Xylo-oligosaccharide (XOS) in combination with inulin modulates both the intestinal environment and immune status in healthy subjects, while XOS alone only shows prebiotic properties

Effect of Xylo-Oligosaccharides Supplementation by Drinking Water on the Bone Properties and Related Calcium Transporters in Growing Mice

Xylo-oligosaccharides (XOS), non-digestible oligosaccharides, have the potential to regulate intestinal microorganisms, and thus, improve host health, but little evidence exists for the prebiotic effects on bone health. This study evaluates the dose-response effect of XOS supplementation on bone properties, the morphology of the intestine, cecum pH, and cecum wall weight, as well as the related calcium transporters. Ninety-six 28-day-old male mice were randomized into one of four groups, fed the same commercial diet, and given different types of deionized water containing 0, 1, 2, or 4% XOS by concentration for 30 days. Eight mice were randomly selected to accomplish particular tasks every 10 days. No significant differences in serum Ca and P levels and growth performance were observed among the four studied groups. XOS intervention significantly decreased cecum pH and increased cecum wall weight in a dose-dependent manner. At the late growth stage, compared with 0% XOS, the bone mineral density (BMD) and bone-breaking strength in 4% XOS were significantly higher. The bone crystallinity with 4% XOS, measured by Raman spectrum, was significantly enhanced compared to that with 0% XOS during later growth. The villus height and villus height to crypt depth (VH:CD) were enhanced with an increase of XOS concentration during the later stage of growth. The expression of transient receptor potential vanillin receptor 6 (TRPV6) and Na⁺/Ca²⁺ exchanger 1 (NCX1) in the duodenum were enhanced by XOS supplementation. XOS exerted a positive influence on bone properties by decreasing the cecum pH, increasing the cecum wall and villus structure, and upregulating the expression of related calcium transporters.

Impact of prebiotics on immune response: from the bench to the clinic

Several preclinical and clinical studies have shown the immunomodulatory role exerted by prebiotics in regulating the immune response. In this review, we describe the mechanistic and clinical studies that decipher the cell signaling pathways implicated in the process. Prebiotic fibers are conventionally known to serve as substrate for probiotic commensal bacteria that release of short-chain fatty acids in the intestinal tract along with several other metabolites. Subsequently, they then act on the local as well as the systemic immune cells and the gut-associated epithelial cells, primarily through G-protein-coupled receptor-mediated pathways. However, other pathways including histone deacetylase inhibition and inflammasome pathway have also been implicated in regulating the immunomodulatory effect. The prebiotics can also induce a microbiota-independent effect by directly acting on the gut-associated epithelial and innate immune cells through the Toll-like receptors. The cumulative effect results in the maintenance of the epithelial barrier integrity and modulation of innate immunity through secretion of pro- and anti-inflammatory cytokines, switches in macrophage polarization and function, neutrophil recruitment and migration, dendritic cell and regulatory T-cell differentiation. Extending these in vitro and ex vivo observations, some prebiotics have been well investigated, with successful human and animal trials demonstrating the association between gut microbes and immunity biomarkers leading to improvement in health endpoints across populations. This review discusses scientific insights into the association between prebiotics, innate immunity and gut microbiome from in vitro to human oral intervention.

Prebiotic Carbohydrates for Therapeutics

The food industry is constantly shifting focus based on prebiotics as health-promoting substrates rather than just food supplements. A prebiotic is "a selectively fermented ingredient that allows specific changes, both in the composition and/or activity in the gastrointestinal microflora that confers benefits upon host well-being and health." Prebiotics exert a plethora of health-promoting effects, which has lead to the establishment of multimillion food and pharma industries. The following are the health benefits attributed to prebiotics: mineral absorption, better immune response, increased resistance to bacterial infection, improved lipid metabolism, possible protection against cancer, relief from poor digestion of lactose, and reduction in the risk of diseases such as intestinal disease, non-insulin-dependent diabetes, obesity and allergy. Numerous studies in both animals and humans have demonstrated the health benefits of prebiotics.

The Role of Milk Components, Pro-, Pre-, and Synbiotic Foods in Calcium Absorption and Bone Health Maintenance

Increasing peak bone mass during adolescence and reducing bone loss in later life are two approaches to reduce the risk of osteoporosis with aging. Osteoporosis affects a large proportion of the elderly population worldwide and the incidence is increasing. Milk consumption is an accepted strategy in building peak bone mass and therefore may reduce the risk of osteoporosis. In childhood calcium, phosphorous, and growth factors are the important components to support bone growth but in adults the positive influence on bone density/maintenance may also be due to other bioactive proteins/peptides or lipids in milk acting directly in the gastrointestinal tract (GIT). Lactose has been known to increase calcium absorption; galactooligosaccharides (GOS) are derived from lactose and are non-digestible oligosaccharides. They have been shown to improve mineral balance and bone properties as well as causing increases in bifidobacteria in the gut, therefore a prebiotic effect. Supplementation with fortified milk and dairy products with added prebiotics, increased both calcium and magnesium absorption and caused some modulation of gut microbiota in animals and humans. Fermented milk is now also recognized to contain highly active components such as vitamins, peptides, oligosaccharides, and organic acids. In this review, the role of milk and milk components in improving calcium absorption and thereby supporting bone health is discussed. In addition, some reference is made to the significance of combining the inherent beneficial components from milk with fortificants/nutrients that will support bone health through adulthood. Novel data suggesting differences in diversity of the microbiota between healthy and osteoporotic women are provided.

Food as medicine: targeting the uraemic phenotype in chronic kidney disease

The observation that unhealthy diets (those that are low in whole grains, fruits and vegetables, and high in sugar, salt, saturated fat and ultra-processed foods) are a major risk factor for poor health outcomes has boosted interest in the concept of 'food as medicine'. This concept is especially relevant to metabolic diseases, such as chronic kidney disease (CKD), in which dietary approaches are already used to ameliorate metabolic and nutritional complications. Increased awareness that toxic uraemic metabolites originate not only from intermediary metabolism but also from gut microbial metabolism, which is directly influenced by diet, has fuelled interest in the potential of 'food as medicine' approaches in CKD beyond the current strategies of protein, sodium and phosphate restriction. Bioactive nutrients can alter the composition and metabolism of the microbiota, act as modulators of transcription factors involved in inflammation and oxidative stress, mitigate mitochondrial dysfunction, act as senolytics and impact the epigenome by altering one-carbon metabolism. As gut dysbiosis, inflammation, oxidative stress, mitochondrial dysfunction, premature ageing and epigenetic changes are common features of CKD, these findings suggest that tailored, healthy diets that include bioactive nutrients as part of the foodome could potentially be used to prevent and treat CKD and its complications.

