Non-digestible carbohydrates in infant formula as substitution for human milk oligosaccharide functions: Effects on microbiota and gut maturation

Galacto-oligosaccharides as infant prebiotics: production, application, bioactive activities and future perspectives

Galacto-oligosaccharides (GOS) are non-digestible oligosaccharides characterized by a mix of structures that vary in their degree of polymerization (DP) and glycosidic linkage between the galactose moieties or between galactose and glucose. They have enjoyed extensive scientific scrutiny, and their health-promoting effects are supported by a large number of scientific and clinical studies. A variety of GOS-associated health-promoting effects have been reported, such as growth promotion of beneficial bacteria, in particular bifidobacteria and lactobacilli, inhibition of pathogen adhesion and improvement of gut barrier function. GOS have attracted significant interest from food industries for their versatility as a bioactive ingredient and in particular as a functional component of infant formulations. These oligosaccharides are produced in a kinetically-controlled reaction involving lactose transgalactosylation, being catalyzed by particular β-galactosidases of bacterial or fungal origin. Despite the well-established technology applied for GOS production, this process may still meet with technological challenges when employed at an industrial scale. The current review will cover relevant scientific literature on the beneficial physiological properties of GOS as a prebiotic for the infant gut microbiota, details of GOS structures, the associated reaction mechanism of β-galactosidase, and its (large-scale) production.

Structure-Specific Fermentation of Galacto-Oligosaccharides, Isomalto-Oligosaccharides and Isomalto/Malto-Polysaccharides by Infant Fecal Microbiota and Impact on Dendritic Cell Cytokine Responses

SCOPE

Next to galacto-oligosaccharides (GOS), starch-derived isomalto-oligosaccharide preparation (IMO) and isomalto/malto-polysaccharides (IMMP) could potentially be used as prebiotics in infant formulas. However, it remains largely unknown how the specific molecular structures of these non-digestible carbohydrates (NDCs) impact fermentability and immune responses in infants.

METHODS AND RESULTS

In vitro fermentation of GOS, IMO and IMMP using infant fecal inoculum of 2- and 8-week-old infants shows that only GOS and IMO are fermented by infant fecal microbiota. The degradation of GOS and IMO coincides with an increase in Bifidobacterium and production of acetate and lactate, which is more pronounced with GOS. Individual isomers with an (1↔1)-linkage or di-substituted reducing terminal glucose residue are more resistant to fermentation. GOS, IMO, and IMMP fermentation digesta attenuates cytokine profiles in immature dendritic cells (DCs), but the extent is dependent on the infants age and NDC structure.

CONCLUSION

The IMO preparation, containing reducing and non-reducing isomers, shows similar fermentation patterns as GOS in fecal microbiota of 2-week-old infants. Knowledge obtained on the substrate specificities of infant fecal microbiota and the subsequent regulatory effects of GOS, IMO and IMMP on DC responses might contribute to the design of tailored NDC mixtures for infants of different age groups.

Human milk oligosaccharides and non-digestible carbohydrates prevent adhesion of specific pathogens via modulating glycosylation or inflammatory genes in intestinal epithelial cells

Human milk oligosaccharides (hMOs) and non-digestible carbohydrates (NDCs) are known to inhibit the adhesion of pathogens to the gut epithelium, but the mechanisms involved are not well understood. Here, the effects of 2'-FL, 3-FL, DP3-DP10, DP10-DP60 and DP30-DP60 inulins and DM7, DM55 and DM69 pectins were studied on pathogen adhesion to Caco-2 cells. As the growth phase influences virulence, E. coli ET8, E. coli LMG5862, E. coli O119, E. coli WA321, and S. enterica subsp. enterica LMG07233 from both log and stationary phases were tested. Specificity for enteric pathogens was tested by including the lung pathogen K. pneumoniae LMG20218. Expression of the cell membrane glycosylation genes of galectin and glycocalyx and inflammatory genes was studied in the presence and absence of 2'-FL or NDCs. Inhibition of pathogen adhesion was observed for 2'-FL, inulins, and pectins. Pre-incubation with 2'-FL downregulated ICAM1, and pectins modified the glycosylation genes. In contrast, K. pneumoniae LMG20218 downregulated the inflammatory genes, but these were restored by pre-incubation with pectins, which reduced the adhesion of K. pneumoniae LMG20218. In addition, DM69 pectin significantly upregulated the inflammatory genes. 2'-FL and pectins but not inulins inhibited pathogen adhesion to the gut epithelial Caco-2 cells through changing the cell membrane glycosylation and inflammatory genes, but the effects were molecule-, pathogen-, and growth phase-dependent.

Changes in HMO Concentrations throughout Lactation: Influencing Factors, Health Effects and Opportunities

Human milk oligosaccharides (HMOs) are important functional biomolecules in human breast milk. Understanding the factors influencing differences in HMO composition and changes in their concentration over lactation can help to design feeding strategies that are well-adapted to infant's needs. This review summarises the total and individual concentration of HMOs from data published from 1999 to 2019. Studies show that the HMO concentrations are highest in colostrum (average 9-22 g/L), followed by slightly lower concentrations in transitional milk (average 8-19 g/L), with a gradual decline in mature milk as lactation progresses, from 6-15 g/L in breast milk collected within one month of birth, to 4-6 g/L after 6 months. Significant differences in HMO composition have been described between countries. Different HMOs were shown to be predominant over the course of lactation, e.g., 3-fucosyllactose increased over lactation, whereas 2'-fucosyllactose decreased. Recent clinical studies on infant formula supplemented with 2'-fucosyllactose in combination with other oligosaccharides showed its limited beneficial effect on infant health.

Acceleration of Small Intestine Development and Remodeling of the Microbiome Following Hyaluronan 35 kDa Treatment in Neonatal Mice

The beneficial effects of human milk suppressing the development of intestinal pathologies such as necrotizing enterocolitis in preterm infants are widely known. Human milk (HM) is rich in a multitude of bioactive factors that play major roles in promoting postnatal maturation, differentiation, and the development of the microbiome. Previous studies showed that HM is rich in hyaluronan (HA) especially in colostrum and early milk. This study aims to determine the role of HA 35 KDa, a HM HA mimic, on intestinal proliferation, differentiation, and the development of the intestinal microbiome. We show that oral HA 35 KDa supplementation for 7 days in mouse pups leads to increased villus length and crypt depth, and increased goblet and Paneth cells, compared to controls. We also show that HA 35 KDa leads to an increased predominance of Clostridiales Ruminococcaceae, Lactobacillales Lactobacillaceae, and Clostridiales Lachnospiraceae. In seeking the mechanisms involved in the changes, bulk RNA seq was performed on samples from the terminal ileum and identified upregulation in several genes essential for cellular growth, proliferation, and survival. Taken together, this study shows that HA 35 KDa supplemented to mouse pups promotes intestinal epithelial cell proliferation, as well as the development of Paneth cells and goblet cell subsets. HA 35 KDa also impacted the intestinal microbiota; the implications of these responses need to be determined.

