Dietary fiber chemical structure determined gut microbiota dynamics

Duck gut metagenome reveals the microbiome signatures linked to intestinal regional, temporal development, and rearing condition

The duck gastrointestinal tract (GIT) harbors an abundance of microorganisms that play an important role in duck health and production. Here, we constructed the first relatively comprehensive duck gut microbial gene catalog (24 million genes) and 4437 metagenome-assembled genomes using 375 GIT metagenomic samples from four different duck breeds across five intestinal segments under two distinct rearing conditions. We further characterized the intestinal region-specific microbial taxonomy and their assigned functions, as well as the temporal development and maturation of the duck gut microbiome. Our metagenomic analysis revealed the similarity within the microbiota of the foregut and hindgut compartments, but distinctive taxonomic and functional differences between distinct intestinal segments. In addition, we found a significant shift in the microbiota composition of newly hatched ducks (3 days), followed by increased diversity and enhanced stability across growth stages (14, 42, and 70 days), indicating that the intestinal microbiota develops into a relatively mature and stable community as the host duck matures. Comparing the impact of different rearing conditions (with and without water) on duck cecal microbiota communities and functions, we found that the bacterial capacity for lipopolysaccharide biosynthesis was significantly increased in ducks that had free access to water, leading to the accumulation of pathogenic bacteria and antibiotic-resistance genes. Taken together, our findings expand the understanding of the microbiome signatures linked to intestinal regional, temporal development, and rearing conditions in ducks, which highlight the significant impact of microbiota on poultry health and production.

Efficient removal of allicin from the stalk of Allium fistulosum for dietary fiber production

The stalk of Allium fistulosum contains dietary fibers with complicated monosaccharide composition and glycosidic bond linkages, which renders it a better dietary fiber supplement. However, the unfavorable odor, majorly contributed by allicin, limits its applications. Although many physical and chemical methods have been developed to remove allicin, there is currently no comparison between their efficiencies. Here, we comprehensively compare all these methods of eliminating allicin in the Allium stalk by starting with optimization of the allicin extraction method. Results indicate that incubation of the chopped Allium stalk with water for 20 min and extraction with 75% ethanol reached a maximal extraction yield. Different methods of allicin elimination are examined, and physical removal of allicin by blanching at 100 °C reaches a maximal clearance rate of 73.3%, rendering it the most efficient and effective method eliminating allicin from the stalk of Allium fistulosum for the preparation of a totally green dietary fiber.

Prebiotic Systems Containing Anthocyanin-Rich Pomegranate Flower Extracts with Antioxidant and Antidiabetic Effects

Pomegranate flower extract, rich in anthocyanins, demonstrates beneficial health-promoting properties such as an anti-diabetic and antioxidant effect, among others. However, the potential health-promoting properties may be hindered by the low stability of anthocyanins. Therefore, the aim of our study was to assess whether stabilizing carriers, namely HP-γ-cyclodextrin (HP-γ-CD), α-cyclodextrin (α-CD), Methyl-β-cyclodextrin (Me-β-CD), Inulin (Inu) and Arabic gum (AGu) affect the antioxidant and antidiabetic activity of lyophilized pomegranate flower extract, how they influence stability, release profile, and whether the systems exhibit prebiotic activity. Interactions between pomegranate flower extract and these factors were analyzed using FT-IR. The structures were examined through microscopic imaging while for the prepared prebiotic systems, antidiabetic activity was determined and confirmed by the inhibition of α-amylase and α-glucosidase; antioxidant activity was expressed by DPPH and CUPRAC assays. The content of pelargonidin-3,5-glucoside in these systems was assessed using the HPLC method. The release profiles of pelargonidin-3,5-glucoside were examined in a medium at pH = 6.8 and pH = 1.2, and the stability was assessed after subjecting the systems to high temperatures (T = 90 °C). The prebiotic potential was evaluated for 10 prebiotic bacterial strains (Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus brevis Lactobacillus rhamnosus gg, Lactobacillus reuteri, Pediococcus pentosaceus, Lactococcus lactis, Lactobacillus fermentum lf, Streptococcus thermophilus). As a result of the conducted research, better functionalities of the obtained systems containing Pomegranate flower extract were proven in terms of prebiotic and antidiabetic effects. The obtained delivery systems for pelargonidin-3,5-glucoside allow for better use of its health-promoting effects.

