Effects of bifidobacteria-produced exopolysaccharides on human gut microbiota in vitro

Role of folic acid in regulating gut microbiota and short-chain fatty acids based on an in vitro fermentation model

Folic acid deficiency is common worldwide and is linked to an imbalance in gut microbiota. However, based on model animals used to study the utilization of folic acid by gut microbes, there are challenges of reproducibility and individual differences. In this study, an in vitro fecal slurry culture model of folic acid deficiency was established to investigate the effects of supplementation with 5-methyltetrahydrofolate (MTHF) and non-reduced folic acid (FA) on the modulation of gut microbiota. 16S rRNA sequencing results revealed that both FA (29.7%) and MTHF (27.9%) supplementation significantly reduced the relative abundance of Bacteroidetes compared with control case (34.3%). MTHF supplementation significantly improved the relative abundance of Firmicutes by 4.49%. Notably, compared with the control case, FA and MTHF supplementation promoted an increase in fecal levels of Lactobacillus, Bifidobacterium, and Pediococcus. Short-chain fatty acid (SCFA) analysis showed that folic acid supplementation decreased acetate levels and increased fermentative production of isobutyric acid. The in vitro fecal slurry culture model developed in this study can be utilized as a model of folic acid deficiency in humans to study the gut microbiota and demonstrate that exogenous folic acid affects the composition of the gut microbiota and the level of SCFAs. KEY POINTS: • Establishment of folic acid deficiency in an in vitro culture model. • Folic acid supplementation regulates intestinal microbes and SCFAs. • Connections between microbes and SCFAs after adding folic acid are built.

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.

Postbiotics in rheumatoid arthritis: emerging mechanisms and intervention perspectives

Rheumatoid arthritis (RA) is a prevalent chronic autoimmune disease that affects individuals of all age groups. Recently, the association between RA and the gut microbiome has led to the investigation of postbiotics as potential therapeutic strategies. Postbiotics refer to inactivated microbial cells, cellular components, or their metabolites that are specifically intended for the microbiota. Postbiotics not only profoundly influence the occurrence and development of RA, but they also mediate various inflammatory pathways, immune processes, and bone metabolism. Although they offer a variety of mechanisms and may even be superior to more conventional "biotics" such as probiotics and prebiotics, research on their efficacy and clinical significance in RA with disruptions to the intestinal microbiota remains limited. In this review, we provide an overview of the concept of postbiotics and summarize the current knowledge regarding postbiotics and their potential use in RA therapy. Postbiotics show potential as a viable adjunctive therapy option for RA.

Milk phospholipids protect Bifidobacterium longum subsp. infantis during in vitro digestion and enhance polysaccharide production

Bifidobacterium longum subsp. infantis is associated with the gut microbiota of breast-fed infants. Bifidobacterium infantis promotes intestinal barrier and immune function through several proposed mechanisms, including interactions between their surface polysaccharides, the host, and other gut microorganisms. Dairy foods and ingredients are some of the most conspicuous food-based niches for this species and may provide benefits for their delivery and efficacy in the gut. Milk phospholipid (MPL)-rich ingredients have been increasingly recognized for their versatile benefits to health, including interactions with the gut microbiota and intestinal cells. Therefore, our objective was to investigate the capacity for MPL to promote survival of B. infantis during simulated digestion and to modulate bacterial polysaccharide production. To achieve these aims, B. infantis was incubated with or without 0.5% MPL in de Man, Rogosa, and Sharpe (MRS) media at 37°C under anaerobiosis. Survival across the oral, gastric, and intestinal phases using in vitro digestion was measured using plate count, along with adhesion to goblet-like intestinal cells. MPL increased B. infantis survival at the end of the intestinal phase by at least 7% and decreased adhesion to intestinal cells. The bacterial surface characteristics, which may contribute to these effects, were assessed by ζ-potential, changes in surface proteins using comparative proteomics, and production of bound polysaccharides. MPL decreased the surface charge of the bifidobacteria from -17 to -24 mV and increased a 50 kDa protein (3-fold) that appears to be involved in protection from stress. The production of bound polysaccharides was measured using FTIR, HPLC, and TEM imaging. These techniques all suggest an increase in bound polysaccharide production at least 1.7-fold in the presence of MPL. Our results show that MPL treatment increases B. infantis survival during simulated digestion, induces a stress resistance surface protein, and yields greater bound polysaccharide production, suggesting its use as a functional ingredient to enhance probiotic and postbiotic effects.