Microbial Glycoside Hydrolases in the First Year of Life: An Analysis Review on Their Presence and Importance in Infant Gut

The first year of life is a crucial period during which the composition and functionality of the gut microbiota develop to stabilize and resemble that of adults. Throughout this process, the gut microbiota has been found to contribute to the maturation of the immune system, in gastrointestinal physiology, in cognitive advancement and in metabolic regulation. Breastfeeding, the “golden standard of infant nutrition,” is a cornerstone during this period, not only for its direct effect but also due to its indirect effect through the modulation of gut microbiota. Human milk is known to contain indigestible carbohydrates, termed human milk oligosaccharides (HMOs), that are utilized by intestinal microorganisms. Bacteria that degrade HMOs like Bifidobacterium longum subsp. infantis, Bifidobacterium bifidum, and Bifidobacterium breve dominate the infant gut microbiota during breastfeeding. A number of carbohydrate active enzymes have been found and identified in the infant gut, thus supporting the hypothesis that these bacteria are able to degrade HMOs. It is suggested that via resource-sharing and cross-feeding, the initial utilization of HMOs drives the interplay within the intestinal microbial communities. This is of pronounced importance since these communities promote healthy development and some of their species also persist in the adult microbiome. The emerging production and accessibility to metagenomic data make it increasingly possible to unravel the metabolic capacity of entire ecosystems. Such insights can increase understanding of how the gut microbiota in infants is assembled and makes it a possible target to support healthy growth. In this manuscript, we discuss the co-occurrence and function of carbohydrate active enzymes relevant to HMO utilization in the first year of life, based on publicly available metagenomic data. We compare the enzyme profiles of breastfed children throughout the first year of life to those of formula-fed infants.

Impact of dietary fibers in infant formulas on gut microbiota and the intestinal immune barrier

Human milk (HM) is the gold standard for the nutrition of infants. An important component of HM is human milk oligosaccharides (hMOs), which play an important role in gut microbiota colonization and gut immune barrier establishment, and thereby contribute to the maturation of the immune system in early life. Guiding these processes is important as disturbances have life-long health effects and can lead to the development of allergic diseases. Unfortunately, not all infants can be exclusively fed with HM. These infants are routinely fed with infant formulas that contain hMO analogs and other non-digestible carbohydrates (NDCs) to mimic the effects of hMOs. Currently, the hMO analogs 2'-fucosyllactose (2'-FL), galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), and pectins are added to infant formulas; however, these NDCs cannot mimic all hMO functions and therefore new NDCs and NDC mixtures need to become available for specific groups of neonates like preterm and disease-prone neonates. In this review, we discuss human data on the beneficial effects of infant formula supplements such as the specific hMO analog 2'-FL and NDCs as well as their mechanism of effects like stimulation of microbiota development, maturation of different parts of the gut immune barrier and anti-pathogenic effects. Insights into the structure-specific mechanisms by which hMOs and NDCs exert their beneficial functions might contribute to the development of new tailored NDCs and NDC mixtures. We also describe the needs for new in vitro systems that can be used for research on hMOs and NDCs. The current data suggest that "tailored infant formulas" for infants of different ages and healthy statuses are needed to ensure a healthy development of the microbiota and the gut immune system of infants.

Bioactive Compounds in Infant Formula and Their Effects on Infant Nutrition and Health: A Systematic Literature Review

Infant formulas are an alternative to replace or supplement human milk when breastfeeding is not possible. The knowledge of human milk's bioactive compounds and their beneficial effects has attracted the interest of researchers in the field of infant nutrition, as well as researchers of technology and food sciences that seek to improve the nutritional characteristics of infant formulas. Several scientific studies evaluate the optimization of infant formula composition. The bioactive compound inclusion has been used to upgrade the quality and nutrition of infant formulas. In this context, the purpose of this systematic literature review is to assess the scientific evidence of bioactive compounds present in infant formulas (α-lactalbumin, lactoferrin, taurine, milk fat globule membrane, folates, polyamines, long-chain polyunsaturated fatty acids, prebiotics, and probiotics) and their effects on infant nutrition and health. Through previously determined criteria, studies published in the last fifteen years from five different databases were included to identify the advances in the optimization of infant formula composition. Over the last few years, there has been optimization of the infant formula composition, not only to increase the similarities in their content of macro and micronutrients but also to include novel bioactive ingredients with potential health benefits for infants. Although the infant food industry has advanced in the last years, there is no consensus on whether novel bioactive ingredients added to infant formulas have the same functional effects as the compounds found in human milk. Thus, further studies about the impact of bioactive compounds in infant nutrition are fundamental to infant health.

Administration of Bovine Milk Oligosaccharide to Weaning Gnotobiotic Mice Inoculated with a Simplified Infant Type Microbiota

Bovine milk oligosaccharides (BMO) share structural similarity to selected human milk oligosaccharides, which are natural prebiotics for infants. Thus, there is a potential in including BMOs as a prebiotic in infant formula. To examine the in vivo effect of BMO-supplementation on the infant gut microbiota, a BMO-rich diet (2% w/w) was fed to gnotobiotic mice (n = 11) inoculated with an infant type co-culture and compared with gnotobiotic mice receiving a control diet (n = 9). Nuclear magnetic resonance metabolomics in combination with high-throughput 16S rRNA gene amplicon sequencing was used to compare metabolic activity and microbiota composition in different compartments of the lower gastrointestinal tract. BMO components were detected in cecum and colon contents, revealing that BMO was available for the gut bacteria. The gut microbiota was dominated by Enterobacteriaceae and minor abundance of Lactobacilliaceae, while colonization of Bifidobacteriaceae did not succeed. Apart from a lower E. coli population in cecum content and lower formate (in colon) and succinate (in colon and cecum) concentrations, BMO supplementation did not result in significant changes in microbiota composition nor metabolic activity. The present study corroborates the importance of the presence of bifidobacteria for obtaining microbial-derived effects of milk oligosaccharides in the gastrointestinal tract.

Gut dysbiosis during early life: causes, health outcomes, and amelioration via dietary intervention

The colonization and maturation of gut microbiota (GM) is a delicate and precise process, which continues to influence not only infancy and childhood but also adulthood health by affecting immunity. However, many perinatal factors, including gestational age, delivery mode, antibiotic administration, feeding mode, and environmental and maternal factors, can disturb this well-designed process, increasing the morbidity of various gut dysbiosis-related diseases, such as type-1-diabetes, allergies, necrotizing enterocolitis, and obesity. In this review, we discussed the early-life colonization and maturation of the GM, factors influencing this process, and diseases related to the disruption of this process. Moreover, we focused on discussing dietary interventions, including probiotics, oligosaccharides, nutritional supplementation, and exclusive enteral nutrition, in ameliorating early-life dysbiosis and diseases related to it. Furthermore, possible mechanisms, and shortcomings, as well as potential solutions to the drawbacks of dietary interventions, were also discussed.

Human Milk Microbiota and Oligosaccharides: A Glimpse into Benefits, Diversity, and Correlations

Human milk represents a cornerstone for growth and development of infants, with extensive array of benefits. In addition to exceptionally nutritive and bioactive components, human milk encompasses a complex community of signature bacteria that helps establish infant gut microbiota, contributes to maturation of infant immune system, and competitively interferes with pathogens. Among bioactive constituents of milk, human milk oligosaccharides (HMOs) are particularly significant. These are non-digestible carbohydrates forming the third largest solid component in human milk. Valuable effects of HMOs include shaping intestinal microbiota, imparting antimicrobial effects, developing intestinal barrier, and modulating immune response. Moreover, recent investigations suggest correlations between HMOs and milk microbiota, with complex links possibly existing with environmental factors, genetics, geographical location, and other factors. In this review, and from a physiological and health implications perspective, milk benefits for newborns and mothers are highlighted. From a microbiological perspective, a focused insight into milk microbiota, including origins, diversity, benefits, and effect of maternal diet is presented. From a metabolic perspective, biochemical, physiological, and genetic significance of HMOs, and their probable relations to milk microbiota, are addressed. Ongoing research into mechanistic processes through which the rich biological assets of milk promote development, shaping of microbiota, and immunity is tackled.

