In a complex ecosystem such as periodontal pocket, bacterial antagonism may be a determinant in oral colonization and compositional changes of periodontopathic microflora. This study was performed to examine the growth inhibitory activities among the periodontopathic and indigenous bacteria. The growth inhibitory activity was examined as both producers and indicators by stab culture method. Inhibitory activities of cell sonicate and culture supernatant of S. mutans OMZ 65, which showed broad and strong inhibition against periodontopathic bacteria, was examined by the diffusion method.
The results were as follows.
1. B. gingivalis, B. intermedius and A. actinomycetemcomitans strains showed weak inhibition against homologous and heterologous strains. Two among three strains of B. intermedius showed moderate inhibition against one strain of B. gingivalis and all of A. actinomycetemcomitans strains showed inhibitory activity to B. gingivalis.
2. The strains of S. mutans showed broad and strong inhibition against B. gingivalis, A. actinomycetemcomitans strains and moderate inhibition against B. intermedius, but S. sanguis strains showed weaker growth inhibitory spectra than those of S. mutans strains. However, the pattern of inhibitory activity showed, to a certain extent, species --specific.
3. S. mutans strains showed broader inhibitory spectrum against A. a. Korean strains than that of S. sanguis strains. But A. actinomycetemcomitans Korean strains has rarely showed growth inhibition against S. sanguis.
4. A. actinomycetemcomitans Korean strains showed weak inhibitory activity to B. i gingivalis and no inhibitory activity to B. intermedius.
Hx 5. .~i. mutans showed strong inhibitory activity to homologous strains and typically speciesspecific than these of S. sanguis. Further investigation should be needed to clarify a relationship between the presence of plasmids and bacteriocin activity.
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