Milk Oligosaccharides Research Articles

Modulating the developing gut microbiota with 2’-fucosyllactose and pooled human milk oligosaccharides

BackgroundSynthetic human milk oligosaccharides (HMOs) are used to supplement infant formula despite limited understanding of their impact on the post-weaned developing gut microbiota. Here, we assess the influence of 0.5 g/L 2-fucosyllactose (2’FL) and 4.0 g/L pooled HMOs (pHMOs) on the composition and activity of cultured fecal-derived microbial communities from seven healthy young children.ResultsExposure to pHMOs induced significant shifts in both the microbial community composition and metabolic output, including an increased abundance of several genera, notably Bacteroides, and the production of health-associated metabolites. In contrast, 2’FL alone did not lead to substantial changes in the communities. A total of 330 bacterial isolates, spanning 157 species, were cultured from these communities and individually evaluated for their responses to HMOs. Over 100 non-Bifidobacterium species showed enhanced growth upon pHMOs treatment and a high degree of intraspecies variation in HMO metabolism was observed.ConclusionOur study provides valuable insight into the health-enhancing properties of HMOs while highlighting the need for future research into the efficacy of incorporating individual structures into infant formula, particularly when aiming to modulate the gut microbiota.DLoTGpXbSBXfYGWsHwkdt7Video

Human milk oligosaccharides 2'-fucosyllactose and 3-fucosyllactose attenuate ovalbumin-induced food allergy through immunoregulation and gut microbiota modulation.

The prebiotic properties of human milk oligosaccharides (HMOs) and emerging evidence of immunomodulatory effects suggest their potential therapeutic value in allergy management. 2'-Fucosyllactose (2'-FL) has been reported to alleviate food allergies, while the effect of other fucosylated HMOs on food allergy remains unclear. In this study, we assess the effect of two HMOs, 2'-FL and 3-fucosyllactose (3-FL), on symptomatology and immunological responses in an ovalbumin (OVA)-sensitized mouse model of food allergy as well as their influence on gut microbiota. The assessment of allergic symptoms, specific immunoglobulin E (IgE), and related gene expression levels in sensitized mice indicated that 3-FL was as effective as 2'-FL in alleviating food allergy. 2'-FL and 3-FL significantly decreased serum levels of OVA-specific IgE, mouse mast cell protease (mMCP-1) and IL-4 while increasing the levels of IFN-γ. Additionally, 2'-FL and 3-FL down-regulated gene expression of allergy-related cytokines in the small intestine and improved intestinal barrier damage. Furthermore, both 2'-FL and 3-FL treatment positively influenced the gut microbial profiles, in particular by enhancing the proportion of beneficial bacteria such as Lactobacillus and Bifidobacterium and decreasing the percentage of Turicibacter and Lachnospiraceae NK4A136 group, thereby modulating the immune system. Therefore, this study can provide insights into 2'-FL and 3-FL to alleviate OVA-induced allergy.

Efficient fermentative production of lactodifucotetraose by controlling sequential glycosyltransferase reactions in Escherichia coli.

Lactodifucotetraose (LDFT) is a human milk oligosaccharide (HMO) that might reduce inflammation in infants. In this study, we established a useful production process of LDFT by engineering two key enzymes, α1,2-fucosyltransferase (α1,2-FucT) and α1,3-fucosyltransferase (α1,3-FucT). First, we verified which of 2'-fucosyllactose (2'-FL) or 3-fucosyllactose (3-FL) (mostly unverified) was more useful. We searched for FucTs that functioned efficiently in vivo against the raw material lactose or the two intermediates 2'-FL or 3-FL by external substrate addition to culture medium. We found that α1,2- FucT (HMFT) from Helicobacter mustelae and the N-terminal truncated form of α1,3-FucT from Bacteroides fragilis (BfFucTΔN10) had high potential. 3-FL was not efficiently converted to LDFT, which might be attributed to the low reactivity of HMFT to 3-FL as well as the low uptake efficiency of 3-FL by LacY, as revealed by a growth test with exogenously added FL as the sole carbon source and heterologously expressed intracellular fucosidase. Furthermore, because 3-FL accumulation had a negative impact on cell growth, we avoided the route passing through 3-FL. By adjusting the copy numbers of HMFT and BffucTΔN10, we produced LDFT from lactose predominantly via 2'-FL. Finally, 17.5 g/L of LDFT (with 6.8 g/L 2'-FL and no 3-FL or residual lactose) accumulated in a 3-L fed-batch culture after 77 h. This study reports the detailed analysis of multiple pathways and shows the control of glycosyltransferases can improve the production efficiency of complex HMOs.

