Abstract
Glucosylsucrose (G2F) and maltosylsucrose (G3F) are principal constituents of coupling sugar, which has a similar taste to cane sugar and is used as a sugar substitute in order to reduce the incidence of dental caries.
The toluene-treated cells of Streptococcus salivarius 13419 possesed cell-bound fructosyltransferase and produced a large amount of fructan with fructose and maltose but no glucose from G2F. To clarify whether fructosyltransferase catalyzed this reaction, the extracellular fructosyltransferase was partially purified from Actinomyces viscosus Ny 1 and S. mutans JC 2. The enzyme obtained could produce fructan, fructose and maltose from G2F. G3F as a substrate of the enzyme was utilized to form fructan, fructose and maltotriose.
These results strongly suggest that a fructosyltransferase catalyzes the first step of metabolism of G2F or G3F. It is possible that G2F and G3F and utilized by an oral bacteria which has a fructosyltransferase. The high fermentative efficiency of G2F and G3F by S. salivarius among oral bacteria might be ascribed to high activity of a cell-bound fructosyltransferase.
