The structure and immunomodulatory activity on intestinal epithelial cells of the EPSs isolated from Lactobacillus helveticus sp. Rosyjski and Lactobacillus acidophilus sp. 5e2.

The Lactic acid bacteria (LAB) Lactobacillus acidophilus sp. 5e2 and Lactobacillus helveticus sp. Rosyjski both secrete exopolysaccharides (EPSs) into their surrounding environments during growth. A number of EPSs have previously been shown to exhibit immunomodulatory activity with professional immune cells, such as macrophages, but only limited studies have been reported of their interaction with intestinal epithelial cells. An investigation of the immunomodulatory potential of pure EPSs, isolated from cultures of Lactobacillus acidophilus sp. 5e2 and Lactobacillus helveticus sp. Rosyjski, with the HT29-19A intestinal epithelial cell line are reported here. For the first time the structure of the EPS from Lactobacillus helveticus sp. Rosyjski which is a hetropolysaccharide with a branched pentasaccharide repeat unit containing d-glucose, d-galactose and N-acetyl-d-mannosamine is described. In response to exposure to lactobacilli EPSs HT29-19A cells produce significantly increased levels of the proinflammatory cytokine IL-8. Additionally, the EPSs differentially modulate the mRNA expression of Toll-like receptors. Finally, the pre-treatment of HT29-19A cells with the EPSs sensitises the cells to subsequent challenge with bacterial antigens. The results reported here suggest that EPSs could potentially play a role in intestinal homeostasis via a specific interaction with intestinal epithelial cells.

Behaviour of xyloisosaccharinic acid and xyloisosaccharino-1,4-lactone in aqueous solutions at varying pHs.

Xyloisosaccharinic acid is one of the major degradation products formed during the alkali catalysed hydrolysis of hemicelluloses. In acidic solution xyloisosaccharinic acid undergoes an acid catalysed lactonisation to generate xyloisosaccharino-1,4-lactone. We report here the solution phase properties of xyloisosaccharinic including measurement of its aqueous pK(a) (3.00 ± 0.05) using (13)C NMR methods. We also report rate constants for the acid catalysed lactonisation, k(lact(D20)), of xyloisosaccharinic acid and the results of our investigations of the kinetics of hydrolysis of xyloisosaccharino-1,4-lactone at acidic and basic pHs. The second-order rate constants for the hydrolysis reactions k(HO-) (25 M(-1)s(-1)) and k(D+) (4.13 E-4M(-1)s(-1)).

Determination of the structure and molecular weights of the exopolysaccharide produced by Lactobacillus acidophilus 5e2 when grown on different carbon feeds.

Lactobacillus acidophilus 5e2 when grown on skimmed milk, skimmed milk supplemented with sodium formate and skimmed milk supplemented with glucose secretes a branched heteropolysaccharide having a weight average molecular weight less than 450 kDa. The exopolysaccharide has a heptasaccharide repeat unit and is composed of D-glucose, D-galactose and N-acetyl-D-glucosamine in the molar ratio 3:3:1. Using chemical techniques and 1D and 2D-NMR spectroscopy the polysaccharide has been shown to possess the following repeat unit structure: