In Vitro Fermentation of Xylooligosaccharides Produced from Miscanthus × giganteus by Human Fecal Microbiota

Preparation of xylooligosaccharides from rice husks and their structural characterization, antioxidant activity, and probiotic properties

Rice husks are rich in xylan, which can be hydrolyzed by xylanase to form xylooligosaccharides (XOS). XOS are a functional oligosaccharide such as improving gut microbiota and antioxidant properties. In this study, the structure and functional characteristics of XOS were studied. The optimal xylanase hydrolysis conditions through response surface methodology (RSM) were: xylanase dosage of 3000 U/g, hydrolysis time of 3 h, hydrolysis temperature of 50 °C. Under this condition, the yield of XOS was 150.9 mg/g. The TG-DTG curve showed that XOS began to decompose at around 200 °C. When the concentration of XOS reached 1.0 g/L, the clearance rate of DPPH reached 65.76 %, and the scavenging rate of OH reached 62.10 %, while the clearance rate of ABTS free radicals reached 97.70 %, which was equivalent to the clearance rate of VC. XOS had a proliferative effect on four probiotics: Lactobacillus plantarum, Lactobacillus brucelli, Lactobacillus acidophilus, and Lactobacillus rhamnosus. However, the further experiments are needed to explore the improvement effect of XOS on human gut microbiota, laying a foundation for the effective utilization of XOS. XOS have a wide range of sources, low price, and broad development prospects. The reasonable utilization of XOS can bring greater economic benefits.

Influence of chain length on the colonic fermentation of xylooligosaccharides

Xylooligosaccharides (XOS) have been employed as prebiotics containing oligomers of varying sizes or molecular ratios. XOS with a low degree of polymerization (DP) has been demonstrated to have high prebiotic potential. However, there is limited information regarding the specific chain length of XOS required to elicit distinct responses in the gut microbiota. In this study, we aimed to explore whether variations in XOS DP could alter the fate of colonic fermentation. Five XOS fractions (BWXFs) with DP ranges of >40, 20-40, 10-20, 5-10, and 2-4 were prepared by beechwood xylan autohydrolysis and tested on human gut microbiota. Extracellular XOS degradation was observed for molecules with a DP exceeding 5. BWXF treatments altered the microbial community structures, and substrate size-dependent effects on the microbial composition and metabolic outputs were observed. Bacteroidaceae were specifically enriched by xylan. Lachnospiraceae were particularly stimulated by XOS with a DP of 20-40 and 2-4. Bifidobacteriaceae were notably enriched by XOS with a DP of 5-20. High butyrate yields were obtained from cultures containing long-chain BWXFs. Microbiota responses differed with XOS DP composition changes, and microbial competition with XOS with a DP of 2-4 requires further exploration.

Protective Effect of Dietary Polysaccharides from Yellow Passion Fruit Peel on DSS-Induced Colitis in Mice

Inflammatory bowel disease (IBD) is a complex inflammatory disorder characterized by chronic and spontaneously relapsing inflammation of the gastrointestinal tract. IBD includes two idiopathic disorders: Crohn’s disease (CD) and ulcerative colitis (UC). In particular, UC causes inflammation and ulceration of the colon and rectum. There is no cure for UC. The pharmacological treatment is aimed at controlling and/or reducing the inflammatory process and promoting disease remission. The present study investigated the possible protective effects of soluble dietary fiber (SDF) isolated from yellow passion fruit peel in the dextran sulfate sodium- (DSS-) induced colitis model in mice, induced by 5% of DSS. The animals were treated with SDF (10, 30, or 100 mg/kg (po)), and the disease activity index was monitored. Colon tissues were collected, measured, and prepared for oxidative stress, inflammation, and histology analysis. SDF improved body weight loss, colon length, and disease activity index and prevented colonic oxidative stress by regulating GSH levels and SOD activity. Furthermore, SDF reduced colonic MPO activity, TNF-α, and IL-1β levels and increased IL-10 and IL-6 levels. As observed by histological analysis, SDF treatment preserved the colonic tissue, the mucus barrier, and reduced inflammatory cell infiltration. Although this is a preliminary study, taken together, our data indicate that SDF may improve the course of DSS-UC. More studies are needed to explore and understand how SDF promotes this protection.