Poultry feeds carry diverse microbial communities that influence chicken intestinal microbiota colonisation and maturation

Microbial colonisation of the gastrointestinal tract of newly hatched chicks starts at hatch, seeded from the immediate hatching environment, and quickly results in dense colonisation. The role of ecological factors in gut colonisation has been extensively investigated, as well as the role of micro- and macronutrients in supporting and selecting for bacterial species highly adapted for utilising those nutrients. However, the microbial community contained in poultry feed and its influence on colonisation and maturation of gut microbiota has not been directly addressed. In this study, we compared the microbiota found in poultry feed, with the microbiota of ileum, cecum and excreta, to identify substantial overlap in core microbiotas of the compared groups. We then investigated the microbiota present in raw feedstuffs: meat and bone meal, wheat, corn, canola, barley, soybean, millrun, sorghum, poultry oil, oats, limestone and bloodmeal from four geographically distinct feedstuff suppliers. Each of the feedstuffs had diverse microbial communities. The meat and bone meal and bloodmeal samples had the most complex and distinct microbial populations. There was substantial overlap in the phylogenetic composition found in the grain and seed samples: barley, canola, corn, millrun, oats, sorghum, soybean meal and wheat. Issues related to methodology, viability of microbial communities in the gut and feed, and the implications for biosecurity are discussed.

Microbiome-intestine cross talk during acute graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation (allo-SCT) offers cure for a variety of conditions, in particular, but not limited to, hematologic malignancies. However, it can be associated with life-threatening complications, including graft-versus-host disease (GVHD) and infections, which are factors limiting its widespread use. Technical advances in the field of microbiome research have allowed for a better understanding of the microbial flora of the human intestine, as well as dissection of their interactions with the host immune system in allo-SCT and posttransplant complications. There is growing evidence that the commensal microbiome is frequently dysregulated following allo-SCT and that this dysbiosis can predispose to adverse clinical outcomes, especially including acute intestinal GVHD and reduced overall survival. In this review, we discuss the interactions between the microbiome and the components of the immune system that play a major role in the pathways leading to the inflammatory state of acute intestinal GVHD. We also discuss the microbiome-centered strategies that have been devised or are actively being investigated to improve the outcomes of allo-SCT patients in regard to acute intestinal GVHD.

The Butyrogenic and Lactic Bacteria of the Gut Microbiota Determine the Outcome of Allogenic Hematopoietic Cell Transplant

Graft versus host disease (GVHD) is a post-transplant pathology in which donor-derived T cells present in the Peyer's patches target the cell-surface alloantigens of the recipient, causing host tissue damages. Therefore, the GVHD has long been considered only a purely immunological process whose prevention requires an immunosuppressive treatment. However, since the early 2010s, the impact of gut microbiota on GVHD has received increased attention. Both a surprising fall in gut microbiota diversity and a shift toward Enterobacteriaceae were described in this disease. Recently, unexpected results were reported that further link GVHD with changes in bacterial composition in the gut and disruption of intestinal epithelial tight junctions leading to abnormal intestinal barrier permeability. Patients receiving allogenic hematopoietic stem cell transplant (allo-HCT) as treatment of hematologic malignancies showed a decrease of the overall diversity of the gut microbiota that affects Clostridia and Blautia spp. and a predominance of lactic acid bacteria (LAB) of the Enterococcus genus, in particular the lactose auxotroph Enterococcus faecium. The reduced microbiota diversity (likely including Actinobacteria, such as Bifidobacterium adolescentis that cross feed butyrogenic bacteria) deprives the butyrogenic bacteria (such as Roseburia intestinalis or Eubacterium) of their capacity to metabolize acetate to butyrate. Indeed, administration of butyrate protects against the GVHD. Here, we review the data highlighting the possible link between GVHD and lactase defect, accumulation of lactose in the gut lumen, reduction of Reg3 antimicrobial peptides, narrower enzyme equipment of bacteria that predominate post-transplant, proliferation of En. faecium that use lactose as metabolic fuels, induction of innate and adaptive immune response against these bacteria which maintains an inflammatory process, elevated expression of myosin light chain kinase 210 (MLCK210) and subsequent disruption of intestinal barrier, and translocation of microbial products (lactate) or transmigration of LAB within the liver. The analysis of data from the literature confirms that the gut microbiota plays a major role in the GVHD. Moreover, the most recent publications uncover that the LAB, butyrogenic bacteria and bacterial cross feeding were the missing pieces in the puzzle. This opens new bacteria-based strategies in the treatment of GVHD.

Microbiota and Lifestyle: A Special Focus on Diet

It is widely known that a good balance and healthy function for bacteria groups in the colon are necessary to maintain homeostasis and preserve health. However, the lack of consensus on what defines a healthy gut microbiota and the multitude of factors that influence human gut microbiota composition complicate the development of appropriate dietary recommendations for our gut microbiota. Furthermore, the varied response to the intake of probiotics and prebiotics observed in healthy adults suggests the existence of potential inter- and intra-individual factors, which might account for gut microbiota changes to a greater extent than diet. The changing dietary habits worldwide involving consumption of processed foods containing artificial ingredients, such as sweeteners; the coincident rise in emotional disorders; and the worsening of other lifestyle habits, such as smoking habits, drug consumption, and sleep, can together contribute to gut dysbiosis and health impairment, as well as the development of chronic diseases. This review summarizes the current literature on the effects of specific dietary ingredients (probiotics, prebiotics, alcohol, refined sugars and sweeteners, fats) in the gut microbiota of healthy adults and the potential inter- and intra-individual factors involved, as well as the influence of other potential lifestyle factors that are dramatically increasing nowadays.

Faster Short-Chain Fatty Acid Absorption from the Cecum Following Polydextrose Ingestion Increases the Salivary Immunoglobulin A Flow Rate in Rats

Salivary immunoglobulin A (IgA) plays a vital role in preventing upper respiratory tract infections (URTI). In our previous study, we showed that the intake of carbohydrates increases the intestinal levels of short-chain fatty acids (SCFAs), which in turn increase salivary IgA levels. However, the mechanism underlying this phenomenon has not been fully elucidated. In this study, we investigated in rats the effect of polydextrose (PDX) ingestion on salivary IgA level and SCFA concentration in cecal digesta and the portal vein. Five-week-old rats were fed with a fiber-free diet (control) or with 40 g/kg of PDX for 28 days. Compared to the control, ingestion of PDX led to a higher salivary IgA flow rate (p = 0.0013) and a higher concentration of SCFAs in the portal vein (p = 0.004). These two data were positively correlated (r_s = 0.88, p = 0.0002, n = 12). In contrast, the concentration of SCFAs in cecal digesta and cecal digesta viscosity were significantly lower following PDX ingestion, compared to the control (p = 0.008 and 0.05, respectively). These findings suggest that the ingestion of PDX increases the absorption rate of SCFAs in the intestine through PDX-induced fermentation, which is accompanied by an increase in SCFA levels in the blood, and ultimately leads to increased salivary IgA levels.

