The in-vitro effect of fungal dextranase on human dental plaque

Abstract

Suspensions of dental plaque from eighteen children with high caries activity were hydrolyzed in vitro by a partially purified fungal dextranase isolated from Penicillium funiculosum NRRL 1768. The dextranase preparation appeared to lack 1,4-glucanhydrolase and sucrase activity. The release of reducing substances from the plaque was measured by use of a 3,5-dinitrosalicylate reagent. Hydrolysis occurred at pH 5.1 but not at pH 7.0. Approximately 20 per cent of the total carbohydrate of plaque was consumed by the dextranase (2-3 per cent of the plaque dry weight). No isomaltose was found when the hydrolysates were analysed by a thin layer chromatography procedure which could detect as little as 0.1 [mu]g of isomaltose. The findings suggest that the quantity of dextran in these plaque samples is low.