Bifidobacterium exopolysaccharides: new insights into engineering strategies, physicochemical functions, and immunomodulatory effects on host health

Bifidobacteria are a prominent type of bacteria that have garnered significant research attention for their exceptional probiotic properties and capacity to produce exopolysaccharides (EPSs). These compounds exhibit diverse physical, chemical, and biological characteristics, prompting numerous investigations into their potential applications. Researchers have noted their beneficial effects as immune modulators within the host's body across various industries. Extensive research has been conducted on the immunomodulatory effects of bifidobacteria-derived EPSs, with emerging engineering strategies aimed at enhancing their immune-modulating capabilities. Understanding the structure, physicochemical properties, and biological activities of these compounds is crucial for their effective utilization across different industries. Our review encompassed numerous studies exploring Bifidobacterium and its metabolites, including EPSs, across various sectors, drawing from diverse databases. The distinctive properties of EPSs have spurred investigations into their applications, revealing their potential to bolster the immune system, combat inflammation, and treat various ailments. Additionally, these compounds possess antioxidant and antimicrobial properties, making them suitable for incorporation into a range of products spanning food, health, and medicine.

Encapsulating potential and functional properties of exopolysaccharide from Limosilactobacillus reuteri KCTC 14626BP isolated from human breast milk

Exopolysaccharides (EPS) are natural, nontoxic, biocompatible and biodegradable macromolecules produced by microorganisms, including the Lactic acid bacteria, to enhance protection against environmental stress conditions. The current study focused on the encapsulation and functional efficiency of EPS produced by probiotic strains isolated from human milk. Among 27 isolates, the potential high EPS-producing strain Limosilactobacillus reuteri KCTC 14626BP was selected based on biofilm production. The structural Characterization of EPS was performed based on FTIR, NMR and functional properties were determined; further, the encapsulation efficiency of EPS was determined with caffeic acid. The results indicate that L. reuteri produced EPS major component consisting of glucose, galactose and arabinose with the ratio of (0.78:0.16: 0.05). The antioxidant efficiency of EPS-LR was determined on DPPH (60.3 %) and ABTS (48.9 %); EPS showed enhanced functional activities. The absence of toxicity was confirmed based on Caenorhabditis elegans. The EPS-loaded Caffeic acid (CA) EPS-LR indicated spherical capsules with rough surfaces, with sizes ranging from 1.39 to 6.75 μm. These findings indicate that EPS-LR can be applied as a bioactive compound and encapsulating material in food, cosmetics, and pharmaceutical industries.

Microbial Conjugated Linolenic Acid-Enriched Fermented Milk Using Lipase-Hydrolyzed Flaxseed Oil: Biochemical, Organoleptic and Storage Traits

The bioactive conjugated linolenic acid (CLNA) can be microbiologically produced by different probiotic strains when in the presence of α-linolenic acid (α-LNA). Food matrices are a good vector, such as has been previously demonstrated with fermented milk enriched with microbial CLNA by Bifidobacterium breve DSM 20091 from lipase-hydrolyzed flaxseed oil. The aim of the present work was to further assess the nutritional, biochemical and organoleptic properties of the developed dairy product, as well as its storage stability throughout 28 days at 4 °C, proving its suitability for consumption. Milk lactose hydrolyzed into glucose (0.89 g/100 g) and galactose (0.88 g/100 g), which were further metabolized into lactic (0.42 g/100 g), acetic (0.44 g/100 g) and propionic (0.85 g/100 g) acids. Titratable acidity reached 0.69% and pH 4.93. Compared with the control (no CLNA), fat content was slightly higher (2.0 g/100 g). Acetic acid was the major volatile (83.32%), lacking important dairy flavor contributors, like acetaldehyde. Sensory analysis revealed predominant astringency and bitterness. No microbial concerns arose during storage, but the CLNA content increased, and some saturated fatty acids seemed to oxidize. In conclusion, the CLNA-enriched fermented milk revealed reasonable compositional properties, yet further improvements are needed for optimal consumer acceptance and a prolonged shelf-life.

Structural Analysis and Antioxidant and Immunoregulatory Activities of an Exopolysaccharide Isolated from Bifidobacterium longum subsp. longum XZ01

Bifidobacterium longum subsp. longum XZ01 (BLSL1) is a new strain (isolated from the intestines of healthy people and deposited with the preservation number GDMCC 61618). An exopolysaccharide, S-EPS-1, was successfully isolated from the strain and then systematically investigated for the first time. Some structural features of S-EPS-1 were analyzed by chemical component, HPLC, ultraviolet, infrared, and nuclear magnetic resonance spectrum analyses. These analyses revealed that S-EPS-1 is a neutral heteropolysaccharide with an α-configuration. It contains mainly mannose and glucose, as well as small amounts of rhamnose and galactose. The molecular weight of S-EPS-1 was calculated to be 638 kDa. Several immunoregulatory activity assays indicated that S-EPS-1 could increase proliferation, phagocytosis, and NO production in vitro. In addition, S-EPS-1 could upregulate the expression of cytokines at the mRNA level through TLR4-mediated activation of the NF-κB signaling pathway in RAW 264.7 cells. Finally, S-EPS-1 was demonstrated to exhibit antioxidant activity by ABTS+• scavenging, DPPH• scavenging, and ferric-ion reducing power assays. Furthermore, S-EPS-1 can protect cells from oxidative stress and shows no cytotoxicity. These beneficial effects can be partly attributed to its antioxidant ability. Thus, the antioxidant S-EPS-1 may be applied as a functional food in the future.