Preparation and nutritional properties of xylooligosaccharide from agricultural and forestry byproducts: A comprehensive review

Xylooligosaccharide (XOS) are functional oligosaccharides with prebiotic activities, which originate from lignocellulosic biomass and have attracted extensive attention from scholars in recent years. This paper summarizes the strategies used in the production of XOS, and introduces the raw materials, preparation methods, and purification technology of XOS. In addition, the biological characteristics and applications of XOS are also presented. The most commonly recommended XOS production strategy is the two-stage method of alkaline pre-treatment and enzymatic hydrolysis; and further purification by membrane filtration to achieve the high yield of XOS is required for prebiotic function. At the same time, new strategies and technologies such as the hydrothermal and steam explosion have been used as pre-treatment methods combined with enzymatic hydrolysis to prepare XOS. XOS have many critical physiological activities, especially in regulating blood glucose, reducing blood lipid, and improving the structure of host intestinal flora.

Characterization of Saponins from Differently Colored Quinoa Cultivars and Their In Vitro Gastrointestinal Digestion and Fermentation Properties

Quinoa contains rich saponins, which are removed during processing and cause ecological waste. We extracted saponins from quinoa (SEQ) in black, white, and red cultivars and compared their composition by spectrophotometric assay and high-performance liquid chromatography analysis combined with acid hydrolysis. The digestion and fermentation properties of SEQ were investigated using an in vitro model. Our results showed that acid hydrolysis released sapogenins, mainly phytolaccagenin (PA), hederagenin (HD), and oleanolic acid from SEQ. Varying from SEQ in red, SEQ in black and white had a similar composition and content of sapogenins. Gastrointestinal digestion did not release sapogenins from SEQ but reduced the antioxidant activity of SEQ. Gut microbiota from human feces released PA and HD from SEQ. Reciprocally, SEQ in black significantly increased the growth of Lactobacillus spp. and Bifidobacterium spp., while reducing the growth of Shigella spp. The present study provides guidance for further investigation about the bioactivities of saponins from quinoa.

Structural Characterization of Lignin-Carbohydrate Complexes (LCCs) and Their Biotransformation by Intestinal Microbiota In Vitro

Lignin-carbohydrate complexes (LCCs) have recently emerged as natural products with pharmaceutical and nutraceutical potential. Here, we compared the structure of LCCs from ginkgo (GK, gymnosperms), wheat straw (WST, monocotyledons), and aspen white poplar (AW, dicotyledons). We also investigated the biotransformation of LCCs by intestinal microbiota in vitro. We found that human intestinal microbiota could use LCCs as a carbon source for growth, breaking resistant cross-linkages in LCCs to generate a plethora of short-chain fatty acids (SCFAs) and aromatic compounds with putative beneficial effects on human health. The yield of SCFAs reached 1837.8 ± 44.1 μmol/g using AW LCCs as a carbon source. The biomass of intestinal microbiota increased the fastest using GK LCCs. The greatest amounts of phenolics were present at 4 h in a WST LCCs fermentation system. Many phenolic acids with potential bioactivity were obtained after 24 h fermentation using each LCCs, such as ferulic acid.

Comparison of Different Soluble Dietary Fibers during the In Vitro Fermentation Process

Soluble dietary fibers being fermented by gut microbiota constitute a pivotal prerequisite for soluble dietary fibers exhibiting physiological functions. However, the relationship between fiber type and gut microbiota metabolism remains unclear. The purpose of this study was to investigate and compare the effect of fiber types on short-chain fatty acid (SCFA) biosynthesis in a simulated colon. Results showed that different soluble dietary fibers caused distinct metabolic profiles both in SCFAs and organic acids. Further analysis revealed that the SCFA biosynthesis pathway was related to the chain structure of fiber polysaccharides. Moreover, the microbial community structure showed substantial difference among experimental groups. Parabacteroides was substantially elevated in the resistant starch group, while Lactobacillus was the predominant genus in other groups. Correlation analysis further revealed that SCFA biosynthesis was correlated with microbial taxa at different taxonomic levels. Totally, the present study provided an insight into targeted intervention of gut microorganisms for dictating SCFA and organic acid production.

