Genome-scale metabolic modeling of the human milk oligosaccharide utilization by Bifidobacterium longum subsp. infantis.

Bifidobacterium longum subsp. infantis is a representative and dominant species in the infant gut and is considered a beneficial microbe. This organism displays multiple adaptations to thrive in the infant gut, regarded as a model for human milk oligosaccharides (HMOs) utilization. These carbohydrates are abundant in breast milk and include different molecules based on lactose. They contain fucose, sialic acid, and N-acetylglucosamine. Bifidobacterium metabolism is complex, and a systems view of relevant metabolic pathways and exchange metabolites during HMO consumption is missing. To address this limitation, a refined genome-scale network reconstruction of this bacterium is presented using a previous reconstruction of B. infantis ATCC 15967 as a template. The latter was expanded based on an extensive revision of genome annotations, current literature, and transcriptomic data integration. The metabolic reconstruction (iLR578) accounted for 578 genes, 1,047 reactions, and 924 metabolites. Starting from this reconstruction, we built context-specific genome-scale metabolic models using RNA-seq data from cultures growing in lactose and three HMOs. The models revealed notable differences in HMO metabolism depending on the functional characteristics of the substrates. Particularly, fucosyl-lactose showed a divergent metabolism due to a fucose moiety. High yields of lactate and acetate were predicted under growth rate maximization in all conditions, whereas formate, ethanol, and 1,2-propanediol were substantially lower. Similar results were also obtained under near-optimal growth on each substrate when varying the empirically observed acetate-to-lactate production ratio. Model predictions displayed reasonable agreement between central carbon metabolism fluxes and expression data across all conditions. Flux coupling analysis revealed additional connections between succinate exchange and arginine and sulfate metabolism and a strong coupling between central carbon reactions and adenine metabolism. More importantly, specific networks of coupled reactions under each carbon source were derived and analyzed. Overall, the presented network reconstruction constitutes a valuable platform for probing the metabolism of this prominent infant gut bifidobacteria.IMPORTANCEThis work presents a detailed reconstruction of the metabolism of Bifidobacterium longum subsp. infantis, a prominent member of the infant gut microbiome, providing a systems view of its metabolism of human milk oligosaccharides.

Bifidobacterium infantis-Mediated Herpes Simplex Virus-TK/Ganciclovir Treatment Inhibits Cancer Metastasis in Mouse Model.

Previous studies have found that Bifidobacterium infantis-mediated herpes simplex virus-TK/ganciclovir (BF-TK/GCV) reduces the expression of VEGF and CD146, implying tumor metastasis inhibition. However, the mechanism by which BF-TK/GCV inhibits tumor metastasis is not fully studied. Here, we comprehensively identified and quantified protein expression profiling for the first time in gastric cancer (GC) cells MKN-45 upon BF-TK/GCV treatment using quantitative proteomics. A total of 159 and 72 differential expression proteins (DEPs) were significantly changed in the BF-TK/GCV/BF-TK and BF-TK/GCV/BF/GCV comparative analysis. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis enriched some metastasis-related pathways such as gap junction and cell adhesion molecules pathways. Moreover, the transwell assay proved that BF-TK/GCV inhibited the invasion and migration of tumor cells. Furthermore, immunohistochemistry (IHC) demonstrated that BF-TK/GCV reduced the expression of HIF-1α, mTOR, NF-κB1-p105, VCAM1, MMP13, CXCL12, ATG16, and CEBPB, which were associated with tumor metastasis. In summary, BF-TK/GCV inhibited tumor metastasis, which deepened and expanded the understanding of the antitumor mechanism of BF-TK/GCV.

Combined Supplementation of Clostridium butyricum and Bifidobacterium infantis Diminishes Chronic Unpredictable Mild Stress-Induced Intestinal Alterations via Activation of Nrf-2 Signaling Pathway in Rats.

Exposure to long-term chronic unpredictable mild stress (CUMS) can cause redox imbalance and inflammation, which may affect the integrity of the gut barrier. The present study was conducted to investigate the effects of a probiotics bacterium mixture, including Clostridium butyricum (C. butyricum) and Bifidobacterium infantis (B. infantis), on the intestinal homeostasis in rats exposed to multiple low-intensity stressors for 28 days. The mechanism of CUMS-induced altered intestinal homeostasis was evaluated by focusing on the nuclear factor-E2-related factor-2 (Nrf-2) pathway. In contrast to the CUMS group, probiotic mixture supplementation significantly (p < 0.01) reversed the stress-induced elevated corticosterone level, protein and lipid oxidation, and increased enzymatic and non-enzymatic antioxidant levels, as well as upregulated Nrf-2/HO-1 pathway. Probiotics supplementation further significantly (p < 0.01) decreased the CUMS-induced inflammation, altered T-lymphocyte levels, and suppressed the protein expression of nuclear factor kappa B (NF-κB) in rat intestines. Improvement in histological changes and intestinal barrier integrity further validate the beneficial effects of probiotic mixtures on CUMS-induced altered intestinal morphology. In conclusion, our results suggest that the combination of C. butyricum and B. infantis significantly attenuated CUMS-induced oxidative stress, inflammation, and T-lymphocyte modulation by upregulating Nrf-2/HO-1 signaling and inhibiting NF-κB expression in rat intestine.

Fucosylated Human Milk Oligosaccharides Drive Structure-Specific Syntrophy between Bifidobacterium infantis and Eubacterium hallii within a Modeled Infant Gut Microbiome.

SCOPE: Fucosylated human milk oligosaccharides (fHMOs) are metabolized by Bifidobacterium infantis and promote syntrophic interactions between microbiota that colonize the infant gut. The role of fHMO structure on syntrophic interactions and net microbiome function is not yet fully understood. METHODS AND RESULTS: Metabolite production and microbial populations are tracked during mono- and co-culture fermentations of 2'fucosyllactose (2'FL) and difucosyllactose (DFL) by two B. infantis strains and Eubacterium hallii. This is also conducted in an in vitro modeled microbiome supplemented by B. infantis and/or E. hallii. Metabolites are quantified by high performance liquid chromatography. Total B. infantis and E. hallii populations are quantified through qRT-PCR and community composition through 16S amplicon sequencing. Differential metabolism of 2'FL and DFL by B. infantis strains gives rise to strain- and fHMO structure-specific syntrophy with E. hallii. Within the modeled microbial community, fHMO structure does not strongly alter metabolite production in aggregate, potentially due to functional redundancy within the modeled community. In contrast, community composition is dependent on fHMO structure. CONCLUSION: Whereas short chain fatty acid production is not significantly altered by the specific fHMO structure introduced to the modeled community, specific fHMO structure influences the composition of the gut microbiome.

Bifidobacterium infantis regulates the programmed cell death 1 pathway and immune response in mice with inflammatory bowel disease.