Combination-Feeding Causes Differences in Aspects of Systemic and Mucosal Immune Cell Phenotypes and Functions Compared to Exclusive Sow-Rearing or Formula-Feeding in Piglets

Combination feeding (human milk and formula) is common and influences immune development compared to exclusive breastfeeding. Infant formulas contain prebiotics, which influence immune development. Herein, immune development of combination-fed (CF), sow-reared (SR) and formula-fed (FF) piglets, and the effect of prebiotics was tested. Piglets (n = 47) were randomized to: SR, FF, CF, FF+prebiotic (FP), and CF+prebiotic (CP). FP and CP received formula with galactooligosaccharides and inulin (4 g/L in a 4:1 ratio). CF and CP piglets were sow-reared for until d5 and then rotated between a sow and formula every 12 h. On day 21, piglets received an intraperitoneal injection of lipopolysaccharide 2 h prior to necropsy. Immune cells from blood, mesenteric lymph nodes (MLN), and spleen were phenotyped. Classical (nitric oxide synthase) and alternative (arginase activity) activation pathways were measured in isolated macrophages. Serum IL-6 and TNF-α were measured by ELISA. SR piglets had lower (p < 0.0001) CD4+ T-helper cells and higher (p < 0.0001) B-cells in PBMC than all other groups. CP piglets had higher (p < 0.0001) arginase activity compared to all other groups. FF piglets had higher (p < 0.05) IL-6 compared to both CF and SR, but were similar to FP and CP. Thus, CF, with or without prebiotics, differentially affected immunity compared to exclusively fed groups.

Breast Milk: A Source of Functional Compounds with Potential Application in Nutrition and Therapy

Breast milk is an unbeatable food that covers all the nutritional requirements of an infant in its different stages of growth up to six months after birth. In addition, breastfeeding benefits both maternal and child health. Increasing knowledge has been acquired regarding the composition of breast milk. Epidemiological studies and epigenetics allow us to understand the possible lifelong effects of breastfeeding. In this review we have compiled some of the components with clear functional activity that are present in human milk and the processes through which they promote infant development and maturation as well as modulate immunity. Milk fat globule membrane, proteins, oligosaccharides, growth factors, milk exosomes, or microorganisms are functional components to use in infant formulas, any other food products, nutritional supplements, nutraceuticals, or even for the development of new clinical therapies. The clinical evaluation of these compounds and their commercial exploitation are limited by the difficulty of isolating and producing them on an adequate scale. In this work we focus on the compounds produced using milk components from other species such as bovine, transgenic cattle capable of expressing components of human breast milk or microbial culture engineering.

Plant Prebiotics and Their Role in the Amelioration of Diseases

Prebiotics are either natural or synthetic non-digestible (non-)carbohydrate substances that boost the proliferation of gut microbes. Undigested fructooligosaccharides in the large intestine are utilised by the beneficial microorganisms for the synthesis of short-chain fatty acids for their own growth. Although various food products are now recognized as having prebiotic properties, several others, such as almonds, artichoke, barley, chia seeds, chicory, dandelion greens, flaxseeds, garlic, and oats, are being explored and used as functional foods. Considering the benefits of these prebiotics in mineral absorption, metabolite production, gut microbiota modulation, and in various diseases such as diabetes, allergy, metabolic disorders, and necrotising enterocolitis, increasing attention has been focused on their applications in both food and pharmaceutical industries, although some of these food products are actually used as food supplements. This review aims to highlight the potential and need of these prebiotics in the diet and also discusses data related to the distinct types, sources, modes of action, and health benefits.

The influence of soy protein hydrolysate (SPH) addition to infant formula powder on Streptococcus thermophilus proliferation and metabolism

Nowadays, more and more infants are getting allergic to cow's milk protein, so it is urgent to search for infant formula powder with milk protein alternatives. In the present work, soy protein hydrolysate (SPH) was added to protein-free infant formula powder and the effects of SPH addition on proliferation and metabolism of Streptococcus thermophilus were studied. Compared with commercially available infant formula powder (CK) and protein-free milk powder (BK), the infant formula powder with 20% SPH significantly enhanced the proliferation of S. thermophilus in MRS medium, resulting in a higher cell density and greater viable counts. Moreover, the influence of SPH on the metabolism of S. thermophilus was investigated by analyzing the content of seven organic acids and H₂O₂ in the medium_. The higher content of organic acids and H₂O₂ is consistent with the stronger antibacterial activity to Escherichia coli. As a consequence, the addition of SPH to infant formula powder can effectively promote the growth of probiotics and SPH may be a promising protein alternative in the infant formula powder.

Current Perspective of Sialylated Milk Oligosaccharides in Mammalian Milk: Implications for Brain and Gut Health of Newborns

Human milk oligosaccharides (HMOs) are the third most abundant solid component after lactose and lipids of breast milk. All mammal milk contains soluble oligosaccharides, including neutral milk oligosaccharides (NMOs) without sialic acid (Sia) moieties and acidic oligosaccharides or sialylated milk oligosaccharides (SMOs) with Sia residues at the end of sugar chains. The structural, biological diversity, and concentration of milk oligosaccharides in mammalian milk are significantly different among species. HMOs have multiple health benefits for newborns, including development of immune system, modification of the intestinal microbiota, anti-adhesive effect against pathogens, and brain development. Most infant formulas lack oligosaccharides which resemble HMOs. Formula-fed infants perform poorly across physical and psychological wellbeing measures and suffer health disadvantages compared to breast-fed infants due to the differences in the nutritional composition of breast milk and infant formula. Of these milk oligosaccharides, SMOs are coming to the forefront of research due to the beneficial nature of Sia. This review aims to critically discuss the current state of knowledge of the biology and role of SMOs in human milk, infant formula milks, and milk from several other species on gut and brain health of human and animal offspring.

The pleiotropic effects of prebiotic galacto-oligosaccharides on the aging gut

BACKGROUND

Prebiotic galacto-oligosaccharides (GOS) have an extensively demonstrated beneficial impact on intestinal health. In this study, we determined the impact of GOS diets on hallmarks of gut aging: microbiome dysbiosis, inflammation, and intestinal barrier defects ("leaky gut"). We also evaluated if short-term GOS feeding influenced how the aging gut responded to antibiotic challenges in a mouse model of Clostridioides difficile infection. Finally, we assessed if colonic organoids could reproduce the GOS responder-non-responder phenotypes observed in vivo.

