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Nutritional supplements are popular among athletes to improve performance and physical recovery. Protein supplements fulfill this function by improving performance and increasing muscle mass; however, their effect on other organs or systems is less well known. Diet alterations can induce gut microbiota imbalance, with beneficial or deleterious consequences for the host. To test this, we performed a randomized pilot study in cross-country runners whose diets were complemented with a protein supplement (whey isolate and beef hydrolysate) (n = 12) or maltodextrin (control) (n = 12) for 10 weeks. Microbiota, water content, pH, ammonia, and short-chain fatty acids (SCFAs) were analyzed in fecal samples, whereas malondialdehyde levels (oxidative stress marker) were determined in plasma and urine. Fecal pH, water content, ammonia, and SCFA concentrations did not change, indicating that protein supplementation did not increase the presence of these fermentation-derived metabolites. Similarly, it had no impact on plasma or urine malondialdehyde levels; however, it increased the abundance of the Bacteroidetes phylum and decreased the presence of health-related taxa including Roseburia, Blautia, and Bifidobacterium longum. Thus, long-term protein supplementation may have a negative impact on gut microbiota. Further research is needed to establish the impact of protein supplements on gut microbiota.

Resident gut bacteria can affect patient responses to cancer immunotherapy (see the Perspective by Jobin). Routy et al. show that antibiotic consumption is associated with poor response to immunotherapeutic PD-1 blockade. They profiled samples from patients with lung and kidney cancers and found that nonresponding patients had low levels of the bacterium Akkermansia muciniphila . Oral supplementation of the bacteria to antibiotic-treated mice restored the response to immunotherapy. Matson et al. and Gopalakrishnan et al. studied melanoma patients receiving PD-1 blockade and found a greater abundance of “good” bacteria in the guts of responding patients. Nonresponders had an imbalance in gut flora composition, which correlated with impaired immune cell activity. Thus, maintaining healthy gut flora could help patients combat cancer. Science , this issue p. 91 , p. 104 , p. 97 ; see also p. 32 Gut bacteria influence patient response to cancer therapy. Anti–PD-1–based immunotherapy has had a major impact on cancer treatment but has only benefited a subset of patients. Among the variables that could contribute to interpatient heterogeneity is differential composition of the patients’ microbiome, which has been shown to affect antitumor immunity and immunotherapy efficacy in preclinical mouse models. We analyzed baseline stool samples from metastatic melanoma patients before immunotherapy treatment, through an integration of 16 S ribosomal RNA gene sequencing, metagenomic shotgun sequencing, and quantitative polymerase chain reaction for selected bacteria. A significant association was observed between commensal microbial composition and clinical response. Bacterial species more abundant in responders included Bifidobacterium longum , Collinsella aerofaciens , and Enterococcus faecium. Reconstitution of germ-free mice with fecal material from responding patients could lead to improved tumor control, augmented T cell responses, and greater efficacy of anti–PD-L1 therapy. Our results suggest that the commensal microbiome may have a mechanistic impact on antitumor immunity in human cancer patients.

Background The importance of the gut microbiota at the early stage of life and their longitudinal effect on host health have recently been well investigated. In particular, Bifidobacterium longum subsp. longum , a common component of infant gut microbiota, appears in the gut shortly after birth and can be detected there throughout an individual’s lifespan. However, it remains unclear whether this species colonizes in the gut over the long term from early infancy. Here, we investigated the long-term colonization of B . longum subsp. longum by comparing the genotypes of isolates obtained at different time points from individual subjects. Strains were isolated over time from the feces of 12 subjects followed from early infancy (the first six months of life) up to childhood (approximately six years of age). We also considered whether the strains were transmitted from their mothers’ perinatal samples (prenatal feces and postnatal breast milk). Results Intra-species diversity of B. longum subsp. longum was observed in some subjects’ fecal samples collected in early infancy and childhood, as well as in the prenatal fecal samples of their mothers. Among the highlighted strains, several were confirmed to colonize and persist in single individuals from as early as 90 days of age for more than six years; these were classified as long-term colonizers. One of the long-term colonizers was also detected from the corresponding mother’s postnatal breast milk. Quantitative polymerase chain reaction data suggested that these long-term colonizers persisted in the subjects’ gut despite the existence of the other predominant species of Bifidobacterium . Conclusions Our results showed that several strains belonging to B. longum subsp. longum colonized in the human gut from early infancy through more than six years, confirming the existence of long-term colonizers from this period. Moreover, the results suggested that these strains persisted in the subjects’ gut while co-existing with the other predominant bifidobacterial species. Our findings also suggested the importance of microbial-strain colonization in early infancy relative to their succession and showed the possibility that probiotics targeting infants might have longitudinal effects. Trial Registration TRN: ISRCTN25216339 . Date of registration: 11/03/2016. Prospectively registered.

