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Symbiotic interactions between humans and our communities of resident gut microbes (microbiota) play many roles in health and disease. Some gut bacteria utilize mucus as a nutrient source and can under certain conditions damage the protective barrier it forms, increasing disease susceptibility. We investigated how Ruminococcus torques-a known mucin degrader that has been implicated in inflammatory bowel diseases (IBDs)-degrades mucin glycoproteins or their component O-linked glycans to understand its effects on the availability of mucin-derived nutrients for other bacteria. We found that R. torques utilizes both mucin glycoproteins and released oligosaccharides from gastric and colonic mucins, degrading these substrates with a panoply of mostly constitutively expressed, secreted enzymes. Investigation of mucin oligosaccharide degradation by R. torques revealed strong α-L-fucosidase, sialidase and ß1,4-galactosidase activities. There was a lack of detectable sulfatase and weak ß1,3-galactosidase degradation, resulting in accumulation of glycans containing these structures on mucin polypeptides. While the Gram-negative symbiont, Bacteroides thetaiotaomicron grows poorly on mucin glycoproteins, we demonstrate a clear ability of R. torques to liberate products from mucins, making them accessible to B. thetaiotaomicron. This work underscores the diversity of mucin-degrading mechanisms in different bacterial species and the probability that some species are contingent on others for the ability to more fully access mucin-derived nutrients. The ability of R. torques to directly degrade a variety of mucin and mucin glycan structures and unlock released glycans for other species suggests that it is a keystone mucin degrader, which might contribute to its association with IBD.IMPORTANCEAn important facet of maintaining healthy symbiosis between host and intestinal microbes is the mucus layer, the first defense protecting the epithelium from lumenal bacteria. Some gut bacteria degrade the various components of intestinal mucins, but detailed mechanisms used by different species are still emerging. It is imperative to understand these mechanisms as they likely dictate interspecies interactions and may illuminate species associated with bacterial mucus damage and subsequent disease susceptibility. Ruminococcus torques is positively associated with IBD in multiple studies. We identified mucin glycan-degrading enzymes in R. torques and found that it shares mucin degradation products with another species of gut bacteria, Bacteroides thetaiotaomicron. Our findings underscore the importance of understanding mucin degradation mechanisms in different gut bacteria and their consequences on interspecies interactions, which may identify keystone bacteria that disproportionately affect mucus damage and could therefore be key players in effects that result from reductions in mucus integrity.
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Bacteroides thetaiotaomicron , Microbioma Gastrointestinal , Mucinas , Oligosacáridos , Ruminococcus , Oligosacáridos/metabolismo , Mucinas/metabolismo , Bacteroides thetaiotaomicron/metabolismo , Ruminococcus/metabolismo , Humanos , Glicoproteínas/metabolismo , SimbiosisRESUMEN
Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is associated with a loss or an imbalance of host-microorganism interactions. However, such interactions at protein levels remain largely unknown. Here, we applied a depletion-assisted metaproteomics approach to obtain in-depth host-microbiome association networks of IBD, where the core host proteins shifted from those maintaining mucosal homeostasis in controls to those involved in inflammation, proteolysis, and intestinal barrier in IBD. Microbial nodes such as short-chain fatty-acid producer-related host-microbial crosstalk were lost or suppressed by inflammatory proteins in IBD. Guided by protein-protein association networks, we employed proteomics and lipidomics to investigate the effects of UC-related core proteins S100A8, S100A9, and cytokines (IL-1ß, IL-6, and TNF-α) on gut bacteria. These proteins suppressed purine nucleotide biosynthesis in stool-derived in vitro communities, which was also reduced in IBD stool samples. Single species study revealed that S100A8, S100A9, and cytokines can synergistically or antagonistically alter gut bacteria intracellular and secreted proteome, with combined S100A8 and S100A9 potently inhibiting beneficial Bifidobacterium adolescentis. Furthermore, these inflammatory proteins only altered the extracellular but not intracellular proteins of Ruminococcus gnavus. Generally, S100A8 induced more significant bacterial proteome changes than S100A9, IL-1ß, IL-6, and TNF-α but gut bacteria degrade significantly more S100A8 than S100A9 in the presence of both proteins. Among the investigated species, distinct lipid alterations were only observed in Bacteroides vulgatus treated with combined S100A8, S100A9, and cytokines. These results provided a valuable resource of inflammatory protein-centric host-microbial molecular interactions.