Assessing the probiotic potential, antioxidant, and antibacterial activities of oat and soy milk fermented with Lactiplantibacillus plantarum strains isolated from Tibetan Kefir

Sufficient intake of probiotics has been shown to help in the digestion, protect the body against pathogenic microorganisms and boost the immune system. Recently, due to high prevalence of milk allergies and lactose intolerance in population, the non-dairy based probiotic alternative are becoming increasing popular. In this context, the oat milk and soya milk-based fermented products can be an ideal alternative for the development of Lactic acid bacteria bacteria based probiotics. These bacteria can not only improve the product's flavor and bioavailability but also increases its antibacterial and antioxidant capabilities due to fermentation process. The purpose of the resent work was to assess the antioxidant and probiotic properties of oat and soy milk that had been fermented with three different strains of Lactiplantibacillus plantarum (L. plantarum) including L. plantarum 12-3, L. plantarum K25, and L. plantarum YW11 isolated from Tibetan Kefir. Different validated assays were used to evaluate the probiotic properties, adhesion and survival in the digestive system (stomach, acid and bile salts resistance), antioxidant and antimicrobial activities and safety (ABTS and DPPH scavenging assays) of these strains. Results of the study showed that soya milk and oat milk fermented with L. plantarum strains possess promising probiotic, antibacterial and antioxidant properties. These results can be helpful to produce dairy-free probiotic replacements, which are beneficial for those who are unable to consume dairy products due to dietary or allergic restrictions.

On the Molecular Selection of Exopolysaccharide-Producing Lactic Acid Bacteria from Indigenous Fermented Plant-Based Foods and Further Fine Chemical Characterization

Exopolysaccharides (EPSs) produced by lactic acid bacteria present a particular interest for the food industry since they can be incorporated in foods via in situ production by selected starter cultures or applied as natural additives to improve the quality of various food products. In the present study, 43 strains were isolated from different plant-based fermented foods and identified by molecular methods. The species found were distinctively specific according to the food source. Only six Lactiplantibacillus plantarum strains, all isolated from sauerkraut, showed the ability to produce exopolysaccharide (EPS). The utilization of glucose, fructose and sucrose was explored with regard to EPS and biomass accumulation by the tested strains. Sucrose was clearly the best carbon source for EPS production by most of the strains, yielding up to 211.53 mg/L by strain Lactiplantibacillus plantarum ZE2, while biomass accumulation reached the highest levels in the glucose-based culture medium. Most strains produced similar levels of EPS with glucose and fructose, while fructose was utilized more poorly for biomass production, yielding about 50% of biomass compared to glucose for most strains. Composition analysis of the EPSs produced by strain Lactiplantibacillus plantarum ZE2 from glucose (EPS-1) and fructose (EPS-2) revealed that glucose (80-83 mol%) and protein (41% w/w) predominated in both analyzed EPSs. However, the yield of EPS-1 was twice higher than that of EPS-2, and differences in the levels of all detected sugars were found, which shows that even for the same strain, EPS yield and composition vary depending on the carbon source. These results may be the basis for the development of tailored EPS-producing starter cultures for food fermentations, as well as technologies for the production of EPS for various applications.

Effect of Probiotics Lactobacillus acidophilus and Lacticaseibacillus rhamnosus on Antibacterial Response Gene Transcription of Human Peripheral Monocytes

Periodontitis and related systemic inflammatory diseases are characterized by imbalanced ratio between pro- and anti-inflammatory factors. Probiotics may control inflammation by altering the inflammatory phenotype of defense cells. We aimed to evaluate the gene transcription of the antibacterial response of monocytes to exposure to probiotic lactobacilli. CD14 + monocytes were obtained by positive selection from peripheral blood mononuclear cells from healthy donors (5 × 10⁴ CD14 + /mL) and cultured with probiotic strains of Lacticaseibacillus rhamnosus (LR-32) and Lactobacillus acidophilus (LA-5) at a 1:10 multiplicity of infection in 24-well plates for 12 h. The gene expression analysis was performed by RT-qPCR using the Kit RT² human antibacterial response, and in the supernatant, the cytokines were determined by ELISA. Tukey's post hoc test following an ANOVA with a p value of 5% was used for statistical analysis. Both probiotic strains increased the levels of cytokines TNF-α and CXCL-8 in the supernatant compared to the control of non-challenged cells (p < 0.05), but for IL-1Β and IL-6, this effect was observed only for LA-5 (p < 0.05). The fold-regulation values for the following genes for LA-5 and LR-32 were, respectively, IL-12B (431.94 and 33.30), IL-1Β (76.73 and 17.14), TNF-α (94.63 and 2.49), CXCL-8 (89.59 and 4.18), and TLR-2 (49.68 and 3.40). Likewise, most of the other genes evaluated showed greater expression for LA-5 compared to LR-32 (p < 0.05). The positive regulation of inflammatory factors such as IL-1β promoted by L. acidophilus LA-5 may increase the antibacterial activity of innate defense in periodontal tissues. However, this property may be deleterious by increasing inflammatory response.

Maltose-Enhanced Exopolysaccharide Synthesis of Lactiplantibacillus plantarum through CRP-like Protein

Carbon sources alter the synthesis of exopolysaccharides (EPS) in Lactiplantibacillus plantarum. Maltose increased the EPS production of L. plantarum 163 6.5-fold. Subsequently, EPS production, transcriptome, and proteome were analyzed using glucose or maltose to further clarify the regulatory mechanism. A cAMP receptor protein (UniProtKB: F9UNI5) has been identified to control EPS synthesis in the presence of cAMP by binding to the EPS synthesis promoter P_cps4A-J. Overexpression of the cAMP synthesis gene cyaA increased cAMP content and EPS production 4.5- and 2.2-fold, respectively. Furthermore, yogurt produced with L. plantarum 163-cyaA had a similar viscosity to that of commercial Greek yogurt; it had 20 and 83.7% greater viscosity than that produced with L. plantarum 163 with maltose and glucose, respectively. These findings indicated that L. plantarum 163-cyaA has potential applications in the production of functional fermented dairy products.

Feeding Lactic Acid Bacteria with Different Sugars: Effect on Exopolysaccharides (EPS) Production and Their Molecular Characteristics

Exopolysaccharides (EPS) are complex molecules produced by some microorganisms and used in foods as texturizers and stabilizers, their properties depending on their chemical structure. In this work, three different lactic acid bacteria (LAB), were tested for their ability to produce EPS, by using five different mono- and disaccharides as their sole carbon source. The growth and acidifying ability were analysed, the EPSs were quantified by the official method AOAC 991.43, and their chemical structure was investigated. The amount of EPS varied from 0.71 g/L to 2.38 g/L, and maltose was the best sugar for EPS production by Lacticaseibacillus paracasei 2333. Lacticaseibacillus rhamnosus 1019 produced the highest amount when fed with lactose, whereas the EPS amount of Lactobacillus bulgaricus 1932 was not significantly different depending on the sugar type. The EPS chains consisted of fructose, galactose, glucose, mannose, ribose, glucosamine, galactosamine, and in some cases rhamnose in different proportions, depending on the strain and carbon source. The molecular weight of EPS ranged from <10 KDa to >500 KDa and was again highly dependent on the strain and the sugar used, suggesting the possibility of growing different strains under different conditions to obtain EPS with different potential applications in the food system.

