Exopolysaccharide from Lactobacillus fermentum Lf2 and its functional characterization as a yogurt additive

Abstract

Lactobacillus fermentum Lf2 is a strain which is able to produce high levels (approximately 1 g/l) of crude exopolysaccharide (EPS) when it is grown in optimised conditions. The aim of this work was to characterize the functional aspects of this EPS extract, focusing on its application as a dairy food additive. Our findings are consistent with an EPS extract that acts as moderate immunomodulator, modifying s-IgA and IL-6 levels in the small intestine when added to yogurt and milk, respectively. Furthermore, this EPS extract, in a dose feasible to use as a food additive, provides protection against Salmonella infection in a murine model, thus representing a mode of action to elicit positive health benefits. Besides, it contributes to the rheological characteristics of yogurt, and could function as a food additive with both technological and functional roles, making possible the production of a new functional yogurt with improved texture.

Evidence for the Modulation of the Immune Response in Peripheral Blood Mononuclear Cells after Stimulation with a High Molecular Weight β-glucan Isolated fromLactobacillus fermentumLf2

“…L. fermentum Lf2 was grown at the Instituto de Lactologia Industrial (Santa Fe, Argentina). The growth conditions, as well as the crude EPS extraction and purification methods have previously been reported (11; 49). Size Exclusion Chromatography coupled with Multi Angle Laser Light Scattering (SEC-MALLS-Wyatt technology, Santa Barbara, CA, USA) was used to determine the composition of the crude EPS.…”

“…L. fermentum Lf2 is a strain that was isolated as a contaminant culture during cheese manufacture (10). The strain produces significant quantities of a mixture of EPS (∼2g/L) and it has been demonstrated that the crude EPS has immunomodulatory activity (11). In previous studies, using EPS from lactic acid bacteria (12; 13), we have shown that specific EPS can stimulate production of pro- and anti-inflammatory cytokines.…”

Statistical optimisation of the exopolysaccharide production by Lactobacillus fermentum Lf2 and analysis of its chemical composition

“…They can play the role of natural texturisers and can function as thickeners, stabilisers and gelling agents in several food matrices (Ahmed and Ahmad ; Rehman et al ). More recently, these molecules have been also associated with beneficial roles for health, since they presented anticancer properties (Deepak et al ), cholesterol‐lowering effects (Korcz et al ), immunomodulatory (Hidalgo‐Cantabrana et al ; Ale et al ) and prebiotic (Hamet et al ; Ale et al ) properties. Besides, EPS from LAB have presented protective roles against pathogenic microorganisms (Nagai et al ; Maruo et al ; Ale et al ) and have been related to the prevention of oxalate stone disease (Sönmez et al ), as well as to oxidative damage protection (Chen et al ).…”

“…The medium MRS (Man, Rogosa and Sharpe broth, De Man et al ), routinely used for the development of lactobacilli, contains components (meat extract, yeast extract and proteose peptone) that interfere with the quantification and analysis of EPS, mainly due to the presence of mannans from the yeast extract, among other compounds of carbohydrate nature (Cerning et al ; Kimmel and Roberts ) that co‐precipitate with EPS. For this reason, a semidefined medium was selected (SDM, Kimmel and Roberts ), which was suitable for evaluating the influence of its composition on EPS production (Ale et al ). According to former studies (Shi et al ), some components have more influence on EPS yield and composition than others, such as the carbon and nitrogen sources used.…”

“…Lactobacillus fermentum Lf2 is an autochthonous strain that was isolated from semihard Tybo cheese as nonstarter culture, and its EPS extract was related to interesting functional and technological properties. This extract, in small doses, was able to protect mice against a Salmonella infection and increase intestinal IgA levels when added in yoghurt (Ale et al ). Furthermore, it was able to modify beneficially the microbiota of mice when added solely or combined with a probiotic strain, reinforcing its ability to act as functional food ingredient (Ale et al ).…”