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Colitis Ulcerosa , Citocinas , Microbioma Gastrointestinal , Colitis Ulcerosa/microbiología , Colitis Ulcerosa/metabolismo , Humanos , Citocinas/metabolismo , Calgranulina B/metabolismo , Calgranulina A/metabolismo , Proteómica , Heces/microbiología , Ruminococcus/metabolismo , Interacciones Microbiota-Huesped , ClostridialesRESUMEN
In this study, we aim to investigate the precise alterations in the gut microbiota during the onset and advancement of diabetic nephropathy (DN) and examine the impact of Ruminococcus gnavus (R. gnavus) on DN. Eight-week-old male KK-Ay mice were administered antibiotic cocktails for a duration of two weeks, followed by oral administration of R. gnavus for an additional eight weeks. Our study revealed significant changes in the gut microbiota during both the initiation and progression of DN. Specifically, we observed a notable increase in the abundance of Clostridia at the class level, higher levels of Lachnospirales and Oscillospirales at the order level, and a marked decrease in Clostridia_UCG-014 in DN group. Additionally, there was a significant increase in the abundance of Lachnospiraceae, Oscillospiraceae, and Ruminococcaceae at the family level. Moreover, oral administration of R. gnavus effectively aggravated kidney pathology in DN mice, accompanied by elevated levels of urea nitrogen (UN), creatinine (Cr), and urine protein. Furthermore, R. gnavus administration resulted in down-regulation of tight junction proteins such as Claudin-1, Occludin, and ZO-1, as well as increased levels of uremic toxins in urine and serum samples. Additionally, our study demonstrated that orally administered R. gnavus up-regulated the expression of inflammatory factors, including nucleotide-binding oligomerization domain-like receptor pyrin domain-containing protein 3 (NLRP3) and Interleukin (IL)-6. These changes indicated the involvement of the gut-kidney axis in DN, and R. gnavus may worsen diabetic nephropathy by affecting uremic toxin levels and promoting inflammation in DN.
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Diabetes Mellitus , Nefropatías Diabéticas , Microbioma Gastrointestinal , Ratones , Masculino , Animales , Nefropatías Diabéticas/metabolismo , Nefropatías Diabéticas/patología , Ruminococcus/metabolismo , ClostridialesRESUMEN
Resistant starch is a prebiotic accessed by gut bacteria with specialized amylases and starch-binding proteins. The human gut symbiont Ruminococcus bromii expresses Sas6 (Starch Adherence System member 6), which consists of two starch-specific carbohydrate-binding modules from family 26 (RbCBM26) and family 74 (RbCBM74). Here, we present the crystal structures of Sas6 and of RbCBM74 bound with a double helical dimer of maltodecaose. The RbCBM74 starch-binding groove complements the double helical α-glucan geometry of amylopectin, suggesting that this module selects this feature in starch granules. Isothermal titration calorimetry and native mass spectrometry demonstrate that RbCBM74 recognizes longer single and double helical α-glucans, while RbCBM26 binds short maltooligosaccharides. Bioinformatic analysis supports the conservation of the amylopectin-targeting platform in CBM74s from resistant-starch degrading bacteria. Our results suggest that RbCBM74 and RbCBM26 within Sas6 recognize discrete aspects of the starch granule, providing molecular insight into how this structure is accommodated by gut bacteria.