RESULTS

Old animals had a distinct microbiome characterized by increased ratios of non-saccharolytic versus saccharolytic bacteria and, correspondingly, a lower abundance of β-galactosidases compared to young animals. GOS reduced the overall diversity, increased the abundance of specific saccharolytic bacteria (species of Bacteroides and Lactobacillus), increased the abundance of β-galactosidases in young and old animals, and increased the non-saccharolytic organisms; however, a robust, homogeneous bifidogenic effect was not observed. GOS reduced age-associated increased intestinal permeability and increased MUC2 expression and mucus thickness in old mice. Clyndamicin reduced the abundance Bifidobacterium while increasing Akkermansia, Clostridium, Coprococcus, Bacillus, Bacteroides, and Ruminococcus in old mice. The antibiotics were more impactful than GOS on modulating serum markers of inflammation. Higher serum levels of IL-17 and IL-6 were observed in control and GOS diets in the antibiotic groups, and within those groups, levels of IL-6 were higher in the GOS groups, regardless of age, and higher in the old compared to young animals in the control diet groups. RTqPCR revealed significantly increased gene expression of TNFα in distal colon tissue of old mice, which was decreased by the GOS diet. Colon transcriptomics analysis of mice fed GOS showed increased expression of genes involved in small-molecule metabolic processes and specifically the respirasome in old animals, which could indicate an increased oxidative metabolism and energetic efficiency. In young mice, GOS induced the expression of binding-related genes. The galectin gene Lgals1, a β-galactosyl-binding lectin that bridges molecules by their sugar moieties and is an important modulator of the immune response, and the PI3K-Akt and ECM-receptor interaction pathways were also induced in young mice. Stools from mice exhibiting variable bifidogenic response to GOS injected into colon organoids in the presence of prebiotics reproduced the response and non-response phenotypes observed in vivo suggesting that the composition and functionality of the microbiota are the main contributors to the phenotype.

CONCLUSIONS

Dietary GOS modulated homeostasis of the aging gut by promoting changes in microbiome composition and host gene expression, which was translated into decreased intestinal permeability and increased mucus production. Age was a determining factor on how prebiotics impacted the microbiome and expression of intestinal epithelial cells, especially apparent from the induction of galectin-1 in young but not old mice. Video abstract.

Impact of dietary components on enteric infectious disease

Diets impact host health in multiple ways and an unbalanced diet could contribute to the initiation or progression of a variety of diseases. Although a wealth of information exists on the connections between diet and chronic metabolic diseases such as cardiovascular disease, diabetes mellitus, etc., how diet influences enteric infectious disease still remain underexplored. The review summarizes the current findings on the link between various dietary components and diverse enteric infectious diseases. Dietary ingredients discussed include macronutrients (carbohydrates, lipids, proteins), micronutrients (vitamins, minerals), and other dietary ingredients (phytonutrients and probiotic supplements). We first describe the importance of enteric infectious diseases and the direct and indirect relationship between diet and enteric infectious diseases. Then we discuss the effects of different dietary components on the susceptibility to or progression of enteric infectious disease. Finally, we delineate current knowledge gap and highlighted future research directions. The literature review revealed that different dietary components affect host resistance to enteric infections through a variety of mechanisms. Dietary components may directly inhibit or bind to enteric pathogens, or indirectly influence enteric infections through modulating immune function and gut microbiota. Elucidating the unique repercussions of different diets on enteric infections in this review may help provide dietary guidelines or design dietary interventions to prevent or alleviate enteric infectious diseases.

Selective Utilization of the Human Milk Oligosaccharides 2'-Fucosyllactose, 3-Fucosyllactose, and Difucosyllactose by Various Probiotic and Pathogenic Bacteria

Prebiotic human milk oligosaccharides (HMOs) are found in human milk, which are not digested by infants but are metabolized by beneficial gut bacteria. We determined the ability of 57 bacterial strains within the Family Lactobacillaceae and genera Bifidobacterium and Bacteroides and potentially pathogenic bacteria to ferment the HMOs 2'-fucosyllactose, 3-fucosyllactose, and difucosyllactose. In addition, prebiotic galacto-oligosaccharides (GOS), lactose, fucose, and glucose were evaluated as carbon sources for these bacterial strains. Bacterial growth was monitored using the automatic Bioscreen C system. Only certain bifidobacteria, such as Bifidobacterium longum subsp. infantis and Bifidobacterium bifidum, as well as Bacteroides fragilis, Bacteroides vulgatus, and Bacteroides thetaiotaomicron utilized the studied HMOs as their sole carbon source, whereas almost all studied bacterial strains were able to utilize GOS, lactose, and glucose. The selectivity in utilization of HMOs by only certain bacteria can be advantageous by promoting beneficial microbes but not supporting the harmful pathogens in contrast to other less selective prebiotics.

Role of IgA in the early-life establishment of the gut microbiota and immunity: Implications for constructing a healthy start

Colonization and maturation of the gut microbiota (GM) during early life is a landmark event that fundamentally influences the (early) immunity and later-life health of various mammals. This is a delicate, systematic process that is biologically actively regulated by infants and their mothers, where (secretory) IgA, an important regulator of microbes found in breast milk and generated actively by infants, may play a key role. By binding to microbes, IgA can inhibit or enhance their colonization, influence their gene expression, and regulate immune responses. IgA dysfunction during early life is associated with disrupted GM maturation and various microbe-related diseases, such as necrotizing enterocolitis and diarrhea, which can also have a lasting effect on GM and host health. This review discusses the process of early GM maturation and its interaction with immunity and the role of IgA (focusing on milk secretory IgA) in regulating this process. The possible application of this knowledge in promoting normal GM maturation processes and immune education has also been highlighted.

Human milk bank and personalized nutrition in the NICU: a narrative review

The number of infants born preterm including extremely premature babies is rising worldwide, particularly in low- and middle-income countries, which challenge neonatologists and milk banks for the provision of the most adequate nutrition for successful infant's growth and development. The benefits of mother's own milk (MOM) have been extensively recognized, but the use of donor milk (DM) is a commonly routine practice in preterm neonates admitted to the NICU. Pasteurized mature milk from milk banks is not the same composition than the mother's colostrum and premature milk, the characteristics of which protect the infant from the risk for necrotizing enterocolitis, late-onset sepsis, and other comorbidities associated with prematurity. The development of a personalized nutrition unit (PNU) allows to obtain DM from mothers who have their infants admitted to the NICU and produce an excess of milk, a practice that matches MOM by gestational age and the stage of lactation, ensuring an adequate composition of DM to target the nutritional requirements of premature infants.Conclusion: This narrative review presents salient data of our current knowledge and concerns regarding milk feeding of preterm infants in the NICU, with special emphasis on personalized DM as a result of establishing a PNU. What is Known: • Donor milk bank is mature or pooled milk from lactating mothers at different stages of lactation. • Milk composition varies by gestational age and stage of lactation. What is New: • Donor milk from mothers delivered prematurely have the most adequate composition for preterm infant feeding. • Personalized nutrition for premature infants with preterm donor milk is feasible.

