Non-digestible Oligosaccharides with Prebiotic Properties

Galactooligosaccharides: Synthesis, metabolism, bioactivities and food applications

Prebiotics are non-digestible ingredients that exert significant health-promoting effects on hosts. Galactooligosaccharides (GOS) have remarkable prebiotic effects and structural similarity to human milk oligosaccharides. They generally comprise two to eight sugar units, including galactose and glucose, which are synthesized from substrate lactose by microbial β-galactosidase. Enzyme sources from probiotics have received particular interest because of their safety and potential to synthesize specific structures that are particularly metabolized by intestinal probiotics. Owing to advancements in modern analytical techniques, many GOS structures have been identified, which vary in degree of polymerization, glycosidic linkage, and branch location. After intake, GOS adjust gut microbiota which produce short chain fatty acids, and exhibit excellent biological activities. They selectively stimulate the proliferation of probiotics, inhibit the growth and adhesion of pathogenic bacteria, alleviate gastrointestinal, neurological, metabolic and allergic diseases, modulate metabolites production, and adjust ion storage and absorption. Additionally, GOS are safe and stable, with high solubility and clean taste, and thus are widely used as food additives. GOS can improve the appearance, flavor, taste, texture, viscosity, rheological properties, shelf life, and health benefits of food products. This review systemically covers GOS synthesis, structure identifications, metabolism mechanisms, prebiotic bioactivities and wide applications, focusing on recent advances.

Xylooligosaccharides from lignocellulosic biomass and their applications as nutraceuticals: a review on their production, purification, and characterization

Xylooligosaccharides (XOS) are considered a potent source of prebiotics for humans. The global prebiotic market is expanding in size, was valued at USD 6.05 billion in 2021, and is expected to grow at a 14.9% compound annual growth rate between 2022 and 2030, indicating a huge demand. These XOS are non-digestible pentose sugar oligomers comprising mainly xylose. Xylose is naturally present in the lignocellulosic biomass (LCB), fruits and vegetables. Apart from the prebiotic effect, these XOS have been reported to reduce blood cholesterol, possess antioxidant effects, increase calcium absorption, reduce colon cancer risk, and benefit diabetic patients. The primary use of XOS is reported in the feed industry followed by health, medical use, food and drinks. LCB mainly contains glucan, xylan and lignin. After glucan, xylan is the second-highest available sugar on the globe composed of xylose. Therefore, the xylan fraction of LCB has great significance in producing food, feed and energy. Glucan has been exploited for the commercial production of ethanol, xylitol, furfural, hydroxymethyl furfural and glucose. As of now, xylan has limited applications. Therefore, xylan can be exploited to convert to XOS. The production of XOS from LCB fraction not only helps to produce these at a very low price, but also helps in the reduction of greenhouse gases. Its use in food and drinks is increasing as it can be derived from the abundantly and cheaply available LCB. The article provides a review on the production, purification and characterization of XOS in view of their use as nutraceuticals. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Prebiotic Strategies to Manage Lactose Intolerance Symptoms

Lactose intolerance, which affects about 65-75% of the world's population, is caused by a genetic post-weaning deficiency of lactase, the enzyme required to digest the milk sugar lactose, called lactase non-persistence. Symptoms of lactose intolerance include abdominal pain, bloating and diarrhea. Genetic variations, namely lactase persistence, allow some individuals to metabolize lactose effectively post-weaning, a trait thought to be an evolutionary adaptation to dairy consumption. Although lactase non-persistence cannot be altered by diet, prebiotic strategies, including the consumption of galactooligosaccharides (GOSs) and possibly low levels of lactose itself, may shift the microbiome and mitigate symptoms of lactose consumption. This review discusses the etiology of lactose intolerance and the efficacy of prebiotic approaches like GOSs and low-dose lactose in symptom management.

Production of β-mannanase, inulinase, and oligosaccharides from coffee wastes and extracts

This study aimed to produce enzymes (beta (β)-mannanase using a recombinant Aspergillus sojae AsT3 and inulinase using Aspergillus niger A42) and oligosaccharides (mannooligosaccharides (MOS), fructooligosaccharides (FOS)) using coffee waste, ground coffee, and coffee extract by solid-state fermentation (SSF). Plackett-Burman Design (PBD) was used to create a design for enzyme production with four different parameters (temperature, pH, solid-to-liquid ratio (SLR), and mix with coffee wastes and ground coffee). The highest β-mannanase and inulinase activities were 71.17 and 564.07 U/mg of protein respectively. Statistical analysis showed that the temperature was statistically significant for the production of both enzymes (P < 0.05). The produced enzymes were utilized in French Pressed coffee extracts to produce oligosaccharides. As a result of the enzymatic hydrolyzation, the highest mannobiose, mannotriose, mannotetraose, and total MOS levels were 109.66, 101.11, 391.02, and 600.64 ppm, respectively. For the FOS production, the maximal 1,1,1-kestopentaose was 38.34 ppm. Consequently, this study demonstrates that a recombinant Aspergillus sojae AsT3 β-mannanase and Aspergillus niger A42 inulinase produced from coffee wastes and ground coffee can be used in coffee extracts to increase the amount of oligosaccharides in coffee extracts.

Exploring β-glucan as a micro-nano system for oral delivery targeted the colon

The critical role of oral colon-specific delivery systems (OCDDS) is important for delivering active agents to the colon and rectum specifically via the oral route. The use of micro/nanostructured OCDDS further improves drug stability, bioavailability, and retention time, leading to enhanced therapeutic effects. However, designing micro/nanoscale OCDDSs is challenging due to pH changes, enzymatic degradation, and systemic absorption and metabolism. Biodegradable natural polysaccharides are a promising solution to these problems, and β-glucan is one of the most promising natural polysaccharides due to its unique structural features, conformational flexibility, and specific processing properties. This review covers the diverse chemical structures of β-glucan, its benefits (biocompatibility, easy modification, and colon-specific degradation), and various β-glucan-based micro/nanosized OCDDSs, as well as their drawbacks. The potential of β-glucan offers exciting new opportunities for colon-specific drug delivery.

Gut firmicutes: Relationship with dietary fiber and role in host homeostasis

Firmicutes and Bacteroidetes are the predominant bacterial phyla colonizing the healthy human gut. Accumulating evidence suggests that dietary fiber plays a crucial role in host health, yet most studies have focused on how the dietary fiber affects health through gut Bacteroides. More recently, gut Firmicutes have been found to possess many genes responsible for fermenting dietary fiber, and could also interact with the intestinal mucosa and thereby contribute to homeostasis. Consequently, the relationship between dietary fiber and Firmicutes is of interest, as well as the role of Firmicutes in host health. In this review, we summarize the current knowledge regarding the molecular mechanism of dietary fiber degradation by gut Firmicutes and explain the communication pathway of the dietary fiber-Firmicutes-host axis, and the beneficial effects of dietary fiber-induced Firmicutes and their metabolites on health. A better understanding of the dialogue sustained by the dietary fiber-Firmicutes axis and the host could provide new insights into probiotic therapy and novel dietary interventions aimed at increasing the abundance of Firmicutes (such as Faecalibacterium, Lactobacillus, and Roseburia) to promote health.