Structural characteristics and functional properties of a fucose containing prebiotic exopolysaccharide from Bifidobacterium breve NCIM 5671

AIM

To evaluate the structure and functions of capsular exopolysaccharide (CPS) from Bifidobacterium breve NCIM 5671.

METHODS AND RESULTS

A CPS produced by the probiotic bacteria B. breve NCIM 5671 was isolated and subjected to characterization through GC analysis, which indicated the presence of rhamnose, fucose, galactose, and glucose in a molar ratio of 3:1:5:3. The average molecular weight of the CPS was determined to be ∼8.5 × 105 Da. Further, NMR analysis revealed the probable CPS structure to be composed of major branched tetra- and penta-saccharide units alternately repeating and having both α- and β-configuration sugar residues. CPS displayed an encouraging prebiotic score for some of the studied probiotic bacteria. Compared to standard inulin, CPS showed better resistance to digestibility against human GI tract in vitro. DPPH, total antioxidant, and ferric reducing assays carried out for CPS displayed decent antioxidant activity too.

CONCLUSION

This study indicates that the CPS from B. breve NCIM 5671 has the potential to be utilized as a prebiotic food supplement. It is a high-molecular-weight (∼8.5 × 105 Da) capsular heteropolysaccharide containing rhamnose, fucose, galactose, and glucose.

Effects of microbial-derived biotics (meta/pharma/post-biotics) on the modulation of gut microbiome and metabolome; general aspects and emerging trends

Potential effects of metabiotics (probiotics effector molecules or signaling factors), pharmabiotics (pro-functional metabolites produced by gut microbiota (GMB)) and postbiotics (multifunctional metabolites and structural compounds of food-grade microorganisms) on GMB have been rarely reviewed. These multifunctional components have several promising capabilities for prevention, alleviation and treatment of some diseases or disorders. Correlations between these essential biotics and GMB are also very interesting and important in human health and nutrition. Furthermore, these natural bioactives are involved in modulation of the immune function, control of metabolic dysbiosis and regulation of the signaling pathways. This review discusses the potential of meta/pharma/post-biotics as new classes of pharmaceutical agents and their effective mechanisms associated with GMB-host cell to cell communications with therapeutic benefits which are important in balance and the integrity of the host microbiome. In addition, cutting-edge findings about bioinformatics /metabolomics analyses related to GMB and these essential biotics are reviewed.

Hypolipidemic mechanism of Pleurotus eryngii polysaccharides in high-fat diet-induced obese mice based on metabolomics

Objective

In this study, the structure of Pleurotus eryngii polysaccharides (PEPs) was characterized, and the mechanism of PEP on obesity and hyperlipidemia induced by high-fat diet was evaluated by metabonomic analysis.

Methods

The structure of PEPs were characterized by monosaccharide composition, Fourier transform infrared spectroscopy and thermogravimetry. In animal experiments, H&E staining was used to observe the morphological difference of epididymal adipose tissue of mice in each group. Ultrahigh performance liquid chromatography (UHPLC)-(QE) HFX -mass spectrometry (MS) was used to analyze the difference of metabolites in serum of mice in each group and the related metabolic pathways.

