Restriction analysis of PBS 1-related phages

The Bacillus subtilis bacteriophages AR 9, 3 NT, and I 10 belong to the same group as the widely used bacteriophage PBS 1. These four phages have in common, among other properties, flagellotropic adsorption to host cells and total substitution of thymine by uracil in their DNAs. We tested the action of different restriction endonucleases on the four genomes. Among 14 enzymes, which did cut the DNAs into discrete fragments, six are known as having at least one thymine residue in their recognition sequences. The electrophoretical patterns of the digested DNAs from the four phages show strong similarities. Nevertheless, the differences are sufficient to allow a clear distinction between them.