INTERSPECIES TRANSDUCTION OF PLASMIDS AMONG BACILLUS-ANTHRACIS, B-CEREUS, AND BACILLUS-THURINGIENSIS

Bacteriophage CP-51, a generalized transducing phage for B. anthracis, B. cereus and B. thuringiensis, mediates transduction of plasmid DNA. B. cereus GP7 harbors the 2.8-megadalton multicopy tetracycline resistance plasmid, pBC16. B. thuringiensis 4D11A carries pC194, the 1.8-megadalton multicopy chloramphenicol resistance plasmid. When phage CP-51 was propagated on these strains, it transferred the plasmid-encoded antibiotic resistances to the nonvirulent Weybridge (Sterne) strain of B. anthracis to B. cereus 569, and to strains of several B. thuringiensis subspecies. The frequency of transfer was as high as 10-5 transductants per plaque-forming unit. Tetracycline-resistant and chloramphenicol-resistant transductants contained newly acquired plasmid DNA having the same MW as that contained in the donor strian. Antibiotic-resistant transductants derived from any of the 3 spp. were effective donors of plasmids to recipients from all 3 spp.