CONJUGAL TRANSFER OF BROAD-HOST-RANGE INCOMPATIBILITY GROUP-P AND GROUP-Q PLASMIDS FROM ESCHERICHIA-COLI TO ACTINOBACILLUS-ACTINOMYCETEMCOMITANS

The first example of conjugal transfer of DNA from Escherichia coli to the periodontal pathogen Actinobacillus actinomycetemcomitans is pres ented. Derivatives of the incompatibility group P (IncP) plasmid RK2 s uccessfully transferred from an E. coli donor to an A. actinomycetemco mitans recipient. The resulting A. actinomycetemcomitans transconjugan ts transferred the plasmids back to E. coli recipients. The IncP trans fer functions were also used in trans to mobilize the IncQ plasmid pBK 1 from E. coli to A. actinomycetemcomitans. The IncP and IncQ plasmids both transferred into A. actinomycetemcomitans at high frequencies (0 .3 to 0.5 transconjugants per donor) and showed no gross deletions, in sertions, or rearrangements. Determinations of MICs of various antibio tics for the A. actinomycetemcomitans transconjugant strains demonstra ted the expression of ampicillin, chloramphenicol, and kanamycin resis tance determinants.