Functional properties of exopolysaccharide (EPS) extract from L. fermentum Lf2 and its analysis when combined with B. animalis INL1 in yogurt

ALE, E.; BURNS, P.; PERALTA, G.; ÁVILA, O.; CONTINI, L.; REINHEIMER J.A.; BINETTI, A.

Córdoba

Congreso; VII Congreso Internacional de Ciencia y Tecnología de los Alimentos (Cicytac); 2018

Ministerio de Ciencia y Tecnología de Córdoba

Lactobacillus fermentum Lf2 is an autochthonous strain which was isolated asnon-starter culture from a local semi-hard cheese. It produces high amounts ofEPS when it grows under controlled conditions of temperature and pH, reaching~1 g/L. In the present study, the functional roles of an EPS extract from L.fermentum Lf2 were studied by means of in vitro and in vivo assays, isolated orcombined with an autochthonous probiotic strain, Bifidobacterium animalissubsp. lactis INL1, and both applied as food ingredients in yogurt. First, an invitro analysis was done with THP-1 cell line. Macrophages derived from THP-1were stimulated with crude or purified EPS, 60 μg/mL and 12.6 μg/mL,respectively. This last concentration was proposed taking into account that,after purification of the crude EPS extract, 21% (approximately) is recovered. Apositive control (treated with lipopolysaccharide, 0.5 μg/mL), and negativecontrol (untreated cells) were included. The cells were incubated for 4 h (37 °C,5% CO2) for the detection of TNF-α, and 8 h for IL-6 and IL-10 determinations.The cytokine analysis was performed from the culture supernatants using theDuoSet ELISA kits (R&D Systems). Besides, an in vivo assay was done, inwhich BALB/c mice (7/group) received yogurt with EPS (600 mg/L, YE),bifidobacteria (5x108 CFU/mL, YB), a combination of both ingredients (YEB) oryogurt with no additives (Y, control group), for 25 days. During treatment,different bacterial groups (Lactobacillus, Bifidobacterium, B. animalis, B.bifidum, B. breve, B. catenulatum, C. leptum, C. coccoides, Staphylococcus,Enterobacteriaceae, Streptococcus, general microbial load with universalprimers) and short chain fatty acids (SCFA) were determined in faeces byqPCR and HPLC, respectively (at 0, 8, 18 and 25 days). Furthermore, IgAlevels were quantified in intestinal fluid, and IL-10, IFN-γ, IL-6 and TNF-αcytokines were measured in small intestine by ELISA. Histological analyseswere carried out in order to evaluate the morphology of small and largeintestines. The group YE presented increased concentrations of acetic, butyricand total SCFA (the sum of acetic, butyric and propionic acids) at the end of the treatment, and increasing levels of the C. coccoides cluster (SCFA producinggroup) over time (p< 0.05). The YEB group presented a possible symbiotic rolereflected mainly in the levels of the species B. animalis at all times evaluated.These results highlight the potential application of the EPS of L. fermentum Lf2 as a functional ingredient, individually or together with B. animalis subsp. lactis INL1.