Dietary Supplementation of Microbial Dextran and Inulin Exerts Hypocholesterolemic Effects and Modulates Gut Microbiota in BALB/c Mice Models

Microbial exopolysaccharides (EPSs), having great structural diversity, have gained tremendous interest for their prebiotic effects. In the present study, mice models were used to investigate if microbial dextran and inulin-type EPSs could also play role in the modulation of microbiomics and metabolomics by improving certain biochemical parameters, such as blood cholesterol and glucose levels and weight gain. Feeding the mice for 21 days on EPS-supplemented feed resulted in only 7.6 ± 0.8% weight gain in the inulin-fed mice group, while the dextran-fed group also showed a low weight gain trend as compared to the control group. Blood glucose levels of the dextran- and inulin-fed groups did not change significantly in comparison with the control where it increased by 22 ± 5%. Moreover, the dextran and inulin exerted pronounced hypocholesterolemic effects by reducing the serum cholesterol levels by 23% and 13%, respectively. The control group was found to be mainly populated with Enterococcus faecalis, Staphylococcus gallinarum, Mammaliicoccus lentus and Klebsiella aerogenes. The colonization of E. faecalis was inhibited by 59–65% while the intestinal release of Escherichia fergusonii was increased by 85–95% in the EPS-supplemented groups, respectively, along with the complete inhibition of growth of other enteropathogens. Additionally, higher populations of lactic acid bacteria were detected in the intestine of EPS-fed mice as compared to controls.

β-Glucan attenuates cognitive impairment of APP/PS1 mice via regulating intestinal flora and its metabolites

BACKGROUND

The intestinal flora has been shown to be involved in the progression of Alzheimer's disease (AD) and can be improved by β-glucan, a polysaccharide derived from Saccharomyces cerevisiae, which affects cognitive function through the intestinal flora. However, it is not known if this effect of β-glucan is involved in AD.

METHOD

This study used behavioral testing to measure cognitive function. After that, high-throughput 16 S rRNA gene sequencing and GC-MS were used to analyze the intestinal microbiota and metabolite SCFAs of AD model mice, and further explore the relationship between intestinal flora and neuroinflammation. Finally, the expressions of inflammatory factors in the mouse brain were detected by Western blot and Elisa methods.

RESULTS

We found that appropriate supplementation of β-glucan during the progression of AD can improve cognitive impairment and reduce A β plaque deposition. In addition, supplementation of β-glucan can also promote changes in the composition of the intestinal flora, thereby changing the flora metabolites in the intestinal content and reduce the activation of inflammatory factors and microglia in the cerebral cortex and hippocampus through the brain-gut axis. While reducing the expression of inflammatory factors in the hippocampus and cerebral cortex, thereby controlling neuroinflammation.

CONCLUSION

The imbalance of the gut microbiota and metabolites plays a role in the progression of AD; β-glucan blocks the development of AD by improving the gut microbiota and its metabolites and reducing neuroinflammation. β-Glucan is a potential strategy for the treatment of AD by reshaping the gut microbiota and improving its metabolites.

Coffee by-products: An underexplored source of prebiotic ingredients

Consumers' demand for foods with high nutritional value and health benefits has fueled the development of prebiotic foods. In coffee industry, cherries transformation into roasted beans generates a large amount of waste/by-products (pulp/husks, mucilage, parchment, defective beans, silverskin and spent coffee grounds) that usually end up in landfills. The possibility to use coffee by-products as relevant sources of prebiotic ingredients is herein ascertained. As a prelude to this discussion, an overview of pertinent literature on prebiotic action was conducted, including on biotransformation of prebiotics, gut microbiota, and metabolites. Existing research indicates that coffee by-products contain significant levels of dietary fiber and other components that can improve gut health by stimulating beneficial bacteria in the colon, making them excellent candidates for prebiotic ingredients. Oligosaccharides from coffee by-products have lower digestibility than inulin and can be fermented by gut microbiota into functional metabolites, such as short-chain fatty acids. Depending on the concentration, melanoidins and chlorogenic acids may also have prebiotic action. Nevertheless, there is still a lack of in vivo studies to validate such findings in vitro. This review shows how coffee by-products can be interesting for the development of functional foods, contributing to sustainability, circular economy, food security, and health.

UPLC-Q-TOF-MS and UPLC-QQQ-MS were used for the qualitative and quantitative analysis of oligosaccharides in Fufang Ejiao Syrup

Fufang Ejiao Syrup (FES) is a syrup made from Colla Corii Asini (CCA) and four botanicals (Codonopsis Radix (CR), Ginseng Radix et Rhizoma Rubra (GRRR), Rehmanniae Radix Praeparata (RRP) and Crataegi Fructus (CF)) as a result of modern processing and refining technology. FES has a lengthy history and is frequently used in clinical practice. Modern pharmacological studies have confirmed that oligosaccharides in any of the main medicinal herbs of FES, such as CR, GRRR, and RRP, have significant immune-enhancing effects. Therefore, the oligosaccharide component in FES could be its important pharmacologic substance, however, no studies on the content, structural analysis and source attribution of oligosaccharides in FES have been reported. The objective of this study is to systematically analyze the oligosaccharide in FES, compare the differences of the major oligosaccharides in different batches of FES produced by one manufacturer, and construct the content determination method for determining the content of the major oligosaccharides in FES, to provide technical support for FES quality assessment. This analysis revealed that a total of 13 oligosaccharides were identified from the FES, including 3 disaccharides, 4 trisaccharides, 3 tetrasaccharides, and 3 pentasaccharides. The constructed UPLC-QQQ-MS fingerprint of FES oligosaccharide is simple, stable, and reproducible, making it a useful tool for assessing FES's quality. There was a significant difference between the oligosaccharide fingerprints of 16 batches of FES,the results of fingerprint analysis combined with the statistical analysis suggested that the differences in stachyose, sucrose and raffinose contents in FES may be the reason for the great variations in oligosaccharide fingerprints of different batches of FES. For the 5 oligosaccharides in FES, the UPLC-QQQ-MS technique showed significant linearity in the linear range, along with good stability, repeatability, and recovery. Mannotriose was found to be higher in FES, followed by sucrose and stachyose, while kestose and raffinose were relatively lower. The results of this study reveal that oligosaccharides are important components of FES, and the method of fingerprinting and content determination constructed has strong practical value and is expected to be used for FES quality control.

Antibiotics in avian care and husbandry-status and alternative antimicrobials

Undoubtedly, the discovery of antibiotics was one of the greatest milestones in the treatment of human and animal diseases. Due to their over-use mainly as antibiotic growth promoters (AGP) in livestock farming, antimicrobial resistance has been reported with increasing intensity, especially in the last decades. In order to reduce the scale of this phenomenon, initially in the Scandinavian countries and then throughout the entire European Union, a total ban on the use of AGP was introduced, moreover, a significant limitation in the use of these feed additives is now observed almost all over the world. The withdrawal of AGP from widespread use has prompted investigators to search for alternative strategies to maintain and stabilize the composition of the gut microbiota. These strategies include substances that are used in an attempt to stimulate the growth and activity of symbiotic bacteria living in the digestive tract of animals, as well as living microorganisms capable of colonizing the host’s gastrointestinal tract, which can positively affect the composition of the intestinal microbiota by exerting a number of pro-health effects, i.e., prebiotics and probiotics, respectively. In this review we also focused on plants/herbs derived products that are collectively known as phytobiotic.

