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 (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:To demonstrate plasmid transferability by conjugation, cultures of the donor S. Infantis, and recipient Escherichia coli (E. coli) K12 were mated. S. Infantis and transconjugant were screened for resistance genes.
