INDUCIBLE BACTERIOPHAGES OF ACTINOBACILLUS-ACTINOMYCETEMCOMITANS

Doses of 0.1 to 1.0 mu g/ml of mitomycin C induced cell lysis of six o f eight strains of Actinobacillus actinomycetemcomitans tested. Infect ious phages were induced from ATCC strains 43717, 29524, 33384, and 43 719; non-plaque-forming, possibly defective phages were induced from A TCC strains 29522 and 29523. No phages were detected in strain FDC 651 or ATCC strain 43718, No correlation between lysogeny and leukotoxin production or serotype of the strains could be established, Gel electr ophoresis of phage DNAs indicated that the induced phages were of thre e types, based on size. By electron microscopy, the phages were found to belong to either morphotype Al or morphotype B1; no other morphotyp es were observed, Curing experiments led to the isolation of nonlysoge nic derivatives of two strains, which supported plaque formation by th e phages they originally carried. On the basis of our results, lysogen y appears to be widespread in A. actinomycetemcomitans.