Simulated Digestion and Fecal Fermentation Behaviors of Levan and Its Impacts on the Gut Microbiota

Mechanisms of levan in ameliorating hyperuricemia: Insight into levan on serum metabolites, gut microbiota, and function in hyperuricemia rats

This study aims to investigate the effects of levan on the progression of hyperuricemia (HUA) rats and elucidate its underlying mechanisms. After levan intervention, both low and high-dose groups exhibited a significant decrease in serum uric acid (UA) levels, reaching 71.0 % and 77.5 %, respectively, compared to the model group. Furthermore, levan could alleviate renal pathological damage caused by glomerular cell vacuolation, inflammatory infiltration and collagen deposition. The results of enzyme activity assay and real-time fluorescence quantitative PCR showed that levan decreased UA production by inhibiting adenosine deaminase (ADA) activity and gene expression in liver; it upregulated ATP-binding cassette subfamily G member 2 protein (ABCG2) and organic anion transporter 1 (OAT1) transporter gene expression in the kidney, promoting UA excretion. Gut microbiome analysis indicated that levan regulated gut flora dysbiosis induced by HUA, resulting in up-regulated the abundance of beneficial bacteria (Muribaculaceae, Faecalibaculum, Bifidobacterium, and Lactobacillus) and decreased conditioned pathogenic bacteria (Escherichia_Shigella and Proteus). Non-targeted metabolomics showed changes in various serum metabolites associated with glycerophospholipid metabolism, lipid metabolism, and inflammation following oral administration of levan. Therefore, levan may be a promising functional dietary supplement for regulating the gut flora and remodeling of metabolic disorders in individuals with HUA.

Revealing the Potential Impacts of Nutraceuticals Formulated with Freeze-Dried Jabuticaba Peel and Limosilactobacillus fermentum Strains Candidates for Probiotic Use on Human Intestinal Microbiota

This study evaluated the impacts of novel nutraceuticals formulated with freeze-dried jabuticaba peel (FJP) and three potentially probiotic Limosilactobacillus fermentum strains on the abundance of bacterial groups forming the human intestinal microbiota, metabolite production, and antioxidant capacity during in vitro colonic fermentation. The nutraceuticals had high viable counts of L. fermentum after freeze-drying (≥ 9.57 ± 0.09 log CFU/g). The nutraceuticals increased the abundance of Lactobacillus ssp./Enterococcus spp. (2.46-3.94%), Bifidobacterium spp. (2.28-3.02%), and Ruminococcus albus/R. flavefaciens (0.63-4.03%), while decreasing the abundance of Bacteroides spp./Prevotella spp. (3.91-2.02%), Clostridium histolyticum (1.69-0.40%), and Eubacterium rectale/C. coccoides (3.32-1.08%), which were linked to positive prebiotic indices (> 1.75). The nutraceuticals reduced the pH and increased the sugar consumption, short-chain fatty acid production, phenolic acid content, and antioxidant capacity, besides altering the metabolic profile during colonic fermentation. The combination of FJP and probiotic L. fermentum is a promising strategy to produce nutraceuticals targeting intestinal microbiota.

Simulated Gastrointestinal Digestion and Fecal Fermentation Characteristics of Exopolysaccharides Synthesized by Schleiferilactobacillus harbinensis Z171

