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: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: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:The purpose of this project was to determine the whole transcriptome response of Bifidobacterium longum subsp. infantis to human milk urea compared to complex nitrogen and L-cysteine.
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:Bifidobacterium longum subsp. infantis (B. infantis) resides in the human infant gut and helps with the utilization of human milk-derived nutrient components. While its utilization of various carbohydrate sources has been studied extensively, mechanisms behind utilization of nitrogen components from human milk remain largely unknown. In this study, we present B. infantis growth profiles on the N-containing human milk oligosaccharides (HMO) as nitrogen sources, namely, lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT). Dietary 2-Oxoglutarate (2-OG) in known in mice model for its protective effects against intestinal inflammation and colitis development. In this study, we have shown that B. infantis had increased 2-OG concentration when utilizes LNT or LNnT as a primary nitrogen source. As LNT and LNnT are the isomers of HMO core structures, N-acetyl glucosamine (NAG), the N-containing monosaccharide, was regarded as the nitrogen provider of the HMO core structures. Differentially expressed gene patterns in B. infantis were analyzed under the less efficient nitrogen conditions (HMOs and NAG) relative to the complex nitrogen controls. Proteomics analysis of B. infantis using 15N-labeled NAG revealed that NAG nitrogen was incorporated into B. infantis metabolism. Transcriptomics results of B. infantis in LNT, LNnT and NAG nitrogen were consistent with the proteomics results. This further indicated that B. infantis metabolism was affected by NAG nitrogen in nitrogen assimilation, HMO catabolism, NAD cofactor biosynthesis and regeneration, and peptidoglycan biosynthesis pathways. In summary, B. infantis can use NAG-containing HMO as a nitrogen source and incorporate NAG nitrogen into metabolism pathways.
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: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:Human milk oligosaccharides (HMOs) enrich beneficial bifidobacteria in the infant gut microbiome which produce molecules that impact development and physiology. 2´fucosyllactose (2´FL) is a highly abundant fucosylated HMO which is utilized by Bifidobacterium longum subsp. infantis, despite limited scientific understanding of the underlying mechanism. Moreover, there is not a current consensus on whether free fucose could be metabolized when not incorporated in a larger oligosaccharide structure. Based on metabolic and genomic analyses, we hypothesize that B. infantis catabolizes both free fucose and fucosyl oligosaccharide residues to produce 1,2-propanediol (1,2-PD). Accordingly, systems-level approaches including transcriptomics and proteomics support this metabolic path. Co-fermentation of fucose and limiting lactose or glucose was found to promote significantly higher biomass and 1,2-PD concentrations than individual substrates, suggesting a synergistic effect. In addition, and during growth on 2´FL, B. infantis achieves significantly higher biomass corresponding to increased 1,2-PD. These findings support a singular fucose catabolic pathway in B. infantis that is active on both free and HMO-derived fucose and intimately linked with central metabolism. The impact of fucose and 2´FL metabolism on B. infantis physiology provides insight into the role of fucosylated HMOs in influencing host- and microbe-microbe interactions within the infant gut microbiome.
Project description:The protein composition of Bifidobacterium longum subsp. infantis (B. infantis) cultured for 2, 4, 6, and 8 hours in glucose, lactose, galactooligosaccharides, and 2'-fucosyllactose, respectively. Sample No. 41 represents the control; sample Nos. 6-9 represent B. infantis cultured for 2, 4, 6, and 8 hours in lactose, respectively; sample Nos. 16-19 represent B. infantis cultured for 2, 4, 6, and 8 hours in glucose, respectively; sample Nos. 26-29 represent B. infantis cultured for 2, 4, 6, and 8 hours in galactooligosaccharides, respectively; and sample Nos. 36-39 represent B. infantis cultured for 2, 4, 6, and 8 hours in 2'-fucosyllactose, respectively.