Project description:In this study, we quantitated the disappearance of intact HMOs and characterized the glycan digestion products in the gut that are produced by the action of microbial enzymes on HMOs and glycoconjugates from breast milk. Oligosaccharides from fecal samples of exclusively breast-fed infants were extracted and profiled using nanoLC-MS. Intact HMOs were found in the fecal samples, additionally, other oligosaccharides were found corresponding to degraded HMOs and non-HMO based compounds. The latter compounds were fragments of N-glycans released through the cleavage of the linkage to the asparagine residue and through cleavage of the chitobiose core of the N-glycan.
Project description:Bifidobacterium longum subsp. infantis (B. infantis) colonizes the infant gut microbiome with a 43-kb gene cluster that enables human milk oligosaccharide (HMO) utilization. Although there is relative genomic homogeneity in this regard, previous observations suggest that B. infantis strains may differ in their utilization phenotype. To test this hypothesis, a panel of B. infantis strains were evaluated for their ability to utilize pooled HMOs to yield differential phenotypes including biomass accumulation, HMO consumption glycoprofile, end-product secretion, and global transcriptomes. Two strains (ATCC 15697 and UMA301) efficiently consumed several HMO isomers/anomers that exhibit degrees of polymerization (DP) ³ 4. These same strains partially consumed the smaller DP HMOs including fucosyllactose and lactodifucotetraose isomers/anomers. In contrast, UMA299 efficiently utilized fucosylated small molecular weight HMOs (DP<4), and accumulated greater biomass on purified 2´FL with significantly higher 1,2-propanediol production. This study identifies several strain-dependent features in HMO utilization phenotypes that are consistent with metabolic variation within a bifidobacterial-dominated infant-gut microbiome.
Project description:The factors that govern the retention and abundance of specific microbial lineages within a developing intestinal microbiota remain poorly defined. Human milk oligosaccharides consumed by nursing infnats pass undigested to the distal gut where they may be consumed by microbes. We investigated the transcriptional response of Bacterides fragilis, a prominent gut resident, to the presence of HMOs. In vitro transcriptional profiles of Bacteroides fragilis obtained from biological duplicate cultures taken at middle log phase in minimal media glucose (MM-Glu) and in minimal media with human milk oligosaccharides (MM-HMO).
Project description:Investigation of the overall in vitro response of Bacteroides thetaiotaomicron to human milk oligosaccharides. Comparison with response to MM-lactose and MM-galactose (Analysis performed using as a baseline datasets GSM301635 and GSM301637 corresponding to Bacteroides thetaiotaomicron response in MM-Glucose) In vitro transcriptional profiles of Bacteroides thetaiotaomicron obtained from biological duplicate cultures taken: (i) at middle log phase in minimal media galactose (MM-Gal) and minimal media lactose (MM-L) and (ii) at two timepoints during log phase in minimal media human milk oligosaccharides (MM-HMO).
Project description:BackgroundWe aimed to estimate associations between human milk oligosaccharides (HMOs) and infant growth (length-for-age (LAZ) and weight-for-length (WLZ) z-scores) at 12 months postnatal age.MethodsIn this secondary analysis of data from a maternal vitamin D trial in Dhaka, Bangladesh (N = 192), absolute concentrations of HMOs were measured in 13 ± 1 week(s) postpartum milk samples, infant anthropometric measurements were obtained soon after birth and at 12 months postpartum, and infant feeding was classified during 6 months postpartum. Associations between individual HMOs or HMO groups and LAZ or WLZ were estimated by multivariable linear regression adjusting for infant feeding pattern, maternal secretor status, and other potential confounders.ResultsThe concentrations of 6'sialyllactose, lacto-N-neotetraose, and the non-fucosylated non-sialylated HMOs were inversely associated with LAZ at 12 months of age, whereas the fucosylated non-sialylated HMO concentration was positively associated with LAZ at 12 months. These associations were robust in analyses restricted to infants who were primarily exclusively/predominantly fed human milk during the first 3 (or 6) months.ConclusionsSince HMOs are both positively and negatively associated with postnatal growth, there is a need for randomized trials to estimate the causal benefits and risks of exogenously administered HMOs on infant growth and other health outcomes.Impact6'sialyllactose, lacto-N-neotetraose, and the non-fucosylated non-sialylated human milk oligosaccharides (HMOs) were inversely associated with length-for-age z-scores (LAZ) at 12 months, whereas the fucosylated non-sialylated HMO concentration was positively associated with LAZ at 12 months among Bangladeshi infants. Associations between individual and grouped HMOs with infant length growth at 12 months were as strong or stronger in analyses restricted to infants who were exclusively or predominantly fed human milk up to 3 (or 6) months. Randomized trials are needed to characterize the effects of specific HMOs on infant growth, particularly in countries where postnatal linear growth faltering is common.
Project description:Newborns are colonized with an intestinal microbiota shortly after birth, but the factors governing the retention and abundance of specific microbial lineages are unknown. Nursing infants consume human milk oligosaccharides (HMOs) that pass undigested to the distal gut, where they may be digested by microbes. We determined that the prominent neonate gut residents, Bacteroides thetaiotaomicron and Bacteroides fragilis, induce the same genes during HMO consumption that are used to harvest host mucus glycans, which are structurally similar to HMOs. Lacto-N-neotetraose, a specific HMO component, selects for HMO-adapted species such as Bifidobacterium infantis, which cannot use mucus, and provides a selective advantage to B. infantis in vivo when biassociated with B. thetaiotaomicron in the gnotobiotic mouse gut. This indicates that the complex oligosaccharide mixture within HMOs attracts both mutualistic mucus-adapted species and HMO-adapted bifidobacteria to the infant intestine that likely facilitate both milk and future solid food digestion.