Effects of a Lactobacillus fermentation product on the fecal characteristics, fecal microbial populations, immune function, and stress markers of adult dogs

The objective of this study was to measure the effects of a Lactobacillus fermentation product (LBFP) on fecal characteristics and microbiota, blood biomarkers, immune function, and serum oxidative stress markers of adult dogs. Thirty adult beagle dogs [23 M, 7 F; mean age = 8.47 ± 2.65 yr old; mean BW = 15.43 ± 4.17 kg] were used in a completely randomized design study. All dogs were fed a basal diet to maintain BW for 5 wk, followed by baseline blood and fecal sample collections. Dogs remained on the same diet, but then were randomly assigned to a placebo (dextrose) or LBFP supplement (Limosilactobacillus fermentum and Lactobacillus delbrueckii). Both treatments were dosed at 4 mg/kg BW via gelatin capsule for 5 wk (n = 15/treatment). Fecal and blood samples were collected at that time. Change from baseline data were analyzed using the Mixed Models procedure of SAS 9.4, with P < 0.05 being significant and P < 0.10 being trends. Most circulating metabolites and immunoglobulins (Ig) were unaltered by treatment, but LBFP-supplemented dogs had lower changes in serum corticosteroid isoenzyme of alkaline phosphatase (P < 0.05), alanine aminotransferase (P < 0.10), and IgM (P < 0.10) than controls. The change in fecal scores tended to be lower (P = 0.068) in LBFP-supplemented dogs than controls, signifying firmer feces in LBFP-supplemented dogs. Regarding the fecal microbiota, alpha diversity indicators tended to be higher (P = 0.087) in LBFP-supplemented dogs than controls. One fecal bacterial phylum (Actinobacteriota) was altered by treatments, with its relative abundance tending to have a greater (P < 0.10) increase in controls than LBFP-supplemented dogs. Fifteen bacterial genera were altered (P < 0.05 or P < 0.10) by treatments, including relative abundances of fecal Peptoclostridium, Sarcina, and Faecalitalea that had a greater (P < 0.05) increase in controls than LBFP-supplemented dogs. In contrast, relative abundances of fecal Faecalibaculum, Bifidobacterium, and uncultured Butyricicoccaceae had a greater (P ≤ 0.05) increase in LBFP-supplemented dogs than controls. After week 5, dogs underwent transport stress (45-min vehicle ride) to assess oxidative stress markers. The change in serum superoxide dismutase after transport had a greater (P < 0.0001) increase in LBFP-supplemented dogs than controls. Our data suggest that LBFP may provide benefits to dogs by stabilizing stool quality, beneficially shifting fecal microbiota, and protecting against oxidative damage when subjected to stress.

Analysis of Chemical Structure and Antibiofilm Properties of Exopolysaccharides from Lactiplantibacillus plantarum EIR/IF-1 Postbiotics

Previous studies have indicated that the exopolysaccharides of lactic acid bacteria exhibit antibiofilm activity against non-oral bacteria by preventing their initial adhesion to surfaces and by downregulating the expression of genes responsible for their biofilm formation. The aims of this study were to (1) characterize the exopolysaccharides (EPSs) of Lactobacillus plantarum EIR/IF-1 postbiotics, (2) test their antibiofilm effect on dual biofilms, and (3) evaluate their bacterial auto-aggregation, co-aggregation, and hydrocarbon-binding inhibitory activity. The EPSs were characterized by FTIR, HPLC, and thermogravimetric analysis. Bacterial auto- and co-aggregation were tested by Kolenbrander’s method and hydrocarbon binding was tested by Rosenberg’s method. Dual biofilms were formed by culturing Fusobacterium nucleatum ATCC 25586 with one of the following bacteria: Prevotella denticola ATCC 33185, P. denticola AHN 33266, Porphyromonas gingivalis ATCC 33277, P. gingivalis AHN 24155, and Filifactor alocis ATCC 35896. The EPSs contained fractions with different molecular weights (51 and 841 kDa) and monosaccharides of glucose, galactose, and fructose. The EPSs showed antibiofilm activity in all the biofilm models tested. The EPSs may have inhibited bacterial aggregation and binding to hydrocarbons by reducing bacterial hydrophobicity. In conclusion, the EPSs of L. plantarum EIR/IF-1, which consists of two major fractions, exhibited antibiofilm activity against oral bacteria, which can be explained by the inhibitory effect of EPSs on the auto-aggregation and co-aggregation of bacteria and their binding to hydrocarbons.

Fucose-containing bacterial exopolysaccharides: Sources, biological activities, and food applications

Bacterial exopolysaccharides are high molecular weight polysaccharides that are secreted by a wide range of bacteria, with diverse structures and easy preparation. Fucose, fucose-containing oligosaccharides (FCOs), and fucose-containing polysaccharides (FCPs) have important applications in the food and medicine fields, including applications in products for removing Helicobacter pylori and infant formula powder. Fucose-containing bacterial exopolysaccharide (FcEPS) is a prospective source of fucose, FCOs, and FCPs. This review systematically summarizes the common sources and applications of FCPs and FCOs and the bacterial strains capable of producing FcEPS reported in recent years. The repeated-unit structures, synthesis pathways, and factors affecting the production of FcEPS are reviewed, as well as the degradation methods of FcEPS for preparing FCOs. Finally, the bioactivities of FcEPS, including anti-oxidant, prebiotic, anti-cancer, anti-inflammatory, anti-viral, and anti-microbial activities, are discussed and may serve as a reference strategy for further applications of FcEPS in the functional food and medicine industries.

