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UBC Theses and Dissertations

Dextran mediated interactions of Actinomyces viscosus Bourgeau, Gene


Actinomyces viscosus was shown to be only the second oral organism capable of being aggregated by low amounts of dextran (as few as 3 molecules of dextran per bacterial cell); Streptococcus mutans being the first. Aggregation was shown to depend on dextran molecular weight and dextran concentration. Ions were required for aggregation to occur but there was no specific ion requirement. Concanavalin A and phytohemagglutinin both inhibited dextran induced aggregation as did the simple sugars sucrose, trehalose, melezitose and mannose. The heating of cells to 100°C in distilled water removed the ability to aggregate while heating at 100°C for up to one hour in the presence of divalent cations lowered but did not eliminate this ability. Treatment of A. viscosus cells with various proteases and a dextranase preparation eliminated the ability to aggregate via dextran. Dextran induced aggregation was not limited to one A. viscosus strain but was a property displayed by several ATCC strains and several freshly isolated strains. Dextran induced aggregation was also shown to be a potential means of interbacterial aggregation in the oral cavity since it mediates an interaction between A. viscosus and both Streptococcus mutans and Streptococcus sanguis. This interaction was similar in most respects to that involving only A. viscosus or only S. mutans.

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