Direct Action of Non-Digestible Oligosaccharides against a Leaky Gut

The epithelial monolayer is the primary determinant of mucosal barrier function, and tight junction (TJ) complexes seal the paracellular space between the adjacent epithelial cells and represent the main "gate-keepers" of the paracellular route. Impaired TJ functionality results in increased permeation of the "pro-inflammatory" luminal contents to the circulation that induces local and systemic inflammatory and immune responses, ultimately triggering and/or perpetuating (chronic) systemic inflammatory disorders. Increased gut leakiness is associated with intestinal and systemic disease states such as inflammatory bowel disease and neurodegenerative diseases such as Parkinson's disease. Modulation of TJ dynamics is an appealing strategy aiming at inflammatory conditions associated with compromised intestinal epithelial function. Recently there has been a growing interest in nutraceuticals, particularly in non-digestible oligosaccharides (NDOs). NDOs confer innumerable health benefits via microbiome-shaping and gut microbiota-related immune responses, including enhancement of epithelial barrier integrity. Emerging evidence supports that NDOs also exert health-beneficial effects on microbiota independently via direct interactions with intestinal epithelial and immune cells. Among these valuable features, NDOs promote barrier function by directly regulating TJs via AMPK-, PKC-, MAPK-, and TLR-associated pathways. This review provides a comprehensive overview of the epithelial barrier-protective effects of different NDOs with a special focus on their microbiota-independent modulation of TJs.

Production of Xylooligosaccharide from Cassava Pulp’s Waste by Endo-β-1,4-D-Xylanase and Characterization of Its Prebiotic Effect by Fermentation of Lactobacillus acidophilus

This study explores the production of prebiotic xylooligosaccharide (XOS) from cassava pulp waste and its effectiveness for the growth of Lactobacillus acidophilus (L. acidophilus). We successfully produced and characterized XOS from cassava pulp xylan using a Bacillus sp. endo-β-1,4-D-xylanase. The XOS was added to modify the MRS medium (MRSm) in various concentrations (0, 1, 3 and 5%) in which the L. acidophilus was inoculated. The growth of L. acidophilus was observed every 12 h for 2 days, and the fermentation products were analyzed for pH, sugar content, and short-chain fatty acids (SCFA) in terms of types and amount. The study showed that L. acidophilus grew well in MRSm. The optimum XOS concentration in MRSm was 5%, indicated by the highest growth of L. acidophilus (8.61 log CFU mL−1). The profile of SCFA products is 14.42 mM acetic acid, 0.25 mM propionic acid, 0.13 mM isobutyric acid, 0.41 mM n-butyric acid, 0.02 mM n-valeric acid, 0.25 mM isovaleric acid, and 25.08 mM lactic acid.

Engineering the β-Fructofuranosidase Fru6 with Promoted Transfructosylating Capacity for Fructooligosaccharide Production

Levan-type fructooligosaccharides (FOS) exhibit enhanced health-promoting prebiotic effects on gut microbiota. The wild type (WT) of β-fructofuranosidase Fru6 could mainly yield 6-ketose. Semirational design and mutagenesis of Fru6 were exploited to promote the transfructosylating capacity for FOS. The promising variants not only improved the formation of 6-kestose but also newly produced tetrasaccharides of 6,6-nystose and 1,6-nystose (a new type of FOS), and combinatorial mutation boosted the production of 6-kestose and tetrasaccharides (39.9 g/L 6,6-nystose and 4.6 g/L 1,6-nystose). Molecular docking and molecular dynamics (MD) simulation confirmed that the mutated positions reshaped the pocket of Fru6 to accommodate bulky 6-kestose in a reactive conformation with better accessibility for tetrasaccharides formation. Using favored conditions, the variant S165A/H357A could yield 6-kestose up to 335 g/L, and tetrasaccharides (6,6-nystose and 1,6-nystose) reached a high level of 121.1 g/L (134.5 times of the mutant S423A). The β-(2,6)-linked FOS may show the potential application for the prebiotic ingredients.

The Effects of Persimmon (Diospyros kaki L.f.) Oligosaccharides on Features of the Metabolic Syndrome in Zebrafish

Metabolic syndrome has become a global health care problem since it is rapidly increasing worldwide. The search for alternative natural supplements may have potential benefits for obesity and diabetes patients. Diospyros kaki fruit extract and its oligosaccharides, including gentiobiose, melibiose, and raffinose, were examined for their anti-insulin resistance and obesity-preventing effect in zebrafish larvae. The results show that D. kaki oligosaccharides improved insulin resistance and high-fat-diet-induced obesity in zebrafish larvae, evidenced by enhanced β-cell recovery, decreased abdominal size, and reduced the lipid accumulation. The mechanism of the oligosaccharides, molecular docking, and enzyme activities of PTP1B were investigated. Three of the oligosaccharides had a binding interaction with the catalytic active sites of PTP1B, but did not show inhibitory effects in an enzyme assay. The catalytic residues of PTP1B were typically conserved and the cellular penetration of the cell membrane was necessary for the inhibitors. The results of the mechanism of action study indicate that D. kaki fruit extract and its oligosaccharides affected gene expression changes in inflammation- (TNF-α, IL-6, and IL-1β), lipogenesis- (SREBF1 and FASN), and lipid-lowering (CPT1A)-related genes. Therefore, D. kaki fruit extract and its oligosaccharides may have a great potential for applications in metabolic syndrome drug development and dietary supplements.

The impact of prebiotic fructooligosaccharides on gut dysbiosis and inflammation in obesity and diabetes related kidney disease

Obesity is an extensive health problem worldwide that is frequently associated with diabetes. It is a risk factor for the development of several diseases including diabetic nephropathy. Recent studies have reported that gut dysbiosis aggravates the progression of obesity and diabetes by increasing the production of uremic toxins in conjunction with gut barrier dysfunction which then leads to increased passage of lipopolysaccharides (LPS) into the blood circulatory system eventually causing systemic inflammation. Therefore, the modification of gut microbiota using a prebiotic supplement may assist in the restoration of gut barrier function and reduce any disturbance of the inflammatory response. In this review information has been compiled concerning the possible mechanisms involved in an increase in obesity, diabetes and kidney dysfunction via the exacerbation of the inflammatory response and its association with gut dysbiosis. In addition, the role of fructooligosaccharides (FOS), a source of prebiotic widely available commercially, on the improvement of gut dysbiosis and attenuation of inflammation on obese and diabetic conditions has been reviewed. The evidence confirms that FOS supplementation could improve the pathological changes associated with obesity and diabetes related kidney disease, however, knowledge concerning the mechanisms involved is still limited and needs further elucidation.