In Vitro Probiotic Modulation of the Intestinal Microbiota and 2′Fucosyllactose Consumption in Fecal Cultures from Infants at Two Months of Age

2′-fucosyllactose (2′FL) is one of the most abundant oligosaccharides in human milk, with benefits on neonatal health. Previous results point to the inability of the fecal microbiota from some infants to ferment 2′FL. We evaluated a probiotic formulation, including the strains Lactobacillus helveticus Rosell^®-52 (R0052), Bifidobacterium longum subsp. infantis Rosell^®-33 (R0033), and Bifidobacterium bifidum Rosell^®-71 (R0071), individually or in an 80:10:10 combination on the microbiota and 2′FL degradation. Independent batch fermentations were performed with feces from six full-term infant donors of two months of age (three breastfed and three formula-fed) with added probiotic formulation or the constituent strains in the presence of 2′FL. Microbiota composition was analyzed by 16S rRNA gene sequencing. Gas accumulation, pH decrease and 2′FL consumption, and levels of different metabolites were determined by chromatography. B. bifidum R0071 was the sole microorganism promoting a partial increase of 2′FL degradation during fermentation in fecal cultures of 2′FL slow-degrading donors. However, major changes in microbiota composition and metabolic activity occurred with L. helveticus R0052 or the probiotic formulation in cultures of slow degraders. Further studies are needed to decipher the role of the host intestinal microbiota in the efficacy of these strains.

Immune Modulatory Effects of Probiotic Streptococcus thermophilus on Human Monocytes

Ingesting probiotics contributes to the development of a healthy microflora in the GIT with established benefits to human health. Some of these beneficial effects may be through the modulation of the immune system. In addition, probiotics have become more common in the treatment of many inflammatory and immune disorders. Here, we demonstrate a range of immune modulating effects of Streptococcus thermophilus by human monocytes, including decreased mRNA expression of IL-1R, IL-18, IFNαR1, IFNγR1, CCL2, CCR5, TLR-1, TLR-2, TLR-4, TLR-5, TLR-6, TLR-8, CD14, CD86, CD4, ITGAM, LYZ, TYK2, IFNR1, IRAK-1, NOD2, MYD88, SLC11A1, and increased expression of IL-1α, IL-1β, IL-2, IL-6, IL-8, IL-23, IFNγ, TNFα, CSF-2. The routine administration of Streptococcus thermophilus in fermented dairy products and their consumption may be beneficial to the treatment/management of inflammatory and autoimmune diseases.

Recent advances in the concept of paraprobiotics: Nutraceutical/functional properties for promoting children health

Probiotics consumption has been associated with various health promoting benefits, including disease prevention and even treatment by modulating gut microbiota. Contrary to this, probiotics may also overstimulate the immune system, trigger systemic infections, harmful metabolic activities, and promote gene transfer. In children, the fragile immune system and impaired intestinal barrier may boost the occurrence of adverse effects following probiotics' consumption. To overcome these health challenges, the key focus has been shifted toward non-viable probiotics, also called paraprobiotics. Cell wall polysaccharides, peptidoglycans, surface proteins and teichoic acid present on cell's surface are involved in the interaction of paraprobiotics with the host, ultimately providing health benefits. Among other benefits, paraprobiotics possess the ability to regulate innate and adaptive immunity, exert anti-adhesion, anti-biofilm, anti-hypertensive, anti-inflammatory, antioxidant, anti-proliferative, and antagonistic effects against pathogens, while also enhance clinical impact and general safety when administered in children in comparison to probiotics. Clinical evidence have underlined the paraprobiotics impact in children and young infants against atopic dermatitis, respiratory and gastrointestinal infections, in addition to be useful for immunocompromised individuals. Therefore, this review focuses on probiotics-related issues in children's health and also discusses the Lactobacillus and Bifidobacterium spp. qualities for qualifying as paraprobiotics and their role in promoting the children's health.

Lactic Acid Bacteria Exopolysaccharides Producers: A Sustainable Tool for Functional Foods

Lactic acid bacteria (LAB) used in the food industry, mainly for the production of dairy products, are able to synthetize exopolysaccharides (EPS). EPS play a central role in the assessment of rheological and sensory characteristics of dairy products since they positively influence texture and organoleptic properties. Besides these, EPS have gained relevant interest for pharmacological and nutraceutical applications due to their biocompatibility, non-toxicity and biodegradability. These bioactive compounds may act as antioxidant, cholesterol-lowering, antimicrobial and prebiotic agents. This review provides an overview of exopolysaccharide-producing LAB, with an insight on the factors affecting EPS production, their dairy industrial applications and health benefits.

Influence of 2'-Fucosyllactose on the Microbiota Composition and Metabolic Activity of Fecal Cultures from Breastfed and Formula-Fed Infants at Two Months of Age

Although breast milk is considered the gold standard of nutrition for infant feeding, some circumstances may make breastfeeding difficult. Several commercial milk preparations include synthetic human milk oligosaccharides (HMOs) in their composition. However, the effect of HMOs on the establishment of the intestinal microbiota remains incompletely understood. Independent batch fermentations were performed with feces from six full-term infant donors of two months of age (three breastfed and three formula-fed, exclusively) in the presence of 2′fucosyllactose (2′FL), one of the most abundant HMOs in human milk. Microbiota composition was analyzed by 16S rRNA gene sequencing at baseline and at 24 h of incubation. The 2′FL consumption, gas accumulation, and levels of different metabolites were determined by chromatography. Microbiota profiles at baseline were clearly influenced by the mode of feeding and by the intrinsic ability of microbiotas to degrade 2′FL. The 2′FL degradation rate clustered fecal cultures into slow and fast degraders, regardless of feeding type, this being a determinant factor influencing the evolution of the microbiota during incubation, although the low number of donors precludes drawing sound conclusions. More studies are needed to decipher the extent to which the early intervention with HMOs could influence the microbiota as a function of its ability to utilize 2′FL.