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Glucanos , Almidón , Humanos , Almidón/química , Almidón/metabolismo , Glucanos/química , Glucanos/metabolismo , Amilopectina/metabolismo , Ruminococcus/metabolismo , Bacterias/metabolismoRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Ganoderma lucidum, a traditional edible medicinal mushroom, has been widely reported to improve liver diseases as a dietary intervention for people. Ganoderma lucidum extracts, primarily total triterpenoids (GLTTs), are one of the bioactive ingredients that have excellent beneficial effects on hepatic fibrosis. Therefore, its prevention and reversal are particularly critical due to the increasing number of patients with chronic liver diseases worldwide. AIM OF THE STUDY: The study aimed to evaluate whether GLTTs had a hepatoprotective effect against hepatic fibrosis through metabolic perturbations and gut microbiota changes and its underlying mechanisms. MATERIALS AND METHODS: The compound compositions of GLTTs were quantified, and carbon tetrachloride (CCl4)-induced hepatic fibrosis rats were used to investigate the cause of the improvement in various physiological states with GLTTs treatment, and to determine whether its consequent effect was associated with endogenous metabolites and gut microbiota using UPLC-Q-TOF-MSE metabolomics and 16S rRNA gene sequencing technology. RESULTS: GLTTs alleviated physical status, reduced liver pathological indicators, proinflammatory cytokines, and deposition of hepatic collagen fibers via regulating the NF-κB and TGF-ß1/Smads pathways. The untargeted metabolomics analysis identified 16 potential metabolites that may be the most relevant metabolites for gut microbiota dysbiosis and the therapeutic effects of GLTTs in hepatic fibrosis. Besides, although GLTTs did not significantly affect the α-diversity indexes, significant changes were observed in the composition of microflora structure. In addition, Spearman analysis revealed strong correlations between endogenous metabolites and gut microbiota g_Ruminococcus with hepatic fibrosis. CONCLUSION: GLTTs could provide a potential target for the practical design and application of novel functional food ingredients or drugs in the therapy of hepatic fibrosis.
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Microbioma Gastrointestinal , Reishi , Humanos , Ratas , Animales , FN-kappa B/metabolismo , Factor de Crecimiento Transformador beta1/metabolismo , Reishi/metabolismo , Ruminococcus/metabolismo , ARN Ribosómico 16S , Cirrosis Hepática/metabolismo , Comunicación , Tetracloruro de Carbono/efectos adversosRESUMEN
We have previously demonstrated abnormal gut microbial composition in castration-resistant prostate cancer (CRPC) patients, here we revealed the mechanism of gut microbiota-derived short-chain fatty acids (SCFAs) as a mediator linking CRPC microbiota dysbiosis and prostate cancer (PCa) progression. By using transgenic TRAMP mouse model, PCa patient samples, in vitro PCa cell transwell and macrophage recruitment assays, we examined the effects of CRPC fecal microbiota transplantation (FMT) and SCFAs on PCa progression. Our results showed that FMT with CRPC patients' fecal suspension increased SCFAs-producing gut microbiotas such as Ruminococcus, Alistipes, Phascolarctobaterium in TRAMP mice, and correspondingly raised their gut SCFAs (acetate and butyrate) levels. CRPC FMT or SCFAs supplementation significantly accelerated mice's PCa progression. In vitro, SCFAs enhanced PCa cells migration and invasion by inducing TLR3-triggered autophagy that further activated NF-κB and MAPK signalings. Meanwhile, autophagy of PCa cells released higher level of chemokine CCL20 that could reprogramme the tumor microenvironment by recruiting more macrophage infiltration and simultaneously polarizing them into M2 type, which in turn further strengthened PCa cells invasiveness. Finally in a cohort of 362 PCa patients, we demonstrated that CCL20 expression in prostate tissue was positively correlated with Gleason grade, pre-operative PSA, neural/seminal vesical invasion, and was negatively correlated with post-operative biochemical recurrence-free survival. Collectively, CRPC gut microbiota-derived SCFAs promoted PCa progression via inducing cancer cell autophagy and M2 macrophage polarization. CCL20 could become a biomarker for prediction of prognosis in PCa patients. Intervention of SCFAs-producing microbiotas may be a useful strategy in manipulation of CRPC.