Altered Intestinal Production of Volatile Fatty Acids in Dogs Triggered by Lactulose and Psyllium Treatment

The intestinal microbiome of dogs can be influenced by a number of factors such as non-starch polysaccharides as well as some non-digestible oligo- and disaccharides. These molecules are only decomposed by intestinal anaerobic microbial fermentation, resulting in the formation of volatile fatty acids (VFAs), which play a central role in maintaining the balance of the intestinal flora and affecting the health status of the host organism. In the present study, the effects of lactulose and psyllium husk (Plantago ovata) were investigated regarding their influence on concentrations of various VFAs produced by the canine intestinal microbiome. Thirty dogs were kept on a standard diet for 15 days, during which time half of the animals received oral lactulose once a day, while the other group was given a psyllium-supplemented diet (in 0.67 and in 0.2 g/kg body weight concentrations, respectively). On days 0, 5, 10 and 15 of the experiment, feces were sampled from the rectum, and the concentration of each VFA was determined by GC-MS (gas chromatography−mass spectrometry). Lactulose administration caused a significant increase in the total VFA concentration of the feces on days 10 and 15 of the experiment (p = 0.035 and p < 0.001, respectively); however, in the case of psyllium supplementation, the concentration of VFAs showed a significant elevation only on day 15 (p = 0.003). Concentrations of acetate and propionate increased significantly on days 5, 10 and 15 after lactulose treatment (p = 0.044, p = 0.048 and p < 0.001, respectively). Following psyllium administration, intestinal acetate, propionate and n-butyrate production were stimulated on day 15, as indicated by the fecal VFA levels (p = 0.002, p = 0.035 and p = 0.02, respectively). It can be concluded that both lactulose and psyllium are suitable for enhancing the synthesis of VFAs in the intestines of dogs. Increased acetate and propionate concentrations were observed following the administration of both supplements; however, elevated n-butyrate production was found only after psyllium treatment, suggesting that the applied prebiotics may exert slightly different effects in the hindgut of dogs. These findings can be also of great importance regarding the treatment and management of patients suffering from intestinal disorders as well as hepatic encephalopathy due to portosystemic shunt.

The Effectiveness of Extruded-Cooked Lentil Flour in Preparing a Gluten-Free Pizza with Improved Nutritional Features and a Good Sensory Quality

Extruded-cooked lentil (ECL) flour was used to fortify (10/100 g dough) gluten-free pizza, which was compared with rice/corn-based pizza (control), and with pizza containing native lentil (NL) flour. Viscoamylograph and Mixolab data evidenced the hydrocolloid properties of ECL flour (initial viscosity = 69.3 BU), which contained pregelatinized starch. The use of ECL flour made it possible to eliminate hydroxymethylcellulose (E464), obtaining a clean label product. Both NL and ECL pizzas showed significantly (p < 0.05) higher contents of proteins (7.4 and 7.3/100 g, respectively) than the control pizza (4.4/100 g) and could be labelled as “source of proteins” according to the Regulation (EC) No. 1924/2006. In addition, NL and ECL pizzas were characterized by higher contents of bioactive compounds, including anthocyanins, and by higher in vitro antioxidant activity (1.42 and 1.35 µmol Trolox/g d.m., respectively) than the control pizza (1.07 µmol Trolox/g d.m.). However, NL and ECL pizzas also contained small amounts of undigestible oligosaccharides, typically present in lentils (verbascose = 0.92–0.98 mg/g d.m.; stachyose = 4.04–5.55 mg/g d.m.; and raffinose = 1.98–2.05 mg/g d.m.). No significant differences were observed in the liking level expressed by consumers between ECL and control pizzas.

Valorization of renewable resources to functional oligosaccharides: Recent trends and future prospective

Lignocellulosic wastes have the ability to be transformed into oligosaccharides and other value-added products. The synthesis of oligosaccharides from renewable sources bestow to growing bioeconomies. Oligosaccharides are synthesized chemically or biologically from agricultural residues. These oligosaccharides are functional food supplements that have a positive impact on humans and livestock. Non-digestible oligosaccharides, refered as prebiotics are beneficial for the colonic microbiota inhabiting the f the digestive system. These microbiota plays a crucial role in stimulating the host immune system and other physiological responses. The commonly known prebiotics, galactooligosaccharides (GOS), xylooligosaccharides (XOS), fructooligosaccharides (FOS), mannanooligosaccharides (MOS), and isomaltooligosaccharides (IOS) are synthesized either through enzymatic or whole cell-mediated approaches using natural or agricultural waste substrates. This review focusses on recent advancements in biological processes, for the synthesis of oligosaccharides using renewable resources (lignocellulosic substrates) for sustainable circular bioeconomy. The work also addresses the limitations associated with the processes and commercialization of the products.

Dietary Fiber in Plant Cell Walls—The Healthy Carbohydrates

Dietary fiber (DF) is one of the major classes of nutrients for humans. It is widely distributed in the edible parts of natural plants, with the cell wall being the main DF-containing structure. The DF content varies significantly in different plant species and organs, and the processing procedure can have a dramatic effect on the DF composition of plant-based foods. Given the considerable nutritional value of DF, a deeper understanding of DF in food plants, including its composition and biosynthesis, is fundamental to the establishment of a daily intake reference of DF and is also critical to molecular breeding programs for modifying DF content. In the past decades, plant cell wall biology has seen dramatic progress, and such knowledge is of great potential to be translated into DF-related food science research and may provide future research directions for improving the health benefits of food crops. In this review, to spark interdisciplinary discussions between food science researchers and plant cell wall biologists, we focus on a specific category of DF—cell wall carbohydrates. We first summarize the content and composition of carbohydrate DF in various plant-based foods, and then discuss the structure and biosynthesis mechanism of each carbohydrate DF category, in particular the respective biosynthetic enzymes. Health impacts of DF are highlighted, and finally, future directions of DF research are also briefly outlined.

Microwave-assisted enzymatic hydrolysis to produce xylooligosaccharides from rice husk alkali-soluble arabinoxylan

The prebiotic properties of xylooligosaccharides (XOS) and arabino-xylooligosaccharides (AXOS) produced from rice husk (RH) using microwave treatment combined with enzymatic hydrolysis were evaluated. The RH was subjected to microwave pretreatment at 140, 160 and 180 °C for 5, 10 and 15 min to obtain crude arabinoxylan (AX). Increasing microwave pretreatment time increased sugar content. Crude AX was extracted with 2% (w/v) sodium hydroxide at 25 °C for 24 h and used as a substrate for XOS production by commercial xylanases. Results showed that oligosaccharides produced by Pentopan Mono BG and Ultraflo Max provided xylobiose and xylotriose as the main products. AXOS was also present in the oligosaccharides that promoted growth of Lactobacillus spp. and resisted degradation by over 70% after exposure to simulated human digestion.

Legumes and Legume-Based Beverages Fermented with Lactic Acid Bacteria as a Potential Carrier of Probiotics and Prebiotics

Fermentation is widely used in the processing of dairy, meat, and plant products. Due to the growing popularity of plant diets and the health benefits of consuming fermented products, there has been growing interest in the fermentation of plant products and the selection of microorganisms suitable for this process. The review provides a brief overview of lactic acid bacteria (LAB) and their use in fermentation of legumes and legume-based beverages. Its scope also extends to prebiotic ingredients present in legumes and legume-based beverages that can support the growth of LAB. Legumes are a suitable matrix for the production of plant-based beverages, which are the most popular products among dairy alternatives. Legumes and legume-based beverages have been successfully fermented with LAB. Legumes are a natural source of ingredients with prebiotic properties, including oligosaccharides, resistant starch, polyphenols, and isoflavones. These compounds provide a broad range of important physiological benefits, including anti-inflammatory and immune regulation, as well as anti-cancer properties and metabolic regulation. The properties of legumes make it possible to use them to create synbiotic food, which is a source of probiotics and prebiotics.