BACKGROUND: Inflammatory bowel disease (IBD) is caused by an abnormal immune response. Programmed cell death 1 (PD-1) is an immunostimulatory molecule, which interacts with PD ligand (PD-L1) playing a prime important role among autoimmune diseases. Bifidobacterium infantis (B. infantis) can promote the differentiation of CD (cluster of differentiation) 4+ T cells into regulatory T cells (Tregs). Tregs participate in the development of IBD and may be related to disease activity. B. infantis amplify the expression level of PD-1, PD-L1 and Tregs' nuclear transcription factor forkhead box protein 3 (Foxp3). But the mechanism of B. infantis on PD-1/PD-L1 signaling remains unclear. AIM: To explore the mechanism of B. infantis regulating the immune response in IBD. METHODS: Forty-eight-week-old BALB/c mice were randomly divided into five groups: The control group, dextran sulphate sodium (DSS) model group, DSS + B. infantis group, DSS + B. infantis + anti-PD-L1 group, and DSS + anti-PD-L1 group. The control group mice were given drinking water freely, the other four groups were given drinking water containing 5% DSS freely. The control group, DSS model group, and DSS + anti-PD-L1 group were given normal saline (NS) 400 µL daily by gastric lavage, and the DSS + B. infantis group and DSS + B. infantis + anti-PD-L1 group were given NS and 1 × 109 colony-forming unit of B. infantis daily by gastric lavage. The DSS + B. infantis + anti-PD-L1 group and DSS + anti-PD-L1 group were given 200 µg of PD-L1 blocker intraperitoneally at days 0, 3, 5, and 7; the control group, DSS + anti-PD-L1 group, and DSS + B. infantis group were given an intraperitoneal injection of an equal volume of phosphate buffered saline (PBS). Changes in PD-L1, PD-1, Foxp3, interleukin (IL)-10, and transforming growth factor ß (TGF-ß) 1 protein and gene expression were observed. Flow cytometry was used to observe changes in CD4+, CD25+, Foxp3+ cell numbers in the blood and spleen. RESULTS: Compared to the control group, the expression of PD-1, Foxp3, IL-10, and TGF-ß1 was significantly decreased in the intestinal tract of the DSS mice (P < 0.05). Compared to the control group, the proportion of CD4+, CD25+, Foxp3+ cells in spleen and blood of DSS group was visibly katabatic (P < 0.05). B. infantis upgraded the express of PD-L1, PD-1, Foxp3, IL-10, and TGF-ß1 (P < 0.05) and increased the proportion of CD4+, CD25+, Foxp3+ cells both in spleen and blood (P < 0.05). After blocking PD-L1, the increase in Foxp3, IL-10, and TGF-ß1 protein and gene by B. infantis was inhibited (P < 0.05), and the proliferation of CD4+, CD25+, Foxp3+ cells in the spleen and blood was also inhibited (P < 0.05). After blocking PD-L1, the messenger ribonucleic acid and protein expression of PD-1 were invariant. CONCLUSION: It is potential that B. infantis boost the proliferation of CD4+, CD25+, Foxp3+ T cells in both spleen and blood, as well as the expression of Foxp3 in the intestinal tract by activating the PD-1/PD-L1 pathway.

Bifidobacterium longum subsp. infantis CECT 7210 Reduces Inflammatory Cytokine Secretion in Caco-2 Cells Cultured in the Presence of Escherichia coli CECT 515.

Previous works have described the activity of Bifidobacterium longum subsp. infantis CECT 7210 (also commercially named B. infantis IM-1®) against rotavirus in mice and intestinal pathogens in piglets, as well as its diarrhea-reducing effect on healthy term infants. In the present work, we focused on the intestinal immunomodulatory effects of B. infantis IM-1® and for this purpose we used the epithelial cell line isolated from colorectal adenocarcinoma Caco-2 and a co-culture system of human dendritic cells (DCs) from peripheral blood together with Caco-2 cells. Single Caco-2 cultures and Caco-2: DC co-cultures were incubated with B. infantis IM-1® or its supernatant either in the presence or absence of Escherichia coli CECT 515. The B. infantis IM-1® supernatant exerted a protective effect against the cytotoxicity caused by Escherichia coli CECT 515 on single cultures of Caco-2 cells as viability reached the values of untreated cells. B. infantis IM-1® and its supernatant also decreased the secretion of pro-inflammatory cytokines by Caco-2 cells and the co-cultures incubated in the presence of E. coli CECT 515, with the response being more modest in the latter, which suggests that DCs modulate the activity of Caco-2 cells. Overall, the results obtained point to the immunomodulatory activity of this probiotic strain, which might underlie its previously reported beneficial effects.

Bifidobacterium infantis Promotes Foxp3 Expression in Colon Cells via PD-L1-Mediated Inhibition of the PI3K-Akt-mTOR Signaling Pathway.

