Genome homology and host range of some SP beta-related bacteriophages of Bacillus subtilis and Bacillus amyloliquefaciens.

Temperate Bacillus subtilis bacteriophages SB beta, phi 3T and SPR and B. amyloliquefaciens phage H2 were compared with respect to DNA-DNA homology by Southern blot analysis to each other and to members of the genus Bacillus. The results show that H2 is a distantly related member of the group III B. subtilis phages. Detectable homology to group III phages could be found in the DNA of several other Bacillus species, including B. natto and B. amyloliquefaciens, demonstrating the widespread occurrence of this group of phages. The host ranges for the phages SP beta, SPR and H2 were determined by adsorption efficiency and by the ability of erythromycin resistance- and chloramphenicol resistance-transducing phages to convert susceptible host strains. Of the three phages examined, only H2 was capable of infecting B. amyloliquefaciens. Based on these results we propose that group III phages should be divided into three subgroups: SP beta, phi 3T, Rho11, IG1, IG3 and Z (subgroup 1), SPR (subgroup 2) and H2 (subgroup 3).