Metabolic activity of Streptococcus mutans biofilms and gene expression during exposure to xylitol and sucrose

Abstract

Sucrose sugar and xylitol sweetener both activate genes involved in tooth decay in a bacterium commonly found in the human mouth. Eva-Maria Decker and her colleagues at the University of Tübingen, Germany, cultured Streptococcus mutans in a glucose-rich broth and in the same broth containing sucrose or xylitol. The bacteria formed complex communities called biofilms under all three conditions. The presence of sucrose increased the bacteria’s metabolic activity throughout the various biofilm layers. Despite previous claims that xylitol helps prevent cavities, the natural sweetener did not affect bacterial viability. Both sucrose- and xylitol-supplemented media led to increased expression of several genes involved in biofilm formation. The study, one of only a few concerning the effects of xylitol on S. mutans biofilms, calls into question the effectiveness of xylitol in preventing tooth decay.

Keywords

biofilms / 5-cyano-2,3-ditolyl tetrazolium chloride / extracellular polysaccharides / gene expression / Streptococcus mutans / sucrose / viability / xylitol

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