Isolation of two bacteriophages from Bacillus larvae, PBL1 and PBL0.5, and partial characterization of PBL1.

Two temperate bacteriophages have been isolated from Bacillus larvae: PBL1 and PBL0 .5. Strains lysogenic for either of these phages are immune to lysis by the same phage but are sensitive to the other phage. PBL1 has an oval head, a non-contractile tail, and a base plate with a pin structure but no apparent tail fibres. The genome of PBL1 consists of double-stranded DNA with a molecular weight of 24.1 (+/-0.6) X 10(6), a G + C content (derived from melting temperature) of 41.5%, and cohesive ends. Restriction enzyme analysis permitted construction of a physical map of the genome.