Streptococcus wuxiensis sp. nov., Streptococcus jiangnanensis sp. nov. and Streptococcus fermentans sp. nov.: three novel species of genus Streptococcus isolated from human breast milk.

Three novel coccoid-shaped strains, designated 21WXBC0057M1T, 21WXBC0044M1T and BJSWXB5TM5T, were isolated from human breast milk in Wuxi, Jiangsu Province, China. These strains were facultative anaerobes, catalase-negative and Gram-positive. Through a comprehensive analysis of rRNA genes, protein-coding housekeeping genes and genomic phylogeny, we identified these strains as belonging to the genus Streptococcus. Specifically, strain 21WXBC0057M1T was phylogenetically most closely related to Streptococcus infantis, strain 21WXBC0044M1T was most closely related to Streptococcus oralis and strain BJSWXB5TM5T displayed similarities to Streptococcus australis, Streptococcus peroris and S. infantis. The pairwise average nucleotide identity and digital DNA-DNA hybridization values for these three strains were below 95 and 70%, respectively, indicating that they occupied evolutionary branches distinct from all previously validly published Streptococcus species. Distinctive phenotypic characteristics discriminated these novel species from the type strains of their most closely related species. The major cellular fatty acids in the three strains were C16 : 0 and C18 : 0. Genome annotation and a thorough examination of carbohydrate-active enzyme distribution highlighted the observation that all strains possessed extensive capabilities for carbohydrate metabolism, particularly human milk oligosaccharides utilization. Thus, based on these findings, we proposed the classification of the strains as representing three novel species within the genus Streptococcus: Streptococcus wuxiensis sp. nov. (type strain 21WXBC0057M1T=GDMCC 1.4126T=KCTC 25760T), Streptococcus jiangnanensis sp. nov. (type strain 21WXBC0044M1T= GDMCC 1.4127T=KCTC 25762T) and Streptococcus fermentans sp. nov. (type strain BJSWXB5TM5T=GDMCC 1.4130T=KCTC 25759T).

Carbohydrate-active enzymes from Akkermansia muciniphila break down mucin O-glycans to completion

Akkermansia muciniphila is a human microbial symbiont residing in the mucosal layer of the large intestine. Its main carbon source is the highly heterogeneous mucin glycoprotein, and it uses an array of carbohydrate-active enzymes and sulfatases to access this complex energy source. Here we describe the biochemical characterization of 54 glycoside hydrolases, 11 sulfatases and 1 polysaccharide lyase from A. muciniphila to provide a holistic understanding of their carbohydrate-degrading activities. This was achieved using a variety of liquid chromatography techniques, mass spectrometry, enzyme kinetics and thin-layer chromatography. These results are supported with A. muciniphila growth and whole-cell assays. We find that these enzymes can act synergistically to degrade the O-glycans on the mucin polypeptide to completion, down to the core N-acetylgalactosaime. In addition, these enzymes can break down human breast milk oligosaccharide, ganglioside and globoside glycan structures, showing their capacity to target a variety of host glycans. These data provide a resource to understand the full degradative capability of the gut microbiome member A. muciniphila.

Synthesising human milk oligosaccharide using biotechnology-driven enzymes

Synthesising human milk oligosaccharide using biotechnology-driven enzymes

Molecular modification of a GH84 β-N-acetylglucosaminidase from Streptomyces violascens for synthesis of lacto-N-triose II using whey powder and chitin-derived N-acetyl chitobiose.

