Fermentation Of Polysaccharides Research Articles

Effects of Prebiotic Dietary Fibers on the Stimulation of the Mucin Secretion in Host Cells by In Vitro Gut Microbiome Consortia

The gastrointestinal microbiota are important for human health. Dietary intake may modulate the composition and metabolic function of the gut microbiome. We examined how the breakdown of prebiotic dietary fibers by the gut microbiome affects mucin secretion by intestinal epithelial cells. Metagenomic analyses of in vitro gut microbiome consortia revealed taxonomic profiles and genetic diversity of carbohydrate-active enzymes that digest polysaccharides. Two independent consortia exhibited different abilities to produce acetic acid, propionic acid, and butyric acid via the fermentation of polysaccharides derived from dietary fibers of grains and mushrooms. Although acetic acid generally had the highest concentration, the ratios of butyric acid and propionic acid to acetic acid varied depending on the polysaccharide source. These short-chain fatty acids affected morphological differentiation and mucin secretion in HT-29 human intestinal epithelial cells. These results suggest that prebiotic dietary fibers can be digested and metabolized by the gut microbiome to short-chain fatty acids, which can affect gut epithelial cells both directly and indirectly via the modulation of the gut microbiota and their enzymes.

In vitro digestion and fermentation of polysaccharides from nine common Polygonatum spp. and their impact on human gut microbiota

This study aimed to investigate the dynamic changes in the physicochemical properties of polysaccharides from nine common Polygonatum spp. during in vitro simulated saliva-gastrointestinal digestion, in vitro fermentation, and their subsequent effects on human gut microbiota. Results revealed that the total sugar contents of Polygonatum spp. polysaccharides almost had little changes during the vitro digestion, and the molecular weight presented a downward trend. The in vitro digestion process produced almost no free monosaccharide, with small variations on FT-IR spectroscopy analysis. However, during the in vitro fermentation process, the polysaccharides generated remarkable changes, the total sugar showed a downward trend, and the molecular weight was degraded. There were significant changes in the monosaccharide composition, and possibly the sugar occurred isomerism. Regarding the concentrations of short-chain fatty acids, both acetic acid and propionic acid were found to be significantly elevated in the treatment group compared to the control group, and the pH value dramatically decreased. Simultaneously, Polygonatum spp. polysaccharides could remarkably modulate the richness of microbial communities and improved their diversity, especially Narrowly Defined Clostridium, and Bacteroidetes. In general, this study can be helpful to better understand the potential digestion and fermentation mechanism of the genus Polygonatum polysaccharides.

In vitro digestion and fecal fermentation of Tremella fuciformis exopolysaccharides from basidiospore-derived submerged fermentation

Tremella fuciformis polysaccharides (TFPS) belong to natural bioactive macromolecule with both edible and medicinal value, possessing much bioactivities such as anti-tumor, antioxidant, antidiabetics, and immunomodulatory. Currently, the production of TFPS through submerged fermentation (TFPS-1) is gradually replacing the polysaccharides extracted from the fruiting body due to improved fermentation efficiency and reduced separation costs. However, it is still unclear about the effect of TFPS-1 on gastrointestinal digestion and gut microbial fermentation, which is directly related to the function of its biological activity. This study aimed to illustrate the effect of TFPS-1 on digestive process through in vitro digestion and fecal fermentation. TFPS-1 was indigestible during the simulated gastrointestinal tract. But TFPS-1 can be digested by intestinal flora leading to alterations in the total polysaccharides content, molecular weight, and apparent viscosity. Moreover, TFPS-1 regulated the composition of gut microbial, lowering the proportion of Firmicutes to Bacteroidetes and enhancing the abundances of Parabacteroides and Bacteroides. The change of intestinal flora produced more short chain fatty acids and lowered the pH. The KEGG metabolic pathway analysis indicated that TFPS-1 enriched lipid metabolism, glycan biosynthesis and metabolism, and biosynthesis of other secondary metabolites. This study demonstrated that T. fuciformis fermented polysaccharide can be a potential prebiotic to optimize intestinal flora homeostasis and maintain host intestinal health.

Anti-Oxidative and Anti-Apoptotic Oligosaccharides from Pichia pastoris-Fermented Cress Polysaccharides Ameliorate Chromium-Induced Liver Toxicity.