Microbial Medicine: Prebiotic and Probiotic Functional Foods to Target Obesity and Metabolic Syndrome

Obesity has become a global epidemic and a public health crisis in the Western World, experiencing a threefold increase in prevalence since 1975. High-caloric diets and sedentary lifestyles have been identified as significant contributors to this widespread issue, although the role of genetic, social, and environmental factors in obesity's pathogenesis remain incompletely understood. In recent years, much attention has been drawn to the contribution of the gut microbiota in the development of obesity. Indeed, research has shown that in contrast to their healthier counterparts the microbiomes of obese individuals are structurally and functionally distinct, strongly suggesting microbiome as a potential target for obesity therapeutics. In particular, pre and probiotics have emerged as effective and integrative means of modulating the microbiome, in order to reverse the microbial dysbiosis associated with an obese phenotype. The following review brings forth animal and human research supporting the myriad of mechanisms by which the microbiome affects obesity, as well as the strengths and limitations of probiotic or prebiotic supplementation for the prevention and treatment of obesity. Finally, we set forth a roadmap for the comprehensive development of functional food solutions in combatting obesity, to capitalize on the potential of pre/probiotic therapies in optimizing host health.

Mechanisms of Action of Prebiotics and Their Effects on Gastro-Intestinal Disorders in Adults

In recent years, research has focused on the use of dietary fibers and prebiotics, since many of these polysaccharides can be metabolized by intestinal microbiota, leading to the production of short-chain fatty acids. The metabolites of prebiotic fermentation also show anti-inflammatory and immunomodulatory capabilities, suggesting an interesting role in the treatment of several pathological conditions. Galacto-oligosaccharide and short- and long-chain fructans (Fructo-oligosaccharides and inulin) are the most studied prebiotics, even if other dietary compounds seem to show the same features. There is an increasing interest in dietary strategies to modulate microbiota. The aim of this review is to explore the mechanisms of action of prebiotics and their effects on the principal gastro-intestinal disorders in adults, with a special focus on Galacto-oligosaccharides, Fructo-oligosaccharides, lactulose and new emerging substances which currently have evidence of prebiotics effects, such as xilooligosaccharides, soybean oligosaccharides, isomaltooligosaccharides, lactobionic acid, resistant starch and polyphenols.

Mechanisms of Action of Prebiotics and Their Effects on Gastro-Intestinal Disorders in Adults

In recent years, research has focused on the use of dietary fibers and prebiotics, since many of these polysaccharides can be metabolized by intestinal microbiota, leading to the production of short-chain fatty acids. The metabolites of prebiotic fermentation also show anti-inflammatory and immunomodulatory capabilities, suggesting an interesting role in the treatment of several pathological conditions. Galacto-oligosaccharide and short- and long-chain fructans (Fructo-oligosaccharides and inulin) are the most studied prebiotics, even if other dietary compounds seem to show the same features. There is an increasing interest in dietary strategies to modulate microbiota. The aim of this review is to explore the mechanisms of action of prebiotics and their effects on the principal gastro-intestinal disorders in adults, with a special focus on Galacto-oligosaccharides, Fructo-oligosaccharides, lactulose and new emerging substances which currently have evidence of prebiotics effects, such as xilooligosaccharides, soybean oligosaccharides, isomaltooligosaccharides, lactobionic acid, resistant starch and polyphenols.

Potential Use of Marine Seaweeds as Prebiotics: A Review

Human gut microbiota plays an important role in several metabolic processes and human diseases. Various dietary factors, including complex carbohydrates, such as polysaccharides, provide abundant nutrients and substrates for microbial metabolism in the gut, affecting the members and their functionality. Nowadays, the main sources of complex carbohydrates destined for human consumption are terrestrial plants. However, fresh water is an increasingly scarce commodity and world agricultural productivity is in a persistent decline, thus demanding the exploration of other sources of complex carbohydrates. As an interesting option, marine seaweeds show rapid growth and do not require arable land, fresh water or fertilizers. The present review offers an objective perspective of the current knowledge surrounding the impacts of seaweeds and their derived polysaccharides on the human microbiome and the profound need for more in-depth investigations into this topic. Animal experiments and in vitro colonic-simulating trials investigating the effects of seaweed ingestion on human gut microbiota are discussed.

Role of Dietary Nutrients in the Modulation of Gut Microbiota: A Narrative Review

Understanding how dietary nutrients modulate the gut microbiome is of great interest for the development of food products and eating patterns for combatting the global burden of non-communicable diseases. In this narrative review we assess scientific studies published from 2005 to 2019 that evaluated the effect of micro- and macro-nutrients on the composition of the gut microbiome using in vitro and in vivo models, and human clinical trials. The clinical evidence for micronutrients is less clear and generally lacking. However, preclinical evidence suggests that red wine- and tea-derived polyphenols and vitamin D can modulate potentially beneficial bacteria. Current research shows consistent clinical evidence that dietary fibers, including arabinoxylans, galacto-oligosaccharides, inulin, and oligofructose, promote a range of beneficial bacteria and suppress potentially detrimental species. The preclinical evidence suggests that both the quantity and type of fat modulate both beneficial and potentially detrimental microbes, as well as the Firmicutes/Bacteroides ratio in the gut. Clinical and preclinical studies suggest that the type and amount of proteins in the diet has substantial and differential effects on the gut microbiota. Further clinical investigation of the effect of micronutrients and macronutrients on the microbiome and metabolome is warranted, along with understanding how this influences host health.

Insights into the role of intestinal microbiota in hematopoietic stem-cell transplantation

The gut microbiota (GM) is able to modulate the human immune system. The development of novel investigation methods has provided better characterization of the GM, increasing our knowledge of the role of GM in the context of hematopoietic stem-cell transplantation (HSCT). In particular, the GM influences the development of the major complications seen after HSCT, having an impact on overall survival. In fact, this evidence highlights the possible therapeutic implications of modulation of the GM during HSCT. Insights into the complex mechanisms and functions of the GM are essential for the rational design of these therapeutics. To date, preemptive and curative approaches have been tested. The current state of understanding of the impact of the GM on HSCT, and therapies targeting the GM balance is reviewed herein.

In vitro versus in situ evaluation of xylan hydrolysis into xylo-oligosaccharides in broiler chicken gastrointestinal tract

Xylan hydrolysis into xylo-oligosaccharides (XOS) was evaluated both in the gizzard and ileum of broiler chickens, and by a 2-step in vitro digestion assay that simulated the pH, temperature and time period of the gastric and small intestine (SI) phases. Twelve dietary treatments with varying soluble and insoluble xylan levels, either with or without supplemental xylanase, were fed to broiler chickens (n = 576) for the in situ analysis, and were exposed to the in vitro assay. Relatedness of the two methods was strong for determination of XOS production in all dietary treatments for X₅, X₄, X₃, X₂ and X_1, respectively, in both the gastric (r = 0.980, 0.853, 0.894, 0.870 and 0.951) and small intestine phase (r = 0.957, 0.923, 0.940, 0.970, 0.969) (P < 0.05). Consequently, the in vitro assay was used to illustrated the diversity of XOS production across different batches of wheat and barley in the presence of xylanase.

