Probiotic foods intended for human nutrition are gaining economic relevance but it is clear that for the application of new strains scientific and rational selection criteria must be used. In this work, the role of exopolysaccharide (EPS) produced by Bifidobacterium strains in their potential beneficial effect was studied. Two in vitro biological models were used to test the interaction of seventeen strains and their polymers with the host. In general, the EPS-producing bifidobacteria showed good adherence properties to Caco2 and HT29 cell lines which could be of interest for a transitory colonisation of the gut. Most purified EPS were able to slightly stimulate the proliferation of peripheral blood mononuclear cells and their cytokine production pattern, depending on the polymer type tested. In general, neutral high molar mass EPS diminished the immune response, whereas acidic and smaller polymers were able to elicit an increased response. Thus, EPS synthesised in situ during dairy fermentations could be involved in some of the beneficial effects attributed to the EPS-producing bacteria. Probiotic functionality of these strains seems to be related to the physico-chemical characteristics of EPS as is known to occur with the technological properties. © 2011 Elsevier Ltd.

This work was financed by FEDER funds (European Union) and the Spanish “Plan Nacional I + D + I” from the “Ministerio de Ciencia e Innovación” (MICINN) through the project AGL2006-03336 and by the CSIC funds through the project PIE-200670I169. P. López acknowledges her research contract supported by project AGL2007-61805 and D. Monteserín for her FPI fellowship, both from MICINN.

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