Oxidative stress impairs the structure and function of the cell, leading to serious chronic diseases. Antioxidant-based therapeutic and nutritional interventions are usually employed for combating oxidative stress-related disorders, including apoptosis. Here, we investigated the hepatoprotective effect of oligosaccharides, produced through Pichia pastoris-mediated fermentation of water-soluble polysaccharides isolated from Lepidium sativum (cress) seed mucilage, on chromium(VI)-induced oxidative stress and apoptosis in mice. Gel permeation chromatography (GPC), using Bio-Gel P-10 column, of the oligosaccharides product of fermentation revealed that P. pastoris effectively fermented polysaccharides as no long chain polysaccharides were observed. At 200 µg/mL, fractions DF73, DF53, DF72, and DF62 exhibited DPPH radical scavenging activity of 92.22 ± 2.69%, 90.35 ± 0.43%, 88.83 ± 3.36%, and 88.83 ± 3.36%, respectively. The antioxidant potential of the fermentation product was further confirmed through in vitro H2O2 radical scavenging assay. Among the screened samples, the highest H2O2 radical scavenging activity was displayed by DF73, which stabilized the free radicals by 88.83 ± 0.38%, followed by DF53 (86.48 ± 0.83%), DF62 (85.21 ± 6.66%), DF72 (79.9 4± 1.21%), and EPP (77.76 ± 0.53%). The oligosaccharide treatment significantly alleviated chromium-induced liver damage, as evident from the increase in weight gain, improved liver functions, and reduced histopathological alterations in the albino mice. A distinctly increased level of lipid peroxide (LPO) free radicals along with the endogenous hepatic enzymes were evident in chromium induced hepatotoxicity in mice. However, oligosaccharides treatment mitigated these effects by reducing the LPO production and increasing ALT, ALP, and AST levels, probably due to relieving the oxidative stress. DNA fragmentation assays illustrated that Cr(VI) exposure induced massive apoptosis in liver by damaging the DNA which was then remediated by oligosaccharides supplementation. Histopathological observations confirmed that the oligosaccharide treatment reverses the architectural changes in liver induced by chromium. These results suggest that oligosaccharides obtained from cress seed mucilage polysaccharides through P. pastoris fermentation ameliorate the oxidative stress and apoptosis and act as hepatoprotective agent against chromium-induced liver injury.

Updated Progress on Polysaccharides with Anti-Diabetic Effects through the Regulation of Gut Microbiota: Sources, Mechanisms, and Structure-Activity Relationships.

Diabetes mellitus (DM) is a common chronic metabolic disease worldwide. The disturbance of the gut microbiota has a complex influence on the development of DM. Polysaccharides are one type of the most important natural components with anti-diabetic effects. Gut microbiota can participate in the fermentation of polysaccharides, and through this, polysaccharides regulate the gut microbiota and improve DM. This review begins by a summary of the sources, anti-diabetic effects and the gut microbiota regulation functions of natural polysaccharides. Then, the mechanisms of polysaccharides in regulating the gut microbiota to exert anti-diabetic effects and the structure-activity relationship are summarized. It is found that polysaccharides from plants, fungi, and marine organisms show great hypoglycemic activities and the gut microbiota regulation functions. The mechanisms mainly include repairing the gut burrier, reshaping gut microbiota composition, changing the metabolites, regulating anti-inflammatory activity and immune function, and regulating the signal pathways. Structural characteristics of polysaccharides, such as monosaccharide composition, molecular weight, and type of glycosidic linkage, show great influence on the anti-diabetic activity of polysaccharides. This review provides a reference for the exploration and development of the anti-diabetic effects of polysaccharides.

Enrichable consortia of microbial symbionts degrade macroalgal polysaccharides in Kyphosus fish.

