Effects of exopolysaccharide from Lactobacillus rhamnosus on human gut microbiota in in vitro fermentation model

Modulating effects of heat-killed and live Limosilactobacillus reuteri PSC102 on the immune response and gut microbiota of cyclophosphamide-treated rats

In the present study, we investigated the potential immunomodulatory effects of heat-killed (hLR) and live Limosilactobacillus reuteri PSC102 (LR; formerly Lactobacillus reuteri PSC102) in RAW264.7 macrophage cells and Sprague-Dawley rats. RAW264.7 murine macrophage cells were stimulated with hLR and LR for 24 h. Cyclophosphamide (CTX)-induced immunosuppressed Sprague-Dawley rats were orally administered with three doses of hLR (L-Low, M-Medium, and H-High) and LR for 3 weeks. The phagocytic capacity, production of nitric oxide (NO), and expression of cytokines in RAW264.7 cells were measured, and the different parameters of immunity in rats were determined. hLR and LR treatments promoted phagocytic activity and induced the production of NO and the expression of iNOS, TNF-α, IL-1β, IL-6, and Cox-2 in macrophage cells. In the in vivo experiment, hLR and LR treatments significantly increased the immune organ indices, alleviated the spleen injury, and ameliorated the number of white blood cells, granulocytes, lymphocytes, and mid-range absolute counts in immunosuppressive rats. hLR and LR increased neutrophil migration and phagocytosis, splenocyte proliferation, and T lymphocyte subsets (CD4+, CD8+, CD45RA+, and CD28+). The levels of immune factors (IL-2, IL-4, IL-6, IL-10, IL-12A, TNF-α, and IFN-γ) in the hLR and LR groups were upregulated compared with those in the CTX-treatment group. hLR and LR treatments could also modulate the gut microbiota composition, thereby increasing the relative abundance of Bacteroidetes and Firmicutes but decreasing the level of Proteobacteria. hLR and LR protected against CTX-induced adverse reactions by modulating the immune response and gut microbiota composition. Therefore, they could be used as potential immunomodulatory agents.

Soluble dietary fiber from Dendrocalamus brandisii (Munro) Kurz shoot improves liver injury by regulating gut microbial disorder in mice

Bamboo shoot has long been regarded as a nutritious and healthy food. It is low in calorie and rich in high-quality dietary fiber (DF), making them a potential DF resource. However, the protective mechanism of soluble dietary fibers from Dendrocalamus brandisii (Munro) Kurz shoot (DS-SDF) on methionine and choline deficient (MCD) diet-induced non-alcoholic fatty liver disease (NAFLD) is still unclear. This study was aimed to investigate the regulation of DS-SDF on gut microbiota in MCD diet-induced mice and its potential protective effect on liver injury. The NAFLD model was induced by the MCD diet for 8 weeks. Through observation of changes in liver function and gut microorganisms, it was found that DS-SDF supplementation could inhibit liver inflammation, improve liver injury, regulate the diversity of gut microorganisms, increase the abundance of beneficial bacteria and short-chain fatty acid-producing bacteria, and reverse the gut disorders induced by the MCD diet in mice. This study showed that DS-SDF supplementation could treat NAFLD by regulating gut microbiota composition, improving liver function, and inhibiting the inflammatory response. It might broaden the idea of high-value utilization of DS-SDF.

Postbiotic properties of exopolysaccharide produced by Levilactobacillus brevis M-10 isolated from natural fermented sour porridge through in vitro simulated digestion and fermentation

The simulated digestion and fermentation characteristics in vitro of exopolysaccharide (EPS) of Levilactobacillus brevis M-10 were studied to evaluate its postbiotic properties. The simulated digestion results showed that EPS could not be degraded in saliva but could be very slightly degraded in gastric juice and could be degraded in intestinal juice. The results of simulated fermentation demonstrated that EPS could lower the intestine pH and be utilized by gut microbes to produce short-chain fatty acids such as propionic acid and butyric acid. Meanwhile, EPS significantly raised the diversity of human gut microbiota, and the relative abundances of Phascolarctobacterium were significantly increased, whereas Fusobacterium and Morganella significantly decreased. In conclusion, EPS from L. brevis M-10 was a good postbiotic as inulin. This was the first report about EPS as the postbiotic of L. brevis M-10 screened from broomcorn millet sour porridge in northwestern Shanxi Province, China.