Optimization of Media Composition to Maximize the Yield of Exopolysaccharides Production by Lactobacillus rhamnosus Strains

Growth media composition is a critical factor influencing the yield of bacterial exopolysaccharides (EPSs), which have attracted the interest of researchers around the world due to their diverse physicochemical and biological properties. This work presents the optimization of media for EPS synthesis by three Lactobacillus rhamnosus strains, namely ŁOCK 0943, ŁOCK 0935, and OM-1. The optimized media led to a more than 13-fold increase in EPS yield for L. rhamnosus ŁOCK 0943 (from 85 to 1138.2 mg/L), an almost 9-fold increase for L. rhamnosus ŁOCK 0935 (from 103.67 to 900 mg/L), and a more than 7-fold increase for L. rhamnosus OM-1 (from 133.67 to 987.84 mg/L) as compared to cultures in standard MRS medium (de Man, Rogosa, and Sharpe). It has been found that the main medium-related determinant of EPS synthesis by the studied L. rhamnosus strains are the carbon source-in this case, it was fructose and sucrose.

Acceptive Immunity: The Role of Fucosylated Glycans in Human Host-Microbiome Interactions

The growth in the number of chronic non-communicable diseases in the second half of the past century and in the first two decades of the new century is largely due to the disruption of the relationship between the human body and its symbiotic microbiota, and not pathogens. The interaction of the human immune system with symbionts is not accompanied by inflammation, but is a physiological norm. This is achieved via microbiota control by the immune system through a complex balance of pro-inflammatory and suppressive responses, and only a disturbance of this balance can trigger pathophysiological mechanisms. This review discusses the establishment of homeostatic relationships during immune system development and intestinal bacterial colonization through the interaction of milk glycans, mucins, and secretory immunoglobulins. In particular, the role of fucose and fucosylated glycans in the mechanism of interactions between host epithelial and immune cells is discussed.

Contributions of exopolysaccharides from lactic acid bacteria as biotechnological tools in food, pharmaceutical, and medical applications

Exopolysaccharides (EPS) are important bioproducts produced by some genera of lactic acid bacteria. EPS are famous for their shelf-life improving properties, techno-functional enhancing abilities in food and dairy industries, besides their beneficial health effects. Furthermore, exopolysaccharides have many prospective and well-established contributions in the field of drugs and diagnostic industry. In this review, classification of EPS produced by LAB was presented. Moreover, current and potential applications of EPS in food, dairy, baking industries, cereal-based, and functional products were described. Also, some clinical and pharmaceutical applications of EPS such as intelligent drug delivery systems (microsystems and nanosystems for sustained delivery), interpenetrating polymer networks (IPNs), anticancer drug-targeting, recombinant macromolecular biopharmaceuticals, gene delivery, tissue engineering, and role of EPS in diagnostics were highlighted. Finally, future prospects concerning enhancing EPS production, minimizing costs of their production, and exploring their contribution in further applications were discussed.

Lactic Acid Bacterial Production of Exopolysaccharides from Fruit and Vegetables and Associated Benefits

Microbial polysaccharides have interesting and attractive characteristics for the food industry, especially when produced by food grade bacteria. Polysaccharides produced by lactic acid bacteria (LAB) during fermentation are extracellular macromolecules of either homo or hetero polysaccharidic nature, and can be classified according to their chemical composition and structure. The most prominent exopolysaccharide (EPS) producing lactic acid bacteria are Lactobacillus, Leuconostoc, Weissella, Lactococcus, Streptococcus, Pediococcus and Bifidobacterium sp. The EPS biosynthesis and regulation pathways are under the dependence of numerous factors as producing-species or strain, nutrient availability, and environmental conditions, resulting in varied carbohydrate compositions and beneficial properties. The interest is growing for fruits and vegetables fermented products, as new functional foods, and the present review is focused on exploring the EPS that could derive from lactic fermented fruit and vegetables. The chemical composition, biosynthetic pathways of EPS and their regulation mode is reported. The consequences of EPS on food quality, especially texture, are explored in relation to producing species. Attention is given to the scientific investigations on health benefits attributed to EPS such as prebiotic, antioxidant, anti-inflammatory and cholesterol lowering activities.

Purification and characterization of novel exopolysaccharides produced from Lactobacillus paraplantarum KM1 isolated from human milk and its cytotoxicity

Background

Microbial origin polysaccharides have gained popularity due to lesser toxicity, better degradability and selectivity as compared to their synthetic counterparts and can be used as emulsifier, stabilizer, thickener, texturizer, flocculating and gelling agent. Here main emphasis on exopolysaccharide production from potential lactic acid bacteria that has GRAS status.

Results

This work was aimed at isolating, purifying and characterizing an extracellular polysaccharide (EPS) produced by a foodgrade lactic acid bacteria Lactobacillus paraplantarum KM1. L. paraplantarum KM1 was isolated from human milk and identified by conventional and molecular techniques. The 16S rRNA sequence of the isolate was registered in National Centre for Biotechnology Information (NCBI) under accession number KX671558. L. paraplantarum KM1 was found to produce EPSs in lactose containing MRS medium, and the maximum yield (47.4 mg/ml) was achieved after 32-h incubation. As evident from TLC and HPLC analyses, the polysaccharide was found to be a heteropolymer-containing glucose, galactose and mannose as main sugars. Different oligosaccharides namely hexoses were obtained after partial hydrolysis of the polymer using MALDI-ToF-MS. The total molecular weight of all polysaccharides present was 348.7 kDa with 100 °C thermal stability as well as water soluble in nature. Cell cytotoxicity revealed that the purified EPS was safe for consumption; thus, it can be used in various food industries as emulsifying and texture agent.

Conclusions

The present study highlighted that exopolysaccharides could be harnessed to improve food products in terms of texture, emulsifying agents, pharmaceutical industry (antioxidants, antitumour, anti-inflammatory and antiviral agents) and as safety purposes.