Cohousing-mediated microbiota transfer from milk bioactive components-dosed mice ameliorate colitis by remodeling colonic mucus barrier and lamina propria macrophages

Human milk oligosaccharides (HMOs) and milk fat globule membrane (MFGM) are highly abundant in breast milk, and have been shown to exhibit potent immunomodulatory effects. Yet, their role in the gut microbiota modulation in relation to colitis remains understudied. Since the mixtures of fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS) perfectly mimic the properties and functions of HMOs, the combination of MFGM, FOS, and GOS (CMFG) has therefore been developed and used in this study. Here, CMFG were pre-fed to mice for three weeks to investigate its preventive effect on dextran sodium sulfate (DSS) induced colitis. Moreover, CMFG-treated and vehicle-treated mice were cohoused to further elucidate the preventive role of the gut microbiota transfer in colitis. At the end of the study, 16S rDNA gene amplicon sequencing, short-chain fatty acids (SCFAs) profiling, transcriptome sequencing, histological analysis, immunofluorescence staining and flow cytometry analysis were conducted. Our results showed that CMFG pre-supplementation alleviated DSS-induced colitis as evidenced by decreased disease activity index (DAI) score, reduced body weight loss, increased colon length and mucin secretion, and ameliorated intestinal damage. Moreover, CMFG reduced macrophages in the colon, resulting in decreased levels of IL-1β, IL-6, IL-8, TNF-α, and MPO in the colon and circulation. Furthermore, CMFG altered the gut microbiota composition and promoted SCFAs production in DSS-induced colitis. Markedly, the cohousing study revealed that transfer of gut microbiota from CMFG-treated mice largely improved the DSS-induced colitis as evidenced by reduced intestinal damage and decreased macrophages infiltration in the colon. Moreover, transfer of the gut microbiota from CMFG-treated mice protected against DSS-induced gut microbiota dysbiosis and promotes SCFAs production, which showed to be associated with colitis amelioration. Collectively, these findings demonstrate the beneficial role of CMFG in the gastrointestinal diseases, and further provide evidence for the rational design of effective prophylactic functional diets in both animals and humans.

Human Milk Oligosaccharides Mediate the Crosstalk Between Intestinal Epithelial Caco-2 Cells and Lactobacillus PlantarumWCFS1in an In Vitro Model with Intestinal Peristaltic Shear Force

BACKGROUND

The intestinal epithelial cells, food molecules, and gut microbiota are continuously exposed to intestinal peristaltic shear force. Shear force may impact the crosstalk of human milk oligosaccharides (hMOs) with commensal bacteria and intestinal epithelial cells.

OBJECTIVES

We investigated how hMOs combined with intestinal peristaltic shear force impact intestinal epithelial cells and crosstalk with a commensal bacterium.

METHODS

We applied the Ibidi system to mimic intestinal peristaltic shear force. Caco-2 cells were exposed to a shear force (5 dynes/cm2) for 3 d, and then stimulated with the hMOs, 2'-fucosyllactose (2'-FL), 3-FL, and lacto-N-triose II (LNT2). In separate experiments, Lactobacillus plantarumWCFS1 adhesion to Caco-2 cells was studied with the same hMOs and shear force. Effects were tested on gene expression of glycocalyx-related molecules (glypican 1 [GPC1], hyaluronan synthase 1 [HAS1], HAS2, HAS3, exostosin glycosyltransferase 1 [EXT1], EXT2), defensin β-1 (DEFB1), and tight junction (tight junction protein 1 [TJP1], claudin 3 [CLDN3]) in Caco-2 cells. Protein expression of tight junctions was also quantified.

RESULTS

Shear force dramatically decreased gene expression of the main enzymes for making glycosaminoglycan side chains (HAS3 by 43.3% and EXT1 by 68.7%) (P <0.01), but did not affect GPC1 which is the gene responsible for the synthesis of glypican 1 which is a major protein backbone of glycocalyx. Expression of DEFB1, TJP1, and CLDN3 genes was decreased 60.0-94.9% by shear force (P <0.001). The presence of L. plantarumWCFS1 increased GPC1, HAS2, HAS3, and ZO-1 expression by 1.78- to 3.34-fold (P <0.05). Under shear force, all hMOs significantly stimulated DEFB1 and ZO-1, whereas only 3-FL and LNT2 enhanced L. plantarumWCFS1 adhesion by 1.85- to 1.90-fold (P <0.01).

CONCLUSIONS

3-FL and LNT2 support the crosstalk between the commensal bacterium L. plantarumWCFS1 and Caco-2 intestinal epithelial cells, and shear force can increase the modulating effects of hMOs.

Nano-enabled personalized nutrition: Developing multicomponent-bioactive colloidal delivery systems

There is growing interest in the production of foods and beverages with nutrient and nutraceutical profiles tailored to an individual's specific nutritional requirements. In principle, these personalized nutrition products are formulated based on the genetics, epigenetics, metabolism, microbiome, phenotype, lifestyle, age, gender, and health status of a person. A challenge in this area is to create customized functional food and beverage products that contain the required combination of bioactive agents, such as lipids, proteins, carbohydrates, vitamins, minerals, nutraceuticals, prebiotics and probiotics. Nanotechnology may facilitate the development of these kind of products since it can be used to encapsulate one or more bioactive agent in a single colloidal delivery system. This delivery system may contain one or more different kinds of colloidal particle, specifically designed to protect each nutrient in the food, but then deliver it in a bioavailable form after ingestion. This review article provides an overview of the different kinds of bioactives that need to be delivered, as well as some of the challenges associated with incorporating them into functional foods and beverages. It then highlights how nanotech-enabled colloidal delivery systems can be developed to encapsulate multiple bioactive agents in a form suitable for functional food applications, particularly in the personalized nutrition field.

Prebiotic Properties of Non-Fructosylated α-Galactooligosaccharides from PEA (Pisum sativum L.) Using Infant Fecal Slurries

The interest for naturally-occurring oligosaccharides from plant origin having prebiotic properties is growing, with special focus being paid to supplemented products for infants. Currently, non-fructosylated α-galactooligosaccharides (α-GOS) from peas have peaked interest as a result of their prebiotic activity in adults and their mitigated side-effects on gas production from colonic bacterial fermentation. In this study, commercially available non-fructosylated α-GOS from peas and β-galactooligosaccharides (β-GOS) derived from lactose were fermented using fecal slurries from children aged 11 to 24 months old during 6 and 24 h. The modulatory effect of both GOS on different bacterial groups and bifidobacteria species was assessed; non-fructosylated α-GOS consumption was monitored throughout the fermentation process and the amounts of lactic acid and short-chain fatty acids (SCFA) generated were analyzed. Non-fructosylated α-GOS, composed mainly of manninotriose and verbascotetraose and small amounts of melibiose, were fully metabolized and presented remarkable bifidogenic activity, similar to that obtained with β-GOS. Furthermore, non-fructosylated α-GOS selectively caused an increase on the population of Bifidobacterium longum subsp. longum and Bifidobacterium catenulatum/pseudo-catenulatum. In conclusion, non-fructosylated α-GOS could be used as potential ingredient in infant formula supplemented with prebiotic oligosaccharides.

A cross-country exploratory study to investigate the labelling, energy, carbohydrate and sugar content of formula milk products marketed for infants

Aims The first aim was to describe the energy, carbohydrate and sugar contents of formula milk products in eleven countries. The second was to assess the labelling methods used. Based on the findings, approaches to facilitate the selection of infant-appropriate formula milk products were proposed.Background Consumption of excess sugar during infancy can increase the risk of non-communicable diseases (NCDs) including obesity, diabetes and dental caries. Reduction of sugar consumption has been high on the global public health agenda. Although most infants are fed formula milk products in addition to, or instead of, breastmilk (with only 38% exclusively breastfed), the sugar content of these products is often not included in sugar reduction strategies.Methods An exploratory study was conducted to describe the labelling and nutritional composition of a sample of infant formula products available in 11 countries. The sample, which was collected between May and August 2019, included commercially available formula products (n = 257) targeted at infants aged <3 years of age. The products were sold in supermarkets and by other major retailers across the sample countries. Primary data were obtained from labels on the packaging of the formula products.Results Findings suggest that the majority of products sampled were higher in total carbohydrate and carbohydrates of which sugar and lactose, than breastmilk, supporting previous research. The nutrition information presented on the products was often unclear and was inconsistent across the 11 counties sampled. None of the products had front-of-pack (FOP) nutritional information.Conclusion Findings suggest that globally, infant formula products are higher in carbohydrates, sugar and lactose than breastmilk. Labelling is unclear and inconsistent across brands and between countries. Based on the findings of this study, mandatory regulation of sugar content in formula products is needed with clear FOP nutrition information to help consumers choose the healthy option for their infants.