Dietary inulin alleviates diverse stages of type 2 diabetes mellitus via anti-inflammation and modulating gut microbiota in db/db mice

Type 2 diabetes mellitus (T2DM) is closely correlated with chronic low-grade inflammation and gut dysbiosis. Prebiotic inulin (INU) is conducive to modulate gut dysbiosis. However, the impact of dietary inulin on the diverse stages of T2DM remains largely unknown. In the present study, according to the fasting blood glucose (FBG) and oral glucose tolerance tests (OGTT), mice were randomly divided into six groups (15 mice per group): pre-diabetic group (PDM group); inulin-treated pre-diabetic group (INU/PDM group); early diabetic group (EDM group); inulin-treated early diabetic group (INU/EDM group); diabetic group (DM group); inulin-treated diabetic group (INU/DM group). All animal experiments were approved by the Ethics Committee of the General Hospital of Ningxia Medical University (No. 2016-232). After 6 weeks of inulin intervention, the mice were euthanized and the associated indicators were investigated. Dietary inulin significantly reduced FBG, body weights (BWs), glycated hemoglobin (GHb), blood lipid, plasma lipopolysaccharide (LPS), interleukin (IL)-6, tumor necrosis factor (TNF)-α and IL-17A in the three inulin-treated groups compared to the untreated groups. But for IL-17A, there remained no significant difference between the PDM group and the INU/PDM group. Moreover, the anti-inflammatory IL-10 showed significant alteration in the INU/PDM and INU/EDM groups, but no significant alteration in the INU/DM group. Sequencing analysis of the gut microbiota showed an elevation in the relative abundance of Cyanobacteria and Bacteroides and a reduction in the relative abundance of Ruminiclostridium_6 in three inulin-treated different stages of T2DM groups, as well as a reduction in the relative abundance of Deferribacteres and Tenericutes in the INU/DM group. A reduction in the relative abundance of Mucispirillum was detected in the INU/PDM and INU/EDM groups. Correlation analysis revealed that Cyanobacteria and Bacteroides abundance were positively correlated with IL-10; Deferribacteres, Tenericutes, Mucispirillum and Ruminiclostridium_6 abundance were closely related to IL-6, TNF-α or IL-17A respectively. Additionally, Mucispirillum and Ruminiclostridium_6 abundance were positively correlated with LPS. Taken together, dietary inulin alleviated the diverse stages of T2DM via suppressing inflammation and modulating gut microbiota.

Relationship Between Dietary Fiber Intake and Short-Chain Fatty Acid-Producing Bacteria During Critical Illness: A Prospective Cohort Study

BACKGROUND

Dietary fiber increases short-chain fatty acid (SCFA)-producing bacteria yet is often withheld in the intensive care unit (ICU). This study evaluated the safety and effect of fiber in ICU patients with gut microbiome sampling.

METHODS

This was a retrospective study nested within a prospective cohort. Adults were included if newly admitted to the ICU and could receive oral nutrition, enteral feedings, or no nutrition. Rectal swabs were performed at admission and 72 hours later. The primary exposure was fiber intake over 72 hours, classified in tertiles and adjusted for energy intake. The primary outcome was the relative abundance (RA) of SCFA producers via 16S RNA sequencing and the tolerability of fiber.

RESULTS

In 129 patients, median fiber intake was 13.4 g (interquartile range 0-35.4 g) over 72 hours. The high-fiber group had less abdominal distension (11% high fiber vs 28% no fiber, P < .01) and no increase in diarrhea (15% high fiber vs 13% no fiber, P = .94) or other adverse events. The median RA of SCFA producers after 72 hours was 0.40%, 0.50%, and 1.8% for the no-, low-, and high-fiber groups (P = .05 for trend). After correcting for energy intake, the median RA of SCFA producers was 0.41%, 0.32%, and 2.35% in the no-, low-, and high-corrected-fiber categories (P < .01). These associations remained significant after adjusting for clinical factors including antibiotics.

CONCLUSIONS

During the 72 hours after ICU admission, fiber was well tolerated, and higher fiber intake was associated with more SCFA-producers.

The role of short-chain fatty acids in microbiota-gut-brain communication

Short-chain fatty acids (SCFAs), the main metabolites produced by bacterial fermentation of dietary fibre in the gastrointestinal tract, are speculated to have a key role in microbiota-gut-brain crosstalk. However, the pathways through which SCFAs might influence psychological functioning, including affective and cognitive processes and their neural basis, have not been fully elucidated. Furthermore, research directly exploring the role of SCFAs as potential mediators of the effects of microbiota-targeted interventions on affective and cognitive functioning is sparse, especially in humans. This Review summarizes existing knowledge on the potential of SCFAs to directly or indirectly mediate microbiota-gut-brain interactions. The effects of SCFAs on cellular systems and their interaction with gut-brain signalling pathways including immune, endocrine, neural and humoral routes are described. The effects of microbiota-targeted interventions such as prebiotics, probiotics and diet on psychological functioning and the putative mediating role of SCFA signalling will also be discussed, as well as the relationship between SCFAs and psychobiological processes. Finally, future directions to facilitate direct investigation of the effect of SCFAs on psychological functioning are outlined.

The Impact of Pectin Supplementation on Intestinal Barrier Function in Healthy Young Adults and Healthy Elderly

Intestinal barrier function is suggested to decrease with aging and may be improved by pectin intake. The aim of this study was to investigate the effects of four weeks pectin supplementation on gastrointestinal barrier function in vivo and ex vivo in different age groups. In a randomized, double-blind, placebo-controlled, parallel study, 52 healthy young adults (18-40 years) and 48 healthy elderly (65-75 years) received 15 g/day pectin or placebo for four weeks. Pre- and post-intervention, in vivo gastrointestinal permeability by a multisugar test, and defense capacity in mucosal samples were assessed. Sigmoid biopsies were collected post-intervention from subgroups for Ussing chamber experiments and gene transcription of barrier-related genes. Pectin intervention did not affect in vivo gastroduodenal, small intestinal, colonic, and whole gut permeability in young adults nor in elderly (p ≥ 0.130). Salivary and fecal sIgA and serum IgA were not significantly different between pectin versus placebo in both age groups (p ≥ 0.128). In both young adults and elderly, no differences in transepithelial electrical resistance and fluorescein flux (p ≥ 0.164) and relative expression of genes analyzed (p ≥ 0.222) were found between pectin versus placebo. In conclusion, intestinal barrier function was not affected by four weeks pectin supplementation neither in healthy young adults nor in healthy elderly.

