Structural investigation of a neutral extracellular glucan from Lactobacillus reuteri SK24.003

• A neutral exopolysaccharide was obtained from Lactobacillus reuteri SK24.003.
• Monosaccharide composition analysis confirmed that exopolysaccharide consisted of glucose residues only.
• The polysaccharide possessed predominantly α-(1→4) glycosidic linkages, with fewer α-(1→6) glycosidic linkages and α-(1→4,6) branching points.
• A promising application of exopolysaccharide was provided.

The structural features of a neutral extracellular glucan derived from Lactobacillus reuteri SK24.003 were investigated. Colonies of the strain SK24.003 exhibited a creamy and slimy morphological appearance on MRS solid medium and were identified as L. reuteri via 16S rDNA sequence analysis. The exopolysaccharide produced from sucrose was composed exclusively of glucose, and the weight-average molecular weight was 4.31 × 107 g/mol. The polysaccharide exhibited an α-(1→4) backbone with an α-(1→6) branch at every fourth residue, as deduced from both NMR and GC–MS data. The exopolysaccharide acted as a natural steel corrosion inhibitor. The results suggested that a novel α-glucan produced by L. reuteri SK24.00 could be broadly used in food and material field.