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Autofagia , Bacteroidetes , Ácidos Grasos Volátiles , Microbioma Gastrointestinal , Macrófagos , Neoplasias de la Próstata Resistentes a la Castración , Ruminococcus , Veillonellaceae , Ácidos Grasos Volátiles/metabolismo , Progresión de la Enfermedad , Macrófagos/patología , Polaridad Celular , Ruminococcus/metabolismo , Neoplasias de la Próstata Resistentes a la Castración/microbiología , Neoplasias de la Próstata Resistentes a la Castración/patología , Ratones Transgénicos , Bacteroidetes/metabolismo , Veillonellaceae/metabolismo , Trasplante de Microbiota Fecal , Humanos , Masculino , Animales , RatonesRESUMEN
The human gut symbiont Ruminococcus gnavus displays strain-specific repertoires of glycoside hydrolases (GHs) contributing to its spatial location in the gut. Sequence similarity network analysis identified strain-specific differences in blood-group endo-ß-1,4-galactosidase belonging to the GH98 family. We determined the substrate and linkage specificities of GH98 from R. gnavus ATCC 29149, RgGH98, against a range of defined oligosaccharides and glycoconjugates including mucin. We showed by HPAEC-PAD and LC-FD-MS/MS that RgGH98 is specific for blood group A tetrasaccharide type II (BgA II). Isothermal titration calorimetry (ITC) and saturation transfer difference (STD) NMR confirmed RgGH98 affinity for blood group A over blood group B and H antigens. The molecular basis of RgGH98 strict specificity was further investigated using a combination of glycan microarrays, site-directed mutagenesis, and X-ray crystallography. The crystal structures of RgGH98 in complex with BgA trisaccharide (BgAtri) and of RgGH98 E411A with BgA II revealed a dedicated hydrogen network of residues, which were shown by site-directed mutagenesis to be critical to the recognition of the BgA epitope. We demonstrated experimentally that RgGH98 is part of an operon of 10 genes that is overexpresssed in vitro when R. gnavus ATCC 29149 is grown on mucin as sole carbon source as shown by RNAseq analysis and RT-qPCR confirmed RgGH98 expression on BgA II growth. Using MALDI-ToF MS, we showed that RgGH98 releases BgAtri from mucin and that pretreatment of mucin with RgGH98 confered R. gnavus E1 the ability to grow, by enabling the E1 strain to metabolise BgAtri and access the underlying mucin glycan chain. These data further support that the GH repertoire of R. gnavus strains enable them to colonise different nutritional niches in the human gut and has potential applications in diagnostic and therapeutics against infection.
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Clostridiales/metabolismo , Mucina-1/metabolismo , Sistema del Grupo Sanguíneo ABO/inmunología , Antígenos de Grupos Sanguíneos/inmunología , Clostridiales/genética , Clostridiales/fisiología , Microbioma Gastrointestinal , Tracto Gastrointestinal , Glicósido Hidrolasas/metabolismo , Humanos , Mucinas/metabolismo , Oligosacáridos/metabolismo , Polisacáridos/metabolismo , Ruminococcus/genética , Ruminococcus/metabolismo , Especificidad por Sustrato , Espectrometría de Masas en Tándem/métodosRESUMEN
To date, much progress has been made in dietary therapy for obese patients. A low-carbohydrate diet (LCD) has reached a revival in its clinical use during the past decade with undefined mechanisms and debatable efficacy. The gut microbiota has been suggested to promote energy harvesting. Here, we propose that the gut microbiota contributes to the inconsistent outcome under an LCD. To test this hypothesis, patients with obesity or patients who were overweight were randomly assigned to a normal diet (ND) or an LCD group with ad libitum energy intake for 12 weeks. Using matched sampling, the microbiome profile at baseline and end stage was examined. The relative abundance of butyrate-producing bacteria, including Porphyromonadaceae Parabacteroides and Ruminococcaceae Oscillospira, was markedly increased after LCD intervention for 12 weeks. Moreover, within the LCD group, participants with a higher relative abundance of Bacteroidaceae Bacteroides at baseline exhibited a better response to LCD intervention and achieved greater weight loss outcomes. Nevertheless, the adoption of an artificial neural network (ANN)-based prediction model greatly surpasses a general linear model in predicting weight loss outcomes after LCD intervention. Therefore, the gut microbiota served as a positive outcome predictor and has the potential to predict weight loss outcomes after short-term LCD intervention. Gut microbiota may help to guide the clinical application of short-term LCD intervention to develop effective weight loss strategies. (This study has been registered at the China Clinical Trial Registry under approval no. ChiCTR1800015156). IMPORTANCE Obesity and its related complications pose a serious threat to human health. Short-term low-carbohydrate diet (LCD) intervention without calorie restriction has a significant weight loss effect for overweight/obese people. Furthermore, the relative abundance of Bacteroidaceae Bacteroides is a positive outcome predictor of individual weight loss after short-term LCD intervention. Moreover, leveraging on these distinct gut microbial structures at baseline, we have established a prediction model based on the artificial neural network (ANN) algorithm that could be used to estimate weight loss potential before each clinical trial (with Chinese patent number 2021104655623). This will help to guide the clinical application of short-term LCD intervention to improve weight loss strategies.