Perspective: Physiologic Importance of Short-Chain Fatty Acids from Nondigestible Carbohydrate Fermentation

In recent years, it has become increasingly obvious that dietary fiber or nondigestible carbohydrate (NDC) consumption is critical for maintaining optimal health and managing symptoms of metabolic disease. In accordance with this, the US FDA released its first official definition of dietary fiber in 2016 for regulation of Nutrition and Supplement Facts labels. Included in this definition is the requirement of an isolated or synthetic NDC to produce an accepted physiologic health benefit, such as improved laxation or reduced fasting cholesterol concentrations, upon consumption. Even though NDC fermentation and production of short-chain fatty acids elicit many physiologic effects, including serving as a source of energy for colonocytes, curbing glycemic response and satiety, promoting weight loss, enhancing mineral absorption, reducing systemic inflammation, and improving intestinal health, the process of fermentation is not considered a physiologic endpoint. Instead, expensive and laborious clinical trials must be conducted and an accepted physiologic benefit observed. In this review, we discuss the physiologic importance of NDC fermentation through extensive examination of clinical evidence and propose that the degree of fermentability of an NDC, rather than the endpoints of a clinical trial, may be appropriate for classifying it as a dietary fiber.

The path toward using microbial metabolites as therapies

Metabolites have emerged as the quintessential effectors mediating the impact of the commensal microbiome on human physiology, both locally at the sites of microbial colonization and systemically. The endocrine activity of the microbiome and its involvement in a multitude of complex diseases has made microbiome-modulated metabolites an attractive target for the development of new therapies. Several properties make metabolites uniquely suited for interventional strategies: natural occurrence in a broad range of concentrations, functional pleiotropy, ease of administration, and tissue bioavailability. Here, we provide an overview of recently discovered physiological effects of microbiome-associated small molecules that may serve as the first examples of metabolite-based therapies. We also highlight challenges and obstacles that the field needs to overcome on the path toward successful clinical trials of microbial metabolites for human disease.

Prebiotics from Seaweeds: An Ocean of Opportunity?

Seaweeds are an underexploited and potentially sustainable crop which offer a rich source of bioactive compounds, including novel complex polysaccharides, polyphenols, fatty acids, and carotenoids. The purported efficacies of these phytochemicals have led to potential functional food and nutraceutical applications which aim to protect against cardiometabolic and inflammatory risk factors associated with non-communicable diseases, such as obesity, type 2 diabetes, metabolic syndrome, cardiovascular disease, inflammatory bowel disease, and some cancers. Concurrent understanding that perturbations of gut microbial composition and metabolic function manifest throughout health and disease has led to dietary strategies, such as prebiotics, which exploit the diet-host-microbe paradigm to modulate the gut microbiota, such that host health is maintained or improved. The prebiotic definition was recently updated to "a substrate that is selectively utilised by host microorganisms conferring a health benefit", which, given that previous discussion regarding seaweed prebiotics has focused upon saccharolytic fermentation, an opportunity is presented to explore how non-complex polysaccharide components from seaweeds may be metabolised by host microbial populations to benefit host health. Thus, this review provides an innovative approach to consider how the gut microbiota may utilise seaweed phytochemicals, such as polyphenols, polyunsaturated fatty acids, and carotenoids, and provides an updated discussion regarding the catabolism of seaweed-derived complex polysaccharides with potential prebiotic activity. Additional in vitro screening studies and in vivo animal studies are needed to identify potential prebiotics from seaweeds, alongside untargeted metabolomics to decipher microbial-derived metabolites from seaweeds. Furthermore, controlled human intervention studies with health-related end points to elucidate prebiotic efficacy are required.

Potential for enriching next-generation health-promoting gut bacteria through prebiotics and other dietary components

The human intestinal commensal microbiota and associated metabolic products have long been regarded as contributors to host health. As the identity and activities of the various members of this community have become clearer, newly identified health-associated bacteria, such as Faecalibacterium prausnitzii, Akkermansia muciniphila, Ruminococcus bromii and Roseburia species, have emerged. Notably, the abundance of many of these bacteria is inversely correlated to several disease states. While technological and regulatory hurdles may limit the use of strains from these taxa as probiotics, it should be possible to utilize prebiotics and other dietary components to selectively enhance their growth in situ. Dietary components of potential relevance include well-established prebiotics, such as galacto-oligosaccharides, fructo-oligosaccharides and inulin, while other putative prebiotics, such as other oligosaccharides, polyphenols, resistant starch, algae and seaweed as well as host gut metabolites such as lactate and acetate, may also be applied with the aim of selectively and/or differentially affecting the beneficial bacterial community within the gastrointestinal environment. The present review provides an overview of the dietary components that could be applied in this manner.

Prebiotic Supplementation of In Vitro Fecal Fermentations Inhibits Proteolysis by Gut Bacteria, and Host Diet Shapes Gut Bacterial Metabolism and Response to Intervention

Metabolism of protein by gut bacteria is potentially detrimental due to the production of toxic metabolites, such as ammonia, amines, p-cresol, and indole. The consumption of prebiotic carbohydrates results in specific changes in the composition and/or activity of the microbiota that may confer benefits to host well-being and health. Here, we have studied the impact of prebiotics on proteolysis within the gut in vitro Anaerobic stirred batch cultures were inoculated with feces from omnivores (n = 3) and vegetarians (n = 3) and four protein sources (casein, meat, mycoprotein, and soy protein) with and without supplementation by an oligofructose-enriched inulin. Bacterial counts and concentrations of short-chain fatty acids (SCFA), ammonia, phenol, indole, and p-cresol were monitored during fermentation. Addition of the fructan prebiotic Synergy1 increased levels of bifidobacteria (P = 0.000019 and 0.000013 for omnivores and vegetarians, respectively). Branched-chain fatty acids (BCFA) were significantly lower in fermenters with vegetarians' feces (P = 0.004), reduced further by prebiotic treatment. Ammonia production was lower with Synergy1. Bacterial adaptation to different dietary protein sources was observed through different patterns of ammonia production between vegetarians and omnivores. In volunteer samples with high baseline levels of phenol, indole, p-cresol, and skatole, Synergy1 fermentation led to a reduction of these compounds.IMPORTANCE Dietary protein intake is high in Western populations, which could result in potentially harmful metabolites in the gut from proteolysis. In an in vitro fermentation model, the addition of prebiotics reduced the negative consequences of high protein levels. Supplementation with a prebiotic resulted in a reduction of proteolytic metabolites in the model. A difference was seen in protein fermentation between omnivore and vegetarian gut microbiotas: bacteria from vegetarian donors grew more on soy and Quorn than on meat and casein, with reduced ammonia production. Bacteria from vegetarian donors produced less branched-chain fatty acids (BCFA).

