Functional properties of exopolysaccharide (EPS) extract from Lactobacillus fermentum Lf2 and its impact when combined with Bifidobacterium animalis INL1 in yoghurt

Abstract

In the present work, the functional roles of an exopolysaccharide (EPS) extract form Lactobacillus fermentum Lf2 were studied by means of in vitro and in vivo assays, individually or combined with a probiotic strain, Bifidobacterium animalis subsp. lactis INL1. From the in vitro assay (macrophages derived from THP-1 cell line), the EPS in its purified form caused an increase in the levels of the proinflammatory cytokine TNFα, while both forms of EPS (purified and crude) produced an increase in the regulatory cytokine IL-10, evidencing an immunomodulatory role. To study the functional role of EPS as a food ingredient, an in vivo assay was done with mice (BALB/c) that received yogurt with EPS (600 mg L-1, YE), with bifidobacteria (5x108 CFU mL-1, YB), a combination of both ingredients (YEB), or yogurt with no additives (Y), for 25 days. The level of diverse bacterial groups and Short Chain Faty Acids (SCFA) were estimated in faeces, and s-IgA and cytokines were determined in small intestine. Among the four groups, only the group YE presented significantly increased concentrations of acetic and butyric acids, together with an increase in the total SCFA (p< 0.05), through the time of treatment. The levels of the C. coccoides cluster (SCFA producing group) rose over time (p< 0.05) for this group as well. When the combination of both ingredients was studied (YEB), a possible bifidogenic role was observed, reflected in the increasing levels of the genus Bifidobacterium along time (p< 0.05), a behaviour that was not observed when the probiotic was administered solely (group YB). But, in this case, no significant differences were observed for the concentration of SCFA. These results highlight the promising application of this EPS as a functional food ingredient: with prebiotic or synbiotic potential roles, when administered individually (due to its effects on the SCFA levels) or combined with B. animalis subsp. lactis INL1 (considering the increase of Bifidobacteria during the time of treatment), respectively.