Aim: Our objective was to investigate whether Bifidobacterium infantis inhibits PI3K-Akt-mTOR signaling and upregulates Foxp3 expression through PD-L1 and to explore the possible mechanism of action of B. infantis in cellular immunosuppression. Method: The effects of B. infantis supernatant on PD-L1, PD-1, Foxp3, and the PI3K-Akt-mTOR signaling pathway were observed by culturing HCT-116 cells. Simultaneously, the effects of blocking PD-L1 on PD-1, on Foxp3 protein and mRNA, and on the PI3K-Akt-mTOR signaling pathway protein were observed. Results: B. infantis supernatant was able to upregulate the protein and mRNA expression of PD-L1 and Foxp3 and downregulate the phosphorylated protein expression of PI3K, Akt, and mTOR (P < 0.05); however, for PI3K, Akt, and mTOR, there was no change in the total protein expression. After the blocking of PD-L1, the stimulatory effect of B. infantis supernatant on Foxp3 and the inhibitory effect on the phosphorylated protein expression of PI3K, Akt, and mTOR were weakened. Conclusion: B. infantis may inhibit the PI3K-Akt-mTOR signaling pathway and promote the expression of Foxp3 through PD-L1, which may be a target via which B. infantis exerts its immunosuppressive effect.

Preterm Infant Fecal Microbiota and Metabolite Profiles Are Modulated in a Probiotic Specific Manner.

OBJECTIVES: To compare the impact of two probiotic supplements on fecal microbiota and metabolites, as well as on gut inflammation in human milk-fed preterm infants. METHODS: In this single-center observational cohort study, we assessed the effects of Bifidobacterium longum subsp. infantis or Lactobacillus reuteri supplementation on the infant gut microbiota by 16S rRNA gene sequencing and fecal metabolome by 1 H nuclear magnetic resonance spectroscopy. Fecal calprotectin was measured as a marker of enteric inflammation. Aliquots of human or donor milk provided to each infant were also assessed to determine human milk oligosaccharide (HMO) content. RESULTS: As expected, each probiotic treatment was associated with increased proportions of the respective bacterial taxon. Fecal HMOs were significantly higher in L. reuteri fed babies despite similar HMO content in the milk consumed. Fecal metabolites associated with bifidobacteria fermentation products were significantly increased in B. infantis supplemented infants. Fecal calprotectin was lower in infants receiving B. infantis relative to L. reuteri ( P < 0.01, Wilcoxon rank-sum test) and was negatively associated with the microbial metabolite indole-3-lactate (ILA). CONCLUSIONS: This study demonstrates that supplementing an HMO-catabolizing Bifidobacterium probiotic results in increased microbial metabolism of milk oligosaccharides and reduced intestinal inflammation relative to a noncatabolizing Lactobacillus probiotic in human milk-fed preterm infants. In this context, Bifidobacterium may provide greater benefit in human milk-fed infants via activation of the microbiota-metabolite-immune axis.

Human milk oligosaccharide-sharing by a consortium of infant derived Bifidobacterium species.

Bifidobacteria are associated with a host of health benefits and are typically dominant in the gut microbiota of healthy, breast-fed infants. A key adaptation, facilitating the establishment of these species, is their ability to consume particular sugars, known as human milk oligosaccharides (HMO), which are abundantly found in breastmilk. In the current study, we aimed to characterise the co-operative metabolism of four commercial infant-derived bifidobacteria (Bifidobacterium bifidum R0071, Bifidobacterium breve M-16V, Bifidobacterium infantis R0033, and Bifidobacterium infantis M-63) when grown on HMO. Three different HMO substrates (2'-fucosyllactose alone and oligosaccharides isolated from human milk representing non-secretor and secretor status) were employed. The four-strain combination resulted in increased bifidobacterial numbers (> 21%) in comparison to single strain cultivation. The relative abundance of B. breve increased by > 30% during co-cultivation with the other strains despite demonstrating limited ability to assimilate HMO in mono-culture. HPLC analysis revealed strain-level variations in HMO consumption. Metabolomics confirmed the production of formate, acetate, 1,2-propanediol, and lactate with an overall increase in such metabolites during co-cultivation. These results support the concept of positive co-operation between multiple bifidobacterial strains during HMO utilisation which may result in higher cell numbers and a potentially healthier balance of metabolites.

Metabolic and enzymatic elucidation of cooperative degradation of red seaweed agarose by two human gut bacteria.