Intestinal Barrier Function-Non-alcoholic Fatty Liver Disease Interactions and Possible Role of Gut Microbiota

Non-alcoholic fatty liver disease (NAFLD) is a metabolic stress liver injury that is closely related to obesity, insulin resistance, type 2 diabetes, atherosclerosis, and metabolic syndrome. The pathological features are diffuse hepatic vesicular steatosis, including non-alcoholic steatohepatitis, liver fibrosis, and even liver cancer. A variety of pathological outcomes cause serious harm to human health. At present, an increasing number of researchers are investigating the pathogenesis of NAFLD from the perspective of changes in the function of the intestinal barrier. The physical, chemical, immunological, and microbiological barriers in the intestinal tract constitute the complete intestinal barrier, which plays an important defensive role against the invasion of harmful substances from the intestines. Protecting the function of the intestinal barrier is a new way to treat NAFLD and its related diseases. In this perspective, we summarized the current knowledge of the role of the intestinal barrier in NAFLD.

Dietary fibers as emerging nutritional factors against diabetes: focus on the involvement of gut microbiota

Diabetes mellitus (DM) increases the risk of cardiovascular diseases and other secondary complications, such as nephropathy, neuropathy, retinopathy, etc. The important risk factors for the pathogenesis of DM are aging, family history, sedentary lifestyle, unhealthy dietary habits, and obesity. Evidence from epidemiological studies also indicates that DM is characterized by specific alterations in the human gut microbiota (GM). GM transplantation in rodents and humans revealed that a specific GM constituent can be the cause and not just the consequence of the DM condition and complications. These findings suggest a potential role of GM in human health, disease prevention, and treatment. Dietary intervention studies using dietary fibers (DFs) suggested that modulation of the GM can suppress the metabolic risk markers in humans. However, a causal role of GM in such studies remains unexplored. Long-term follow-up studies disclosed that the diet rich in insoluble and non-viscous fibers are responsible for DF-mediated antidiabetic activities, while soluble and viscous fibers have little influence on DM despite having a profound impact on glycemia. However, general conclusions cannot be drawn simply based on these findings. Long-term follow-up studies are urgently required in this area to explore the therapeutic potential of different DFs in treating DM and to delineate the exact role of GM involvement. Here we review and discuss the signature of GM during DM, antidiabetic activity of metformin via GM modulation, DFs from different sources and their antidiabetic activity, and the possible role of GM involvement.

Shaping the Infant Microbiome With Non-digestible Carbohydrates

Natural polysaccharides with health benefits are characterized by a large structural diversity and differ in building blocks, linkages, and lengths. They contribute to human health by functioning as anti-adhesives preventing pathogen adhesion, stimulate immune maturation and gut barrier function, and serve as fermentable substrates for gut bacteria. Examples of such beneficial carbohydrates include the human milk oligosaccharides (HMOs). Also, specific non-digestible carbohydrates (NDCs), such as galacto-oligosaccharides (GOS) and fructo-oligosaccharides (FOS) are being produced with this purpose in mind, and are currently added to infant formula to stimulate the healthy development of the newborn. They mimic some functions of HMO, but not all. Therefore, many research efforts focus on identification and production of novel types of NDCs. In this review, we give an overview of the few NDCs currently available [GOS, FOS, polydextrose (PDX)], and outline the potential of alternative oligosaccharides, such as pectins, (arabino)xylo-oligosaccharides, and microbial exopolysaccharides (EPS). Moreover, state-of-the-art techniques to generate novel types of dietary glycans, including sialylated GOS (Sia-GOS) and galactosylated chitin, are presented as a way to obtain novel prebiotic NDCs that help shaping the infant microbiome.

Causal Relationship between Diet-Induced Gut Microbiota Changes and Diabetes: A Novel Strategy to Transplant Faecalibacterium prausnitzii in Preventing Diabetes

The incidence of metabolic disorders, including diabetes, has elevated exponentially during the last decades and enhanced the risk of a variety of complications, such as diabetes and cardiovascular diseases. In the present review, we have highlighted the new insights on the complex relationships between diet-induced modulation of gut microbiota and metabolic disorders, including diabetes. Literature from various library databases and electronic searches (ScienceDirect, PubMed, and Google Scholar) were randomly collected. There exists a complex relationship between diet and gut microbiota, which alters the energy balance, health impacts, and autoimmunity, further causes inflammation and metabolic dysfunction, including diabetes. Faecalibacterium prausnitzii is a butyrate-producing bacterium, which plays a vital role in diabetes. Transplantation of F. prausnitzii has been used as an intervention strategy to treat dysbiosis of the gut’s microbial community that is linked to the inflammation, which precedes autoimmune disease and diabetes. The review focuses on literature that highlights the benefits of the microbiota especially, the abundant of F. prausnitzii in protecting the gut microbiota pattern and its therapeutic potential against inflammation and diabetes.

In Vitro Fermentation of Selected Prebiotics and Their Effects on the Composition and Activity of the Adult Gut Microbiota

Recently, the concept of prebiotics has been revisited to expand beyond non-digestible oligosaccharides, and the requirements for selective stimulation were extended to include microbial groups other than, and additional to, bifidobacteria and lactobacilli. Here, the gut microbiota-modulating effects of well-known and novel prebiotics were studied. An in vitro fermentation screening platform (i-screen) was inoculated with adult fecal microbiota, exposed to different dietary fibers that had a range of concentrations (inulin, alpha-linked galacto-oligosaccharides (alpha-GOS), beta-linked GOS, xylo-oligosaccharides (XOS) from corn cobs and high-fiber sugar cane, and beta-glucan from oats), and compared to a positive fructo-oligosaccharide (FOS) control and a negative control (no fiber addition). All dietary fibers displayed prebiotic activity, with beta-glucan showing more distinct effects on the microbial composition and metabolism compared to the other fibers. Beta-glucan induced the growth of Prevotella and Roseburia with a concomitant increase in propionate production. Inulin and both forms of GOS and XOS had a strong bifidogenic effect on the microbial composition. A dose-response effect was observed for butyrate when exposed to beta-glucan and inulin. The findings of this study support the potential for alpha-GOS, XOS, and oat beta-glucan to serve as novel prebiotics, due to their association with the positive shifts in microbiome composition and short-chain fatty acid production that point to potential health benefits.