Coastal herbivorous fishes consume macroalgae, which is then degraded by microbes along their digestive tract. However, there is scarce genomic information about the microbiota that perform this degradation. This study explores the potential of Kyphosus gastrointestinal microbial symbionts to collaboratively degrade and ferment polysaccharides from red, green, and brown macroalgae through in silico study of carbohydrate-active enzyme and sulfatase sequences. Recovery of metagenome-assembled genomes (MAGs) from previously described Kyphosus gut metagenomes and newly sequenced bioreactor enrichments reveals differences in enzymatic capabilities between the major microbial taxa in Kyphosus guts. The most versatile of the recovered MAGs were from the Bacteroidota phylum, whose MAGs house enzyme collections able to decompose a variety of algal polysaccharides. Unique enzymes and predicted degradative capacities of genomes from the Bacillota (genus Vallitalea) and Verrucomicrobiota (order Kiritimatiellales) highlight the importance of metabolic contributions from multiple phyla to broaden polysaccharide degradation capabilities. Few genomes contain the required enzymes to fully degrade any complex sulfated algal polysaccharide alone. The distribution of suitable enzymes between MAGs originating from different taxa, along with the widespread detection of signal peptides in candidate enzymes, is consistent with cooperative extracellular degradation of these carbohydrates. This study leverages genomic evidence to reveal an untapped diversity at the enzyme and strain level among Kyphosus symbionts and their contributions to macroalgae decomposition. Bioreactor enrichments provide a genomic foundation for degradative and fermentative processes central to translating the knowledge gained from this system to the aquaculture and bioenergy sectors.IMPORTANCESeaweed has long been considered a promising source of sustainable biomass for bioenergy and aquaculture feed, but scalable industrial methods for decomposing terrestrial compounds can struggle to break down seaweed polysaccharides efficiently due to their unique sulfated structures. Fish of the genus Kyphosus feed on seaweed by leveraging gastrointestinal bacteria to degrade algal polysaccharides into simple sugars. This study reconstructs metagenome-assembled genomes for these gastrointestinal bacteria to enhance our understanding of herbivorous fish digestion and fermentation of algal sugars. Investigations at the gene level identify Kyphosus guts as an untapped source of seaweed-degrading enzymes ripe for further characterization. These discoveries set the stage for future work incorporating marine enzymes and microbial communities in the industrial degradation of algal polysaccharides.

Changes in physicochemical and gut microbiota fermentation property induced by acetylation of polysaccharides from Cyperus esculentus

In this study, the impact of acetylation on physicochemical, digestive behavior and fermentation characteristics of Cyperus esculentus polysaccharides (CEP) was investigated. Results indicated that the acetylation led the molecules to be more likely aggregated, followed by a higher crystallinity, a lower apparent viscosity and a higher ratio of G" to G' (tan δ). Importantly, the acetylated polysaccharides (ACEP) had a lower digestibility, but its molecular weight was lower than that of original polysaccharides (CEP) following a simulated saliva-gastrointestinal digestion. Gut microbiota fermentation indicated that both polysaccharides generated outstanding short-chain fatty acids (SCFAs), in which the acetylated polysaccharides had a faster fermentation kinetics than the original one, followed by a quicker reduction of pH and a more accumulation of SCFAs, particularly butyrate. Fermentation of both polysaccharides promoted Akkermansia, followed by a reduced richness of Klebsiella. Importantly, the current study revealed that the fermentation of acetylated polysaccharides enriched Parabacteroides, while fermentation of original ones promoted Bifidobacterium, for indicating their individual fermentation characteristics and gut environmental benefits.

Impact of rumen microbiome on cattle carcass traits

Rumen microbes are crucial in the anaerobic fermentation of plant polysaccharides to produce volatile fatty acids. However, limited information exists about the specific microbial species and strains in the rumen that affect carcass traits, and it is unclear whether there is a relationship between rumen metabolic functions and these traits. This study investigated the relationship between the rumen microbiome and carcass traits in beef cattle using 16S rRNA amplicon and shotgun sequencing. Metagenomic sequencing was used to compare the rumen microbiome between high-carcass weight (HW) and low-carcass weight (LW) cattle, and high-marbling (HM) and low-marbling (LM) cattle. Prokaryotic communities in the rumen of HW vs. LW and HM vs. LM were separated using 16S rRNA amplicon sequencing. Notably, shotgun metagenomic sequencing revealed that HW cattle had more methane-producing bacteria and ciliate protozoa, suggesting higher methane emissions. Additionally, variations were observed in the abundances of certain glycoside hydrolases and polysaccharide lyases involved in the ruminal degradation of plant polysaccharides between HW and LW. From our metagenome dataset, 807 non-redundant metagenome-assembled genomes (MAGs) of medium to high quality were obtained. Among these, 309 and 113 MAGs were associated with carcass weight and marbling, respectively.