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Dieta Baja en Carbohidratos/métodos , Microbioma Gastrointestinal/fisiología , Obesidad/dietoterapia , Porphyromonas/metabolismo , Ruminococcus/metabolismo , Adulto , Bacteroidetes/clasificación , Bacteroidetes/aislamiento & purificación , Bacteroidetes/metabolismo , Peso Corporal , Femenino , Humanos , Masculino , Persona de Mediana Edad , Porphyromonas/aislamiento & purificación , Ruminococcus/aislamiento & purificación , Pérdida de Peso , Programas de Reducción de Peso/métodos , Adulto JovenRESUMEN
Emerging research evidence has established the critical role of the gut-liver axis in the development of alcohol-associated liver disease (ALD). The present study employed 16S rRNA gene and whole genome shotgun (WGS) metagenomic analysis in combination with a revised microbial dataset to comprehensively detail the butyrate-producing microbial communities and the associated butyrate metabolic pathways affected by chronic ethanol feeding. Specifically, the data demonstrated that a decrease in several butyrate-producing bacterial genera belonging to distinct families within the Firmicutes phyla was a significant component of ethanol-induced dysbiosis. WGS analysis of total bacterial genomes encompassing butyrate synthesizing pathways provided the functional characteristics of the microbiome associated with butyrate synthesis. The data revealed that in control mice microbiome, the acetyl-coenzyme A (CoA) butyrate synthesizing pathway was the most prevalent and was significantly and maximally decreased by chronic ethanol feeding. Further WGS analysis i) validated the ethanol-induced decrease in the acetyl-CoA pathway by identifying the decrease in two critical genes but - (butyryl-CoA: acetate CoA transferase) and buk - (butyrate kinase) that encode the terminal condensing enzymes required for converting butyryl-CoA to butyrate and ii) detection of specific taxa of butyrate-producing bacteria containing but and buk genes. Notably, the administration of tributyrin (Tb) - a butyrate prodrug - significantly prevented ethanol-induced decrease in butyrate-producing bacteria, hepatic steatosis, inflammation, and injury. Taken together, our findings strongly suggest that the loss of butyrate-producing bacteria using the acetyl-CoA pathway is a significant pathogenic feature of ethanol-induced microbial dysbiosis and ALD and can be targeted for therapy.
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Butiratos/metabolismo , Enfermedad Hepática Inducida por Sustancias y Drogas/etiología , Enfermedad Hepática Inducida por Sustancias y Drogas/fisiopatología , Coenzima A Transferasas/metabolismo , Disbiosis/inducido químicamente , Etanol/metabolismo , Microbioma Gastrointestinal/efectos de los fármacos , Ruminococcus/metabolismo , Animales , Modelos Animales de Enfermedad , Disbiosis/fisiopatología , Humanos , Redes y Vías Metabólicas , RatonesRESUMEN
Pullulanases are glycoside hydrolase family 13 (GH13) enzymes that target α1,6 glucosidic linkages within starch and aid in the degradation of the α1,4- and α1,6- linked glucans pullulan, glycogen and amylopectin. The human gut bacterium Ruminococcus bromii synthesizes two extracellular pullulanases, Amy10 and Amy12, that are incorporated into the multiprotein amylosome complex that enables the digestion of granular resistant starch from the diet. Here we provide a comparative biochemical analysis of these pullulanases and the x-ray crystal structures of the wild type and the nucleophile mutant D392A of Amy12 complexed with maltoheptaose and 63-α-D glucosyl-maltotriose. While Amy10 displays higher catalytic efficiency on pullulan and cleaves only α1,6 linkages, Amy12 has some activity on α1,4 linkages suggesting that these enzymes are not redundant within the amylosome. Our structures of Amy12 include a mucin-binding protein (MucBP) domain that follows the C-domain of the GH13 fold, an atypical feature of these enzymes. The wild type Amy12 structure with maltoheptaose captured two oligosaccharides in the active site arranged as expected following catalysis of an α1,6 branch point in amylopectin. The nucleophile mutant D392A complexed with maltoheptaose or 63-α-D glucosyl-maltotriose captured ß-glucose at the reducing end in the -1 subsite, facilitated by the truncation of the active site aspartate and stabilized by stacking with Y279. The core interface between the co-crystallized ligands and Amy12 occurs within the -2 through + 1 subsites, which may allow for flexible recognition of α1,6 linkages within a variety of starch structures.
