of the phages recovered as cell-free plaque-forming units were assignable to the lambda family. It is proposed that the biological attributes of the phages belonging to the two principal families are reflected in the distribution patterns observed. The virions of phage HK256 show multiple tail fibers and may thus represent a "new" virion form among the temperate coliphages.

DNA of lambda and seven related phages was digested with restriction endonuclease, EcoRI. Seven different fragment patterns were observed, only two of the eight phages showing identical profiles. Restriction enzyme fragment analysis is thus shown to be a sensitive tool for the differentiation of biologically indistinguishable phages.

Using Serratia marcescens 2170 harbouring plasmid pTroy11 (encoding for LamB), and lambda (lambda:: Tn5) we constructed a collection of 25 auxotrophic mutations induced by Tn5 insertions. These mutants permitted the use an easy screening method for generalized transducing bacteriophages. Out of twelve bacteriophages isolated from natural sources only one (phage 3M) was able to transduce all Tn5 insertions tested. The preliminary characterization of bacteriophage 3M indicates that it belongs to the Myoviridae family.