Hypoglycemic Effects of Gynura divaricata (L.) DC Polysaccharide and Action Mechanisms via Modulation of Gut Microbiota in Diabetic Mice

Aiming to provide a basis for the application of Gynura divaricata (L.) DC polysaccharide (GDP) in functional foods, the hypoglycemic effects of GDP, and action mechanisms, were investigated. Results showed that GDP effectively inhibited α-glucosidase and remarkably increased the glucose absorption, glycogen content, and pyruvate kinase and hexokinase activities of insulin-resistant HepG2 cells, indicating its potent in vitro hypoglycemic effect. In streptozotocin-induced type 2 diabetes mice, GDP significantly improved various glycolipid metabolism-related indices in serum and liver, e.g., fasting blood glucose, oral glucose tolerance, glycosylated serum protein content, serum insulin level, antioxidant enzyme activities, TG, TC, LDL-C, and HDL-C levels, and hepatic glycogen content, and recovered the structure of gut microbiota to the normal level. It was also found that GDP significantly affected the expression of related genes in the PI3K/Akt, AMPK, and GS/GSK-3β signaling pathways. Therefore, GDP regulates blood glucose possibly by directly inhibiting α-glucosidase, exerting antioxidant activity, and regulating intestinal microbiota.

Effects of Lacticaseibacillus paracasei SNB-derived postbiotic components on intestinal barrier dysfunction and composition of gut microbiota

The bacterial surface components are considered as effector molecules and show the potential to support intestinal health, but the detailed mechanism of how the gut microbiota changes after the intervention of surface molecules is still unknown. In the present study, capsular polysaccharide (B-CPS) and surface layer protein (B-SLP) were extracted from Lacticaseibacillus paracasei S-NB. The protective effect of direct administration of B-CPS (100 μg/mL) and B-SLP (100 μg/mL) on intestinal epithelial barrier dysfunction was verified based on the LPS-induced Caco-2 cell model. Additionally, the B-CPS and B-SLP could be utilized as carbon source and nitrogen source for the growth of several Lactobacillus strains, respectively. The postbiotic potential of B-CPS and B-SLP was further evaluated by in vitro fermentation with fecal cultures. The B-CPS and a combination of B-CPS and B-SLP regulated the composition of gut microbiota by increasing the relative abundances of Bacteroides, Bifidobacterium, Phascolarctobacterium, Parabacteroides, Subdoligranulum and Collinsella and decreasing the abundance of pathogenic bacteria like Escherichia-Shigella, Blautia, Citrobacter and Fusobacterium. Meanwhile, the total short-chain fatty acid production markedly increased after fermentation with either B-CPS individually or in combination with B-SLP. These results provided an important basis for the application of B-CPS and B-SLP as postbiotics to improve human intestinal health.

Evaluation of antioxidation, regulation of glycolipid metabolism and potential as food additives of exopolysaccharide from Sporidiobolus pararoseus PFY-Z1

At present, there are relatively few studies on the production of exopolysaccharide (EPS) by yeasts. Therefore, exploring the properties of EPS produced by yeast can not only enrich the source of EPS, but also play an important role in its future application in the food field. The aim of this study was to explore the biological activities of EPS (named SPZ) from Sporidiobolus pararoseus PFY-Z1, as well as the dynamic changes in physical and chemical properties that occur during simulated gastrointestinal digestion, and the effects of SPZ on microbial metabolites during fecal fermentation in vitro. The results revealed that SPZ had good water solubility index, water-holding capacity, emulsifying ability, coagulated skim milk, antioxidant properties, hypoglycemic activities, and bile acid-binding abilities. Furthermore, the content of reducing sugars increased from 1.20 ± 0.03 to 3.34 ± 0.11 mg/mL after gastrointestinal digestion, and had little effect on antioxidant activities. Moreover, SPZ could promote the production of short-chain fatty acids during fermentation for 48 h, in particular, propionic acid and n-butyric acid increased to 1.89 ± 0.08 and 0.82 ± 0.04 mmol/L, respectively. Besides this, SPZ could inhibit LPS production. In general, this study can help us to better understand the potential bioactivities, and the changes in bio-activities of compounds after digestion of SPZ.