β-N-acetylhexosaminidases garnered attention in the enzymatic synthesis of lacto-N-triose II (LNT2) as the backbone precursor of human milk oligosaccharides (HMOs). In this study, β-N-acetylglucosaminidases Hex(Sv)-2557 from Streptomyces violascens ATCC 27968 was engineered based on a stabilizing intermediate strategy to improve its transglycosylation activity for LNT2 synthesis. A mutant Hex(Sv)-2557(D297K) with a transglycosylation activity of 38.4U/mg with pNP-GlcNAc -1.9-fold higher than that of Hex(Sv)-2557- was obtained and characterized. Instead, the hydrolase activity of the mutant was 73% lower compared to the wild-type enzyme. Importantly, the mutant can use N-acetyl chitobiose (GlcNAc2) as the donor for LNT2 synthesis. The LNT2 yield of 14.85% was obtained when the synthetic reaction, catalyzed by the mutant Hex(Sv)-2557(D297K), started from whey powder and GlcNAc2-prepared from chitin by chitinase ChiA and ChiB. This study has altered the donor for the action by directed modification and promoting the high-value utilization of whey powder and chitin.

A Pilot Study Exploring the Relationship Between Milk Composition and Microbial Capacity in Breastfed Infants.

Maternal obesity may contribute to childhood obesity in a myriad of ways, including through alterations of the infant gut microbiome. For example, maternal obesity may contribute both directly by introducing a dysbiotic microbiome to the infant and indirectly through the altered composition of human milk that fuels the infant gut microbiome. In particular, indigestible human milk oligosaccharides (HMOs) are known to shape the composition of the infant gut microbiome. The goal of this study was to characterize the HMO profiles of normal-weight and overweight mothers and to quantitatively link HMO concentrations to the taxonomic composition and functional potential of the infant gut microbiome. Normal-weight (BMI = 18.5-24.9; n = 9) and overweight/obese (OW/OB; BMI > 25; n = 11) breastfeeding mothers and their infants were enrolled in this single-center, cross-sectional pilot study. Human milk from the mothers and rectal stool swabs from the infants were collected 7-9 weeks postpartum. The HMO composition, microbiome composition, and microbial functions were assessed using HPLC, 16S rRNA gene sequencing, and metagenomic sequencing, respectively. Neither the HMO profiles nor the infant microbiome composition varied according to maternal BMI status. Taxonomically, the gut microbiota of infants were dominated by typical gut lineages including Bifidobacterium. Significant correlations between individual HMOs and bacterial genera were identified, including for Prevotella, a genus of the Bacteroidota phylum that was positively correlated with the concentrations of lacto-N-neotetraose (LNnT) and lacto-N-hexaose (LNH). Using metagenomic assembled genomes, we were also able to identify the broad HMO-degradative capacity across the Bifidobacterium and Prevotella genera. These results suggest that the maternal BMI status does not impact the HMO profiles of human milk. However, select HMOs were correlated with specific bacterial taxa, suggesting that the milk composition influences both the taxonomic composition and the functional capacity of the infant gut microbiome.

Metabolic Engineering of Escherichia coli BL21(DE3) for 2'-Fucosyllactose Synthesis in a Higher Productivity.

2'-Fucosyllactose (2'-FL) is the most abundant human milk oligosaccharides (HMOs). 2'-FL exhibits great benefits for infant health, such as preventing infantile diarrhea and promoting the growth of intestinal probiotics. The microbial cell factory technique has shown promise for the massive production of 2'-FL. Here, we aimed to construct a recombinant E. coli BL21(DE3) strain for the hyperproduction of 2'-FL. Initially, multicopy genomic integration and expression of the lactose permease gene lacY reduced the formation of byproducts. Furthermore, a more efficient Shine-Dalgarno sequence was used to replace the wild-type sequence in the manC-manB and gmd-wcaG gene clusters, which significantly increased the 2'-FL titer. Based on these results, we overexpressed the sugar efflux transporter SetA and knocked out the pgi gene. This further improved 2'-FL synthesis when glycerol was used as the sole carbon source. Finally, a new α-1,2-fucosyltransferase was identified in Neisseria sp., which exhibited a higher capacity for 2'-FL production. Fed-batch fermentation produced 141.27 g/L 2'-FL in 45 h with a productivity of 3.14 g/L × h. This productivity rate achieved the highest recorded 2'-FL levels, indicating the potential of engineered E. coli BL21 (DE3) strains for use in the industrial production of 2'-FL.

