Scanning electron microscope study on the removal of artificial dental plaque treated with a bacteriolytic enzyme from Streptomyces globisporus--its synergistic effects with dextranase and lysozyme (author's transl)

Abstract

It has been reported in our laboratory that Streptococcus mutans strain BHT formed bacterial deposits on human enamel after cultivation at 37°C for 4 days in 5% sucrose broth and that by the treatment of the artificial plaque with the bacteriolytic enzyme derived from Streptomyces glovisporus strain 1829, strain BHT cells in the plaque were lyzed into the string form and the membranous bands which intersected with each other and with the fibrils protruduing from the cell peripheries, and constructed filamentous networks. The purposes of the present manuscript were to demonstrate that the residual networks could be removed by the treatment with various kinds of enzymes such as dextranase and lysozyme, and to obtain a clue for clarifying the nature of the lyzate which persisted on the enamel surface.The artificial plaque on enamel piece was incubated with the bacteriolytic enzyme in vitro under the same conditions described elsewhere. After the residual networks were further treated for 1 hour with dextranse from Spicaria violaceae, a coarse networks intersected with membranous bands with a clear outline appeared and remained on the enamel surfaces, whereas the fine network formed by the fibrils and the string virtually disappeared. Intact cells were also observed to be reduced in number. On the contrary, when the artificial bacterial deposition was incubated for 1hour with the lytic enzyme and egg-white lysozyme simultaneously, the membranous bands and intact cells disappeared and a monolayer of relatively fine network structure formed by the fibrils and the string still remained. Furthermore the artificial plaque was almost completely removed from the tooth surface after the treatment with those three enzymes. Dextranase P, trypsin and nucleases had no effect on either the nontreated control or the lytic enzyme-treated plaque.Based on the results obtained, the mechanisms of the plaque-eliminating ability of lysozyme and dextranase as the synergist with the bacteriolytic enzyme were discussed in relatiot to the natures of the filamentous and membranous components which constructed the residual networks after the lytic enzyme treatment of the artificial plaque.