Interaction between Bacteroidetes species in the fermentation of Lycium barbarum arabinogalactan

In vitro effects of structurally diverse low molecular weight chondroitin sulfates on gut microbiota and metabolome

In this study, low molecular weight chondroitin sulfates (LMCSs) with different structures, named LMCSO, LMCSD, and LMCSH, were prepared by oxidative degradation, deamidation cleavage, and hydrothermal depolymerization, respectively. In vitro fermentation modeling was used to study the effects of CS and LMCSs on gut microbiota and metabolite composition. The degree of carbohydrate metabolism was in the order of CS > LMCSH > LMCSO > LMCSD. Significantly, GlcA in chondroitin-6-sulfate (CSC) was more readily utilized by gut microbiota during fermentation, and this trend was more pronounced in LMCSs. The LMCSs group notably increased microbial richness and evenness, especially in the LMCSD group. Bacteroides fragilis was identified as a potential primary degrader of CS and LMCSs through species-level analysis. The abundance of Escherichia-Shigella was reduced by LMCSs, and short-chain fatty acids production was enhanced, particularly by LMCSO, while the production of beneficial metabolites such as N-acetyl-D-Glucosamine 6-Phosphate (GlcNAc-6P), lactate, and progesterone was stimulated. Among these, the metabolism of the key metabolite GlcNAc-6P was significantly and positively correlated with the abundance of Bacteroides, Clostridium_sensu_stricto_1, and Parabacteroides. Exploring the mechanisms by which gut microbiota metabolize LMCSs with different structures can provide theoretical support for the targeted preparation of LMCSs that modulate the gut microbiota.

Comparison of different longan polysaccharides during gut Bacteroides fermentation

The bioactivity of polysaccharide was closely related to its fermentation utilization by gut Bacteroides, and its utilization degree was determined by various gut Bacteroides species and different polysaccharides characteristics. The effects of longan polysaccharide (LP) and LP treated by ultrasonic-assisted hydrogen peroxide for 8 h (DLP-8) on gut Bacteroides growth, and their fermentation utilization were compared. The results of LP and DLP-8 on the proliferation of six Bacteroides species showed that Bacteroides uniformis had the highest proliferation index. In fermentation by B. uniformis, DLP-8 (with a lower molecular weight), the viable count of which was higher than that of LP, was degraded more and especially utilized more glucose and glucuronic acid. The microstructure of the two polysaccharides changed differently during fermentation. Moreover, DLP-8 promoted greater short-chain fatty acids production than LP. These results indicated that the fermentation properties of DLP-8 by B. uniformis were superior to those of LP.

Photoelectrocatalytic degradation of hyaluronic acid and regulation effects of its degradation products on gut microbiota in vitro

Hyaluronic acid (HA) has multiple biological activities which are closely related to its molecular weight. In the present study, the photoelectrocatalytic method was established for HA degradation and the influences of bias potentials, H2O2 additions and reaction times on the degradation results were investigated to optimize the reaction condition. Moreover, a series of analysis methods, such as FT-IR and NMR were used to analyze chemical compositions of the degradation products, revealing that photoelectrocatalytic degradation did not damage the structural blocks of HA obviously. Then 11 oligosaccharides with polymerization degrees from 2 to 8 in the degradation products were identified by mass spectroscopy and their reducing ends were all GlcA or AraA. In addition, in the photoelectrocatalytic degradation of HA, ·OH were identified as the most influential among the produced free radicals, and it could be proposed that ·OH specifically targeted the anomeric carbon of GlcA, resulting in the disaggregation of polysaccharides chain. Furthermore, the results of in vitro fermentation with fecal microbiota demonstrated that HA and its degradation products regulated microbiota structure discriminately, indicating their possible different outcomes as nutritional supplements and agents.