Profiles of 71 Human Milk Oligosaccharides and Novel Sub-Clusters of Type I Milk: Results from the Ulm SPATZ Health Study.

Although approximately 160 human milk oligosaccharides (HMOs) have been identified, current studies on HMO quantitation are limited to the 10-19 most abundant HMOs. We assessed the variations in the relative concentrations of 71 HMO structures over lactation in human milk samples by an advanced liquid chromatography-mass spectrometry approach. Samples were collected from 64 mothers at 6 weeks, 6 months, and 12 months of lactation in the Ulm SPATZ Health Study, a German birth cohort. In this longitudinal study, we fitted linear mixed-effect models to analyze changes in the log2-transformed and standardized HMO concentration over time. Based on the profile of 71 HMOs, we also fitted a group-based multi-trajectory (GBMT) model to cluster mothers secreting cluster type I milk, who account for the majority of lactating mothers. We found that 52 HMOs had a decreasing trend (regression coefficients ranging from -1.41 to -0.17) and 9 had an increasing trend (regression coefficients ranging from 0.25 to 0.64) during lactation, and the findings were statistically significant after multiple testing corrections. Using human milk samples of 49 mothers with type I milk, we further identified two novel sub-clusters with distinct longitudinal trajectories of concentrations of 71 HMOs during lactation: Type I-a (N = 20) and I-b (N = 29). These sub-clusters were not associated with maternal non-genetic characteristics. Our findings extend existing knowledge about the structural diversity of HMOs and their variations over lactation. These may pave the way to investigate the potential nutritional benefits of various HMOs on infant health and early life development in the future.

Interactions of human milk oligosaccharides with the immune system.

Human milk oligosaccharides (HMOs) are abundant, diverse and complex sugars present in human breast milk. HMOs are well-characterized barriers to microbial infection and by modulating the human microbiome they are also thought to be nutritionally beneficial to the infant. The structural variety of over 200 HMOs, including neutral, fucosylated and sialylated forms, allows them to interact with the immune system in various ways. Clinically, HMOs impact allergic diseases, reducing autoimmune and inflammatory responses, and offer beneficial support to the preterm infant immune health. This review examines the HMO composition and associated immunomodulatory effects, including interactions with immune cell receptors and gut-associated immune responses. These immunomodulatory properties highlight the potential for HMO use in early stage immune development and for use as novel immunotherapeutics. HMO research is rapidly evolving and promises innovative treatments for immune-related conditions and improved health outcomes.

Unusual free trisaccharides in caprine colostrum discovered by logically derived sequence tandem mass spectrometry

Free oligosaccharides in human milk have many biological functions for infant health. The reducing end of most human milk oligosaccharides is lactose, and caprine milk was reported to contain oligosaccharides structurally similar to those present in human milk. The structures of oligosaccharides were traditionally determined using nuclear magnetic resonance spectroscopy or enzyme digestion followed by various detection methods, e.g., liquid. Mass spectrometry has much higher sensitivity than nuclear magnetic resonance spectroscopy and enzyme digestion. However, conventional mass spectrometry methods only determine part of the structures of oligosaccharides, i.e., compositions and linkage positions. In this study, we used the latest developed mass spectrometry method, namely logically derived sequence tandem mass spectrometry, to determine the complete structures (i.e., composition, linkage positions, anomericities, and stereoisomers) of free neutral trisaccharides in caprine colostrum and mature milk. The high sensitivity of mass spectrometry enables us to discover oligosaccharides of low abundance. Isomers of (Hex)2HexNAc, (Hex)3, and (Hex)2Fuc which have not been reported before were identified. Many of them do not have lactose at the reducing end. Instead, the reducing end is either Glcβ-(1–4)-Glc or Glcβ-(1–4)-GlcNAc. These unusual oligosaccharides are higher in concentration and more structurally diverse in caprine colostrum than that in caprine mature milk and human milk. The structural diversity indicates more complicated biosynthetic pathways of caprine milk compared to that of human milk.