Integrated Functional-Omics Analysis of Thermomyces lanuginosus Reveals its Potential for Simultaneous Production of Xylanase and Substituted Xylooligosaccharides

Thermophiles have several beneficial properties for the conversion of biomass at high temperatures. Thermomyces lanuginosus is a thermophilic filamentous fungus that was shown to secrete 40 glycoside hydrolases and 25 proteases when grown on different carbon sources. Among the 13 identified glycoside hydrolases with high expression levels, 9 were reduced sugar glycosidases (RSGs) belonging to seven GH families, and 7 of the 10 identified proteases were exopeptidases belonging to six different protease families. High expression of RSGs and exopeptidases may allow the fungus to efficiently degrade oligosaccharides and oligopeptides in saprophytic habitats. There were no xylan side chain-degrading enzymes predicted in the genome of T. lanuginosus, and only one thermophilic GH11 xylanase (g4601.t1) and one GH43 xylosidase (g3706.t1) were detected by liquid chromatography-mass spectrometry/mass spectrometry when T. lanuginosus grown on xylan, which led to the accumulation of substituted xylooligosaccharides (SXOS) during corncob xylan degradation where SXOS output made up more than 8% of the total xylan. The SXOS are beneficial prebiotics and important inducers for enzymes secretion of microorganisms. Thus, T. lanuginosus exhibits distinct advantages in utilizing cheap raw materials producing one thermostable xylanase and the high value-added SXOS as well as microbial inoculants to compost by batch fermentation.

Potential of Fructooligosaccharides and Xylooligosaccharides as Substrates To Counteract the Undesirable Effects of Several Antibiotics on Elder Fecal Microbiota: A First in Vitro Approach

Fructooligosaccharides (FOS) and xylooligosaccharides (XOS) were employed as substrates for in vitro fermentations to assess their capacity to counteract the effects caused by three antibiotics (ABs) at different doses on the elderly gut microbiota and its metabolic activity. The AB type and dose scarcely affected the total bacterial numbers and the microbiota composition after 24 h. However, in the presence of ABs, the relative percentages of Lactobacillus decreased (from 11.4% to 3.2% in the presence of XOS1), as well as the butyrate production, whereas the population of Bacteroides increased significantly in the presence of XOS1 (from 27.5% to 55.7%). FOS were able to counteract these effects by increasing the butyrate production and the number of Lactobacillus, while maintaining the number of Bacteroides almost constant and decreasing the clostridia. XOS2 (mainly DP = 2-4) also showed ability to increase the percentages of Bifidobacterium and the production of both butyrate and acetate.

Endo-xylanases as tools for production of substituted xylooligosaccharides with prebiotic properties

Xylan has a main chain consisting of β-1,4-linked xylose residues with diverse substituents. Endoxylanases cleave the xylan chain at cleavage sites determined by the substitution pattern and thus give different oligosaccharide product patterns. Most known endoxylanases belong to glycoside hydrolase (GH) families 10 and 11. These enzymes work well on unsubstituted xylan but accept substituents in certain subsites. The GH11 enzymes are more restricted by substituents, but on the other hand, they are normally more active than the GH10 enzymes on insoluble substrates, because of their smaller size. GH5 endoxylanases accept arabinose substituents in several subsites and require it in the - 1 subsite. This specificity makes the GH5 endoxylanases very useful for degradation of highly arabinose-substituted xylans and for the selective production of arabinoxylooligosaccharides, without formation of unsubstituted xylooligosaccharides. The GH30 endoxylanases have a related type of specificity in that they require a uronic acid substituent in the - 2 subsite, which makes them very useful for the production of uronic acid substituted oligosaccharides. The ability of dietary xylooligosaccharides to function as prebiotics in humans is governed by their substitution patterns. Endoxylanases are thus excellent tools to tailor prebiotic oligosaccharides to stimulate various types of intestinal bacteria and to cause fermentation in different parts of the gastrointestinal tract. Continuously increasing knowledge on the function of the gut microbiota and discoveries of novel endoxylanases increase the possibilities to achieve health-promoting effects.

Use of a combination of in vitro models to investigate the impact of chlorpyrifos and inulin on the intestinal microbiota and the permeability of the intestinal mucosa

Dietary exposure to the organophosphorothionate pesticide chlorpyrifos (CPF) has been linked to dysbiosis of the gut microbiota. We therefore sought to investigate whether (i) CPF's impact extends to the intestinal barrier and (ii) the prebiotic inulin could prevent such an effect. In vitro models mimicking the intestinal environment (the SHIME®) and the intestinal mucosa (Caco-2/TC7 cells) were exposed to CPF. After the SHIME® had been exposed to CPF and/or inulin, we assessed the system's bacterial and metabolic profiles. Extracts from the SHIME®'s colon reactors were then transferred to Caco-2/TC7 cultures, and epithelial barrier integrity and function were assessed. We found that inulin co-treatment partially reversed CPF-induced dysbiosis and increased short-chain fatty acid production in the SHIME®. Furthermore, co-treatment impacted tight junction gene expression and inhibited pro-inflammatory signaling in the Caco-2/TC7 intestinal cell line. Whereas, an isolated in vitro assessment of CPF and inulin effects provides useful information on the mechanism of dysbiosis, combining two in vitro models increases the in vivo relevance.

Role of prebiotics in regulation of microbiota and prevention of obesity

There is an increasing incidence in non-communicable diseases (NCD) such as obesity, diabetes and metabolic syndrome all over the world, despite of the governmental investments in healthy policies. Some of these diseases represent a high economic burden to individuals and society, demanding urgency in the identification of risk factors and appropriate solutions. Inadequate nutrition habits are an important risk factor for developing these diseases, and the consumption of functional foods such as prebiotics, probiotics, and phenolic compounds may contribute to mitigate them. It has been reported that the consumption of prebiotics can cause positive changes in the intestinal microbiota. The healthy microbiota, consisting mainly of Bifidobacterium and Lactobacillus, ferment prebiotics producing compounds that appear to play a protective role against metabolic diseases. Despite the growing number of publications on the effects of regular consumption of prebiotics in experimental models, additional studies on their effects on humans are needed to bring more subsidies to public health programs. This manuscript aims to review the literature on the possible benefits of ingestion of prebiotics in the control of obesity.

Review article: short chain fatty acids as potential therapeutic agents in human gastrointestinal and inflammatory disorders

BACKGROUND

Butyrate, propionate and acetate are short chain fatty acids (SCFA), important for maintaining a healthy colon and are considered as protective in colorectal carcinogenesis. However, they may also regulate immune responses and the composition of the intestinal microbiota. Consequently, their importance in a variety of chronic inflammatory diseases is emerging.

AIMS

To review the physiology and metabolism of SCFA in humans, cellular and molecular mechanisms by which SCFA may act in health and disease, and approaches for therapeutic delivery of SCFA.

METHODS

A PubMed literature search was conducted for clinical and pre-clinical studies using search terms: 'dietary fibre', short-chain fatty acids', 'acetate', 'propionate', 'butyrate', 'inflammation', 'immune', 'gastrointestinal', 'metabolism'.