Effect of Lactobacillus rhamnosus on Physicochemical Properties of Fermented Plant-Based Raw Materials

Texture and flavor are currently the main challenges in the development of plant-based dairy alternatives. To overcome them, the potential of microorganisms for fermentation of plant-based raw materials is generating great interest in the food industry. This study examines the effect of Lactobacillus rhamnosus, LGG® (LGG® is a trademark of Chr. Hansen A/S) on the physicochemical properties of fermented soy, oat, and coconut. LGG® was combined with different lactic acid bacteria (LAB) strains and Bifidobacterium, BB-12® (BB-12® is a trademark of Chr. Hansen A/S). Acidification, titratable acidity, and growth of LGG® and BB-12® were evaluated. Oscillation and flow tests were performed to analyze the rheological properties of fermented samples. Acids, carbohydrates, and volatile organic compounds in fermented samples were identified, and a sensory evaluation with a trained panel was conducted. LGG® reduced fermentation time in all three bases. LGG® and BB-12® grew in all fermented raw materials above 107 CFU/g. LGG® had no significant effect on rheological behavior of the samples. Acetoin levels increased and acetaldehyde content decreased in the presence of LGG® in all three bases. Diacetyl levels increased in fermented oat and coconut samples when LGG® was combined with YOFLEX® YF-L01 and NU-TRISH® BY-01 (YOFLEX® and NU-TRISH® are trademarks of Chr. Hansen A/S). In all fermented oat samples, LGG® significantly enhanced fermented flavor notes, such as sourness, lemon, and fruity taste, which in turn led to reduced perception of the attributes related to the base. In fermented coconut samples, gel firmness perception was significantly improved in the presence of LGG®. These findings suggest supplementation of LAB cultures with LGG® to improve fermentation time and sensory perception of fermented plant-based products.

Effect of inulin-type fructans and galactooligosaccharides on cultures of Lactobacillus strains isolated in Algeria from camel's milk and human colostrum

Bacteria from the genus Lactobacillus are responsible for spontaneous food fermentations. Some species, such as Lactobacillus casei and Lactobacillus brevis, have the "Qualified Presumption of Safety" status recognized by the European Food Safety Authority. Several of their strains are used as probiotics in foods and sometimes are included in synbiotic combinations together with prebiotics. New microbial strains isolated from different sources represent an opportunity to use them for the production of traditional food products. The capacity of three selected strains (one isolated from Camel's milk and identified by partial 16 S rRNA gene sequencing as L. brevis, and two isolated from human colostrum and identified as L. paracasei/L. casei and L. brevis, respectively) was assessed in vitro for the ability to survive in gastrointestinal conditions (low pH and high bile salts concentrations). We also tested the capacity of growth and the production of organic acids and volatile compounds by high-performance liquid chromatography and gas chromatography, respectively, when these bacteria were incubated anaerobically in the presence of inulin, fructooligosaccharides, or galactooligosaccharides as the main carbon sources. The strains were able to survive in simulated gastrointestinal conditions and to grow in inulin, fructooligosaccharides, and galactooligosaccharides. However, they displayed different profiles of organic acids and volatile compounds, mainly depending on the microbial species and the prebiotic used. The influence that the combined use of strains and different prebiotics could exert on the organic acids and volatiles formed in food and in the gut should be assessed for each synbiotic combination and food product.

Streptococcus thermophilus alters the expression of genes associated with innate and adaptive immunity in human peripheral blood mononuclear cells

Consumption of probiotics contributes to a healthy microbiome of the GIT leading to many health benefits. They also contribute to the modulation of the immune system and are becoming popular for the treatment of a number of immune and inflammatory diseases. The main objective of this study was to evaluate anti-inflammatory and modulatory properties of Streptococcus thermophilus. We used peripheral blood mononuclear cells from healthy donors and assessed modifications in the mRNA expression of their genes related to innate and adaptive immune system. Our results showed strong immune modulatory effects of S. thermophilus 285 to human peripheral blood mononuclear cells with an array of anti-inflammatory properties. S. thermophilus 285 reduced mRNA expression in a number of inflammatory immune mediators and markers, and upregulated a few of immune markers. S. thermophilus is used in the dairy industry, survives during cold storage, tolerates well upon ingesting, and their consumption may have beneficial effects with potential implications in inflammatory and autoimmune disorders.

Bifidobacteria cell wall-derived exo-polysaccharides, lipoteichoic acids, peptidoglycans, polar lipids and proteins - their chemical structure and biological attributes

A variety of health benefits has been documented to be associated with the consumption of probiotic bacteria, namely bifidobacteria and lactobacilli. Thanks to the scientific advances in recent years we are beginning to understand the molecular mechanisms by which bacteria in general and probiotic bacteria in particular act as host physiology and immune system modulators. More recently, the focus has shifted from live bacteria towards bacteria-derived defined molecules, so called postbiotics. These molecules may represent safer alternative compared to the live bacteria while retaining the desired effects on the host. The excellent source of effector macromolecules is the bacterial envelope. It contains compounds that are pivotal in the adhesion phenomenon, provide direct bacteria-to-host signaling capacity and the associated physiological impact and immunomodulatory properties of bacteria. Here we comprehensively review the structure and biological role of Bifidobacterium surface and cell wall molecules: exopolysaccharides, cell wall polysaccharides, lipoteichoic acids, polar lipids, peptidoglycans and proteins. We discuss their involvement in direct signaling to the host cells and their described immunomodulatory effects.

The Effect of Encapsulated Powder of Goji Berry (Lycium barbarum) on Growth and Survival of Probiotic Bacteria

The aim of the present work was to investigate the potential prebiotic action of Goji berry powder on selected probiotic bacteria grown in a nutritive synthetic substrate and in simulated gastric and intestinal juices. Different probiotic strains of Bifidobacterium and Lactobacillus were grown in these substrates with or without the addition of encapsulated goji berry extracts of different polysaccharide and polyphenol contents. The results proved that the addition of the extracts promoted the proliferation of probiotic strains and, in particular, increased the number of bacterial colonies of Bifidobacterium animalis subsp. lactis (Bb12), Bifidobacterium longum (Bb46), and Lactobacillus casei by 2, 0.26, and 1.34 (log cfu/mL), respectively. Furthermore, the prebiotic effect seems to be correlated to Goji berry polysaccharides and/or polyphenols, higher contents of which (under the tested concentrations) could increase the stress tolerance of B. lactis and B. longum in a simulated gastrointestinal environment. According to the findings of the present research, it can be suggested that the Goji berry encapsulated extracts could be used as prebiotic additives in food or nutraceuticals, in order to stimulate growth or protect the viability of probiotic strains of Bifidobacterium and Lactobacillus.