Studies of peach gum polysaccharide on gut microbiota in vitro fermentation by human feces

Peach gum polysaccharides have multiple biological functions, such as anti-oxidation, blood lipids reduction, and immune protection. However, their impact on the gut microbiota was still unclear. Here, high throughput sequencing was used to study the regulatory effects of peach gum polysaccharide on gut microbiota using an in vitro fermentation model of human gut microbiota. The results showed that gut microbiota species increased significantly and α-diversity index (Sobs, Ace, Chao1, Shannon) decreased significantly after polysaccharide fermentation compared with control group (distilled water). At phylum level, the relative abundance of Firmicutes and Actinomyces increased (61.76% vs. 56.64%, 28.24% vs. 23.11%). In contrast, relative abundance of Bacteroides decreased significantly (8.10% vs. 19.21%). At genus level, the relative abundance of Bifidobacteria, Colinella and Parazobacteria increased significantly (21.43% vs. 19.08%, 6.32% vs. 3.73%, 6.37% vs. 0.00%), while the relative abundance of Bacteroides and Prevotella decreased significantly (3.83% vs. 5.52%, 3.49% vs. 12.15%). Precisely, peach gum polysaccharide can effectively regulate the structure of gut microbiota and has potential probiotic effects including anti-obesity, anti-inflammatory, maintenance of gut epithelial barrier and so on.

Polygonatum odoratum fermented polysaccharides enhance the immunity of mice by increasing their antioxidant ability and improving the intestinal flora

Polygonatum odoratum is widely used as a food and medicine in Chinese folk culture. In this study, small-molecule polysaccharides were obtained by fermenting the roots of Polygonatum odoratum with Bacillus subtilis (denoted as PFP). The effects of PFP on the mouse immune response were investigated. The results of the in vitro experiments showed that PFP significantly improved the immune capacity of RAW264.7 macrophages. To verify whether PFP exhibited immune activity in vivo and was safe for animals, mouse experiments were carried out and LPS (lipopolysaccharide) was used to induce inflammation as an inflammatory positive control. The results indicated that compared to the normal control group (NC), PFP significantly increased the levels of TNF-α (tumour necrosis factor-alpha), IL-1β (interleukin-1 beta) and IL-6 (interleukin-6) in the serum of mice. Furthermore, the mRNA expression levels of iNOs, Nf-κB and Nrf2 in the livers of the mice were significantly upregulated, as were the contents of SOD (superoxide dismutase) and CAT (catalase). In contrast, the level of Akt1 mRNA in the liver was significantly downregulated. The mRNA expression levels of Tnf-α, Nf-κB, and the tight junction proteins ZO-1 (zonula occludens protein 1) and Occludin in the ileum of mice in the PFP group were significantly enhanced. Meanwhile, PFP significantly improved the structure of the gut microbiota in mice and significantly increased the abundance of various probiotics that produce short-chain fatty acids. In summary, these findings indicate that PFP can enhance the immunity of mice by improving their antioxidant capacity and the gut microbiota without causing inflammatory damage or the death of liver and intestinal tissues.

Microbial community structure in dementia and depression as a mirror of ageing “intestinal microbiota - immune system - brain” axis

Aim. To assess changes in the structure of the small intestine microbial community in the context of the “gut microbiota-immune system-brain axis” in healthy aging, depression and dementia. Materials and methods. 74 elderly people included in the groups: “Healthy ageing”, “Depression”, “Dementia” were investigated. Evaluation of 5 main types of microorganisms of the small intestine (Bacteroidetes, Firmicutes, Actinobacteria, Proteobacteria, Fusobacteria) by method of gas chromatography - mass spectrometry of microbial markers was carried out. For statistics, hierarchical cluster analysis with the construction of a heat map was used. Results. Reconstruction affected 15 out of 30 studied bacterial species of the phylums Firmicutes, Actinobacteria, Proteobacteria in the “Dementia” and “Depression” groups in relation to the “Healthy ageing” group. In depression, the number of all types of bacteria involved in the fermentation of food polysaccharides increased in relation to the “Healthy ageing” group. In dementia, low levels of Clostridium spp., Eubacterium spp., Bifidobacterium spp. was shown, in relation to depression, but number of C. perfringens, С. difficile and facultative anaerobes: Streptococcus spp., Enterococcus spp., Lactobacillus spp., S. aureus, S. epidermidis was increased, compared to “Healthy ageing” group. Conclusions. The indicators of the systems included in the axis “intestinal microbiota - immune system - brain” indicated a pronounced disintegration of the axis in dementia in relation to depression and healthy ageing. The results can be used as biological markers in the differential diagnosis of these pathologies (dementia/depression), which have common risk factors and clinical symptoms.

