Structural characterisation and enzymic modification of the exopolysaccharide produced by Lactococcus lactis subsp cremoris B39

Lactococcus lactis subsp, cremoris B39 grown on whey permeate produced an e xopolysaccharide containing L-Rha, D-Gal and D-Glc in a molar ratio of 2:3: 2. The polysaccharide was modified using an enzyme preparation from Aspergi llus aculeatus, resulting in the release of Gal and a polymer with approxim ately the same hydrodynamic volume as the native polysaccharide. Linkage an alysis and H-1 NMR studies of both the native and modified exopolysaccharid es elucidated that terminally linked Gal was released during modification a nd that the chemical structure of the branches within the repeating units i s: beta-D-Galp-(1 --> 4)-beta-D-Glcp-(1 -->. 2D NMR experiments (both H-1-H -1 and H-1-C-13) revealed that exopolysaccharide B39 consists of a branched heptasaccharide repeating unit with the following structure: [GRAPHICS] (C) 2000 Elsevier Science Ltd. All rights reserved.