Glycoside Hydrolase family 30 harbors fungal subfamilies with distinct polysaccharide specificities

Efficient bioconversion of agro-industrial side streams requires a wide range of enzyme activities. Glycoside Hydrolase family 30 (GH30) is a diverse family that contains various catalytic functions and has so far been divided into ten subfamilies (GH30_1-10). In this study, a GH30 phylogenetic tree using over 150 amino acid sequences was contructed. The members of GH30 cluster into four subfamilies and eleven candidates from these subfamilies were selected for biochemical characterization. Novel enzyme activities were identified in GH30. GH30_3 enzymes possess β-(1→6)-glucanase activity. GH30_5 targets β-(1→6)-galactan with mainly β-(1→6)-galactobiohydrolase catalytic behavior. β-(1→4)-Xylanolytic enzymes belong to GH30_7 targeting β-(1→4)-xylan with several activities (e.g. xylobiohydrolase, endoxylanase). Additionally, a new fungal subfamily in GH30 was proposed, i.e. GH30_11, which displays β-(1→6)-galactobiohydrolase. This study confirmed that GH30 fungal subfamilies harbor distinct polysaccharide specificity and have high potential for the production of short (non-digestible) di- and oligosaccharides.

Adsorption-Enhanced Glucan Oligomer Production from Cellulose Hydrolysis over Hyper-Cross-Linked Polymer in Molten Salt Hydrate

Selective saccharification of cellulose into glucose is a critical step for utilization of lignocellulosic biomass. Molten salt hydrates (MSHs) have shown promising performance in selectively converting cellulose into glucose because of the high solubility of cellulose in the solvent. However, the separation of formed glucose from the MSHs is still a grand challenge. To address this issue, we developed a two-step process, where crystalline cellulose is hydrolyzed into short-chain glucan oligomers in MSHs followed by separation and subsequent hydrolysis of the formed oligomers into glucose under mild conditions. The two-step method provides an easy separation for glucan oligomers from the MSHs without sacrificing the selectivity to glucose. Application of the method for crystalline cellulose is, however, limited to a relatively low concentration, 26.2 mg/mL, because of the formation of byproducts in the MSH that facilitate oligomers degradation. In this work, reactive adsorption was employed to in situ remove the byproducts formed during cellulose hydrolysis in the MSH. It was found that hyper-cross-linked polymer (HCP) made from the polymerization of 4-vinylbenzyl chloride and divinylbenzene can selectively adsorb 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA) while showing negligible sugar adsorption in both water and the MSH. With the reactive adsorption approach, byproducts including 5-HMF and LA were removed from the reaction media under reaction conditions, and their negative effects on oligomer degradation were inhibited. In the presence of the HCP, the obtained glucan oligomer concentration was enhanced from less than 54.2 to 247.1 mg mL-1 when the weight ratio of cellulose was increased to MSH from 1:60 to 1:4, exhibiting an oligomer yield of 69.5%. The HCP can be effectively separated from the reaction media by filtration and regenerated by oxidation with hydrogen peroxide. Application of reactive adsorption with HCP for cellulose hydrolysis in the MSH provides a promising method to produce glucan oligomers and glucose with an improved yield and efficiency.

Gut microbiome colonization and development in neonatal ruminants: Strategies, prospects, and opportunities

Colonization and development of the gut microbiome is a crucial consideration for optimizing the health and performance of livestock animals. This is mainly attributed to the fact that dietary and management practices greatly influence the gut microbiota, subsequently leading to changes in nutrient utilization and immune response. A favorable microbiome can be implanted through dietary or management interventions of livestock animals, especially during early life. In this review, we explore all the possible factors (for example gestation, colostrum, and milk feeding, drinking water, starter feed, inoculation from healthy animals, prebiotics/probiotics, weaning time, essential oil and transgenesis), which can influence rumen microbiome colonization and development. We discuss the advantages and disadvantages of potential strategies used to manipulate gut development and microbial colonization to improve the production and health of newborn calves at an early age when they are most susceptible to enteric disease. Moreover, we provide insights into possible interventions and their potential effects on rumen development and microbiota establishment. Prospects of latest techniques like transgenesis and host genetics have also been discussed regarding their potential role in modulation of rumen microbiome and subsequent effects on gut development and performance in neonatal ruminants.

Effects of Combinations of Goat Milk and Oligosaccharides on Altering the Microbiota, Immune Responses, and Short Chain Fatty Acid Levels in the Small Intestines of Mice

Goat milk and oligosaccharides play important roles in gastrointestinal health. A combination of goat milk with three oligosaccharides, stachyose (STS), fructo-oligosaccharide (FOS), and a prebiotics mixture (FGS), was fed to mice. Changes and functions of the microbiota, short chain fatty acid (SCFA) concentrations, and immune gene expression in the small intestines were determined. The FOS treatment increased the beneficial bacteria Lactobacillus and Bifidobacterium, the FGS treatment helped stabilize the microbial community, and the STS treatment significantly enhanced microbial diversity and the growth of Bacteroidetes. The oligosaccharide treatments regulated the gene expression levels of the immune factors tumor necrosis factor alpha (Tnfα), granzyme B (Gzmb), perforin (Prf), and aryl hydrocarbon receptor (Ahr). Stachyose significantly increased the concentrations of acetate and propionate compared with other treatments. These findings demonstrate that STS is the preferred carbon source for microbiota, slightly modulates SCFA production, and results in low immunogenicity in the small intestines of mice.

Kabuli and Apulian black Chickpea Milling By-Products as Innovative Ingredients to Provide High Levels of Dietary Fibre and Bioactive Compounds in Gluten-Free Fresh Pasta

Gluten-free (GF) products, including pasta, are often characterised by nutritional deficiencies, such as scarce dietary fibre and excess of calories. Chickpea flour is increasingly being used by the food industries. Hulls, rich in dietary fibre and bioactive compounds, are discarded after milling. The aim of this work was to evaluate the quality features of short-cut GF fresh pasta added of hull (8% w/w) derived from kabuli (KH) or Apulian black (ABH) chickpeas, in comparison with control GF pasta prepared without hull. The enriched pasta, which could be labelled as "high fibre", was characterised by a higher level of bioactive compounds and antioxidant activity than the control. ABH-enriched pasta showed the highest anthocyanins (33.37 ± 1.20 and 20.59 ± 0.11 mg/kg of cyanidin-3-O-glucoside on dry matter in raw and cooked pasta, respectively). Hull addition increased colour intensity and structural quality of GF pasta: ABH-enriched pasta had the lowest cooking loss and the highest water absorption capacity; KH-enriched pasta showed the highest firmness. No significant differences in sensory liking were found among the samples, except for "aftertaste". Chickpea hull can be used as an innovative ingredient to produce potentially functional GF pasta, meeting the dietary needs of consumers without affecting quality.

MALDI-TOF-MS analysis of hydrolysis products of beechwood and birchwood xylans catalyzed by xylanase from Bacillus subtilis

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used to analyze the polymerization distribution of xylo-oligosaccharides from birchwood and beechwood xylans following hydrolysis by the xylanase (XynA) from Bacillus subtilis, which was obtained by recombinant expression and purified by Ni2+ affinity column chromatography. The hydrolysis products of birchwood and beechwood xylans were analyzed by thin layer chromatography (TLC) and MALDI-TOF-MS. In the birchwood hydrolysate, the main neutral xylo-oligosaccharides were xylobiose (X2 ) and xylotriose (X3 ), and the acidic xylo-oligosaccharides (polymerization degree 4-12) were attached via a single methyl-glucuronic acid sidechain (MeG). Both X2 and X3 were identified in the beechwood xylan hydrolysate and acidic xylo-oligosaccharides (polymerization degree 4-16), which were structurally similar to those in the birchwood xylan hydrolysate. Therefore, the recombinant xylanase, XynA, has the potential to produce xylobiose (X2 ) and xylotriose (X3 ) as well as acidic xylo-oligosaccharides (MeGXn ) that would be applied in food industry. PRACTICAL APPLICATIONS: Xylo-oligosaccharides are a novel functional food additive, which has great potential in improving the quality of food. Xylo-oligosaccharides with methyl-glucuronic acid sidechains (MeG) are acidic xylo-oligosaccharides (MeGXn), which can be applied in the preparation of drugs for the treatment of cystitis and mucopolysaccharidosis. In this study, xylanase XynA was first obtained by gene cloning and expression and then used to hydrolyze the birchwood and beechwood xylans. The polymerization distribution of xylo-oligosaccharides generated during the enzymatic digestion was then determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Through enzyme hydrolysis, we are able to produce xylobiose and xylotriose for food additives.