Various health beneficial outcomes associated with red seaweeds, especially their polysaccharides, have been claimed, but the molecular pathway of how red seaweed polysaccharides are degraded and utilized by cooperative actions of human gut bacteria has not been elucidated. Here, we investigated the enzymatic and metabolic cooperation between two human gut symbionts, Bacteroides plebeius and Bifidobacterium longum ssp. infantis, with regard to the degradation of agarose, the main carbohydrate of red seaweed. More specifically, B. plebeius initially decomposed agarose into agarotriose by the actions of the enzymes belonging to glycoside hydrolase (GH) families 16 and 117 (i.e., BpGH16A and BpGH117) located in the polysaccharide utilization locus, a specific gene cluster for red seaweed carbohydrates. Then, B. infantis extracted energy from agarotriose by the actions of two agarolytic ß-galactosidases (i.e., Bga42A and Bga2A) and produced neoagarobiose. B. plebeius ultimately acted on neoagarobiose by BpGH117, resulting in the production of 3,6-anhydro-L-galactose, a monomeric sugar possessing anti-inflammatory activity. Our discovery of the cooperative actions of the two human gut symbionts on agarose degradation and the identification of the related enzyme genes and metabolic intermediates generated during the metabolic processes provide a molecular basis for agarose degradation by gut bacteria.

Mechanism of the Immunomodulatory Effect of the Combination of Live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus on Immunocompromised Rats.

Immunodeficiency is a very common condition in suboptimal health status and during the development or treatment of many diseases. Recently, probiotics have become an important means for immune regulation. The present study aimed to investigate the mechanism of the immunomodulatory effect of a combination of live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus (CBLEB), which is a drug used by approximately 10 million patients every year, on cyclophosphamide-immunosuppressed rats. Cyclophosphamide (40 mg/kg) was intraperitoneally injected to induce immunosuppression in a rat model on days 1, 2, 3, and 10. Starting from day 4, the rats were continuously gavaged with CBLEB solution for 15 days. The samples were collected to determine routine blood test parameters, liver and kidney functions, serum cytokine levels, gut microbiota, fecal and serum metabolomes, transcriptomes, and histopathological features. The results indicated that CBLEB treatment reduced cyclophosphamide-induced death, weight loss, and damage to the gut, liver, spleen, and lungs and eliminated a cyclophosphamide-induced increase in the mean hemoglobin content and GGT, M-CSF, and MIP-3α levels and a decrease in the red blood cell distribution width and total protein and creatinine levels in the blood. Additionally, CBLEB corrected cyclophosphamide-induced dysbiosis of the gut microbiota and eliminated all cyclophosphamide-induced alterations at the phylum level in rat feces, including the enrichment in Proteobacteria, Fusobacteriota, and Actinobacteriota and depletion of Spirochaetota and Cyanobacteria. Furthermore, CBLEB treatment alleviated cyclophosphamide-induced alterations in the whole fecal metabolome profile, including enrichment in 1-heptadecanol, succinic acid, hexadecane-1,2-diol, nonadecanoic acid, and pentadecanoic acid and depletion of benzenepropanoic acid and hexane. CBLEB treatment also alleviated cyclophosphamide-induced enrichment in serum D-lyxose and depletion of serum succinic acid, D-galactose, L-5-oxoproline, L-alanine, and malic acid. The results of transcriptome analysis indicated that the mechanism of the effect of CBLEB was related to the induction of recovery of cyclophosphamide-altered carbohydrate metabolism and signal transduction. In conclusion, the present study provides an experimental basis and comprehensive analysis of application of CBLEB for the treatment of immunodeficiency.

Gut Microbiota Profile in Children with IgE-Mediated Cow's Milk Allergy and Cow's Milk Sensitization and Probiotic Intestinal Persistence Evaluation.

Food allergy (FA) and, in particular, IgE-mediated cow's milk allergy is associated with compositional and functional changes of gut microbiota. In this study, we compared the gut microbiota of cow's milk allergic (CMA) infants with that of cow's milk sensitized (CMS) infants and Healthy controls. The effect of the intake of a mixture of Bifidobacterium longum subsp. longum BB536, Bifidobacterium breve M-16V and Bifidobacterium longum subsp. infantis M-63 on gut microbiota modulation of CMA infants and probiotic persistence was also investigated. Gut microbiota of CMA infants resulted to be characterized by a dysbiotic status with a prevalence of some bacteria as Haemophilus, Klebsiella, Prevotella, Actinobacillus and Streptococcus. Among the three strains administered, B.longum subsp. infantis colonized the gastrointestinal tract and persisted in the gut microbiota of infants with CMA for 60 days. This colonization was associated with perturbations of the gut microbiota, specifically with the increase of Akkermansia and Ruminococcus. Multi-strain probiotic formulations can be studied for their persistence in the intestine by monitoring specific bacterial probes persistence and exploiting microbiota profiling modulation before the evaluation of their therapeutic effects.