Effects of Low-Dose Antibiotics on Gut Immunity and Antibiotic Resistomes in Weaned Piglets

Widespread antibiotic use increases the risk of livestock acting as potential reservoirs of antimicrobial resistance genes (ARGs) that may be transferred to human and animal pathogens. Particularly, maternal-infant transmission of antibiotics via breastmilk represents a great concern regarding infant health. In this study, we investigated the effects of 4-week low-dose antibiotic (LDA) treatment on the host immunity and antibiotic resistomes in weaned piglets. Transcriptomic analyses of ileum tissues revealed that the affected genes were largely enriched in innate immunity-related pathways. Significantly reduced protein expression of inflammatory factors, i.e., IFN-γ, IL-6 were observed. In addition, analyses of antibiotic resistomes identified a total of 1,021 ARGs related to 39 classes of antibiotics. The samples exhibited highly individual-specific diversity and no significant difference in the structure and diversity of ARGs and mobile gene elements (MGE) after LDA exposure for both colon and ileum samples. Despite of that, there were significant changes in the abundance of two transferrable ARGs [Erm(T) and tcr3] related to the antibiotics administered, implying an increased risk of transferrable antibiotic resistance. There was a significant change in the abundance of one pathogenic species after LDA exposure in the colon samples and one in the ileum samples, but there were no significant differences in the matched ARGs. Collectively, our findings reveal considerable changes in intestinal immunity-related genes, but minimal effects on gut antibiotic resistomes (ARGs and MGEs) in weaned piglets after 4 weeks LDA exposure. Our study provides a foundation for evaluating the longer-term cumulative effects of LDA use, especially the effects of maternal–infant LDA transmission, on antibiotic resistance and risks to infant health.

Endo-1,3(4)-β-Glucanase-Treatment of Oat β-Glucan Enhances Fermentability by Infant Fecal Microbiota, Stimulates Dectin-1 Activation and Attenuates Inflammatory Responses in Immature Dendritic Cells

Background: Non-digestible carbohydrates are added to infant formula to mimic the effects of human milk oligosaccharide by acting as prebiotics and stimulating the immune system. Although not yet used in infant formulas, β-glucans are known to have beneficial health effects, and are therefore of potential interest for supplementation. Methods and results: We investigated the in vitro fermentation of native and endo-1,3(4)-β-glucanase-treated oat β-glucan using pooled fecal inocula of 2- and 8-week-old infants. While native oat β-glucan was not utilized, both inocula specifically utilized oat β-glucan oligomers containing β(1→4)-linkages formed upon enzyme treatment. The fermentation rate was highest in the fecal microbiota of 2-week-old infants, and correlated with a high lactate production. Fermentation of media supplemented with native and enzyme-treated oat β-glucans increased the relative abundance of Enterococcus and attenuated pro-inflammatory cytokine production (IL-1β, IL-6, TNFα) in immature dendritic cells. This attenuating effect was more pronounced after enzyme treatment. This attenuation might result from the enhanced ability of fermented oat β-glucan to stimulate Dectin-1 receptors. Conclusion: Our findings demonstrate that endo-1,3(4)-β-glucanase treatment enhances the fermentability of oat β-glucan and attenuates pro-inflammatory responses. Hence, this study shows that especially enzyme-treated oat β-glucans have a high potential for supplementation of infant formula.

Recent advances in understanding the neonatal microbiome

The neonatal developmental window represents a key time for establishment of the gut microbiota. First contact with these microbes within the infant gastrointestinal tract signifies the start of a critical mutualistic relationship, which is central for short- and longer-term health. Recent research has provided insights into the origin of these microbial pioneers, how they are maintained within the gut environment, and how factors such as antibiotics or preterm birth may disrupt the succession of beneficial microbes.  The acquisition, colonisation, and maintenance of the early life microbiota, and subsequent interactions with the host is a rapidly developing research area. In this review we explore some of these key topics which have been illuminated by recent research, and we highlight some of the important unresolved questions which currently limit our overall understanding of the neonatal gut microbiome.

Galacto- and Fructo-oligosaccharides Utilized for Growth by Cocultures of Bifidobacterial Species Characteristic of the Infant Gut

Bifidobacterial species are common inhabitants of the gut of human infants during the period when milk is a major component of the diet. Bifidobacterium breve, Bifidobacterium bifidum, Bifidobacterium longum subspecies longum, and B. longum subspecies infantis have been detected frequently in infant feces, but B. longum subsp. infantis may be disadvantaged numerically in the gut of infants in westernized countries. This may be due to the different durations of breast milk feeding in different countries. Supplementation of the infant diet or replacement of breast milk using formula feeds is common in Western countries. Formula milks often contain galacto- and/or fructo-oligosaccharides (GOS and FOS, respectively) as additives to augment the concentration of oligosaccharides in ruminant milks, but the ability of B. longum subsp. infantis to utilize these potential growth substrates when they are in competition with other bifidobacterial species is unknown. We compared the growth and oligosaccharide utilization of GOS and FOS by bifidobacterial species in pure culture and coculture. Short-chain GOS and FOS (degrees of polymerization [DP] 2 and 3) were favored growth substrates for strains of B. bifidum and B. longum subsp. longum, whereas both B. breve and B. longum subsp. infantis had the ability to utilize both short- and longer-chain GOS and FOS (DP 2 to 6). B. breve was nevertheless numerically dominant over B. longum subsp. infantis in cocultures. This was probably related to the slower use of GOS of DP 3 by B. longum subsp. infantis, indicating that the kinetics of substrate utilization is an important ecological factor in the assemblage of gut communities.IMPORTANCE The kinds of bacteria that form the collection of microbes (the microbiota) in the gut of human infants may influence health and well-being. Knowledge of how the composition of the infant diet influences the assemblage of the bacterial collection is therefore important because dietary interventions may offer opportunities to alter the microbiota with the aim of improving health. Bifidobacterium longum subspecies infantis is a well-known bacterial species, but under modern child-rearing conditions it may be disadvantaged in the gut. Modern formula milks often contain particular oligosaccharide additives that are generally considered to support bifidobacterial growth. However, studies of the ability of various bifidobacterial species to grow together in the presence of these oligosaccharides have not been conducted. These kinds of studies are essential for developing concepts of microbial ecology related to the influence of human nutrition on the development of the gut microbiota.

Does the contribution of human milk oligosaccharides to the beneficial effects of breast milk allow us to hope for an improvement in infant formulas?

Human milk is a source of nutrients and contains many distinct bioactive components. Among these, human milk oligosaccharides (HMOs) have attracted considerable attention and are being investigated as a "novel foods". Human milk is unique in its oligosaccharide composition. Recent research has focused on the complexity of HMOs by highlighting their diversity, structural variability, concentration variance, and structure-function relationships. In vitro and in vivo studies have demonstrated that HMOs drive infant gut microbiota, improve intestinal barrier functions, and modulate cell receptor signaling, thereby contributing to the development of infant immunity. These studies, combined with epidemiological data, indicate that some HMO may confer health benefits by preventing infections and diseases such as necrotizing enterocolitis and allergies. However, randomized controlled trials are restricted to structurally simple compounds such as 2' fucosyllactose and lacto-N-neotetraose. More controlled clinical trials are needed to justify routine supplementation of formula. It is felt that a better understanding of the role of HMOs leading to the development of inexpensive methods for large-scale HMO production is needed.