The β-Fructofuranosidase from Rhodotorula dairenensis: Molecular Cloning, Heterologous Expression, and Evaluation of Its Transferase Activity

The β-fructofuranosidase from the yeast Rhodotorula dairenensis (RdINV) produces a mixture of potential prebiotic fructooligosaccharides (FOS) of the levan-, inulin- and neo-FOS series by transfructosylation of sucrose. In this work, the gene responsible for this activity was characterized and its functionality proved in Pichia pastoris. The amino acid sequence of the new protein contained most of the characteristic elements of β-fructofuranosidases included in the family 32 of the glycosyl hydrolases (GH32). The heterologous yeast produced a protein of about 170 kDa, where N-linked and O-linked carbohydrates constituted about 15% and 38% of the total protein mass, respectively. Biochemical and kinetic properties of the heterologous protein were similar to the native enzyme, including its ability to produce prebiotic sugars. The maximum concentration of FOS obtained was 82.2 g/L, of which 6-kestose represented about 59% (w/w) of the total products synthesized. The potential of RdINV to fructosylate 19 hydroxylated compounds was also explored, of which eight sugars and four alditols were modified. The flexibility to recognize diverse fructosyl acceptors makes this protein valuable to produce novel glycosyl-compounds with potential applications in food and pharmaceutical industries.

Oligosaccharides from Traditional Chinese Herbal Medicines: A Review of Chemical Diversity and Biological Activities

Most of traditional Chinese herbal medicine (TCHM) substances come from medicinal plants, among which oligosaccharides have gradually attracted widespread attention at home and abroad due to their important biological activities and great medicinal potential. Numerous in vitro and in vivo experiments exhibited that oligosaccharides possess various activities, such as antitumor, anti-oxidation, modulate the gut microflora, anti-inflammatory, anti-infection, and immune-regulatory activities. Generally, biological activities are closely related to chemical structures, including molecular weight, monosaccharide composition, glycosidic bond connection, etc. The structural analysis of oligosaccharides is an important basis for studying their structure-activity relationship, but the structural diversity and complexity of carbohydrate compounds limit the study of oligosaccharides activities. Understanding the structures and biological functions of oligosaccharides is important for the development of new bioactive substances with natural oligosaccharides. This review provides a systematic introduction of the current knowledge of the chemical structures and biological activities of oligosaccharides. Most importantly, the reported chemical characteristics and biological activities of the famous TCHM oligosaccharides were briefly summarized, including Morinda officinalis, Rehmannia glutinosa, Arctium lappa, Polygala tenuifolia, Panax ginseng, Lycium barbarum and Astragalus membranaceus. TCHM oligosaccharides play an important role in nutrition, health care, disease diagnosis and prevention as well as have broad application prospects in the field of medicine.

Recent advances in the therapeutic application of short-chain fatty acids (SCFAs): An updated review

Over the past decade, the gut microbiota has emerged as an important frontier in understanding the human body's homeostasis and the development of diseases. Gut flora in human beings regulates various metabolic functionalities, including enzymes, amino acid synthesis, bio-transformation of bile acid, fermentation of non-digestible carbohydrates (NDCs), generation of indoles and polyamines (PAs), and production of short-chain fatty acids (SCFAs). Among all the metabolites produced by gut microbiota, SCFAs, the final product of fermentation of dietary fibers by gut microbiota, receive lots of attention from scientists due to their pharmacological and physiological characteristics. However, the molecular mechanisms underlying the role of SCFAs in the interaction between diet, gut microbiota, and host energy metabolism is still needed in-depth research. This review highlights the recent biotechnological advances in applying SCFAs as important metabolites to treat various diseases and maintain colonic health.

Friend or Foe? Impacts of Dietary Xylans, Xylooligosaccharides, and Xylanases on Intestinal Health and Growth Performance of Monogastric Animals

This paper discusses the structural difference and role of xylan, procedures involved in the production of xylooligosaccharides (XOS), and their implementation into animal feeds. Xylan is non-starch polysaccharides that share a β-(1-4)-linked xylopyranose backbone as a common feature. Due to the myriad of residues that can be substituted on the polymers within the xylan family, more anti-nutritional factors are associated with certain types of xylan than others. XOS are sugar oligomers extracted from xylan-containing lignocellulosic materials, such as crop residues, wood, and herbaceous biomass, that possess prebiotic effects. XOS can also be produced in the intestine of monogastric animals to some extent when exogenous enzymes, such as xylanase, are added to the feed. Xylanase supplementation is a common practice within both swine and poultry production to reduce intestinal viscosity and improve digestive utilization of nutrients. The efficacy of xylanase supplementation varies widely due a number of factors, one of which being the presence of xylanase inhibitors present in common feedstuffs. The use of prebiotics in animal feeding is gaining popularity as producers look to accelerate growth rate, enhance intestinal health, and improve other production parameters in an attempt to provide a safe and sustainable food product. Available research on the impact of xylan, XOS, as well as xylanase on the growth and health of swine and poultry, is also summarized. The response to xylanase supplementation in swine and poultry feeds is highly variable and whether the benefits are a result of nutrient release from NSP, reduction in digesta viscosity, production of short chain xylooligosaccharides or a combination of these is still in question. XOS supplementation seems to benefit both swine and poultry at various stages of production, as well as varying levels of XOS purity and degree of polymerization; however, further research is needed to elucidate the ideal dosage, purity, and degree of polymerization needed to confer benefits on intestinal health and performance in each respective species.

Novel Insights Into Pathogenesis and Therapeutic Strategies of Hepatic Encephalopathy, From the Gut Microbiota Perspective

Since the 1950s, gradual changes in the gut microbiota of patients with hepatic encephalopathy have been observed. Previous research has indicated potential associations between the gut and brain, and the gut microbiota is becoming a hot topic in research on diseases of the nervous system. However, for the past few decades, studies of hepatic encephalopathy have been restricted to controlling the gut microbiota during macroscopic manipulation, such as probiotic intervention, while its clinical use remains controversial, and the cellular mechanisms underlying this condition are still poorly understood. This thesis seeks to comprehensively understand and explain the role of gut microbiota in hepatic encephalopathy as well as analyze the effects of intervention by regulating the gut microbiota. Evidence is presented that shows that dysbiosis of the gut microbiota is the primary pathological driver of hepatic encephalopathy and impacts pathologic progression via complex regulatory networks. As a result, suggestions were identified for future mechanistic research and improvements in therapeutic strategies for hepatic encephalopathy.