Generating a fucose permease deletion mutant in Bifidobacterium longum subspecies infantis ATCC 15697.

Bifidobacterium longum subsp. infantis ATCC 15697 has emerged as a model for infant gut-associated bifidobacterial strains. Here we present a genetic system for B. longum subsp. infantis ATCC 15697 using its own DNA restriction-modification systems and create a fucose permease deletion mutant lacking the ability to use free fucose as a carbon source.

Cross-feeding between Bifidobacterium infantis and Anaerostipes caccae on lactose and human milk oligosaccharides.

The establishment of the gut microbiota immediately after birth is a dynamic process that may impact lifelong health. At this important developmental stage in early life, human milk oligosaccharides (HMOs) serve as specific substrates to shape the gut microbiota of the nursling. The well-orchestrated transition is important as an aberrant microbial composition and bacterial-derived metabolites are associated with colicky symptoms and atopic diseases in infants. Here, we study the trophic interactions between an HMO-degrader, Bifidobacterium infantis and the butyrogenic Anaerostipes caccae using carbohydrate substrates that are relevant in the early life period including lactose and total human milk carbohydrates. Mono- and co-cultures of these bacterial species were grown at pH 6.5 in anaerobic bioreactors supplemented with lactose or total human milk carbohydrates. A. caccae was not able to grow on these substrates except when grown in co-culture with B. infantis, leading to growth and concomitant butyrate production. Two levels of cross-feeding were observed, in which A. caccae utilised the liberated monosaccharides as well as lactate and acetate produced by B. infantis. This microbial cross-feeding points towards the key ecological role of bifidobacteria in providing substrates for other important species that will colonise the infant gut. The progressive shift of the gut microbiota composition that contributes to the gradual production of butyrate could be important for host-microbial crosstalk and gut maturation.

A Whey Fraction Rich in Immunoglobulin G Combined with Bifidobacterium longum subsp. infantis ATCC 15697 Exhibits Synergistic Effects against Campylobacter jejuni.

Evidence that whey proteins and peptides have health benefits beyond basic infant nutrition has increased dramatically in recent years. Previously, we demonstrated that a whey-derived immunoglobulin G-enriched powder (IGEP) enhanced adhesion of Bifidobacterium longum subsp. infantis ATCC 15697 (B. infantis) to HT-29 cells. In this study, we investigated the synergistic effect of IGEP-treated B. infantis on preventing the attachment of highly invasive Campylobacter jejuni 81-176 (C. jejuni) to intestinal HT-29 cells. The combination decreased the adherence of C. jejuni to the HT-29 cells by an average of 48% compared to the control (non-IGEP-treated B. infantis). We also confirmed that treatment of IGEP with sodium metaperiodate, which disables the biological recognition of the conjugated oligosaccharides, reduced adhesion of B. infantis to the intestinal cells. Thus, glycosylation of the IGEP components may be important in enhancing B. infantis adhesion. Interestingly, an increased adhesion phenotype was not observed when B. infantis was treated with bovine serum-derived IgG, suggesting that bioactivity was unique to milk-derived immunoglobulin-rich powders. Notably, IGEP did not induce growth of B. infantis within a 24 hours incubation period, as demonstrated by growth curves and metabolite analysis. The current study provides insight into the functionality of bovine whey components and highlights their potential in positively impacting the development of a healthy microbiota.

Galacto- and Fructo-oligosaccharides Utilized for Growth by Cocultures of Bifidobacterial Species Characteristic of the Infant Gut.

