Formation of Leucrose in Dextran-Producing Cultures of Streptococcus bovis

Abstract

IN addition to dextran and fructose a mixture of reducing disaccharides, containing glucose and fructose, is formed when Leuconostoc mesenteroides strains are grown in sucrose media¹. The same disaccharides are produced when cell-free dextransucrase, obtained from a sucrose culture of L. mesenteroides, is incubated with sucrose². From this disaccharide mixture Stodola, Sharpe and Koepsell² isolated one of the components as a crystalline compound. The pure sugar, named leucrose, was markedly resistant to acid hydrolysis and was shown to have the structure 5-O-α-D-glucopyranosyl-D-fructose². In recent studies on the production of dextran from sucrose by rumen strains of Streptococcus bovis ^3,4 it was noted that similar acid-resistant reducing disaccharides were formed in good yield when dextran was being produced. The exact nature of the sugars was not determined at the time. An examination of the disaccharide fraction has now been made.