TRANSFECTION OF ACTINOMYCES SPP BY GENOMIC DNA OF BACTERIOPHAGES FROMHUMAN DENTAL PLAQUE

Bacteriophages that produced turbid or clear zones of lysis in strains of Actinomyces were isolated from 22 of 124 samples of fresh human de ntal:plaque. All human and nonhuman strains of Actinomyces viscosus or Actinomyces naeslundii tested in this study were sensitive to infecti on by one or more of these phages. In contrast, none of the Actinomyce s odontolyticus, Actinomyces israelii, or Actinomyces bovis strains te sted were susceptible. Results of restriction endonuclease analyses in dicated that the genomes of these phages consisted of double-stranded DNA molecules ranging in size between 16 and 60 kbp. Sequence homology under hybridization conditions of high stringency was observed among a few of the isolated phages. A lysogenized isolate of A. viscosus MG- 1 was obtained following infection with a temperate phage, designated phi 225. Results of Southern blot analyses indicated that phi 225 repl icated as a plasmid in the lysogenized strain. Genomic DNA from severa l lytic phages was used to establish conditions for transfection by el ectroporation of strains of Actinomyces spp. Efficiencies of DNA trans fer ranged from 10(2) to 10(5) plaque-forming units per microgram of D NA were obtained under optimal transfection conditions. The results of these studies demonstrate that transfer of genetic information in Act inomyces spp. can be achieved by transfection. (C) 1997 Academic Press .