Influence of the heating mechanism during the aqueous processing of vine shoots for the obtaining of hemicellulosic oligosaccharides

This work deals with the revalorization of an important winery residue such as the vine shoots by the obtaining of oligosaccharides with potential prebiotic activity. The manufacture of these added-value products was performed by an autohydrolysis treatment assisted with microwaves to make the process less time consuming and more environmentally friendly. The influence of the reaction time (0-40 min) and the temperature (140-200) on the production of oligosaccharides during the microwave-assisted autohydrolysis was evaluated. The highest concentration of oligosaccharides (168.3 g/Kg oven-dried vines shoots) was achieved during the treatment carried out at 180 °C for 20 min. To assess the benefits of the assistance of the autohydrolysis treatment with the microwaves a conventionally heated treatment was performed using conditions (180 °C for 15 min) that provoked similar effects on the solubilisation of the hemicellulosic fraction. This treatment permitted the obtaining of 203.5 g oligosaccharides/Kg oven-dried vines shoots using 61.0% more of the time needed to carry out the microwaves-assisted autohydrolysis. Although the microwave-assisted treatment permitted the manufacture of a lower amount of oligosaccharides, only consumed 28.8% of the energy needed to perform the conventionally heated treatment. The oligosaccharides manufactured by the two treatments were substituted xyloglucans with different polymerization and acetylation degrees, which due to their potential prebiotic activity could be highly appreciated by pharmaceuticals and food industries. Thus, this work demonstrated the environmental sustainability of the microwave-assisted autohydrolysis for the revalorisation of the vine shoots.

An In Vitro Batch-culture Model to Estimate the Effects of Interventional Regimens on Human Fecal Microbiota

The emerging role of the gut microbiome in several human diseases demands a breakthrough of new tools, techniques and technologies. Such improvements are needed to decipher the utilization of microbiome modulators for human health benefits. However, the large-scale screening and optimization of modulators to validate microbiome modulation and predict related health benefits may be practically difficult due to the need for large number of animals and/or human subjects. To this end, in vitro or ex vivo models can facilitate preliminary screening of microbiome modulators. Herein, it is optimized and demonstrated an ex vivo fecal microbiota culture system that can be used for examining the effects of various interventions of gut microbiome modulators including probiotics, prebiotics and other food ingredients, aside from nutraceuticals and drugs, on the diversity and composition of the human gut microbiota. Inulin, one of the most widely studied prebiotic compounds and microbiome modulators, is used as an example here to examine its effect on the healthy fecal microbiota composition and its metabolic activities, such as fecal pH and the fecal levels of organic acids including lactate and short-chain fatty acids (SCFAs). The protocol may be useful for studies aimed at estimating the effects of different interventions of modulators on fecal microbiota profiles and at predicting their health impacts.

In Vitro Digestion and Fermentation of Three Polysaccharide Fractions from Laminaria japonica and Their Impact on Lipid Metabolism-Associated Human Gut Microbiota

Our previous study has proved that the three polysaccharide fractions from L. japonica (LP-A4, LP-A6, and LP-A8) had significantly different structure characterization. Herein, we conducted in vitro simulated digestion and fermentation to study the digestive mechanism of LP-As. The results of gastrointestinal digestion indicated that LP-A6 and LP-A8 would be easier to trap the enzyme molecules for their denser interconnected macromolecule network compared with LP-A4. Fermentation of LP-As by human gut microbiota, especially for LP-A8, generated a large amount of short-chain fatty acids (SCFAs), which could upregulate the abundance of Firmicutes ( Lachnoclostridium and Eubacterium). The high content of sulfate and highly branched sugar residue of LP-A8 might help it be easily used by Firmicutes in gut microbiota of hyperlipidemic patients. Functional analysis revealed that the increased metabolic activities of glycerophospholipid metabolism, ether lipid metabolism, and fatty acid metabolism induced by LP-A8 treatment were closely associated with metabolic syndromes and hyperlipidemia.