Impact of in vitro gastrointestinal digestion on the chemical composition, bioactive properties, and cytotoxicity of Vitis vinifera L. cv. Syrah grape pomace extract

Grape pomace (GP) is a major byproduct worldwide, and it is well known for its bioactive compounds, such as fibers and phenolic compounds, that are popular for their impact upon human health, including gastrointestinal health. The objective of this work was to evaluate the chemical composition and biological activities of an enzymatic GP extract, as well as to investigate how gastrointestinal digestion (GID) modulates these properties. GP extract was previously produced using an enzymatic cocktail with xylanase activity and was then exposed to simulated conditions of GID, characterized for its chemical composition, and screened for antimicrobial, prebiotic, and antioxidant activities. The safety of this ingredient after GID was also assessed. GP extract presented high contents of dietary fiber and other carbohydrates, including xylooligosaccharides, in addition to minerals and phenolic compounds. In vitro simulated GID revealed that xylobiose was resistant to gastric conditions, unlike phenolic compounds. The use of 2% (w/v) of this ingredient proved to be a potential carbon source that could be fermented by Lactobacillus and Bifidobacterium spp, even after digestion. The extract also exhibited strong antioxidant and antimicrobial activities against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa; however, after GID, the antioxidant capacity decreased, and the antimicrobial capacity was strongly reduced or lost. Furthermore, the extract safety was also guaranteed on Caco-2 intestinal cells. This novel and green GP extract proved to be composed of relevant bioactive molecules, including xylooligosaccharides, polyphenols, organic acids, and minerals, which provided different biological properties; it has potential applications in the food industry such that it can be used as an ingredient in the development of new functional foods.

Monosaccharide composition influence and immunomodulatory effects of probiotic exopolysaccharides

Exopolysaccharides (EPSs) are metabolites of probiotics that have gained wide interest recently. A strain of Lactobacillus reuteri Mh-001 with high exopolysaccharide (EPS) production ability was isolated, identified, and were used to investigate the anti-inflammatory effects of the EPSs. Among the three unpurified EPSs, RAW246.7 murine macrophages treated with 5 ppm of EPS 1 revealed the lowest tumour necrosis factor α (TNF-α) secretion (325.32 ± 51.10 pg/ug DNA). The second lowest TNF- α secretion occurred with EPS 2 (701.12 ± 86.108 pg/ug DNA) from Mh-002. EPSs 4, 5, and 6 were further purified from EPS 1. Cells treated with 1 ppm of EPS 4 had the lowest TNF-α secretion of all (209.20 ± 84.34 pg/ug DNA). The monosaccharide components, EPS 4 and EPS 1, had the highest galactose content (45 ± 2.75% and 39 ± 2.75%, respectively). The monosaccharide percentages (galactose > rhamnose > glucose) were related to the anti-inflammatory activity of the EPSs. The galactose content of EPSs enhanced their anti-inflammatory effects on the macrophages. These data indicate that EPS possesses beneficial physiological effects such as anti-inflammatory properties, and the monosaccharide content of the EPS was the factor influencing the anti-inflammatory properties.

Use of Glucose Oxidase Immobilized on Magnetic Chitosan Nanoparticles in Probiotic Drinking Yogurt

The aim of this study was to investigate the effect of glucose oxidase (GOX) immobilized on magnetic chitosan nanoparticles (MCNP) on the viability of probiotic bacteria and the physico-chemical properties of drinking yogurt. Different concentrations (0, 250, and 500 mg/kg) of free and immobilized GOX were used in probiotic drinking yogurt samples. The samples were stored at 4°C for 21 d. During storage, reduction of the number of probiotic bacteria in the samples with enzyme was lower than the control sample (without enzyme). The sample containing 500 mg/kg immobilized enzyme had the highest number of Bifidobacterium lactis and Lactobacillus acidophilus. The samples containing immobilized enzyme had lower acidity than other samples. Moreover, moderate proteolytic activity and enough contents of flavor compounds were observed in these samples. It can be concluded that use of immobilized GOX is economically more feasible because of improving the viability of probiotic bacteria and the physico-chemical characteristics of drinking yogurt.

Characterization and immunomodulatory activity of an exopolysaccharide produced by Lactobacillus plantarum JLK0142 isolated from fermented dairy tofu

A purified neutral exopolysaccharide (EPS) designated as EPS0142 was obtained from Lactobacillus plantarum JLK0142. EPS0142 consisted of glucose and galactose in an approximate molar ratio of 2.13:1.06 and had a molecular weight of 1.34 × 10⁵ Da. The FT-IR spectrum showed that EPS0142 had a typical polysaccharide absorption pattern. ¹H NMR and ¹³C NMR spectra analysis showed the presence of N-acetylated sugar residues. EPS0142 had no toxic effects on RAW 264.7 cells and significantly improved their phagocytic activity and NO secretion in vitro. Further in vivo studies revealed that the spleen index and splenic lymphocyte proliferation activities of the cyclophosphamide-induced immunosuppression mice treated with a middle-dose (50 mg/kg body weight) or a high-dose (100 mg/kg body weight) of EPS0142 were significantly increased (P < 0.01). In addition, the intestinal immunoglobulin A (sIgA) content and the serum levels of the cytokines, IL-2 and TNF-α, were also significantly (P < 0.05) improved in the high-dose EPS0142 group compared to that in the model control group. These data indicate that the EPS isolated from L. plantarum JLK0142 can effectively improve the immunomodulatory activity of RAW 264.7 cells and stimulate the immune system in cyclophosphamide-induced immunosuppressed mice.

Comparative analysis of probiotic bacteria based on a new definition of core genome

The commensal genus Bifidobacterium has probiotic properties. We prepared a public library of the gene functions of the genus Bifidobacterium for its online annotation. Orthologous gene cluster analysis showed that the pan genomes of Bifidobacterium and Lactobacillus exhibit striking similarities when mapped to the Clusters of Orthologous Group (COG) database of proteins. When the core genes in each genus were selected based on our statistical definition of "core genome", core genes were present in at least 92% of 52 Bifidobacterium and in 97% of 178 Lactobacillus genomes. Functional comparison of the core genes of the two genera revealed a significant difference in the categories "amino acid transport and metabolism" representing their difference in niche specificity. Over-represented Bifidobacterium protein families were primarily involved in host interactions, the complex compound metabolism, and in stress responses. These findings coincide with the published information and validate our bias-resilient definition of the core genome.