A total of 57 infants hospitalized with rotavirus disease were included in this study. The children were randomly divided into the study's two treatment groups: three days of the oral administration of (i) a probiotics formula containing both BORI and AD031 ( = 28); or (ii) a placebo (probiotic-free skim milk, = 29) and the standard therapy for diarrhea. There were no differences in age, sex, or blood characteristics between the two groups. When the 57 cases completed the protocol, the duration of the patients' diarrhea was significantly shorter in the probiotics group (4.38 ± 1.29, = 28) than the placebo group (5.61 ± 1.23, = 29), with a -value of 0.001. Symptoms such as duration of fever ( = 0.119), frequency of diarrhea ( = 0.119), and frequency of vomiting ( = 0.331) tended to be ameliorated by the probiotic treatment; however, differences were not statistically significant between the two groups. There were no serious, adverse events and no differences in the frequency of adverse events in both groups.

Hypercholesterolemia is an independent risk factor of cardiovascular disease, which is among the major causes of death worldwide. The aim of this study was to explore whether Bifidobacterium longum strains exerted intra-species differences in cholesterol-lowering effects in hypercholesterolemic rats and to investigate the potential mechanisms. SD rats underwent gavage with each B. longum strain (CCFM 1077, I3, J3 and B3) daily for 28 days. B. longum CCFM 1077 exerted the most potent cholesterol-lowering effect, followed by B. longum I3 and B3, whereas B. longum B3 had no effect in alleviating hypercholesterolemia. Divergent alleviation of different B. longum strains on hypercholesterolemia can be attributed to the differences in bile salt deconjugation ability and cholesterol assimilation ability in vitro. By 16S rRNA metagenomics analysis, the relative abundance of beneficial genus increased in the B. longum CCFM 1077 treatment group. The expression of key genes involved in cholesterol metabolism were also altered after the B. longum CCFM 1077 treatment. In conclusion, B. longum exhibits strain-specific effects in the alleviation of hypercholesterolemia, mainly due to differences in bacterial characteristics, bile salt deconjugation ability, cholesterol assimilation ability, expressions of key genes involved in cholesterol metabolism and alterations of gut microbiota.

The infant gut microbiome is essential for long-term health and is linked to atopic dermatitis (AD), although the underlying mechanisms are not fully understood. This study investigated gut microbiome-host interactions in 31 infants with AD and 29 healthy controls using multi-omics approaches, including metagenomic, host transcriptomic, and metabolomic analyses. Microbial diversity was significantly altered in AD, with Bifidobacterium longum and Clostridium innocuum associated with these changes. At the strain-level, only B. longum differed significantly between groups, with pangenome analyses identifying genetic variations potentially affecting amino acid and lipid metabolites. Notably, B. longum subclade I, which was more prevalent in healthy controls, correlated with host transcriptomic pathways involved in phosphatidylinositol 3-kinase-AKT signaling and neuroactive ligand-receptor pathways, as well as specific metabolites, including tetrahydrocortisol and ornithine. These findings highlight the role of B. longum strain-level variation in infants, offering new insights into microbiome-host interactions related to AD.

Background Human milk oligosaccharides (HMOs) are one of the major glycan source of the infant gut microbiota. The two species that predominate the infant bifidobacteria community, Bifidobacterium longum subsp. infantis and Bifidobacterium bifidum, possess an arsenal of enzymes including α-fucosidases, sialidases, and β-galactosidases to metabolise HMOs. Recently bifidobacteria were obtained from the stool of six month old Kenyan infants including species such as Bifidobacterium kashiwanohense, and Bifidobacterium pseudolongum that are not frequently isolated from infant stool. The aim of this study was to characterize HMOs utilization by these isolates. Strains were grown in presence of 2′-fucosyllactose (2′-FL), 3′-fucosyllactose (3′-FL), 3′-sialyl-lactose (3′-SL), 6′-sialyl-lactose (6′-SL), and Lacto-N-neotetraose (LNnT). We further investigated metabolites formed during L-fucose and fucosyllactose utilization, and aimed to identify genes and pathways involved through genome comparison. Results Bifidobacterium longum subsp. infantis isolates , Bifidobacterium longum subsp. suis BSM11-5 and B. kashiwanohense strains grew in the presence of 2′-FL and 3′- FL. All B. longum isolates utilized the L-fucose moiety, while B. kashiwanohense accumulated L-fucose in the supernatant. 1,2-propanediol (1,2-PD) was the major metabolite from L-fucose fermentation, and was formed in equimolar amounts by B. longum isolates. Alpha-fucosidases were detected in all strains that degraded fucosyllactose. B. longum subsp. infantis TPY11-2 harboured four α-fucosidases with 95–99 % similarity to the type strain. B. kashiwanohense DSM 21854 and PV20-2 possessed three and one α-fucosidase, respectively. The two α-fucosidases of B. longum subsp. suis were 78–80 % similar to B. longum subsp. infantis and were highly similar to B. kashiwanohense α-fucosidases (95–99 %). The genomes of B. longum strains that were capable of utilizing L-fucose harboured two gene regions that encoded enzymes predicted to metabolize L-fucose to L-lactaldehyde, the precursor of 1,2-PD, via non-phosphorylated intermediates. Conclusion Here we observed that the ability to utilize fucosyllactose is a trait of various bifidobacteria species. For the first time, strains of B. longum subsp. infantis and an isolate of B. longum subsp. suis were shown to use L-fucose to form 1,2-PD. As 1,2-PD is a precursor for intestinal propionate formation, bifidobacterial L-fucose utilization may impact intestinal short chain fatty acid balance. A L-fucose utilization pathway for bifidobacteria is suggested.