Interactions between intestinal microbial fermentation products of Pleurotus eryngii polysaccharide with gut mucus.

Recently, Pleurotus eryngii (P. eryngii) polysaccharide (PEP) has received a lot of attention from many researchers as the primary active substance. The PEP influences the gut microbiota in several ways, including the interaction of fermentation products with the intestinal mucus layer (IML) and intestinal epithelial cells. Herein, we characterized interactions between the IML and PEP after degradation by the gut microbes. Our results showed that fermented P. eryngii polysaccharide (FPEP) can interact with intestinal mucus (IM), and this interaction can reduce the degree of molecular aggregation of polysaccharides. At the same time, the fermentation time of FPEP also affects the interaction between the two. SEM showed that the FPEP solution tended to aggregate into larger particles, while with the addition of IM, the FPEP molecules were dispersed. Particle size measurements unveil substantial differences in the fermented polysaccharides' particle size between the group with supplementary IM (0 hours of fermentation: 485.1 ± 11.3 nm) and the group without IM (0 hours of fermentation: 989.33 ± 21.3 nm). Remarkably, within the group with added IM, the particle size reached its maximum at 24 hours of fermentation (585.87 ± 42.83 nm). Additionally, turbidity assessments demonstrate that, during the 12-hour interaction period, the 24-hour fermented polysaccharides consistently exhibit the highest OD values, ranging between 0.57 and 0.61. This work investigates the interaction between FPEP and IM, predicting the adhesion of polysaccharides to IM. Meanwhile, this provides a theoretical basis for further studies on the absorption and transport pathways of PEP and provides a novel research viewpoint on intestinal digestion and absorption.

Optimized Extraction and Fermentation of Antioxidant Polysaccharides from Polygonatum odoratum

Purpose: We wished to determine the optimal method for the extraction of polysaccharides with antioxidant activities from <i>Polygonatum odoratum</i>.Methods: Single-factor and orthogonal tests were applied to identify the best parameters for water extraction and fermentation. The solid-liquid ratio, temperature, and duration of water extraction were determined according to the total polysaccharide content. The fermentation temperature, agitation speed, inoculation amount, and fermentation time were investigated according to the optical density of Saccharomyces cerevisiae. The molecular weight distributions of water- and fermentation-extracted polysaccharides were determined by high performance gel permeation chromatography. The antioxidant activities of the polysaccharides were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) ABTS radical scavenging capacities, and ferric reducing antioxidant power (FRAP).Results: The optimum water extraction parameters were 80°C for 2.5 h with a 1:60 solid-liquid ratio. For fermentation, an 8% extraction volume was inoculated with <i>S. cerevisiae</i>. Optimal fermentation occurred at 28°C for 28 h, with an agitation speed of 180 r/min. The molecular weights of water- and fermentation-extracted polysaccharides were 2.067×10<sup>4</sup> and 9.475×10<sup>3</sup> Da, respectively. The DPPH, ABTS, and FRAP results demonstrated an obvious increase in antioxidant activity after fermentation.Conclusion: The fermentation extraction of <i>P. odoratum</i> may provide valuable materials for future cosmetic use.

Polyguluronate alleviates ulcerative colitis by targeting the gut commensal Lactobacillus murinus and its anti-inflammatory metabolites

Polyguluronate (PG) is a fermentable polysaccharide from edible algae. The present study was designed to investigate the therapeutic effect of PG on ulcerative colitis (UC) and its underlying mechanisms. Our results suggest that oral intake of PG attenuates UC and improves gut microbiota dysbiosis by promoting the growth of Lactobacillus spp. in dextran sulfate sodium-fed mice. Five different species of Lactobacillus were isolated from the feces of PG-treated mice and L. murinus was identified to have the best anti-colitis effect, suggesting a critical role for L. murinus in mediating the therapeutic effect of PG. Furthermore, PG was degraded potentially by the beta-glucuronidase from L. murinus and adding PG to the culture medium of L. murinus remarkably increased its production of anti-inflammatory metabolites, including itaconic acid, cis-11,14-eicosadienoic acid, and 3-amino-3-(2-chlorophenyl)-propionic acid. Additionally, L. salivarius, a human intestine-derived PG-utilizing species that is closely related to L. murinus, was also demonstrated to have potent anti-colitis effects, suggesting that it is a candidate target of PG in the human gut. Altogether, our study illustrates an unprecedented application of PG in the treatment of UC and establishes the basis for understanding its therapeutic effect from the perspective of L. murinus and its metabolites.