Effects of Non-Starch Polysaccharides on Inflammatory Bowel Disease

The incidence of inflammatory bowel disease (IBD) has increased considerably over the past few decades. In the present review, we discuss several disadvantages existing in the treatment of IBD and current understandings of the structures, sources, and natures of various kinds of non-starch polysaccharides (NSPs). Available evidences for the use of different sources of NSPs in IBD treatment both in vitro and in vivo are analyzed, including glucan from oat bran, mushroom, seaweed, pectin, gum, prebiotics, etc. Their potential mechanisms, especially their related molecular mechanism of protective action in the treatment and prevention of IBD, are also summarized, covering the anti-inflammation, immune-stimulating, and gut microbiota-modulating activities, as well as short-chain fatty acids (SCFAs) production, anti-oxidative stress accompanied with inflammation, the promotion of gastric epithelial cell proliferation and tissue healing, and the reduction of the absorption of toxins of NSPs, thus ameliorating the symptoms and reducing the reoccurrence rate of IBD. In summary, NSPs exhibit the potential to be promising agents for an adjuvant therapy and for the prevention of IBD. Further investigating of the crosstalk between immune cells, epithelial cells, and gut microorganisms in addition to evaluating the effects of different kinds and different molecular weights of NSPs will lead to well-designed clinical intervention trials and eventually improve the treatment and prevention of IBD.

Repeated sub-chronic oral toxicity study of xylooligosaccharides (XOS) in dogs

In this study, Beagle dogs were administered xylooligosaccharide (XOS, CAS # 87099-0) at doses of 0, 1250, 2500, and 5000 mg/kg/day by oral gavage for 26 weeks. A 4-week recovery period was added to observe delayed or reversible toxicity. Measurements included body weight, food consumption, clinical observations, temperature, electrocardiogram (ECG), urinalysis, blood chemistry, hematology, organ weight, gross necropsy, and histopathological examination. Except for transient diarrhea or vomiting, no treatment-related adverse effects were noted. In the mid-dose groups, transitional diarrhea was observed in the initial 1-2 weeks. In the high-dose groups, diarrhea and/or vomiting were observed episodically over the duration of treatment. However, they disappeared after XOS was withdrawn in the recovery period. Although there was a tendency toward less weight gain in the high-dose group animal group, this is typical in animals and humans fed non-digestible carbohydrates. This chronic toxicity study demonstrated that the no observed adverse effect level (NOAEL) of XOS is 2500 mg/kg body weight (BW)/day. Based on body surface area (conversion factor of 0.54 for dogs to human), this corresponds to daily doses of 1350 mg/kg BW or 81-108 g XOS in human adults weighing 60-80 kg.

Structural Characterization and in Vitro Fermentation of β-Mannooligosaccharides Produced from Locust Bean Gum by GH-26 endo-β-1,4-Mannanase (ManB-1601)

Size exclusion chromatography of β-mannooligosaccharides (β-MOS) mixtures, obtained from ManB-1601 hydrolysis of locust bean gum, resulted in separation of oligosaccharides with various degrees of polymerization (DP 2, 3, and 5). The oligosaccharides were structurally [ESI-MS, FTIR, XRD, TGA, and NMR (¹H and ¹³C)] and functionally (in vitro fermentation) characterized. DP2 oligosaccharide was composed of two species, (A) mannopyranose β-1,4 mannopyranose and (B) α-1,6-galactosyl-mannopyranose, while DP3 oligosaccharide showed the presence of only one species, i.e. α-d-galactosyl-β-d-mannobiose. ManB-1601 was capable of cleaving near the branch points in the substrate, resulting in oligosaccharides with galactose at the terminal position apart from attacking unsubstituted β-1,4-glycosidic linkages. DP2 and DP3 improved the growth of three out of seven species of Lactobacillus while DP5 resulted in poor growth of all Lactobacillus spp. under in vitro conditions. DP2, DP3, and DP5 were found to inhibit the growth of Escherichia coli, Listeria monocytogenes and Salmonella typhi.