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Glicósido Hidrolasas , Ruminococcus , Glicósido Hidrolasas/química , Humanos , Ruminococcus/genética , Ruminococcus/metabolismo , Almidón/metabolismo , Especificidad por SustratoRESUMEN
The gut microbiota has emerged as a key factor in the pathogenesis of intestinal viruses, including enteroviruses, noroviruses and rotaviruses (RVs), where stimulatory and inhibitory effects on infectivity have been reported. With the aim of determining whether members of the microbiota interact with RVs during infection, a combination of anti-RV antibody labeling, fluorescence-activated cell sorting and 16S rRNA amplicon sequencing was used to characterize the interaction between specific bacteria and RV in stool samples of children suffering from diarrhea produced by G1P[8] RV. The genera Ruminococcus and Oxalobacter were identified as RV binders in stools, displaying enrichments between 4.8- and 5.4-fold compared to samples nonlabeled with anti-RV antibodies. In vitro binding of the G1P[8] Wa human RV strain to two Ruminococcus gauvreauii human isolates was confirmed by fluorescence microscopy. Analysis in R. gauvreauii with antibodies directed to several histo-blood group antigens (HBGAs) indicated that these bacteria express HBGA-like substances on their surfaces, which can be the target for RV binding. Furthermore, in vitro infection of the Wa strain in differentiated Caco-2 cells was significantly reduced by incubation with R. gauvreauii. These data, together with previous findings showing a negative correlation between Ruminococcus levels and antibody titers to RV in healthy individuals, suggest a pivotal interaction between this bacterial group and human RV. These results reveal likely mechanisms of how specific bacterial taxa of the intestinal microbiota could negatively affect RV infection and open new possibilities for antiviral strategies.
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Microbioma Gastrointestinal , Infecciones por Rotavirus/microbiología , Rotavirus/metabolismo , Ruminococcus/metabolismo , Proteínas Bacterianas/metabolismo , Células CACO-2 , Preescolar , Humanos , Intestinos/microbiología , Intestinos/virología , Unión Proteica , Rotavirus/patogenicidad , Infecciones por Rotavirus/virología , Ruminococcus/patogenicidadRESUMEN
BACKGROUND AND AIMS: Previous small studies have appraised the gut microbiome (GM) in steatosis, but large-scale studies are lacking. We studied the association of the GM diversity and composition, plasma metabolites, predicted functional metagenomics, and steatosis. APPROACH AND RESULTS: This is a cross-sectional analysis of the prospective population-based Rotterdam Study. We used 16S ribosomal RNA gene sequencing and determined taxonomy using the SILVA reference database. Alpha diversity and beta diversity were calculated using the Shannon diversity index and Bray-Curtis dissimilarities. Differences were tested across steatosis using permutational multivariate analysis of variance. Hepatic steatosis was diagnosed by ultrasonography. We subsequently selected genera using regularized regression. The functional metagenome was predicted based on the GM using Kyoto Encyclopedia of Genes and Genomes pathways. Serum metabolomics were assessed using high-throughput proton nuclear magnetic resonance. All analyses were adjusted for age, sex, body mass index, alcohol, diet, and proton-pump inhibitors. We included 1,355 participants, of whom 472 had steatosis. Alpha diversity was lower in steatosis (P = 1.1â10-9 ), and beta diversity varied across steatosis strata (P = 0.001). Lasso selected 37 genera of which three remained significantly associated after adjustment (Coprococcus3: ß = -65; Ruminococcus Gauvreauiigroup: ß = 62; and Ruminococcus Gnavusgroup: ß = 45, Q-value = 0.037). Predicted metagenome analyses revealed that pathways of secondary bile-acid synthesis and biotin metabolism were present, and D-alanine metabolism was absent in steatosis. Metabolic profiles showed positive associations for aromatic and branched chain amino acids and glycoprotein acetyls with steatosis and R. Gnavusgroup, whereas these metabolites were inversely associated with alpha diversity and Coprococcus3. CONCLUSIONS: We confirmed, on a large-scale, the lower microbial diversity and association of Coprococcus and Ruminococcus Gnavus with steatosis. We additionally showed that steatosis and alpha diversity share opposite metabolic profiles.