In Vitro Fermentation Characteristics of Fungal Polysaccharides Derived from Wolfiporia cocos and Their Effect on Human Fecal Microbiota.

Gut microbiota has been described as a new 'organ' that interferes with host physiology by its metabolites produced from the utilization and biotransformation of undigested food components. Fu Ling (FL), the sclerotia of fungi Wolfiporia cocos, contains β-glucan, which is a known natural polysaccharide with strong medicinal efficacy. This study endeavors to evaluate the fermentability of FL and polysaccharides extracted from its sclerotia. An in vitro fermentation of structurally characterized FL and its β-glucan by human fecal microbiota was conducted. Total bacterial count, pH change, short-chain fatty acid profile and microbiota profile were assessed post-fermentation. FL containing over 70% of β-(1 → 3) and (1 → 6)-glucans with a low degree of branching of 0.24 could enhance acetic acid (a major microbial metabolite) production. Both FL and its extracted β-glucan had similar modulation on microbial composition. They enriched Phascolarctobacterium faecium, Bacteroides dorei and Parabacteroides distasonis, all of which are shown to possess anti-inflammatory effects. FL polysaccharide can be utilized as a natural whole food for its potential health benefits to human gut bacteria.

Gastrointestinal Fermentable Polysaccharide Is Beneficial in Alleviating Loperamide-Induced Constipation in Mice.

To investigate the role of gastrointestinal (GI) polysaccharide fermentation in alleviating constipation, two polysaccharide fractions were isolated from a soluble fiber extract with determined anti-constipation activity: a 2.04 kDa neutral fraction (SSP-1) contained 99.29% glucose, and a 41.66 kDa acidic fraction (SSP-2) contained 63.85% uronic acid. After mice were given loperamide for 14 d to induce constipation, the GI transit rate increased significantly in the SSP-1 group (p < 0.05) but not in the SSP-2 group. The stool weight in the SSP-2 group was significantly higher than that in SSP-1 (383.60 mg vs. 226.23 mg) (p < 0.05). Both SSP-1 and SSP-2 groups had significantly increased serum gastrin and motilin levels (p < 0.05) and changes in their fecal short-chain fatty acid (SCFA) profiles, while SSP-1 showed better fermentation properties than SSP-2 in terms of statistically higher fecal contents of acetic acid and total SCFAs (p < 0.05). Bioinformatic analysis indicated that SSP-1 upregulated bacteria such as Oscillibacter to improve SCFA metabolism and stimulate GI hormone secretion, while SSP-2 had less influence on the gut microbiota. These results suggest that the neutral polysaccharide with superior GI fermentation properties exerted beneficial effects on constipation, while the less fermentable pectic fraction might act as a stool-bulking agent.

Gut feelings in the islets: The role of the gut microbiome and the FFA2 and FFA3 receptors for short chain fatty acids on β-cell function and metabolic regulation.

Short-chain fatty acids (SCFAs) are biosynthesized via fermentation of polysaccharides by gastrointestinal microbiota and have been shown to have wide-reaching effects on almost all tissues, including the pancreatic islets. Historically, the effects of SCFAs have been attributed to their intracellular metabolism and function as energy sources, but the discovery of free fatty acid G protein-coupled receptors (GPCRs) in the 2000s suggested that many functional outcomes of SCFAs are receptor-mediated. The SCFA receptors FFA2/GPR43 and FFA3/GPR41 are expressed on β-cells, where they regulate glucose-dependent insulin secretion, making them attractive targets for treatment of diabetes and other metabolic disorders. Here, we provide an update on the current evidence regarding regulation of FFA2/FFA3 receptors by specific probiotic bacterial species within the gut microbiome that synthesize SCFAs. We also review the body of research regarding the FFA2- and FFA3 receptor-specific function of SCFAs on β-cells and discuss the somewhat controversial and opposing findings within these studies.

In Vitro Fermentation of Polysaccharide from Edible Alga Enteromorpha clathrata by the Gut Microbiota of Patients with Ulcerative Colitis.