Exopolysaccharides (EPSs) produced by Lactobacillus have important physiological activities and are commonly used as novel prebiotics. A strain of Lactobacillus with high EPS yield was identified as Schleiferilactobacillus harbinensis (S. harbinensis Z171), which was isolated from Chinese sauerkraut. The objective of this study was to investigate the in vitro simulated digestion and fecal fermentation behavior of the purified exopolysaccharide fraction F-EPS1A from S. harbinensis Z171 and its influence on the human intestinal flora composition. The in vitro digestion results showed that the primary structural characteristics of F-EPS1A, such as morphology, molecular weight, and monosaccharide composition remained stable after saliva and gastrointestinal digestion. Compared with the blank group, the fermentation of F-SPS1A by fecal microbiota decreased the diversity of the bacterial communities, significantly promoted the relative abundance of Bifidobacterium and Faecalibacterium, and decreased the relative abundance of Lachnospiraceae_Clostridium, Fusobacterium, and Oscillospira. Reverse transcription polymerase chain reaction (RT-PCR) analysis also showed that the population of Bifidobacterium markedly increased. Furthermore, the total short-chain fatty acid levels increased significantly, especially for butyric acid. Gas chromatography-mass spectrometry (GC-MS) results showed that F-EPS1A could be fermented by the human gut microbiota to synthesize organic acids and derivative metabolites that are beneficial to gut health. Therefore, these findings suggest that F-EPS1A could be exploited as a potential prebiotic.

In vitro digestive properties and the bioactive effect of walnut green husk on human gut microbiota

Introduction

Walnut green husk (WGH) is a waste byproduct from walnut industry. However, it is not well-known about its bioactive effect on human gut health.

Methods

This study conducted in vitro digestion and fermentation experiments to study the bioactive effect of WGH.

Results

Microbial fermentation was the primary mechanism to efficiently release phenolics and flavonoids, resulting in more excellent antioxidant capacities (DPPH, ABTS, and FRAP assays), which reached a highest value with 14.82 ± 0.01 mg VcE/g DW, 3.47 ± 0.01 mmol TE/g DW, and 0.96 ± 0.07 mmol FeSO4·7H2O/g DW, respectively. The surface microstructure of WGH became loose and fragmented after microbial fermentation. The analytical results of gut microbiota demonstrated that WGH could significantly increase the relative abundance of Proteobacteria in phylum level and Phascolarctobacterium in genus level while certain pro-inflammatory bacteria (such as Clostridium_sensu_stricto_1, Dorea, Alistipes, and Bilophila) was inhibited. Additionally, 1,373 differential metabolites were identified and enriched in 283 KEGG pathways. Of which some metabolites were significantly upregulated including ferulic acid, chlorogenic acid, umbelliferone, scopolin, muricholic acid, and so forth.

Discussion

These results indicated that WGH could have antioxidant and anti-inflammatory activities in the human gut, which could improve the economical value of WGH in the food industry.

Bifidobacterium bifidum Ameliorates DSS-Induced Colitis in Mice by Regulating Microbial Metabolome and Targeting Gut Microbiota

Inflammatory bowel disease (IBD) is a recurrent inflammatory condition affecting the gastrointestinal tract, and its clinical treatment remains suboptimal. Probiotics have shown effectiveness in alleviating dextran sulfate sodium salt (DSS)-induced colitis, exhibiting strain-specific anti-inflammatory properties. In this study, we compared the therapeutic effects of five strains of Bifidobacterium bifidum isolated from healthy adult feces on DSS-induced colitis in mice. Additionally, we investigated the underlying mechanisms by examining gut microbiota composition and microbial metabolome. Our findings highlighted the superior efficacy of B. bifidum M1-3 compared to other strains. It significantly improved colitis symptoms, mitigated gut barrier disruption, and reduced colonic inflammation in DSS-treated mice. Moreover, gut microbiota composition analysis revealed that B. bifidum M1-3 treatment increased the abundance and diversity of gut microbiota. Specifically, it significantly increased the abundance of Muribaculaceae, Lactobacillus, Bacteroides, and Enterorhabdus, while decreasing the abundance of Escherichia-Shigella. Furthermore, our nontargeted metabolomics analysis illustrated that B. bifidum M1-3 treatment had a regulatory effect on various metabolic pathways, including tyrosine metabolism, lysine degradation, and tryptophan metabolism. Importantly, we confirmed that the therapeutic efficiency of B. bifidum M1-3 was dependent on the gut microbiota. These results are conducive to the development of probiotic products for alleviating colitis.