Bifidobacterial species are common inhabitants of the gut of human infants during the period when milk is a major component of the diet. Bifidobacterium breve, Bifidobacterium bifidum, Bifidobacterium longum subspecies longum, and B. longum subspecies infantis have been detected frequently in infant feces, but B. longum subsp. infantis may be disadvantaged numerically in the gut of infants in westernized countries. This may be due to the different durations of breast milk feeding in different countries. Supplementation of the infant diet or replacement of breast milk using formula feeds is common in Western countries. Formula milks often contain galacto- and/or fructo-oligosaccharides (GOS and FOS, respectively) as additives to augment the concentration of oligosaccharides in ruminant milks, but the ability of B. longum subsp. infantis to utilize these potential growth substrates when they are in competition with other bifidobacterial species is unknown. We compared the growth and oligosaccharide utilization of GOS and FOS by bifidobacterial species in pure culture and coculture. Short-chain GOS and FOS (degrees of polymerization [DP] 2 and 3) were favored growth substrates for strains of B. bifidum and B. longum subsp. longum, whereas both B. breve and B. longum subsp. infantis had the ability to utilize both short- and longer-chain GOS and FOS (DP 2 to 6). B. breve was nevertheless numerically dominant over B. longum subsp. infantis in cocultures. This was probably related to the slower use of GOS of DP 3 by B. longum subsp. infantis, indicating that the kinetics of substrate utilization is an important ecological factor in the assemblage of gut communities.IMPORTANCE The kinds of bacteria that form the collection of microbes (the microbiota) in the gut of human infants may influence health and well-being. Knowledge of how the composition of the infant diet influences the assemblage of the bacterial collection is therefore important because dietary interventions may offer opportunities to alter the microbiota with the aim of improving health. Bifidobacterium longum subspecies infantis is a well-known bacterial species, but under modern child-rearing conditions it may be disadvantaged in the gut. Modern formula milks often contain particular oligosaccharide additives that are generally considered to support bifidobacterial growth. However, studies of the ability of various bifidobacterial species to grow together in the presence of these oligosaccharides have not been conducted. These kinds of studies are essential for developing concepts of microbial ecology related to the influence of human nutrition on the development of the gut microbiota.

Probiotic extracts ameliorate nasal allergy by inducing interleukin-35-producing dendritic cells in mice.

BACKGROUND: The therapeutic efficacy of allergic rhinitis (AR) needs to be improved. Probiotics have immunoregulatory functions. In this study we evaluated the effects of protein extracts of probiotics in the amelioration of AR. METHODS: Extracts of Bifidobacterium infantis (EBI) were prepared by lysing the live probiotics. AR mice were developed to be used to evaluate the therapeutic efficacy of EBI. RESULTS: The results show that EBI induced interleukin (IL)-10-producing dendritic cells (DCs) via increasing IL-35 and signal transducer and activator of transcription 3 (STAT3) phosphorylation. IL-10-expressing DCs induced IL-10-producing B cells (B10 cells), with the latter showing immunosuppressive functions. After challenge with specific antigens, AR mice showed sneezing, nasal itch, and increases in serum-specific immunoglobulin E (IgE) and mouse mast cell protease-1; higher levels of T helper 2 (Th2) cytokines (IL-4, 67.17 ± 10.66; IL-5, 62.83 ± 9.70; IL-13, 51.00 ± 6.69, before treatment) in nasal mucosal protein extracts, which were significantly suppressed (IL-4, 27.00 ± 6.66; IL-5, 23.86 ± 4.53; IL-13, 25.67 ± 4.93, after treatment (p < 0.001) by administration with EBI nasal drops. CONCLUSION: EBI can suppress AR via inducing B10 cells. Thus, after carrying out required preclinical experiments and tests, EBI has the translational potential to be used in the treatment of AR and other allergic diseases.

Novel Genes and Metabolite Trends in Bifidobacterium longum subsp. infantis Bi-26 Metabolism of Human Milk Oligosaccharide 2'-fucosyllactose.