Bifidobacterium breve IPLA20005 affects in vitro the expression of hly and luxS genes, related to the virulence of Listeria monocytogenes Lm23

Mechanistic features that characterize the interaction and inhibition of the food-borne pathogen Listeria monocytogenes by members of the genus Bifidobacterium still remain unclear. In the present work, we tried to shed light on the influence that co-cultivation of L. monocytogenes with Bifidobacterium breve may exert on both microorganisms and on virulence of the pathogen. Production of acetate and lactate was measured by gas chromatography and high-performance liquid chromatography, respectively; bacterial counts were obtained by plate count; gene expression was determined by RT-qPCR; and haemolytic activity was analyzed against goat erythrocytes. We found slightly but significantly lower final counts of Listeria and Bifidobacterium (p < 0.05) and lower haemolytic efficiency in L. monocytogenes cells from cocultures than in those from monocultures. In contrast, the hly and luxS genes, which code for the cytolysin listeriolysin O and participate in biofilm formation, respectively, were overexpressed when L. monocytogenes was grown in coculture. This indicates that the presence of Bifidobacterium is able to modify the gene expression and haemolytic activity of L. monocytogenes when both microorganisms grow together.

Omics of bifidobacteria: research and insights into their health-promoting activities

Members of the genus Bifidobacterium include gut commensals that are particularly abundant among the microbial communities residing in the gut of healthy breast-fed infants, where their presence has been linked to many beneficial host effects. Next-generation DNA sequencing and comparative and functional genome methodologies have been shown to be particularly useful in exploring the diversity of this genus. These combined approaches have allowed the identification of genetic features related to bifidobacterial establishment in the gut, involving host-microbe as well as microbe-microbe interactions. Among these, proteinaceous structures, which protrude from the bacterial surface, i.e. pili or fimbriae, and exopolysaccharidic cell surface layers or capsules represent crucial features that assist in their colonization and persistence in the gut. As bifidobacteria are colonizers of the large intestine, they have to be able to cope with various sources of osmotic, oxidative, bile and acid stress during their transit across the gastric barrier and the small intestine. Bifidobacterial genomes thus encode various survival mechanisms, such as molecular chaperones and efflux pumps, to overcome such challenges. Bifidobacteria represent part of an anaerobic gut community, and feed on nondigestible carbohydrates through a specialized fermentative metabolic pathway, which in turn produces growth substrates for other members of the gut community. Conversely, bifidobacteria may also be dependent on other (bifido)bacteria to access host- and diet-derived glycans, and these complex co-operative interactions, based on resource sharing and cross-feeding strategies, represent powerful driving forces that shape gut microbiota composition.

Complexes of lutein with bovine and caprine caseins and their impact on lutein chemical stability in emulsion systems: Effect of arabinogalactan

Lutein is an important xanthophyll carotenoid with many benefits to human health. Factors affecting the application of lutein as a functional ingredient in low-fat dairy-like beverages (pH 6.0-7.0) are not well understood. The interactions of bovine and caprine caseins with hydrophobic lutein were studied using UV/visible spectroscopy as well as fluorescence. Our studies confirmed that the aqueous solubility of lutein is improved after binding with bovine and caprine caseins. The rates of lutein solubilization by the binding to bovine and caprine caseins were as follows: caprine α_S1-II-casein 34%, caprine α_S1-I-casein 10%, and bovine casein 7% at 100 μM lutein. Fluorescence of the protein was quenched on binding supporting complex formation. The fluorescence experiments showed that the binding involves tryptophan residues and some nonspecific interactions. Scatchard plots of lutein binding to the caseins demonstrated competitive binding between the caseins and their sites of interaction with lutein. Competition experiments suggest that caprine α_S1-II casein will bind a larger number of lutein molecules with higher affinity than other caseins. The chemical stability of lutein was largely dependent on casein type and significant increases occurred in the chemical stability of lutein with the following pattern: caprine α_S1-II-casein > caprine α_S1-I-casein > bovine casein. Addition of arabinogalactan to lutein-enriched emulsions increases the chemical stability of lutein-casein complexes during storage under accelerated photo-oxidation conditions at 25°C. Therefore, caprine α_S1-II-casein alone and in combination with arabinogalactan can have important applications in the beverage industry as carrier of this xanthophyll carotenoid (lutein).

A Human Gut Commensal Ferments Cranberry Carbohydrates To Produce Formate

Commensal bifidobacteria colonize the human gastrointestinal tract and catabolize glycans that are impervious to host digestion. Accordingly, Bifidobacterium longum typically secretes acetate and lactate as fermentative end products. This study tested the hypothesis that B. longum utilizes cranberry-derived xyloglucans in a strain-dependent manner. Interestingly, the B. longum strain that efficiently utilizes cranberry xyloglucans secretes 2.0 to 2.5 mol of acetate-lactate. The 1.5 acetate:lactate ratio theoretical yield obtained in hexose fermentations shifts during xyloglucan metabolism. Accordingly, this metabolic shift is characterized by increased acetate and formate production at the expense of lactate. α-l-Arabinofuranosidase, an arabinan endo-1,5-α-l-arabinosidase, and a β-xylosidase with a carbohydrate substrate-binding protein and carbohydrate ABC transporter membrane proteins are upregulated (>2-fold change), which suggests carbon flux through this catabolic pathway. Finally, syntrophic interactions occurred with strains that utilize carbohydrate products derived from initial degradation from heterologous bacteria.IMPORTANCE This was a study of bacterial metabolism of complex cranberry carbohydrates termed xyloglucans that are likely not digested prior to reaching the colon. This is significant, as bifidobacteria interact with this dietary compound to potentially impact human host health through energy and metabolite production by utilizing these substrates. Specific bacterial strains utilize cranberry xyloglucans as a nutritive source, indicating unknown mechanisms that are not universal in bifidobacteria. In addition, xyloglucan metabolism proceeds by using an alternative pathway that could lead to further research to investigate mechanisms underlying this interaction. Finally, we observed cross-feeding between bacteria in which one strain degrades the cranberry xyloglucan to make it available to a second strain. Similar nutritive strategies are known to occur within the gut. In aggregate, this study may lead to novel foods or supplements used to impact human health through rational manipulation of the human microbiome.