Fecal fermentation and high-fat diet-induced obesity mouse model confirmed exopolysaccharide from Weissella cibaria PFY06 can ameliorate obesity by regulating the gut microbiota

Obesity associated with diet and intestinal dysbiosis is a worldwide public health crisis, and exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) have prebiotic potential to ameliorate obesity. Therefore, the present study obtained LAB with the ability to produce high EPS, examined the structure of EPS, and explained its mechanism of alleviating obesity by in vivo and in vitro models. The results showed that Weissella cibaria PFY06 with a high EPS yield was isolated from strawberry juice, and pure polysaccharide (PFY06-EPS) was purified by Sephadex G-100. The structural characteristics of PFY06-EPS showed that the molecular weight was 8.08 × 10⁶ Da and composed of α-(1,6)-D glucosyl residues. An in vitro simulated human colon fermentation test demonstrated that PFY06-EPS increased the abundance of Prevotella and Bacteroides. Cell tests confirmed that PFY06-EPS after fecal fermentation inhibited fat accumulation by promoting the secretion of endogenous gastrointestinal hormones and insulin and inhibiting the secretion of inflammatory factors. Notably, PFY06-EPS reduced weight gain, fat accumulation, inflammatory reactions and insulin resistance in a high-fat diet-induced obesity mouse model and improved glucolipid metabolism. PFY06-EPS intervention reversed obesity-induced microflora disorders, such as reducing the Firmicutes/Bacteroides ratio and increasing butyrate-producing bacteria (Roseburia and Oscillibacter), and reduced endotoxemia to maintain intestinal barrier integrity. Therefore, in vivo and in vitro models showed that PFY06-EPS had potential as a prebiotic that may play an anti-obesity role by improving the function of the gut microbiota.

Characterization of soluble dietary fiber from citrus peels (Citrus unshiu), and its antioxidant capacity and beneficial regulating effect on gut microbiota

This study aimed to evaluate the physicochemical, structural and functional properties of soluble dietary fiber extracted from citrus peels (Citrus unshiu) by ultrasound-assisted alkaline extraction. Unpurified soluble dietary fiber (CSDF) was compared with purified soluble dietary fiber (PSDF) in terms of composition, molecular weight, physicochemical properties, antioxidant activity, and intestinal regulatory capacity. Results showed that the molecular weight of soluble dietary fiber was >15 kDa, which showed good shear thinning characteristics and belonged to non-Newtonian fluid. The soluble dietary fiber showed good thermal stability under 200 °C. The contents of total sugar, arabinose and sulfate in PSDF were higher than those in CSDF. At the same concentration, PSDF showed stronger free radical scavenging ability. In fermentation model experiments, PSDF promoted the production of propionic acid and increased the abundance of Bacteroides. These findings suggested that soluble dietary fiber extracted by the ultrasound-assisted alkaline extraction has good antioxidant capacity and promotes intestinal health. It has broad development space in the field of functional food ingredients.

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.

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.

Exopolysaccharide from Lactobacillus rhamnosus ZFM231 alleviates DSS-induced colitis in mice by regulating gut microbiota

BACKGROUND

The exopolysaccharides (EPS) produced by Lactobacillus and other probiotics are associated with many benefits, such as immune regulation, antioxidant properties, antitumor effect, and regulation of intestinal microbe homeostasis. In the present study, the modulatory effect of EPS produced by Lactobacillus rhamnosus ZFM231 on the intestinal flora of mice with inflammatory bowel disease induced by dextran sulfate solution was investigated.