In vitro digestion and fecal fermentation of basidiospore-derived exopolysaccharides from Naematelia aurantialba

Mushroom polysaccharides exhibit numerous health-enhancing attributes that are intricately linked to the breakdown, assimilation, and exploitation of polysaccharides within the organism. Naematelia aurantialba polysaccharides (NAPS-A), highly prized polysaccharides derived from mushrooms, remain shrouded in uncertainty regarding their characteristics pertaining to gastrointestinal digestion and gut microbial fermentation. The study aimed to understand the digestion and fecal fermentation patterns of NAPS-A. After simulated digestion, NAPS-A's physicochemical properties remained unchanged. However, during in vitro fecal fermentation, indigestible NAPS-A underwent significant changes in various properties, such as reducing sugar, chemical composition, constituent monosaccharides, Molecular weight, apparent viscosity, FT-IR spectra, and microscopic morphology. Notably, NAPS-A was effectively utilized by the gut microbiota, with unchanged properties after digestion but altered after fermentation. It influenced gut microbe composition by increasing beneficial bacteria (Lactobacillus, Faecalibacterium, and Roseburia), lowering pH, and producing short-chain fatty acids. NAPS-A fermentation enriches carbohydrate, fatty acid, and amino acid metabolic pathways through PICRUSt prediction analysis. Overall, these findings emphasize NAPS-A's role in regulating gut bacteria and their metabolic functions, despite its challenging digestibility.

Identification and biotransformation analysis of volatile markers during the early stage of Salmonella contamination in chicken

Salmonella is one of the most prevalent foodborne pathogens in poultry and its products. Its rapid detection based on volatile organic compounds (VOC) has been widely accepted. However, the variation in the VOCs of Salmonella-contaminated chicken during the early stage (48 h) remains uncertain. Headspace-SPME-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace-gas chromatography-ion migration spectroscopy (HS-GC-IMS) were used to identify VOCs and their variations after the chicken meat was contaminated with Salmonella. Chemometric and KEGG enrichment analyses were performed to identify VOC markers and their potential metabolic pathways. A total of 64 volatile compounds were detected using HS-GC-IMS, which showed a better differentiation than HS-SPME-GC-MS (45 volatile compounds) based on principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA). Fatty acid degradation was the main cause of VOC variation. 2-Propanol, hexadecane, 3-methylbutanol, acetic acid, propyl acetate, acetic acid methyl ester, and 3-butenenitrile were identified as VOC markers in the middle stage of decomposition, and 1-octen-3-ol was recognized as a VOC marker of Salmonella-contaminated chicken during the first 48 h of contamination. This provides a theoretical basis for the study of Salmonella contamination VOC markers in poultry meat.

Preparation, Structural Analysis, and Intestinal Probiotic Properties of a Novel Oligosaccharide from Enzymatic Degradation of Huangshui Polysaccharide

Huangshui polysaccharide (HSP) has attracted more and more interest due to its potential health benefits. Despite being an excellent source for the preparation of oligosaccharides, there are currently no relevant research reports on HSP. In the present study, a novel oligosaccharide (HSO) with a molecular weight of 1791 Da and a degree of polymerization of 11 was prepared through enzymatic degradation of crude HSP (cHSP). Methylation and NMR analyses revealed that the main chain of HSO was (1 → 4)-α-d-glucose with two O-6-linked branched chains. Morphological observations indicated that HSO exhibited smooth surface with lamellar and filamentary structure, and the glycan size ranged from 0.03 to 0.20 μm. Notably, HSO significantly promoted the proliferation of Bifidobacterium, Bacteroides, and Phascolarctobacterium, thereby making positive alterations in intestinal microbiota composition. Moreover, HSO markedly increased the content of short-chain fatty acids during in vitro fermentation. Metabolomics analysis illustrated the important metabolic pathways primarily involving glucose metabolism, amino acid metabolism, and fatty acid metabolism.