Results

The PEPs contained nine monosaccharides: 1.05% fucose, 0.30% arabinose, 17.94% galactose, 53.49% glucose, 1.24% xylose, 23.32% mannose, 1.30% ribose, 0.21%galacturonic acid, and 1.17% glucuronic acid. The PEPs began to degrade at 251°C (T0), while the maximum thermal degradation rate temperature (Tm) appeared at 300°C. The results histopathological observation demonstrated that the PEPs had signifificant hypolipidemic activities. After PEPs intervention, the metabolic profile of mice changed significantly. A total of 29 different metabolites were selected as adjunctive therapy to PEPs, for treatment of obesity and hyperlipidemia-related complications caused by a high-fat diet. These metabolites include amino acids, unsaturated fatty acids, choline, glycerol phospholipids, and other endogenous compounds, which can prevent and treat obesity and hyperlipidemia caused by a high-fat diet by regulating amino acid metabolism, fatty acid metabolism, and changes in metabolic pathways such as that involved in the citric cycle (TCA cycle).

Conclusions

The presented results indicate that PEPs treatment can alleviate the obesity and hyperlipidemia caused by a high-fat diet and, thus, may be used as a functional food adjuvant, providing a theoretical basis and technical guidance for the prevention and treatment of high-fat diet-induced obesity and hyperlipidemia.

Bacterial Exopolysaccharides as Emerging Bioactive Macromolecules: From Fundamentals to Applications

Microbial exopolysaccharides (EPS) are extracellular carbohydrate polymers forming capsules or slimy coating around the cells. EPS can be secreted by various bacterial genera that can help bacterial cells in attachment, environmental adaptation, stress tolerance and are an integral part of microbial biofilms. Several gut commensals (e.g., Lactobacillus, Bifidobacterium) produce EPS that possess diverse bioactivities. Bacterial EPS also has extensive commercial applications in the pharmaceutical and food industries. Owing to the structural and functional diversity, genetic and metabolic engineering strategies are currently employed to increase EPS production. Therefore, the current review provides a comprehensive overview of the fundamentals of bacterial exopolysaccharides, including their classification, source, biosynthetic pathways, and functions in the microbial community. The review also provides an overview of the diverse bioactivities of microbial EPS, including immunomodulatory, anti-diabetic, anti-obesity, and anti-cancer properties. Since several gut microbes are EPS producers and gut microbiota helps maintain a functional gut barrier, emphasis has been given to the intestinal-level bioactivities of the gut microbial EPS. Collectively, the review provides a comprehensive overview of microbial bioactive exopolysaccharides.

Citrus Peel Flavonoid Extracts: Health-Beneficial Bioactivities and Regulation of Intestinal Microecology in vitro

Citrus peel and its extracts are rich in flavonoids, which are beneficial to human health. In this study, the extraction, component analysis, biological activity and intestinal microbiota regulation of citrus peel flavonoid extracts (CPFEs) were investigated. CPFEs from 14 Chinese cultivars were purified by ultrasound-assisted extraction and XAD-16 macroporous resin. The total flavonoid content of lemon was greatest at 103.48 ± 0.68 mg/g dry weight (DW) by NaNO2-Al(NO3)3-NaOH spectrophotometry. Using high-performance liquid chromatography–diode array detection, the highest concentrations of naringin, hesperidin and eriocitrin were found in grapefruit (52.03 ± 0.51 mg/g DW), chachiensis (43.02 ± 0.37 mg/g DW) and lemon (27.72 ± 0.47 mg/g DW), respectively. Nobiletin was the most polymethoxylflavone in chachiensis at 16.91 ± 0.14 mg/g DW. CPFEs from chachiensis and grapefruit had better antioxidant activity, α-glucosidase inhibitory and sodium glycocholate binding ability. In addition, chachiensis and grapefruit CPFEs had positive effects on intestinal microecology, as evidenced by a significant increase in the relative abundance of Bifidobacterium spp., and production of short-chain fatty acids, especially acetic acid, by a simulated human intestinal model. Collectively, our results highlight the biological function of CPFEs as prebiotic agents, indicating their potential use in food and biomedical applications.

Why Are Bifidobacteria Important for Infants?