Framework as a Service, FaaS: Personalized Prebiotic Development for Infants with the Elements of Time and Parametric Modelling of in vitro Fermentation

We proposed a framework with parametric modeling to obtain biological relevant parameters from the total probiotic growth pattern and metabolite production curves. The lag phase, maximum increase rate, and maximum capacity were obtained via a 205-h exploratory In vitro fermentation of a library of 13 structural-characterized prebiotic candidates against an exclusively breastfed infant fecal inoculum. We also conducted 16S rRNA amplicon sequencing of the infant fecal inoculum. Moreover, we introduce a robust composite metabolite-based indicator that reflects the eubiosis/dysbiosis of microbiota to complement the conventional microbial markers. In terms of short-chain fatty acid, we discovered that polymeric beta-glucans from barley demonstrated potential as prebiotic candidates, while alpha-glucans as glycogen showed the least dissolved ammonia production. In terms of total probiotic, beta-glucans from oat and mushroom sclerotia of Pleurotus tuber-regium showed comparable sustainability when compared to alpha-glucans after 48 h. Being classical prebiotic, galacto-oligosaccharides gave the second-highest metabolite-based indicator, followed by lactose. While limited improvement could be made to lactose and oligosaccharides, polymeric beta-glucans from barley avails more capacity for novel prebiotic development, such as structural modification. We anticipate that more similar parallel screening with the element of time and parametric modeling will provide more novel insights.

More than sugar in the milk: human milk oligosaccharides as essential bioactive molecules in breast milk and current insight in beneficial effects

Human milk is the gold standard for newborn infants. Breast milk not only provides nutrients, it also contains bioactive components that guide the development of the infant's intestinal immune system, which can have a lifelong effect. The bioactive molecules in breast milk regulate microbiota development, immune maturation and gut barrier function. Human milk oligosaccharides (hMOs) are the most abundant bioactive molecules in human milk and have multiple beneficial functions such as support of growth of beneficial bacteria, anti-pathogenic effects, immune modulating effects, and stimulation of intestine barrier functions. Here we critically review the current insight into the benefits of bioactive molecules in mother milk that contribute to neonatal development and focus on current knowledge of hMO-functions on microbiota and the gastrointestinal immune barrier. hMOs produced via genetically engineered microorganisms are now applied in infant formulas to mimic the nutritional composition of breast milk as closely as possible, and their prospects and scientific challenges are discussed in depth.

Neutral Human Milk Oligosaccharides Are Associated with Multiple Fixed and Modifiable Maternal and Infant Characteristics

We aimed to identify if maternal and infant factors were associated with neutral human milk oligosaccharides (HMOs) variability and examined the associations between HMOs concentration and infant growth and disease status in healthy Chinese mothers over a 6-month lactation period. We recruited mothers and their full-term infants as our subjects. At 1–5 days, 8–14 days, 4 weeks, and 6 months postpartum, all participants were interviewed to collect breast milk samples, obtain follow-up data and measure infant length and weight at their local hospital. A total of 23 neutral HMOs were analyzed by high performance liquid chromatography (HPLC)- mass spectrometer (MS). Secretor and Lewis phenotype were determined by the concentration of 2′-fucosyllactose (2′-FL) and Lacto-N-fucopentaose (LNFP)-II. The associations between maternal and infant factors with HMOs concentrations were investigated. A total of 464 human breast milk samples were collected from 116 mothers at four different time points. In total, 76.7% mothers were found to be Secretor and Lewis positive phenotype (Se+Le+), 17.2% were Se-Le+, 4.3% were Se+Le-, and 1.7% were Se-Le-. Several individual HMOs, including 2′-FL, Lactodifucotetraose (LDFT), LNFP-I were determined by Secretor phenotype. Most individual HMOs decreased at the later stage of lactation, except 3′-FL. We suggest that Secretor phenotype and lactation stage could influence most of the neutral HMOs. Concentrations of specific HMOs may be associated with maternal age, allergic history, pre-pregnancy body mass index (BMI), parity, delivery mode, infant gestational age and gender.

Symposium review: Dairy-derived oligosaccharides-Their influence on host-microbe interactions in the gastrointestinal tract of infants

Oligosaccharides are the third most abundant component in human milk. It is widely accepted that they play several important protective, physiological, and biological roles, including selective growth stimulation of beneficial gut microbiota, inhibition of pathogen adhesion, and immune modulation. However, until recently, very few commercial products on the market have capitalized on these functions. This is mainly because the quantities of human milk oligosaccharides required for clinical trials have been unavailable. Recently, clinical studies have tested the potential beneficial effects of feeding infants formula containing 2'-fucosyllactose, which is the most abundant oligosaccharide in human milk. These studies have opened this field for further well-designed studies, which are required to fully understand the role of human milk oligosaccharides. However, one of the most striking features of human milk is its diversity of oligosaccharides, with over 200 identified to date. It may be that a mixture of oligosaccharides is even more beneficial to infants than a single structure. For this reason, the milk of domestic animals has become a focal point in recent years as an alternative source of complex oligosaccharides with associated biological activity. This review will focus specifically on free oligosaccharides found in bovine and caprine milk and the biological roles associated with such structures. These dairy streams are ideal sources of oligosaccharides, given their wide availability and use in so many regularly consumed dairy products. The aim of this review was to provide an overview of research into the functional role of bovine and caprine milk oligosaccharides in host-microbial interactions in the gut and provide current knowledge related to the isolation of oligosaccharides as ingredients for incorporation in functional or medical foods.

Harvesting of Prebiotic Fructooligosaccharides by Nonbeneficial Human Gut Bacteria

Prebiotics are increasingly used as food supplements, especially in infant formulas, to modify the functioning and composition of the microbiota. However, little is currently known about the mechanisms of prebiotic recognition and transport by gut bacteria, while these steps are crucial in their metabolism. In this study, we established a new strategy to profile the specificity of oligosaccharide transporters, combining microbiomics, genetic locus and strain engineering, and state-of-the art metabolomics. We revisited the transporter classification database and proposed a new way to classify these membrane proteins based on their structural and mechanistic similarities. Based on these developments, we identified and characterized, at the molecular level, a fructooligosaccharide transporting phosphotransferase system, which constitutes a biomarker of diet and gut pathology. The deciphering of this prebiotic metabolization mechanism by a nonbeneficial bacterium highlights the controversial use of prebiotics, especially in the context of chronic gut diseases.