Human milk oligosaccharides: bridging the gap in intestinal microbiota between mothers and infants.

Breast milk is an essential source of infant nutrition. It is also a vital determinant of the structure and function of the infant intestinal microbial community, and it connects the mother and infant intestinal microbiota. Human milk oligosaccharides (HMOs) are a critical component in breast milk. HMOs can reach the baby's colon entirely from milk and become a fermentable substrate for some intestinal microorganisms. HMOs can enhance intestinal mucosal barrier function and affect the intestinal function of the host through immune function, which has a therapeutic effect on specific infant intestinal diseases, such as necrotizing enterocolitis. In addition, changes in infant intestinal microbiota can reflect the maternal intestinal microbiota. HMOs are a link between the maternal intestinal microbiota and infant intestinal microbiota. HMOs affect the intestinal microbiota of infants and are related to the maternal milk microbiota. Through breastfeeding, maternal microbiota and HMOs jointly affect infant intestinal bacteria. Therefore, HMOs positively influence the establishment and balance of the infant microbial community, which is vital to ensure infant intestinal function. Therefore, HMOs can be used as a supplement and alternative therapy for infant intestinal diseases.

Metabolic engineering of Priestia megaterium for 2’-fucosyllactose production

Background2′-Fucosyllactose (2′-FL) is a predominant human milk oligosaccharide that significantly enhances infant nutrition and immune health. This study addresses the need for a safe and economical production of 2’-FL by employing Generally Recognized As Safe (GRAS) microbial strain, Priestia megaterium ATCC 14581. This strain was chosen for its robust growth and established safety profile and attributing suitable for industrial-scale production.ResultsThe engineering targets included the deletion of the lacZ gene to prevent lactose metabolism interference, introduction of α-1,2-fucosyltransferase derived from the non-pathogenic strain, and optimization of the GDP-L-fucose biosynthesis pathway through the overexpression of manA and manC. These changes, coupled with improvements in lactose uptake and utilization through random mutagenesis, led to a high 2’-FL yield of 28.6 g/L in fed-batch fermentation, highlighting the potential of our metabolic engineering strategies on P. megaterium.ConclusionsThe GRAS strain P. megaterium ATCC 14581 was successfully engineered to overproduce 2’-FL, a valuable human milk oligosaccharide, through a series of genetic modifications and metabolic pathway optimizations. This work underscores the feasibility of using GRAS strains for the production of oligosaccharides, paving the way for safer and more efficient methods in biotechnological applications. Future studies could explore additional genetic modifications and optimization of fermentation conditions of the strain to further enhance 2’-FL yield and scalability.

Characterization of Bifidobacterium bifidum growth and metabolism on whey protein phospholipid concentrate.

Whey protein phospholipid concentrate (WPPC) is a co-product generated during the manufacture of whey protein isolate. WPPC is depleted of simple sugars but contains numerous glycoconjugates embedded in the milk fat globule membrane, suggesting this fraction may serve as a carbon source for growth of bifidobacteria commonly enriched in breast fed infants. In this work, we demonstrate that WPPC can serve as a sole carbon source for the growth of Bifidobacterium bifidum, a species common to the breastfed infant and routinely used as a probiotic. Growth on WPPC fractions resulted in expression of key extracellular glycosyl hydrolases in B. bifidum associated with the catabolism of glycoproteins. Interestingly, this included induction of fucosidase genes in B. bifidum linked to catabolism of fucosylated human milk oligosaccharides even though the WPPC glycan possesses little fucose. Additional growth studies revealed that WPPC-glycan components N-acetylglucosamine or N-acetylgalactosamine were required for pre-activation of B. bifidum toward rapid growth on the fucosylated human milk oligosaccharides. Growth on WPPC fractions also resulted in expression of extracellular sialidases in B. bifidum which promoted a consistent release of sialic acid, a well-known component of bovine milk oligosaccharides and glycoconjugates with potential impacts on gut microbial ecology and host cognition. These studies suggest WPPC may serve as a promising bioactive component to facilitate probiotic activity for use in infant formulas and other synbiotic applications.