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Hígado Graso/etiología , Microbioma Gastrointestinal , Estudios Transversales , Hígado Graso/genética , Hígado Graso/metabolismo , Hígado Graso/microbiología , Femenino , Microbioma Gastrointestinal/genética , Humanos , Masculino , Metabolómica , Metagenoma/genética , Persona de Mediana Edad , ARN Ribosómico 16S/genética , Factores de Riesgo , Ruminococcus/metabolismoRESUMEN
The present study investigated the association between fibre degradation and the concentration of dissolved molecular hydrogen (H2) in the rumen. Napier grass (NG) silage and corn stover (CS) silage were compared as forages with contrasting structures and degradation patterns. In the first experiment, CS silage had greater 48-h DM, neutral-detergent fibre (NDF) and acid-detergent fibre degradation, and total gas and methane (CH4) volumes, and lower 48-h H2 volume than NG silage in 48-h in vitro incubations. In the second experiment, twenty-four growing beef bulls were fed diets including 55 % (DM basis) NG or CS silages. Bulls fed the CS diet had greater DM intake (DMI), average daily gain, total-tract digestibility of OM and NDF, ruminal dissolved methane (dCH4) concentration and gene copies of protozoa, methanogens, Ruminococcus albus and R. flavefaciens, and had lower ruminal dH2 concentration, and molar proportions of valerate and isovalerate, in comparison with those fed the NG diet. There was a negative correlation between dH2 concentration and NDF digestibility in bulls fed the CS diet, and a lack of relationship between dH2 concentration and NDF digestibility with the NG diet. In summary, the fibre of CS silage was more easily degraded by rumen microorganisms than that of NG silage. Increased dCH4 concentration with the CS diet presumably led to the decreased ruminal dH2 concentration, which may be helpful for fibre degradation and growth of fibrolytic micro-organisms in the rumen.
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Bovinos/fisiología , Fibras de la Dieta/metabolismo , Digestión , Microbioma Gastrointestinal , Hidrógeno/análisis , Rumen/metabolismo , Ensilaje , Animales , Bovinos/crecimiento & desarrollo , Dieta , Fibras de la Dieta/administración & dosificación , Euryarchaeota/clasificación , Euryarchaeota/genética , Euryarchaeota/metabolismo , Masculino , Metano/análisis , Poaceae , Rumen/microbiología , Rumen/parasitología , Ruminococcus/clasificación , Ruminococcus/genética , Ruminococcus/metabolismo , Ensilaje/análisis , Zea maysRESUMEN
We used castrated and fistulated Japanese Black beef cattle (n = 9) to measure the pH and bacterial communities in the rumen liquid, rumen solid, and reticulum liquid during early, middle, and late fattening stages (10-14, 15-22, and 23-30 months of age, respectively). The pH was measured in the rumen and reticulum during the last 13 days of each fattening stage and was significantly lower in the rumen at the early and middle fattening stage and in the reticulum during the late stage. Sequencing analysis indicated similar bacterial compositions in the rumen and reticulum liquid fractions and stability of bacterial diversity in the rumen and reticulum liquid fractions and rumen solid fraction. By contrast, major operational taxonomic units (OTUs), such as Ruminococcus bromii strain ATCC 27255 (OTU1, OTU10, and OTU15), were differently correlated to the fermentation parameters among the rumen and reticulum liquid fractions. Therefore, the long-term feeding of Japanese Black beef cattle with a high-concentrate diet might reverse the trend of pH in the rumen and reticulum during the late fattening stage, and the bacterial communities adapted to changes in fermentation by preserving their diversity throughout fattening.