Effect of supplemental prebiotics, probiotics and bioactive proteins on the microbiome composition and fecal calprotectin in C57BL6/j mice

The composition and metabolic activity of the microbiome affect many aspects of health, and there is current interest in dietary constituents that may affect this system. The purpose of this study was to evaluate the effects of a mix of probiotics, a mix of prebiotics and a bioactive protein fraction on the microbiome, when fed to mice alone and in combination at physiologically relevant doses. Mice were fed the total western diet (TWD) supplemented with prebiotics, probiotics, and bioactive proteins individually and in combination for four weeks. Subsequently, effects on the composition of the gut microbiome, gut short-chain fatty acids (SCFAs) concentration, and gut inflammation were measured. Ruminococcus gnavus was increased in mice gut microbiome after feeding prebiotics. Bifidobacterium longum was increased after feeding probiotics. The treatments significantly affected beta-diversity with minor treatment effects on cecal or fecal SCFAs levels, and the treatments did not affect gut inflammation as measured by fecal calprotectin.

Valorization of outer tunic of the marine filter feeder Ciona intestinalis towards the production of second-generation biofuel and prebiotic oligosaccharides

BACKGROUND

One of the sustainable development goals focuses on the biomass-based production as a replacement for fossil-based commodities. A novel feedstock with vast potentials is tunicate biomass, which can be pretreated and fermented in a similar way to lignocellulose. Ciona intestinalis is a marine filter feeder that is cultivated to produce fish feed. While the inner tissue body is used for feed production, the surrounding tunic remains as a cellulose-rich by-product, which can be further separated into outer and inner tunic. Ethanol production from organosolv-pretreated whole-tunic biomass was recently validated. The aim of the present study was to evaluate the potential of organosolv pretreated outer-tunic biomass for the production of biofuels and cellobiose that is a disaccharide with prebiotic potential.

RESULTS

As a result, 41.4 g/L of ethanol by Saccharomyces cerevisiae, corresponding to a 90.2% theoretical yield, was achieved under the optimal conditions when the tunicate biomass was pretreated at 195 °C for 60 min at a liquid-to-solid ratio of 50. In addition, cellobiose production by enzymatic hydrolysis of the pretreated tunicate biomass was demonstrated with a maximum conversion yield of 49.7 wt. %.

CONCLUSIONS

The utilisation of tunicate biomass offers an eco-friendly and sustainable alternative for value-added biofuels and chemicals. The cultivation of tunicate biomass in shallow coastal sea improves the quality of the water and ensures sustainable production of fish feed. Moreover, there is no competition for arable land, which leaves the latter available for food and feed production.

Yarrowia lipolytica as an emerging biotechnological chassis for functional sugars biosynthesis

Functional sugars have unique structural and physiological characteristics with applied perspectives for modern biomedical and biotechnological sectors, such as biomedicine, pharmaceutical, cosmeceuticals, green chemistry, and agro-food. They can also be used as starting matrices to produce biologically active metabolites of interests. Though numerous chemical synthesis routes have been proposed and deployed for the synthesis of rare sugars, however, many of them are limited and economically incompetent because of expensive raw starting feedstocks. Whereas, the biosynthesis by enzymatic means are often associated with high catalyst costs and low space-time yields. Microbial production of rare sugars via green routes using bio-renewable resources offers noteworthy solutions to overcome the aforementioned limitations of synthetic and enzymatic synthesis routes. From the microbial-based synthesis perspective, the lipogenic yeast Yarrowia lipolytica is rapidly evolving as the most prevalent and unique "non-model organism" in the bio-production arena. Due to high flux tendency through the tri-carboxylic acid cycle intermediates and precursors such as acetyl-CoA and malonyl-CoA, this yeast has been widely investigated to meet the increasing demand of industrially relevant fine chemicals, including functional sugars. Incredible interest in Y. lipolytica originates from its robust tolerance to unstable pH, salt levels, and organic compounds, which subsequently enable easy bioprocess optimization. Meaningfully, GRAS (generally recognized as safe) status creates Y. lipolytica as an attractive and environmentally friendly microbial host for the manufacturing of nutraceuticals, fermented food, and dietary supplements. In this review, we highlight the recent and state-of-the-art research progress on Y. lipolytica as a host to synthesize bio-based compounds of interest beyond the realm of well-known fatty acid production. The unique physicochemical properties, biotechnological applications, and biosynthesis of an array of value-added functional sugars including erythritol, threitol, fructooligosaccharides, galactooligosaccharides, isomalto-oligosaccharides, isomaltulose, trehalose, erythrulose, xylitol, and mannitol using sustainable carbon sources are thoroughly vetted. Finally, we conclude with perspectives that would be helpful to engineer Y. lipolytica in greening the twenty-first century biomedical and biotechnological sectors of the modern world.

Isolation and characterization of Lactococcus garvieae from the fish gut for in vitro fermentation with carbohydrates from agro-industrial waste

This study focused on agro-industrial waste such as fruit peels by extracting prebiotics as a carbon source for lactic acid bacteria (LAB). Four strains of LAB were selected from Oreochromis niloticus (B2 and B3) and Nemipterus japonicas (R4 and R5), and identified as Lactococcus garvieae through 16S rRNA gene sequencing. The analysis of probiotic characteristics revealed that all four strains were able to tolerate sodium chloride (up to 7 %), bile salt (up to 3 %), and broad range of pH (2-9). Further, analysis of polysaccharide contents in the agro-industrial waste materials such as peels of pineapple, orange, lemon, sugarcane, pomegranate, and sweet lemon revealed that the concentration ranged from 3.91-163.85 mg/g. It was observed that orange peels (20.38-140.99 mg/g), sweet lemon peels (22.03-161.93 mg/g), and pomegranate peels (38.19-163.85 mg/g) yielded maximum indigestible polysaccharide. Evaluation of synbiotic combination of probiotic and prebiotic revealed that L. garvieae strains had better fermentation efficiency with orange, sweet lemon, and pineapple compared to lemon, sugarcane, and pomegranate. In nutshell, different types of agro-industrial waste evaluated in this research were found to be a cheap and fermentable carbon sources for LAB. Further study should be conducted to analyze this symbiotic combination as feed supplements for fish in aquaculture as well as various fermentation industries.

β-Glucan Metabolic and Immunomodulatory Properties and Potential for Clinical Application

β-glucans are complex polysaccharides that are found in several plants and foods, including mushrooms. β-glucans display an array of potentially therapeutic properties. β-glucans have metabolic and gastro-intestinal effects, modulating the gut microbiome, altering lipid and glucose metabolism, reducing cholesterol, leading to their investigation as potential therapies for metabolic syndrome, obesity and diet regulation, gastrointestinal conditions such as irritable bowel, and to reduce cardiovascular and diabetes risk. β-glucans also have immune-modulating effects, leading to their investigation as adjuvant agents for cancers (solid and haematological malignancies), for immune-mediated conditions (e.g., allergic rhinitis, respiratory infections), and to enhance wound healing. The therapeutic potential of β-glucans is evidenced by the fact that two glucan isolates were licensed as drugs in Japan as immune-adjuvant therapy for cancer in 1980. Significant challenges exist to further clinical testing and translation of β-glucans. The diverse range of conditions for which β-glucans are in clinical testing underlines the incomplete understanding of the diverse mechanisms of action of β-glucans, a key knowledge gap. Furthermore, important differences appear to exist in the effects of apparently similar β-glucan preparations, which may be due to differences in sources and extraction procedures, another poorly understood issue. This review will describe the biology, potential mechanisms of action and key therapeutic targets being investigated in clinical trials of β-glucans and identify and discuss the key challenges to successful translation of this intriguing potential therapeutic.