Metagenomic and transcriptomic profiling of the hypoglycemic and hypotriglyceridemic actions of Tremella fuciformis-derived polysaccharides in high-fat-diet- and streptozotocin-treated mice

Mushroom polysaccharides have great anti-diabetes potential. The fruiting body of Tremella fuciformis is rich in polysaccharides. However, few studies have been performed to date on T. fuciformis-derived polysaccharides (TPs) in terms of anti-diabetes potential. Our previous studies showed that novel TPs with medium molecular weights exhibited the highest anti-skin aging activities among the tested samples in D-galactose-treated mice. In the present study, the effects of these novel TPs, named TP, on high-fat-diet- and streptozotocin-treated mice were assessed, and their potential biological mechanisms were explored by metagenomic and transcriptomic analyses. Oral administration of TP markedly reduced blood glucose and TG levels, alleviated emaciation, improved anti-oxidant capacity, and protected the functions of β-cells at a dose of 100 mg kg-1 in diabetic mice. Meanwhile, the taxonomic compositions and functional properties of fecal microbiota were altered considerably by TP, as evidenced by partial restoration of the imbalanced gut microbiota and the higher abundances of Bacteroides, Phocaeicola, Bifidobacterium, and Alistipes compared to the model mice, corresponding to the upregulation of four enriched KEGG pathways of microbial communities such as the digestive system, cardiovascular disease, parasitic infectious disease, and cell growth and death. Further transcriptomic analysis of liver tissues identified 35 enriched KEGG pathways associated with metabolism and cellular signaling processes in response to TP. These results demonstrated the biological mechanisms underlying the hypoglycemic and hypotriglyceridemic activities of TP. The findings expanded our understanding of the anti-diabetic mechanisms for mushroom polysaccharides and provided new clues for future studies.

Recent advances in wolfberry polysaccharides and whey protein-based biopolymers for regulating the diversity of gut microbiota and its mechanism: A review

Imbalances in gut microbiota diversity are associated with various health issues, including obesity and related disorders. There is a growing interest in developing synergistic biopolymers based on wolfberry polysaccharides and whey protein to address these problems due to their potential health benefits. This review explores recent advances in understanding how functional foods based on Lycium barbarum polysaccharides (LBP) and whey protein (WP) influence gut microbiota diversity and their underlying mechanisms. We examine the impact of these biopolymers on microbial composition and functionality, focusing on their roles in improving health by regulating gut microbiota. The combined effects of WP and LBP significantly enhance gut microbiome metabolic activities and taxonomic diversity, offering promising avenues for treating obesity and related disorders.

Modulation of gut microbiota and metabolites by Flammulina velutipes polysaccharides during in vitro human fecal fermentation: Unveiling Bacteroides as a potential primary degrader

Flammulina velutipes, a widely cultivated species of edible fungus, exhibits diverse functional activities attributed to its polysaccharides. In this study, we employed an in vitro model to investigate the impact of F. velutipes polysaccharides (FVP) fermentation on gut microbiota, with a particular focus on Bacteroides. FVP fermentation resulted in the proliferation of microbiota associated with short-chain fatty acid (SCFA) metabolism and suppression of Escherichia-Shigella. Bacteroides emerged as potential primary degraders of FVP, with species-level analysis identifying the preference of B. thetaiotaomicron and B. intestinalis in FVP degradation. Metabolomics analysis revealed significant increases in hypoxanthine and 7-methyladenine contents, with histidine metabolism emerging as the most enriched pathway. B. nordii and B. xylanisolvens exhibited the most influence on amino acid and SCFA metabolism. Understanding the mechanisms by which gut microbiota metabolize FVP can provide valuable insights into the potential of FVP to promote intestinal health and disease prevention.

Simultaneously efficient dissolution and structural modification of chrysanthemum pectin: Targeting at proliferation of Bacteroides

Pectic polysaccharide is a bioactive ingredient in Chrysanthemum morifolium Ramat. 'Hangbaiju' (CMH), but the high proportion of HG domain limited its use as a prebiotic. In this study, hot water, cellulase-assisted, medium-temperature alkali, and deep eutectic solvent extraction strategies were firstly used to extract pectin from CMH (CMHP). CMHP obtained by cellulase-assisted extraction had high purity and strong ability to promote the proliferation of Bacteroides and mixed probiotics. However, 4 extraction strategies led to general high proportion of HG domain in CMHPs. To further enhance the dissolution and prebiotic potential of CMHP, pectinase was used alone and combined with cellulase. The key factor for the optimal extraction was enzymolysis by cellulase and pectinase in a mass ratio of 3:1 at 1 % (w/w) dosage. The optimal CMHP had high yield (15.15 %), high content of total sugar, and Bacteroides proliferative activity superior to inulin, which was probably due to the cooperation of complex enzyme on the destruction of cell wall and pectin structural modification for raised RG-I domain (80.30 %) with relatively high degree of branching and moderate HG domain. This study provided a green strategy for extraction of RG-I enriched prebiotic pectin from plants.