Prebiotic oligosaccharides, such as fructooligosaccharides, are increasingly being used to modulate the composition and activity of the gut microbiota. However, carbohydrate utilization analyses and metagenomic studies recently revealed the ability of deleterious and uncultured human gut bacterial species to metabolize these functional foods. Moreover, because of the difficulties of functionally profiling transmembrane proteins, only a few prebiotic transporters have been biochemically characterized to date, while carbohydrate binding and transport are the first and thus crucial steps in their metabolization. Here, we describe the molecular mechanism of a phosphotransferase system, highlighted as a dietary and pathology biomarker in the human gut microbiome. This transporter is encoded by a metagenomic locus that is highly conserved in several human gut Firmicutes, including Dorea species. We developed a generic strategy to deeply analyze, in vitro and in cellulo, the specificity and functionality of recombinant transporters in Escherichia coli, combining carbohydrate utilization locus and host genome engineering and quantification of the binding, transport, and growth rates with analysis of phosphorylated carbohydrates by mass spectrometry. We demonstrated that the Dorea fructooligosaccharide transporter is specific for kestose, whether for binding, transport, or phosphorylation. This constitutes the biochemical proof of effective phosphorylation of glycosides with a degree of polymerization of more than 2, extending the known functional diversity of phosphotransferase systems. Based on these new findings, we revisited the classification of these carbohydrate transporters.

IMPORTANCE Prebiotics are increasingly used as food supplements, especially in infant formulas, to modify the functioning and composition of the microbiota. However, little is currently known about the mechanisms of prebiotic recognition and transport by gut bacteria, while these steps are crucial in their metabolism. In this study, we established a new strategy to profile the specificity of oligosaccharide transporters, combining microbiomics, genetic locus and strain engineering, and state-of-the art metabolomics. We revisited the transporter classification database and proposed a new way to classify these membrane proteins based on their structural and mechanistic similarities. Based on these developments, we identified and characterized, at the molecular level, a fructooligosaccharide transporting phosphotransferase system, which constitutes a biomarker of diet and gut pathology. The deciphering of this prebiotic metabolization mechanism by a nonbeneficial bacterium highlights the controversial use of prebiotics, especially in the context of chronic gut diseases.

A Sustainable Wholesome Foodstuff; Health Effects and Potential Dietotherapy Applications of Yacon

A sustainable food supply is an ever-growing public and planetary health concern influenced by food culture, food practices, and dietary patterns. Globally, the consumption of plant foods that offer physiological and biochemical benefits is increasing. In recent years, products made from yacon (Smallanthus sonchifolius) tubers and leaves, e.g., in the form of syrup, powder, and herbal tea, have steadily emerged with scientific evidence to validate their possible health claims. Yacon was introduced to New Zealand in 1966, and its products can now be produced on a commercial scale. This paper reviews literature published mainly in the last 10 years concerning the health-related properties of yacon as a wholesome foodstuff and its bioactive components, e.g., fructooligosaccharides. Literature was sourced from Web of Science, PubMed, EBSCO Health, and Google Scholar up to June 2019. The potential markets for yacon in the field of food technology and new dietotherapy applications are discussed. Furthermore, the unique features of New Zealand-produced yacon syrup are introduced as a case study. The paper explores the scientific foundation in response to the growing public interest in why and how to use yacon.

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.

Characterization of GH2 and GH42 β-galactosidases derived from bifidobacterial infant isolates

Bifidobacteria are among the first and most abundant bacterial colonizers of the gastrointestinal tract of (breast-fed) healthy infants. Their success of colonising the infant gut is believed to be, at least partly, due to their ability to metabolize available carbon sources by means of secreted or intracellular glycosyl hydrolases (GHs). Among these, β-galactosidases are particularly relevant as they allow bifidobacteria to grow on β-galactosyl-linked saccharidic substrates, which are present in copious amounts in the milk-based diet of their infant host (e.g. lactose and human milk oligosaccharides). In the present study we employed an in silico analysis to identify GH family 2 and 42 β-galactosidases encoded by typical infant-associated bifidobacteria. Comparative genome analysis followed by characterisation of selected β-galactosidases revealed how these GH2 and GH42 members are distributed among these infant-associated bifidobacteria, while their hydrolytic activity towards growth substrates commonly available in the infant gut were also assessed.

Human Milk Oligosaccharides: 2'-Fucosyllactose (2'-FL) and Lacto-N-Neotetraose (LNnT) in Infant Formula

The authors reviewed the published evidence on the presence of oligosaccharides in human milk (HMO) and their benefits in in vitro and in vivo studies. The still limited data of trials evaluating the effect of mainly 2′-fucosyllactose (2′-FL) on the addition of some of HMOs to infant formula were also reviewed. PubMed was searched from January 1990 to April 2018. The amount of HMOs in mother’s milk is a dynamic process as it changes over time. Many factors, such as duration of lactation, environmental, and genetic factors, influence the amount of HMOs. HMOs may support immune function development and provide protection against infectious diseases directly through the interaction of the gut epithelial cells or indirectly through the modulation of the gut microbiota, including the stimulation of the bifidobacteria. The limited clinical data suggest that the addition of HMOs to infant formula seems to be safe and well tolerated, inducing a normal growth and suggesting a trend towards health benefits. HMOs are one of the major differences between cow’s milk and human milk, and available evidence indicates that these components do have a health promoting benefit. The addition of one or two of these components to infant formula is safe, and brings infant formula closer to human milk. More prospective, randomized trials in infants are need to evaluate the clinical benefit of supplementing infant formula with HMOs.

Carbohydrate Syntrophy enhances the establishment of Bifidobacterium breve UCC2003 in the neonatal gut

The non-digestible oligosaccharide fraction of maternal milk represents an important of carbohydrate and energy source for saccharolytic bifidobacteria in the gastrointestinal tract during early life. However, not all neonatal bifidobacteria isolates can directly metabolise the complex sialylated, fucosylated, sulphated and/or N-acetylglucosamine-containing oligosaccharide structures present in mothers milk. For some bifidobacterial strains, efficient carbohydrate syntrophy or crossfeeding is key to their establishment in the gut. In this study, we have adopted advanced functional genomic approaches to create single and double in-frame deletions of the N-acetyl glucosamine 6-phosphate deacetylase encoding genes, nagA1 and nagA2, of B. breve UCC2003. In vitro phenotypic analysis followed by in vivo studies on co-colonisation, mother to infant transmission, and evaluation of the relative co-establishment of B. bifidum and B. breve UCC2003 or UCC2003ΔnagA1ΔnagA2 in dam-reared neonatal mice demonstrates the importance of crossfeeding on sialic acid, fucose and N-acetylglucosamine-containing oligosaccharides for the establishment of B. breve UCC2003 in the neonatal gut. Furthermore, transcriptomic analysis of in vivo gene expression shows upregulation of genes associated with the utilisation of lactose, sialic acid, GlcNAc-6-S and fucose in B. breve UCC2003, while for UCC2003ΔnagA1ΔnagA2 only genes for lactose metabolism were upregulated.

Impact of gut microbiota on neurological diseases: Diet composition and novel treatments

Gut microbiota has significant effects on the structure and function of the enteric and central nervous system including human behaviour and brain regulation. Herein, we analyze the role of this intestinal ecosystem, the effects of dietary changes and the administration of nutritional supplements, such as probiotics, prebiotics, or fecal transplantation in neuropsychiatric disorders. Numerous factors have been highlighted to influence gut microbiota composition, including genetics, health status, mode of birth delivery and environment. However, diet composition and nutritional status has been repeatedly shown to be one of the most critical modifiable factors of this ecosystem. A comprehensively analysis of the microbiome-intestine-brain axis has been performed, including the impact of intestinal bacteria in alterations in the nervous, immune and endocrine systems and their metabolites. Finally, we discuss the latest literature examining the effects of diet composition, nutritional status and microbiota alterations in several neuropsychiatric disorders, such as autism, anxiety, depression, Alzheimer's disease and anorexia nervosa.