2'-Fucosyllactose as a prebiotic modulates the probiotic responses of Bifidobacterium bifidum.

2'-Fucosyllactose (2'-FL), one of the most representative oligosaccharides in human milk, is intimately linked to the enrichment of specific Bifidobacterium species. However, the efficacy of 2'-FL in modulating the probiotic responses of bifidobacterium has been rarely researched. Thereinto, three key issues have yet to be reported: the effects of 2'-FL hydrolysis on bifidobacterial growth, the protective effects of 2'-FL on bifidobacterium under gastrointestinal stress and the inhibitory activity of 2'-FL metabolites against Cronobacter spp. This work intended to address these concerns. 2'-FL dramatically accelerated the growth and proliferation of Bifidobacterium bifidum YH17 and Bifidobacterium bifidum BBI01. The glucose in lactose core on 2'-FL was preferable for B. bifidum to achieve substantial increases in biomass while the galactose was not readily available. Additionally, 2'-FL showed unique advantages in ameliorating the resistance of B. bifidum to gastrointestinal challenges. 2'-FL considerably improved the adhesive property of B. bifidum, thus facilitating the competitive elimination of Cronobacter sakazakii ATCC 29544 and Cronobacter muytjensii ATCC 51329 by B. bifidum. The growth inhibition of 2'-FL on the Cronobacter strains was mediated by promoting the secretion of antibacterial substances from B. bifidum. The inhibitory activity hinged on the B. bifidum strains. 2'-FL specifically induced B. bifidum BBI01 to produce some antibacterial substances that were proteinaceous, thermostable and relatively stable even at pH 8.0. These antibacterial substances played a key role in the inhibitory activity and had a synergistic effect with acidification. These observations provide a useful guideline for developing synbiotic supplements to intervene the infant gut microbiota.

Recent advances in the science of human milk oligosaccharides

Recent advances in the science of human milk oligosaccharides

The Bifidogenic Effect of 2'Fucosyllactose Is Driven by Age-Specific Bifidobacterium Species, Demonstrating Age as an Important Factor for Gut Microbiome Targeted Precision Medicine.

The human gut microbiota develops in concordance with its host over a lifetime, resulting in age-related shifts in community structure and metabolic function. Little is known about whether these changes impact the community's response to microbiome-targeted therapeutics. Providing critical information on this subject, faecal microbiomes of subjects from six age groups, spanning from infancy to 70-year-old adults (n = six per age group) were harvested. The responses of these divergent communities to treatment with the human milk oligosaccharide 2'-fucosyllactose (2'FL), fructo-oligosaccharides (FOS), and lactose was investigated using the Ex vivo SIFR® technology that employs bioreactor fermentation and is validated to be predictive of clinical findings. Additionally, it was evaluated whether combining faecal microbiomes of a given age group into a single pooled microbiome produced similar results as the individual microbiomes. First, marked age-dependent changes in community structure were identified. Bifidobacterium levels strongly declined as age increased, and Bifidobacterium species composition was age-dependent: B. longum, B. catenulatum/pseudocatenulatum, and B. adolescentis were most prevalent for breastfed infants, toddlers/children, and adults, respectively. Metabolomic analyses (LA-REIMS) demonstrated that these age-dependent differences particularly impacted treatment effects of 2'FL (more than FOS/lactose). Further analysis revealed that while 2'FL enhanced production of short-chain fatty acids (SCFAs) and exerted potent bifidogenic effects, regardless of age, the specific Bifidobacterium species enhanced by 2'FL, as well as subsequent cross-feeding interactions, were highly age-dependent. Furthermore, single-pooled microbiomes produced results that were indicative of the average treatment response for each age group. Nevertheless, pooled microbiomes had an artificially high diversity, thus overestimating treatment responses (especially for infants), did not recapitulate interindividual variation, and disallowed for the correlative analysis required to unravel mechanistic actions. Age is an important factor in shaping the gut microbiome, with the dominant taxa and their metabolites changing over a lifetime. This divergence affects the response of the microbiota to therapeutics, demonstrated in this study using 2'FL. These results evidence the importance of screening across multiple age groups separately to provide granularity of how therapeutics impact the microbiome and, consequently, human health.