Human milk oligosaccharides (HMOs) function as prebiotics for beneficial bacteria in the developing gut, often dominated by Bifidobacterium spp. To understand the relationship between bifidobacteria utilizing HMOs and how the metabolites that are produced could affect the host, we analyzed the metabolism of HMO 2'-fucosyllactose (2'-FL) in Bifidobacterium longum subsp. infantis Bi-26. RNA-seq and metabolite analysis (NMR/GCMS) 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. Transcriptomic analysis revealed many gene clusters including three novel ABC-type sugar transport clusters to be upregulated in Bi-26 involved in processing of 2'-FL along with metabolism of its monomers glucose, fucose and galactose. Metabolite data confirmed the production of formate, acetate, 1,2-propanediol, lactate and cleaving of fucose from 2'-FL. The formation of acetate, formate, and lactate showed how the cell uses metabolites during fermentation to produce higher levels of ATP (mid-log compared to other stages) or generate cofactors to balance redox. We concluded that 2'-FL metabolism is a complex process involving multiple gene clusters, that produce a more diverse metabolite profile compared to lactose. These results provide valuable insight on the mode-of-action of 2'-FL utilization by Bifidobacterium longum subsp. infantis Bi-26.

Cutibacterium avidum is phylogenetically diverse with a subpopulation being adapted to the infant gut.

The infant gut harbors a diverse microbial community consisting of several taxa whose persistence depends on adaptation to the ecosystem. In healthy breast-fed infants, the gut microbiota is dominated by Bifidobacterium spp.. Cutibacterium avidum is among the initial colonizers, however, the phylogenetic relationship of infant fecal isolates to isolates from other body sites, and C. avidum carbon utilization related to the infant gut ecosystem have been little investigated. In this study, we investigated the phylogenetic and phenotypic diversity of 28 C. avidum strains, including 16 strains isolated from feces of healthy infants. We investigated the in vitro capacity of C. avidum infant isolates to degrade and consume carbon sources present in the infant gut, and metabolic interactions of C. avidum with infant associated Bifidobacterium longum subsp. infantis and Bifidobacterium bifidum. Isolates of C. avidum showed genetic heterogeneity. C. avidum consumed d- and l-lactate, glycerol, glucose, galactose, N-acetyl-d-glucosamine and maltodextrins. Alpha-galactosidase- and ß-glucuronidase activity were a trait of a group of non-hemolytic strains, which were mostly isolated from infant feces. Beta-glucuronidase activity correlated with the ability to ferment glucuronic acid. Co-cultivation with B. infantis and B. bifidum enhanced C. avidum growth and production of propionate, confirming metabolic cross-feeding. This study highlights the phylogenetic and functional diversity of C. avidum, their role as secondary glycan degraders and propionate producers, and suggests adaptation of a subpopulation to the infant gut.

Compatibility and safety of five lectin-binding putative probiotic strains for the development of a multi-strain protective culture for poultry.

The ban on the use of antibiotics as feed additives for animal growth promotion in the European Union and United States and the expectation of this trend to further expand to other countries in the short term have prompted a surge in probiotic research. Multi-species probiotics including safe and compatible strains with the ability to bind different nutritional lectins with detrimental effects on poultry nutrition could replace antibiotics as feed additives. Lactobacillus salivarius LET201, Lactobacillus reuteri LET210, Enterococcus faecium LET301, Propionibacterium acidipropionici LET103 and Bifidobacterium infantis CRL1395 have proved to be compatible as evaluated through three different approaches: the production and excretion of antimicrobial compounds, growth inhibition by competition for essential nutrients and physical contact, and a combination of both. The safety of P. acidipropionici LET103 was confirmed, since no expression of virulence factors or antibiotic resistance was detected. The innocuity of E. faecium LET301 should be further evaluated, since the presence of genes coding for certain virulence factors (gelE, efaAfm and efaAfs) was observed, albeit no expression of gelE was previously detected for this strain and there are no reports of involvement of efaAfm in animal pathogenicity. Finally, a combination of the five strains effectively protected intestinal epithelial cells of broilers from the cytotoxicity of mixtures of soybean agglutinin, wheat germ agglutinin and concanavalin A. To our knowledge, this is the first time that a combination of strains is evaluated for their protection against lectins that might be simultaneously present in poultry feeds.