Systematic review of the ingestion of fructooligosaccharides on the absorption of minerals and trace elements versus control groups

BACKGROUND & AIMS

Fructooligosaccharides (FOS) are non-caloric and unconventional sugars that are not metabolized by the human body, but can be fermented by the colonic microbiota, leading to some beneficial effects on the absorption of minerals and trace elements. There is, however, a lack of research that describes the continued consumption of FOS in the diet between healthy and ill individuals and their impact. The objective of this systematic review was to evaluate the evidence behind the role of FOS in the absorption of minerals and trace elements in the human body.

METHODS

The bibliographic research covered the period from January 2000 to August 2020. Four databases were investigated. We follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA). The systematic review protocol was recorded in PROSPERO (139621). Two reviewers examined and extracted data from qualitative and quantitative studies published in the main databases, through a careful analysis. The risk of bias was assessed by four reviewers.

RESULTS

Of a total of 1494 texts, 30 complete articles composed this review. Two overarching categories represented the results: animal models and human models (randomized crossover design). Regarding human models, the results showed an improvement in minerals, especially the absorption of calcium, magnesium and iron after the ingestion of FOS, and specifically the absorption of minerals and trace elements in postmenopausal women was improved.

CONCLUSIONS

The use of FOS to improve the absorption of minerals and trace elements seems to be beneficial with evidence corroborating both in human and animal studies. However, the literature lacks articles exploring the daily dose and duration for FOS benefits, as well as long-term side effects in healthy or unhealthy subjects. Future research should focus on addressing the extent of the functional effect of this fiber and identifying the impact on overall health.

Development of Fish Immunity and the Role of β-Glucan in Immune Responses

Administration of β-glucans through various routes, including immersion, dietary inclusion, or injection, have been found to stimulate various facets of immune responses, such as resistance to infections and resistance to environmental stress. β-Glucans used as an immunomodulatory food supplement have been found beneficial in eliciting immunity in commercial aquaculture. Despite extensive research involving more than 3000 published studies, knowledge of the receptors involved in recognition of β-glucans, their downstream signaling, and overall mechanisms of action is still lacking. The aim of this review is to summarize and discuss what is currently known about of the use of β-glucans in fish.

Environmentally Friendly Approach for the Production of Glucose and High-Purity Xylooligosaccharides from Edible Biomass Byproducts

Xylooligosaccharides (XOS) production from sweet sorghum bagasse (SSB) has been barely studied using other edible biomasses. Therefore, we evaluated the XOS content as well as its purity by comparing the content of total sugars from SSB. An environmentally friendly approach involving autohydrolysis was employed, and the reaction temperature and time had variations in order to search for the conditions that would yield high-purity XOS. After autohydrolysis, the remaining solid residues, the glucan-rich fraction, were used as substrates to be enzymatically hydrolyzed for glucose conversion. The highest XOS was observed for total sugars (68.7%) at 190 °C for 5 min among the autohydrolysis conditions. However, we also suggested two alternative conditions, 180 °C for 20 min and 190 °C for 15 min, because the former condition might have the XOS at a low degree of polymerization with a high XOS ratio (67.6%), while the latter condition presented a high glucose to total sugar ratio (91.4%) with a moderate level XOS ratio (64.4%). Although it was challenging to conclude on the autohydrolysis conditions required to obtain the best result of XOS content and purity and glucose yield, this study presented approaches that could maximize the desired product from SSB, and additional processes to reduce these differences in conditions may warrant further research.

Enhancement of catalytic performance of a metagenome-derived thermophilic oligosaccharide-specific xylanase by binding module removal and random mutagenesis

Xylo-oligosaccharide (XO) is a promising pre-biotic with applications in food, feed and healthcare products. XO can be produced by enzymatic digestion of xylan with xylanase. In this study, we aimed to improve the biochemical properties relevant to catalysis and kinetics of X11, a thermophilic glycosyl hydrolase (GH) family 11 endo-β-1,4-xylanase derived from a metagenomic library isolated from sugarcane bagasse, under high-temperature conditions preferred for XO synthesis. Removal of a carbohydrate-binding module (X11C) resulted in 6.5 fold greater catalytic efficiency. X11C was further improved by a Pro71Thr mutation in the X11P variant obtained from a random mutagenesis library, which exhibited 15.9 fold greater catalytic efficiency compared with wild-type X11 under the enzyme's optimal conditions of 80°C and pH 6.0. Homology modeling suggested that the improved performance of X11P could be attributed to formation of an extra H-bond between Thr71 and Ser75, which stabilizes the key catalytic residue Glu180 at the active pocket and β-sheet layers and agrees with the respective increase in melting temperature (T_m) where X11P >X11C >X11 as determined by differential scanning fluorimetry. The X11P variant was tested for hydrolysis of beechwood xylan, which showed X6 as the major product followed by X3 and X4 XOs. The highest yield of 5.5 g total XOs product/mg enzyme was observed for X11P, equivalent to 3.7 fold higher than that of wild-type with XO production of >800 mg/g xylan. The X11P enzyme could be developed as a thermophilic biocatalyst for XO synthesis in biorefineries.

Short-Chain Cello-oligosaccharides: Intensification and Scale-up of Their Enzymatic Production and Selective Growth Promotion among Probiotic Bacteria

Short-chain cello-oligosaccharides (COS; degree of polymerization, DP ≤ 6) are promising water-soluble dietary fibers. An efficient approach to their bottom-up synthesis is from sucrose and glucose using glycoside phosphorylases. Here, we show the intensification and scale up (20 mL; gram scale) of COS production to 93 g/L product and in 82 mol % yield from sucrose (0.5 M). The COS were comprised of DP 3 (33 wt %), DP 4 (34 wt %), DP 5 (24 wt %), and DP 6 (9 wt %) and involved minimal loss (≤10 mol %) to insoluble fractions. After isolation (≥95% purity; ≥90% yield), the COS were examined for growth promotion of probiotic strains. Benchmarked against inulin, trans-galacto-oligosaccharides, and cellobiose, COS showed up to 4.1-fold stimulation of cell density for Clostridium butyricum, Lactococcus lactis subsp. lactis, Lactobacillus paracasei subsp. paracasei, and Lactobacillus rhamnosus but were less efficient with Bifidobacterium sp. This study shows the COS as selectively functional carbohydrates with prebiotic potential and demonstrates their efficient enzymatic production.

Gut microbiome and osteoporosis: a review

Osteoporosis (OP) is a chronic metabolic bone disease characterized by the decrease of bone tissue per unit volume under the combined action of genetic and environmental factors, which leads to the decrease of bone strength, makes the bone brittle, and raises the possibility of bone fracture. However, the exact mechanism that determines the progression of OP remains to be underlined. There are hundreds of trillions of symbiotic bacteria living in the human gut, which have a mutually beneficial symbiotic relationship with the human body that helps to maintain human health. With the development of modern high-throughput sequencing (HTS) platforms, there has been growing evidence that the gut microbiome may play an important role in the programming of bone metabolism. In the present review, we discuss the potential mechanisms of the gut microbiome in the development of OP, such as alterations of bone metabolism, bone mineral absorption, and immune regulation. The potential of gut microbiome-targeted strategies in the prevention and treatment of OP was also evaluated.

Cite this article: Bone Joint Res 2020;9(8):524–530.