The presence of Bifidobacterium species in the maternal vaginal and fecal microbiota is arguably an evolutionary trait that allows these organisms to be primary colonizers of the newborn intestinal tract. Their ability to utilize human milk oligosaccharides fosters their establishment as core health-promoting organisms throughout life. A reduction in their abundance in infants has been shown to increase the prevalence of obesity, diabetes, metabolic disorder, and all-cause mortality later in life. Probiotic strains have been developed as supplements for premature babies and to counter some of these ailments as well as to confer a range of health benefits. The ability to modulate the immune response and produce short-chain fatty acids, particularly acetate and butyrate, that strengthen the gut barrier and regulate the gut microbiome, makes Bifidobacterium a core component of a healthy infant through adulthood.

Purification, structural characterization, and PCSK9 secretion inhibitory effect of the novel alkali-extracted polysaccharide from Cordyceps militaris

One novel alkali-extracted polysaccharide, CM3-SII, was obtained from the fruiting body of C. militaris via column chromatography. Its structural characteristics were investigated via chemical and spectroscopic methods. The backbone of CM3-SII was composed of →4)-β-D-Manp(1→, →6)-β-D-Manp(1→, and →6)-α-D-Manp(1→ glycosyls, and branching at the O-4 positions of →6)-β-D-Manp(1→ glycosyls with β-D-Galp, (1→2) linked-β-D-Galf, and →2,6)-α-D-Manp(1→ residues. Furthermore, O-6 and O-2 positions of the →2,6)-α-D-Manp(1→ residues were substituted with methyl and β-D-Galp, respectively. This polysaccharide significantly enhanced the intracellular protein expression of low-density lipoprotein receptor and proprotein convertase subtilisin/kexin type 9 (PCSK9) via regulating sterol regulatory element-binding protein 2 in hepatoma Huh7 cells. Of note, CM3-SII significantly decreased PCSK9 secretion at the concentration of 200 μg/mL. Collectively, CM3-SII is different from the previously reported alkali-extracted polysaccharides isolated from the fruiting body of C. militaris, and it may have potential application in hypolipidemia or as a pharmaceutical additive.

Exopolysaccharide Producing Bifidobacterium animalis subsp. lactis Strains Modify the Intestinal Microbiota and the Plasmatic Cytokine Levels of BALB/c Mice According to the Type of Polymer Synthesized

Bacteria-host interactions are mediated by different microbial associated molecular patterns which are most often surface structures such as, among others, exopolysaccharides (EPSs). In this work, the capability of two isogenic EPS-producing Bifidobacterium animalis subsp. lactis strains to modulate the gut microbiota of healthy mice, was assessed. Each strain produces a different type of polymer; the ropy strain S89L synthesized a rhamnose-rich, high-molecular weight EPS in highest abundance than the non-ropy DMS10140 one. BALB/c mice were orally fed for 10 days with milk-bifidobacterial suspensions and followed afterward for 7 post-intervention days (wash-out period). The colonic content of mice was collected in several sampling points to perform a metataxonomic analysis. In addition, the influence of specific microbial clades, apparently stimulated by the ropy and non-ropy strains, on mouse plasmatic cytokine levels was investigated through hierarchical association testing. Analysis of 16S rRNA gene sequences showed that the abundance of Firmicutes phylum significantly increased 7 days after cessing the treatment with both strains. The relative abundance of Alloprevotella genus also rose, but after shorter post-treatment times (3 days for both DMS10140 and S89L strains). Some bacterial clades were specifically modulated by one or another strain. As such, the non-ropy DMS10140 strain exerted a significant influence on Intestinomonas genus, which increased after 4 post-administration days. On the other hand, feeding with the ropy strain S89L led to an increase in sequences of Faecalibaculum genus at 4 post-treatment days, while the abundance of Erysipelotrichaceae and Lactobacillaceae families increased for prolonged times. Association testing revealed that several lactobacilli and bifidobacterial significantly stimulated by ropy S89L strain were positively associated with the levels of certain cytokines, including IL-5 and IL-27. These results highlight relevant changes in mice gut microbiota produced after administration of the ropy S89L strain that were associated to a potential immune modulation effect.