Project description:Background: Breastfed human infants are predominantly colonized by bifidobacteria that thrive on human milk oligosaccharides (HMO). The two most predominant species of bifidobacteria in infant feces are Bifidobacterium breve (B. breve) and Bifidobacterium longum subsp. infantis (B. infantis), both avid HMO-consumer strains. Our laboratory has previously shown that B. infantis, when grown on HMO, increase adhesion to intestinal cells and increase the expression of the anti-inflammatory cytokine interleukin-10. The purpose of the current study was to investigate the effects of carbon source—glucose, lactose, or HMO—on the ability of B. breve and B. infantis to adhere to and affect the transcription of intestinal epithelial cells on a genome-wide basis. Results: HMO-grown B. infantis had higher percent binding to Caco-2 cell monolayers compared to B. infantis grown on glucose or lactose. B. breve had low adhesive ability regardless of carbon source. Despite differential binding ability, both HMO-grown strains significantly differentially affected the Caco-2 transcriptome compared to their glucose or lactose grown controls. HMO-grown B. breve and B. infantis both down-regulated genes in Caco-2 cells associated with chemokine activity. Conclusion: The choice of carbon source affects the interaction of bifidobacteria with intestinal epithelial cells. HMO-grown bifidobacteria reduce markers of inflammation, compared to glucose or lactose-grown bifidobacteria. In the future, the design of preventative or therapeutic probiotic supplements may need to include appropriately chosen prebiotics.
Project description:ObjectiveThe aim of this study was to measure consumption and absorption of human milk oligosaccharides (HMOs) in a cohort of premature infants treated with probiotic Bifidobacterium breve.MethodsTwenty-nine premature infants (median gestational age 28 weeks, range 23-32 weeks) cared for in the neonatal intensive care unit of the King Edward and Princess Margaret Hospital in Perth, Australia, were treated with B breve at a dose of 1.66 billion organisms per day. Samples of feces, urine, and milk were obtained at initiation of the probiotic and again 3 weeks later. 16S ribosomal RNA from the feces was analyzed by next-generation sequencing. Quantitation of HMO content of the milk, urine, and feces was performed using nano-high-performance liquid chromatography-chip/time-of-flight mass spectrometry.ResultsThere was heterogeneity in colonization with bifidobacteria. "Responders" received milk with higher percentages of fucosylated HMOs and had higher percentages of bifidobacteria and lower percentages of Enterobacteriaceae in their feces than "nonresponders." Several individual HMOs in the milk were associated with changes in fecal bifidobacteria over time. Changes over time in milk, fecal, and urine HMOs suggested heterogeneity among HMO structures in consumption by microbes in the gut lumen and absorption from the intestine.ConclusionsColonization of the premature infant intestinal tract with probiotic B breve is influenced by prebiotic HMOs. B breve is a selective consumer of HMOs in the premature infant.
Project description:Diet-microbe interactions play an important role in modulating the early-life microbiota, with Bifidobacterium strains and species dominating the gut of breast-fed infants. Here, we sought to explore how infant diet drives distinct bifidobacterial community composition and dynamics within individual infant ecosystems. Genomic characterisation of 19 strains isolated from breast-fed infants revealed a diverse genomic architecture enriched in carbohydrate metabolism genes, which was distinct to each strain, but collectively formed a pangenome across infants. Presence of gene clusters implicated in digestion of human milk oligosaccharides (HMOs) varied between species, with growth studies indicating that within single infants there were differences in the ability to utilise 2'FL and LNnT HMOs between strains. Cross-feeding experiments were performed with HMO degraders and non-HMO users (using spent or 'conditioned' media and direct co-culture). Further 1H-NMR analysis identified fucose, galactose, acetate, and N-acetylglucosamine as key by-products of HMO metabolism; as demonstrated by modest growth of non-HMO users on spend media from HMO metabolism. These experiments indicate how HMO metabolism permits the sharing of resources to maximise nutrient consumption from the diet and highlights the cooperative nature of bifidobacterial strains and their role as 'foundation' species in the infant ecosystem. The intra- and inter-infant bifidobacterial community behaviour may contribute to the diversity and dominance of Bifidobacterium in early life and suggests avenues for future development of new diet and microbiota-based therapies to promote infant health.
Project description:Background: Breastfed human infants are predominantly colonized by bifidobacteria that thrive on human milk oligosaccharides (HMO). The two most predominant species of bifidobacteria in infant feces are Bifidobacterium breve (B. breve) and Bifidobacterium longum subsp. infantis (B. infantis), both avid HMO-consumer strains. Our laboratory has previously shown that B. infantis, when grown on HMO, increase adhesion to intestinal cells and increase the expression of the anti-inflammatory cytokine interleukin-10. The purpose of the current study was to investigate the effects of carbon source—glucose, lactose, or HMO—on the ability of B. breve and B. infantis to adhere to and affect the transcription of intestinal epithelial cells on a genome-wide basis. Results: HMO-grown B. infantis had higher percent binding to Caco-2 cell monolayers compared to B. infantis grown on glucose or lactose. B. breve had low adhesive ability regardless of carbon source. Despite differential binding ability, both HMO-grown strains significantly differentially affected the Caco-2 transcriptome compared to their glucose or lactose grown controls. HMO-grown B. breve and B. infantis both down-regulated genes in Caco-2 cells associated with chemokine activity. Conclusion: The choice of carbon source affects the interaction of bifidobacteria with intestinal epithelial cells. HMO-grown bifidobacteria reduce markers of inflammation, compared to glucose or lactose-grown bifidobacteria. In the future, the design of preventative or therapeutic probiotic supplements may need to include appropriately chosen prebiotics.