Production and use of glycosyltransferases from new strains Leuconostoc mesenteroides for the synthesis of glucooligosaccharides

The present study reports on the biosynthesis of an extracellular glucosyltransferase by two strains Leuconostoc mesenteroides - LM22 and LM28 isolated from bulgarian dairy products. A total glucosyltransferase activities of 10,84 U/ml for LM28 strain and 8,80 U/ml for LM22 were measured in batch culture. The enzymes from supernatant were purified using aqueous two-phase partititon between dextran and PEG phases, yielding a preparation with 36,3 U/mg protein. It was shown that both extracellular enzymes from strains LM22 and LM28 catalyze acceptor reactions and transfer the glucose unit from sucrose onto maltose to produce glucooligosaccharides. By increasing the sucrose/maltose ratio (S/M), it was possible to catalyze the synthesis of oligosaccharides of increasing degree of polymerisation. For an S/M ratio of 7, both linear oligosaccharides (only composed of alpha-1,6) linkages and a maltose residue at the reducing end) and branched oligosaccharides were produced.