Isolation and structural elucidation of prebiotic oligosaccharides from Ziziphi Spinosae Semen

Six oligosaccharides were discovered and isolated for the first time from Ziziphi Spinosae Semen. On the basis of spectroscopic analysis, their structures were determined to be verbascose (1), verbascotetraose (2), stachyose (3), manninotriose (4), raffinose (5), and melibiose (6). The prebiotic effect of the oligosaccharide fraction was assayed by eight gut bacterial growth in vitro, revealing a significant increase in cell density, up to 4-fold, for Lactobacillus acidophilus, Lactobacillus gasseri, and Lactobacillus johnsonii. The impact of six oligosaccharides with different degrees of polymerization (DPs) and structures on the growth of Lactobacillus acidophilus was evaluated. As a result, stachyose and raffinose demonstrated superior support for bacterial growth compared to the other oligosaccharides. This study explored the structure-activity relationship of raffinose family oligosaccharides (RFOs) and showed that the more the monosaccharide type, the more supportive the gut bacteria growth when oligosaccharides have the same molecular weight.

Gut microbiota-derived short chain fatty acids act as mediators of the gut-brain axis targeting age-related neurodegenerative disorders: a narrative review

Neurodegenerative diseases associated with aging are often accompanied by cognitive decline and gut microbiota disorder. But the impact of gut microbiota on these cognitive disturbances remains incompletely understood. Short chain fatty acids (SCFAs) are major metabolites produced by gut microbiota during the digestion of dietary fiber, serving as an energy source for gut epithelial cells and/or circulating to other organs, such as the liver and brain, through the bloodstream. SCFAs have been shown to cross the blood-brain barrier and played crucial roles in brain metabolism, with potential implications in mediating Alzheimer's disease (AD) and Parkinson's disease (PD). However, the underlying mechanisms that SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, the dietary sources which determine these SCFAs production was not thoroughly evaluated yet. This comprehensive review explores the production of SCFAs by gut microbiota, their transportation through the gut-brain axis, and the potential mechanisms by which they influence age-related neurodegenerative disorders. Also, the review discusses the importance of dietary fiber sources and the challenges associated with harnessing dietary-derived SCFAs as promoters of neurological health in elderly individuals. Overall, this study suggests that gut microbiota-derived SCFAs and/or dietary fibers hold promise as potential targets and strategies for addressing age-related neurodegenerative disorders.

Carrot RG-I Reduces Interindividual Differences between 24 Adults through Consistent Effects on Gut Microbiota Composition and Function Ex Vivo

The human gut microbiota is characterized by large interpersonal differences, which are not only linked to health and disease but also determine the outcome of nutritional interventions. In line with the growing interest for developing targeted gut microbiota modulators, the selectivity of a carrot-derived rhamnogalacturonan I (cRG-I) was compared to substrates with demonstrated low (inulin, IN) and high selectivity (xanthan, XA), at a human equivalent dose (HED) of 1.5 g/d. The high throughput of the ex vivo SIFR^® technology, validated to generate predictive insights for clinical findings, enabled the inclusion of 24 human adults. Such an unprecedented high number of samples in the context of in vitro gut microbiota modelling allowed a coverage of clinically relevant interpersonal differences in gut microbiota composition and function. A key finding was that cRG-I supplementation (already at an HED of 0.3 g/d) lowered interpersonal compositional differences due to the selective stimulation of taxa that were consistently present among human adults, including OTUs related to Bacteroides dorei/vulgatus and Bifidobacterium longum (suspected keystone species), Bacteroides thetaiotaomicron, Bifidobacterium adolescentis and butyrate-producing taxa such as Blautia sp., Anaerobutyricum hallii, and Faecalibacterium prausnitzii. In contrast, both IN and XA treatments increased interpersonal compositional differences. For IN, this followed from its low specificity. For XA, it was rather the extremely high selectivity of XA fermentation that caused large differences between 15 responders and 9 nonresponders, caused by the presence/absence of highly specific XA-fermenting taxa. While all test compounds significantly enhanced acetate, propionate, butyrate, and gas production, cRG-I resulted in a significantly higher acetate (+40%), propionate (+22%), yet a lower gas production (-44%) compared to IN. cRG-I could thus result in overall more robust beneficial effects, while also being better tolerated. Moreover, owing to its remarkable homogenization effect on microbial composition and metabolite production, cRG-I could lead to more predictable outcomes compared to substrates that are less specific or overly specific.