Dietary intake of the sulfated polysaccharide from edible alga E. clathrata (ECP) has recently been illustrated to attenuate ulcerative colitis (UC) by targeting gut dysbiosis in mice. However, ECP is not easily absorbed in the gut and, as a potential candidate for next-generation prebiotics development, how it is fermented by human gut microbiota has not been characterized. Here, using in vitro anaerobic fermentation and 16S high-throughput sequencing, we illustrate for the first time the detailed fermentation characteristics of ECP by the gut microbiota of nine UC patients. Our results indicated that, compared to that of glucose, fermentation of ECP by human gut microbiota produced a higher amount of anti-inflammatory acetate and a lower amount of pro-inflammatory lactate. Additionally, ECP fermentation helped to shape a more balanced microbiota composition with increased species richness and diversity. Moreover, ECP significantly stimulated the growth of anti-colitis bacteria in the human gut, including Bacteroides thetaiotaomicron, Bacteroides ovatus, Blautia spp., Bacteroides uniformis, and Parabacteroides spp. Altogether, our study provides the first evidence for the prebiotic effect of ECP on human gut microbiota and sheds new light on the development of ECP as a novel prebiotic candidate for the prevention and potential treatment of UC.

Physicochemical characterization, digestion profile and gut microbiota regulation activity of intracellular polysaccharides from Chlorella zofingiensis

A number of studies have shown that the polysaccharides from microalgae exhibit diverse biological activities, however, little is known about their digestibility and impact on human gut microbiota. In this study, a simulating digestion and fermentation system were established to investigate the digestibility and fermentation of intracellular polysaccharides from Chlorella zofingiensis (CZIP-S3). The results indicated that CZIP-S3 is a macromolecular polysaccharide composed of mannose, glucose, galactose and rhamnose, consisting of a main chain and two branched repeating units. CZIP-S3 could not be digested in the upper gastrointestinal tract. However, CZIP-S3 could be metabolized into smaller molecules by the gut microbiota. The pH values continuously decrease during fermentation, whereas, the amount of short-chain fatty acids steadily increase. Furthermore, CZIP-S3 could modulate the composition of gut microbiota, via lowering the ratio of Firmicutes/Bacteroidetes and increasing the relative abundance of Bacteroides, Bifidobacterium and Akkermansia. The data suggested that CZIP-S3 could potentially be used as an ingredient for functional foods or prebiotics to improve human health by promoting the relative abundances of beneficial bacteria.

Auricularia auricula polysaccharides attenuate obesity in mice through gut commensal Papillibacter cinnamivorans

IntroductionAuricularia auricula is a well-known traditional edible and medical fungus with high nutritional and pharmacological values, as well as metabolic and immunoregulatory properties. Nondigestible fermentable polysaccharides are identified as primary bioactive constituents of Auricularia auricula extracts. However, the exact mechanisms underlying the effects of Auricularia auricula polysaccharides (AAP) on obesity and related metabolic endpoints, including the role of the gut microbiota, remain insufficiently understood. MethodsThe effects of AAP on obesity were assessed within high-fat diet (HFD)-based mice through obesity trait analysis and metabolomic profiling. To determine the mechanistic role of the gut microbiota in observed anti-obesogenic effects AAP, faecal microbiota transplantation (FMT) and pseudo-germ-free mice model treated with antibiotics were also applied, together with 16S rRNA genomic-derived taxonomic profiling. ResultsHigh-fat diet (HFD) murine exposure to AAP thwarted weight gains, reduced fat depositing and enhanced glucose tolerance, together with upregulating thermogenesis proteomic biomarkers within adipose tissue. Serum metabolome indicated these effects were associated with changes in fatty acid metabolism. Intestine-dwelling microbial population assessments discovered that AAP selectively enhanced Papillibacter cinnamivorans, a commensal bacterium with reduced presence in HFD mice. Notably, HFD mice treated with oral formulations of P. cinnamivorans attenuated obesity, which was linked to decreased intestinal lipid transportation and hepatic thermogenesis. Mechanistically, it was demonstrated that P. cinnamivorans regulated intestinal lipids metabolism and liver thermogenesis by reducing the proinflammatory response and gut permeability in a JAK-STAT signaling-related manner. ConclusionDatasets from the present study show that AAP thwarted dietary-driven obesity and metabolism-based disorders by regulating intestinal lipid transportation, a mechanism that is dependent on the gut commensal P. cinnamivorans. These results indicated AAP and P. cinnamivorans as newly identified pre- and probiotics that could serve as novel therapeutics against obesity.