Project description:Diet-microbe interactions play a crucial role in infant development and modulation of the early-life microbiota. The genus Bifidobacterium dominates the breast-fed infant gut, with strains of B. longum subsp. longum (B. longum) and B. longum subsp. infantis (B. infantis) particularly prevalent within the early-life microbiota. Although, transition from milk to a more diversified diet later in infancy initiates a shift to a more complex microbiome, with concurrent reductions in Bifidobacterium abundance, specific strains of B. longum may persist in individual hosts for prolonged periods of time. Here, we sought to investigate the adaptation of B. longum to the changing infant diet during the early-life developmental window. Genomic characterisation of 75 strains isolated from nine either exclusively breast- or formula-fed infants in the first 18 months of their lives revealed subspecies- and strain-specific intra-individual genomic diversity with respect to glycosyl hydrolase families and enzymes, which corresponded to different dietary stages. Complementary phenotypic growth studies indicated strain-specific differences in human milk oligosaccharide and plant carbohydrate utilisation profiles between and within individual infants, while proteomic profiling identified proteins involved in metabolism of selected carbohydrates. Our results indicate a strong link between infant diet and B. longum subspecies/strain genomic and carbohydrate utilisation diversity, which aligns with a changing nutritional environment i.e. moving from breast milk to a solid food diet. These data provide additional insights into possible mechanisms responsible for the competitive advantage of this bifidobacterial species and their long-term persistence in a single host and may contribute to rational development of new dietary therapies for this important development window.
Project description:Human milk oligosaccharides (HMOs) are highly diverse complex carbohydrates secreted in human milk. HMOs are indigestible by the infant and instead are metabolized by bifidobacteria in the infant gut microbiome to produce molecules that promote infant health and development. 2´fucosyllactose (2´FL) is an abundant HMO and is utilized by Bifidobacterium longum subsp. infantis, a predominant member of the infant gut microbiome. Currently, there is not a scientific consensus on how or if bifidobacteria metabolize the fucose portion of 2´FL or free fucose. This proteomic analysis was conducted in order to characterize the metabolic pathway by which B. infantis utilizes fucose.
Project description:The purpose of this project was to determine the whole transcriptome response of Bifidobacterium longum subsp. longum SC596 to pooled and individual human milk oligosaccharides (HMO) relative to lactose
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 purpose of this project was to determine the whole transcriptome response of Bifidobacterium longum subsp. Infantis to pooled and individual human milk oligosaccharides (HMO) relative to lactose
Project description:Human milk oligosaccharides (HMOs) function as prebiotics for beneficial bacteria in the developing gut, often dominated by Bifidobacterium spp. To understand the relationship between Bifidobacterium utilizing HMOs and how the metabolites that are produced could affect the host, we analyzed the metabolism of HMO 2’-fucosyllactose (2’-FL), 3-fucosyllactose (3FL and difucosyllactose (DFL) in Bifidobacterium longum ssp. infantis Bi-26 and ATCC15697. RNA-seq and metabolite analysis was performed on samples at early (A600=0.25), mid-log (0.5-0.7) and late-log phases (1.0-2.0) of growth.
Project description:The purpose of this project was to determine the whole transcriptome response of Bifidobacterium longum subsp. Infantis to pooled and individual human milk oligosaccharides (HMO) relative to lactose Bacterial isolates grown on lactose, pooled human milk oligosaccharides (HMO), lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT), 2âfucosyllactose (2âFL), 3-fucosyllactose (3FL), and 6âsialyllactose (6âSL). RNA was extracted and sequenced, in duplicate, on an Illumina HiSeq. Early, mid, and late timepoints in response to pooled HMO were additionally sequenced in duplicate.
Project description:Bifidobacterium longum subsp. infantis is a bacterial commensal that colonizes the breast-fed infant gut where it utilizes indigestible components delivered in human milk. Accordingly, human milk contains several non-protein nitrogenous molecules, including urea at high abundance. This project investigates the degree to which urea is utilized as a primary nitrogen source by Bifidobacterium longum subsp. infantis and incorporation of hydrolysis products into the expressed proteome.
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: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.