RESULTS

A wide range of pre-clinical evidence supports roles for SCFA as modulators of not only colonic function, but also multiple inflammatory and metabolic processes. SCFA are implicated in many autoimmune, allergic and metabolic diseases. However, translating effects of SCFA from animal studies to human disease is limited by physiological and dietary differences and by the challenge of delivering sufficient amounts of SCFA to the target sites that include the colon and the systemic circulation. Development of novel targeted approaches for colonic delivery, combined with postbiotic supplementation, may represent desirable strategies to achieve adequate targeted SCFA delivery.

CONCLUSIONS

There is a large array of potential disease-modulating effects of SCFA. Adequate targeted delivery to the sites of action is the main limitation of such application. The ongoing development and evaluation of novel delivery techniques offer potential for translating promise to therapeutic benefit.

Dietary fiber intervention on gut microbiota composition in healthy adults: a systematic review and meta-analysis

Background

Dysfunction of the gut microbiota is frequently reported as a manifestation of chronic diseases, and therefore presents as a modifiable risk factor in their development. Diet is a major regulator of the gut microbiota, and certain types of dietary fiber may modify bacterial numbers and metabolism, including short-chain fatty acid (SCFA) generation.

Objective

A systematic review and meta-analysis were undertaken to assess the effect of dietary fiber interventions on gut microbiota composition in healthy adults.

Design

A systematic search was conducted across MEDLINE, EMBASE, CENTRAL, and CINAHL for randomized controlled trials using culture and/or molecular microbiological techniques evaluating the effect of fiber intervention on gut microbiota composition in healthy adults. Meta-analyses via a random-effects model were performed on alpha diversity, prespecified bacterial abundances including Bifidobacterium and Lactobacillus spp., and fecal SCFA concentrations comparing dietary fiber interventions with placebo/low-fiber comparators.

Results

A total of 64 studies involving 2099 participants were included. Dietary fiber intervention resulted in higher abundance of Bifidobacterium spp. (standardized mean difference (SMD): 0.64; 95% CI: 0.42, 0.86; P < 0.00001) and Lactobacillus spp. (SMD: 0.22; 0.03, 0.41; P = 0.02) as well as fecal butyrate concentration (SMD: 0.24; 0.00, 0.47; P = 0.05) compared with placebo/low-fiber comparators. Subgroup analysis revealed that fructans and galacto-oligosaccharides led to significantly greater abundance of both Bifidobacterium spp. and Lactobacillus spp. compared with comparators (P < 0.00001 and P = 0.002, respectively). No differences in effect were found between fiber intervention and comparators for α-diversity, abundances of other prespecified bacteria, or other SCFA concentrations.

Conclusions

Dietary fiber intervention, particularly involving fructans and galacto-oligosaccharides, leads to higher fecal abundance of Bifidobacterium and Lactobacillus spp. but does not affect α-diversity. Further research is required to better understand the role of individual fiber types on the growth of microbes and the overall gut microbial community. This review was registered at PROSPERO as CRD42016053101.

Transcriptomic Analysis of Xylan Oligosaccharide Utilization Systems in Pediococcus acidilactici Strain BCC-1

Xylan oligosaccharides (XOS) are the hydrolysates of xylan. To compare the proliferation effect of XOS, glucose, fructo oligosaccharides (FOS), xylose, XOS, and a media without carbohydrate source (control) on Pediococcus acidilactici strain BCC-1, the de novo sequencing of Pediococcus acidilactici strain BCC-1 was conducted, and the underlying mechanism of prebiotic xylo oligosaccharide between xylose and XOS was revealed through transcriptomic analysis. Compared to FOS, glucose, and xylose, XOS exhibits a good performance in promoting the fermentation of Pediococcus acidilactici BCC-1. The genome of Pediococcus acidilactici BCC-1 revealed genes encoding XOS transportation and utilized related enzymes, including ATP-binding cassette (ABC) transporters, arabinofuranosidase, xylanase, xylosidase, xylose isomerase, and xylulose kinase. Transcriptome analysis showed that XOS treatment enhanced genes involving carbohydrate metabolism, an ABC transporter sugar system, pentose and glucuronate interconversions, pyruvate metabolism, and the TCA process when compared to xylose treatment. It suggested XOS treatment enhanced sugar absorption and utilization. These results are useful in the understanding of the metabolic pathway of XOS in Pediococcus acidilactici BBC-1 and may contribute to the optimization of the probiotic effect of Pediococcus acidilactici BCC-1 as novel complex feed additives.

The Role of Prebiotics and Probiotics in Gastrointestinal Disease

With the advent of the scientific realization that the microbiota of the gastrointestinal tract was more than the cells that exist in the body, the full importance of prebiotics and probiotics has come forth. The importance has been stressed and is available in the new textbook entitled, "The Microbiota in Gastrointestinal Pathophysiology: Implication for Human Health, Prebiotics, Probiotics and Dysbiosis." There is enough evidence now published in the literature so that the scientific world now believes that prebiotics and probiotics are important in gastrointestinal disease.

Microbial Mechanistic Insight into the Role of Inulin in Improving Maternal Health in a Pregnant Sow Model

General consumption of “western diet” characterized by high refined carbohydrates, fat and energy intake has resulted in a global obesity epidemics and related metabolic disturbance even for pregnant women. Pregnancy process is accompanied by substantial hormonal, metabolic and immunological changes during which gut microbiota is also remarkably remodeled. Dietary fiber has been demonstrated to have a striking role in shifting the microbial composition so as to improve host metabolism and health in non-pregnant individuals. The present study was conducted to investigate effects of adding a soluble dietary fiber inulin (0 or 1.5%) to low- or high- fat (0 or 5% fat addition) gestational diet on maternal and neonatal health and fecal microbial composition in a sow model. Results showed that inulin addition decreased the gestational body weight gain and fat accumulation induced by fat addition. Circulating concentrations of pro-inflammatory cytokine IL-6, adipokine leptin and chemerin were decreased by inulin supplementation. Inulin addition remarkably reduced the average BMI of newborn piglets and the within litter BMI distributions (%) ranging between 17 and 20 kg/m², and increased the BMI distribution ranging between 14 and 17 kg/m². 16S rRNA gene sequencing of the V3-V4 region showed that fecal microbial changes at different taxonomic levels triggered by inulin addition predisposed the pregnant sow to be thinner and lower inflammatory. Meanwhile, fecal microbial composition was also profoundly altered by gestation stage with distinct changes occurring at perinatal period. Most representative volatile fatty acid (VFA) producing-related genera changed dramatically when reaching the perinatal period and varied degrees of increases were detected with inulin addition. Fecal VFA concentrations failed to show any significant effect with dietary intervention, however, were markedly increased at perinatal period. Our findings indicate that positive microbial changes resulted by 1.5% soluble fiber inulin addition would possibly be the potential mechanisms under which maternal body weight, metabolic and inflammatory status and neonatal BMI were improved. Besides, distinct changes of microbial community at perinatal period indicated the mother sow is undergoing a catabolic state with increased energy loss and inflammation response at that period compared with other stages of gestation.