Investigating the Potential of Phenolic Compounds and Carbohydrates as Acceptor Substrates for Levansucrasse-Catalyzed Transfructosylation Reaction.

This study characterizes the acceptor specificity of levansucrases (LSs) from Gluconobacter oxydans (LS1), Vibrio natriegens (LS2), Novosphingobium aromaticivorans (LS3), and Paraburkholderia graminis (LS4) using sucrose as fructosyl donor and selected phenolic compounds and carbohydrates as acceptors. Overall, V. natriegens LS2 proved to be the best biocatalyst for the transfructosylation of phenolic compounds. More than one fructosyl unit could be attached to fructosylated phenolic compounds. The transfructosylation of epicatechin by P. graminis LS4 resulted in the most diversified products, with up to five fructosyl units transferred. The acceptor specificity of LS towards phenolic compounds and their transfructosylation products were found to greatly depend on their chemical structure: number of phenolic rings,  reactivity of hydroxyl groups and  presence of aliphatic chains or methoxy groups. As for carbohydrates, the transfructosylation yield was more dependent on the acceptor type than LS source. The highest yield of fructosylated-trisaccharides  was Erlose from the transfructosylation of maltose catalyzed by LS2, with production reaching 200 g/L. LS2 was more selective towards the transfructosylation of phenolic compounds and carbohydrates, while reactions catalyzed by LS1, LS3 and LS4 also produced  fructooligosaccharides. This study shows the high potential for the application of LSs in the glycosylation of phenolic compounds and carbohydrates.