RESULTS

Results indicated that weight loss, colonic length, the disease activity index score and colonic tissue damage in mice were significantly improved by EPS treatment. Compared with the model group, in the EPS-treated group, the diversity of and the composition of gut microbiota at both phylum and genus levels were found to recover to the levels of normal group, indicating the effective modulation on gut microbiota by EPS; short-chain fatty acids, including acetic acid, propionic acid and butyric acid produced by intestinal microbial metabolism, increased significantly; the level of anti-inflammatory factor transforning growth factor-β significantly increased and the level of pro-inflammatory factor tumor necrosis factor-α significantly decreased in the colonic cells of EPS-treated mice.

CONCLUSION

It is clear that EPS produced by L. rhamnosus ZFM231 could find application in functional foods with the property of anti-ulcerative colitis. The experimental results provide new insights into the probiotic effect of EPS. © 2022 Society of Chemical Industry.

Prebiotic Properties of Exopolysaccharides from Lactobacillus helveticus LZ-R-5 and L. pentosus LZ-R-17 Evaluated by In Vitro Simulated Digestion and Fermentation

The in vitro digestion and fermentation behaviors of Lactobacillus helveticus LZ-R-5- and L. pentosus LZ-R-17-sourced exopolysaccharides (LHEPS and LPEPS) were investigated by stimulated batch-culture fermentation system. The results illustrated that LHEPS was resistant to simulated saliva and gastrointestinal (GSI) digestion, whereas LPEPS generated a few monosaccharides after digestion without significant influence on its main structure. Additionally, LHEPS and LPEPS could be consumed by the human gut microbiota and presented stronger bifidogenic effect comparing to α-glucan and β-glucan, as they promote the proliferation of Lactobacillus and Bifidobacterium in cultures and exhibited high values of selectivity index (13.88 and 11.78, respectively). Furthermore, LPEPS achieved higher contents of lactic acid and acetic acid (35.74 mM and 45.91 mM, respectively) than LHEPS (35.20 mM and 44.65 mM, respectively) during fermentation for 48 h, thus also resulting in a larger amount of total SCFAs (110.86 mM). These results have clearly indicated the potential prebiotic property of EPS fractions from L. helveticus LZ-R-5 and L. pentosus LZ-R-17, which could be further developed as new functional food prebiotics to beneficially improve human gut health.

Exopolysaccharides of Lactic Acid Bacteria: Production, Purification and Health Benefits towards Functional Food

Lactic acid bacteria (LAB) are capable of synthesising metabolites known as exopolysaccharides (EPS) during fermentation. Traditionally, EPS plays an important role in fermented dairy products through their gelling and thickening properties, but they can also be beneficial to human health. This bioactivity has gained attention in applications for functional foods, which leads them to have prebiotic, immunomodulatory, antioxidant, anti-tumour, cholesterol-lowering and anti-obesity activity. Understanding the parameters and conditions is crucial to optimising the EPS yields from LAB for applications in the food industry. This review provides an overview of the functional food market together with the biosynthesis of EPS. Factors influencing the production of EPS as well as methods for isolation, characterisation and quantification are reviewed. Finally, the health benefits associated with EPS are discussed.

In vitro fecal fermentation characteristics of bamboo shoot (Phyllostachys edulis) polysaccharide

The effects of Moso bamboo (Phyllostachys edulis) shoot polysaccharide (BSP) on the human gut microbiota composition and volatile metabolite components were investigated by in vitro fermentation. After fermentation for 48 h, BSP utilization reached 40.29% and the pH of the fermentation solution decreased from 6.89 to 4.57. Moreover, the total short-chain fatty acid concentration significantly (P < 0.05) increased from 13.46 mM (0 h) to 43.20 mM (48 h). 16S rRNA analysis revealed several differences in the gut microbiota community structure of the BSP-treated and water-treated (control) cultures. In the BSP group, the abundance of Firmicutes, Actinobacteria, and Proteobacteria was significantly increased, while that of Bacteroidetes and Fusobacteria significantly decreased. Moreover, the concentrations of benzene, its substituted derivatives, and carbonyl compounds in the volatile metabolites of the BSP-treated group decreased, while that of organic acids significantly increased after 48 h of fermentation. These results demonstrate that BSP improves gastrointestinal health.