Prebiotics are food ingredients that improve health by modulating the colonic microbiota. The bifidogenic effect of the prebiotic inulin is well established; however, it remains unclear which species of Bifidobacterium are stimulated in vivo and whether bacterial groups other than lactic acid bacteria are affected by inulin consumption. Changes in the faecal microbiota composition were examined by real-time PCR in twelve human volunteers after ingestion of inulin (10 g/d) for a 16-d period in comparison with a control period without any supplement intake. The prevalence of most bacterial groups examined did not change after inulin intake, although the low G+C % Gram-positive species Faecalibacterium prausnitzii exhibited a significant increase (10·3 % for control period v. 14·5 % during inulin intake, P = 0·019). The composition of the genus Bifidobacterium was studied in four of the volunteers by clone library analysis. Between three and five Bifidobacterium spp. were found in each volunteer. Bifidobacterium adolescentis and Bifidobacterium longum were present in all volunteers, and Bifidobacterium pseudocatenulatum, Bifidobacterium animalis, Bifidobacterium bifidum and Bifidobacterium dentium were also detected. Real-time PCR was employed to quantify the four most prevalent Bifidobacterium spp., B. adolescentis, B. longum, B. pseudocatenulatum and B. bifidum, in ten volunteers carrying detectable levels of bifidobacteria. B. adolescentis showed the strongest response to inulin consumption, increasing from 0·89 to 3·9 % of the total microbiota (P = 0·001). B. bifidum was increased from 0·22 to 0·63 % (P < 0·001) for the five volunteers for whom this species was present.

Thirty-four strains of bifidobacteria belonging to Bifidobacterium adolescentis, Bifidobacterium animalis, Bifidobacterium bifidum, Bifidobacterium breve, Bifidobacterium longum, and Bifidobacterium pseu-docatenulatum were assayed in vitro for the ability to assimilate cholesterol and for bile salt hydrolase (BSH) against glycocholic and taurodeoxycholic acids (GCA and TDCA). Cholesterol assimilation was peculiar characteristic of two strains belonging to the species B. bifidum (B. bifidum MB 107 and B. bifidum MB 109), which removed 81 and 50 mg of cholesterol per gram of biomass, being the median of specific cholesterol absorption by bifidobacteria 19 mg/g. Significant differences in BSH activities were not established among bifidobacterial species. However, the screening resulted in the selection of promising strains able to efficiently deconjugate GCA and TDCA. No relationship was recognized between BSH phenotype and the extent of cholesterol assimilation. On the basis of cholesterol assimilation or BSHGCA and BSHTDCA activities, B. bifidum MB 109 (DSMZ 23731), B. breve MB 113 (DSMZ 23732), and B. animalis subsp. lactis MB 2409 (DSMZ 23733) were combined in a probiotic mixture to be fed to hypercholesterolemic rats. The administration of this probiotic formulation resulted in a significant reduction of total cholesterol and low-density cholesterol (LDL-C), whereas it did not affect high-density cholesterol (HDL-C) and HDL-C/LDL-C ratio.

This study aimed to evaluate the effects of three treatments, i.e., Bifidobacterium longum BB-46 (T1), B. longum BB-46 combined with the pectin (T2), and harsh extracted pectin from lemon (T3) on obesity-related microbiota using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®). The effects of the treatments were assessed by the analysis of the intestinal microbial composition (using 16S rRNA gene amplicon sequencing) and the levels of short-chain fatty acids (SCFAs) and ammonium ions (NH4+). Treatments T2 and T3 stimulated members of the Ruminococcaceae and Succinivibrionaceae families, which were positively correlated with an increase in butyric and acetic acids. Proteolytic bacteria were reduced by the two treatments, concurrently with a decrease in NH4+. Treatment T1 stimulated the production of butyric acid in the simulated transverse and descending colon, reduction of NH4+ as well as the growth of genera Lactobacillus, Megamonas, and members of Lachnospiracea. The results indicate that both B. longum BB-46 and pectin can modulate the obesity-related microbiota; however, when the pectin is combined with B. longum BB-46, the predominant effect of the pectin can be observed. This study showed that the citric pectin is able to stimulate butyrate-producing bacteria as well as genera related with anti-inflammatory effects. However, prospective clinical studies are necessary to evaluate the anti/pro-obesogenic and inflammatory effects of this pectin for future prevention of obesity.