Human Milk Oligosaccharides: Decoding Their Structural Variability, Health Benefits, and the Evolution of Infant Nutrition

Human milk oligosaccharides (HMOs), the third most abundant solid component in human milk, vary significantly among women due to factors such as secretor status, race, geography, season, maternal nutrition and weight, gestational age, and delivery method. In recent studies, HMOs have been shown to have a variety of functional roles in the development of infants. Because HMOs are not digested by infants, they act as metabolic substrates for certain bacteria, helping to establish the infant’s gut microbiota. By encouraging the growth of advantageous intestinal bacteria, these sugars function as prebiotics and produce short-chain fatty acids (SCFAs), which are essential for gut health. HMOs can also specifically reduce harmful microbes and viruses binding to the gut epithelium, preventing illness. HMO addition to infant formula is safe and promotes healthy development, infection prevention, and microbiota. Current infant formulas frequently contain oligosaccharides (OSs) that differ structurally from those found in human milk, making it unlikely that they would reproduce the unique effects of HMOs. However, there is a growing trend in producing OSs resembling HMOs, but limited data make it unclear whether HMOs offer additional therapeutic benefits compared to non-human OSs. Better knowledge of how the human mammary gland synthesizes HMOs could direct the development of technologies that yield a broad variety of complex HMOs with OS compositions that closely mimic human milk. This review explores HMOs’ complex nature and vital role in infant health, examining maternal variation in HMO composition and its contributing factors. It highlights recent technological advances enabling large-scale studies on HMO composition and its effects on infant health. Furthermore, HMOs’ multifunctional roles in biological processes such as infection prevention, brain development, and gut microbiota and immune response regulation are investigated. The structural distinctions between HMOs and other mammalian OSs in infant formulas are discussed, with a focus on the trend toward producing more precise replicas of HMOs found in human milk.

Personalized modeling of gut microbiome metabolism throughout the first year of life

BackgroundEarly-life exposures including diet, and the gut microbiome have been proposed to predispose infants towards multifactorial diseases later in life. Delivery via Cesarian section disrupts the establishment of the gut microbiome and has been associated with negative long-term outcomes. Here, we hypothesize that Cesarian section delivery alters not only the composition of the developing infant gut microbiome but also its metabolic capabilities. To test this, we developed a metabolic modeling workflow targeting the infant gut microbiome.MethodsThe AGORA2 resource of human microbial genome-scale reconstructions was expanded with a human milk oligosaccharide degradation module. Personalized metabolic modeling of the gut microbiome was performed for a cohort of 20 infants at four time points during the first year of life as well as for 13 maternal gut microbiome samples.ResultsHere we show that at the earliest stages, the gut microbiomes of infants delivered through Cesarian section are depleted in their metabolic capabilities compared with vaginal delivery. Various metabolites such as fermentation products, human milk oligosaccharide degradation products, and amino acids are depleted in Cesarian section delivery gut microbiomes. Compared with maternal gut microbiomes, infant gut microbiomes produce less butyrate but more L-lactate and are enriched in the potential to synthesize B-vitamins.ConclusionsOur simulations elucidate the metabolic capabilities of the infant gut microbiome demonstrating they are altered in Cesarian section delivery at the earliest time points. Our workflow can be readily applied to other cohorts to evaluate the effect of feeding type, or maternal factors such as diet on host-gut microbiome inactions in early life.