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Crianza de Animales Domésticos , Bovinos/metabolismo , Bovinos/microbiología , Fermentación , Contenido Digestivo , Microbioma Gastrointestinal , Concentración de Iones de Hidrógeno , Reticulum/metabolismo , Reticulum/microbiología , Rumen/metabolismo , Rumen/microbiología , Factores de Edad , Alimentación Animal/análisis , Animales , Contenido Digestivo/química , Contenido Digestivo/microbiología , Japón , Masculino , Ruminococcus/metabolismoRESUMEN
The purpose of this work was to identify the features of the gut microbiome in cases of ankylosing spondylitis (AS) testing positive for human leukocyte antigen- (HLA-) B27 and healthy controls (HCs) as well as to determine how bacterial populations were correlated with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Fecal DNA extracted from fecal samples from 10 AS cases and 12 HCs was subjected to 16S rRNA gene sequencing. The two research groups did not differ significantly regarding alpha diversity. By comparison to HCs, AS cases displayed a lower relative level of Bacteroidetes (P < 0.05), but a higher level of Firmicutes and Verrucomicrobia (P < 0.05). Furthermore, the correlation between the specific gut bacteria and ESR or CRP was investigated. At the phylum level, Firmicutes and Verrucomicrobia had a positive association with ESR and CRP, while Bacteroidetes exhibited an inverse correlation with ESR and CRP. Meanwhile, in terms of genus, Bacteroides had a positive association with ESR and CRP, whereas Ruminococcus and Parasutterella had an inverse correlation with ESR and CRP, and Helicobacter also displayed an inverse correlation with CRP. Such findings indicated dissimilarities between AS cases and HCs regarding the gut microbiome, as well as the existence of correlations between bacterial populations and both ESR and CRP.
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Sedimentación Sanguínea , Proteína C-Reactiva/biosíntesis , Heces/microbiología , Espondilitis Anquilosante/sangre , Espondilitis Anquilosante/metabolismo , Adulto , Bacteroides/metabolismo , Femenino , Microbioma Gastrointestinal , Antígeno HLA-B27/biosíntesis , Humanos , Inflamación , Masculino , Persona de Mediana Edad , ARN Ribosómico 16S/metabolismo , Ruminococcus/metabolismo , Índice de Severidad de la EnfermedadRESUMEN
The in vitro digestive and fermentation properties of Sargassum pallidum polysaccharide (SPP) after ultrasound degradation were investigated. The results showed that SPP and its degraded fractions were not affected by human saliva, but slightly degraded by breaking glycosidic bonds under simulated gastrointestinal digestion. The DPPH radical scavenging activity, α-glucosidase inhibitory activity, and bile acid-binding capacity of SPP and its degraded fractions were decreased after digestion, which was attributed to the reduction of molecular weights (MWs) and viscosity. Furthermore, in vitro fermentation assay indicated that SPP and its degraded fractions showed good fermentability. The predominant compositional monosaccharides including arabinose, galactose, glucose, xylose, and uronic acid were significantly decreased, and the degraded SPP fractions were more easily fermented and utilized by gut bacteria. SPP and its degraded fractions could modulate gut health by decreasing the Firmicutes/Bacteroidetes ratio and increasing the relative abundances of some beneficial genera, such as Prevotella, Dialister, Phascolarctobacterium, Ruminococcus, and Bacteroides. These findings suggested that SPP and its degraded fractions exhibited similar influence on gut microbiota community, but appropriate degraded SPP fractions were more easily fermented by gut microbiota.
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Fermentación , Microbioma Gastrointestinal , Polisacáridos/química , Sargassum/química , Ultrasonido , Antioxidantes/química , Bacteroides/metabolismo , Bacteroidetes/metabolismo , Secuencia de Bases , Ácidos y Sales Biliares/química , Compuestos de Bifenilo/química , Carbohidratos de la Dieta , Firmicutes/metabolismo , Glicósidos/química , Humanos , Concentración de Iones de Hidrógeno , Peso Molecular , Monosacáridos , Picratos/química , Prevotella/metabolismo , Análisis de Componente Principal , Ruminococcus/metabolismo , Saliva/metabolismo , Viscosidad , alfa-Glucosidasas/metabolismoRESUMEN
Sialic acid (N-acetylneuraminic acid (Neu5Ac)) is commonly found in the terminal location of colonic mucin glycans where it is a much-coveted nutrient for gut bacteria, including Ruminococcus gnavus. R. gnavus is part of the healthy gut microbiota in humans, but it is disproportionately represented in diseases. There is therefore a need to understand the molecular mechanisms that underpin the adaptation of R. gnavus to the gut. Previous in vitro research has demonstrated that the mucin-glycan-foraging strategy of R. gnavus is strain dependent and is associated with the expression of an intramolecular trans-sialidase, which releases 2,7-anhydro-Neu5Ac, rather than Neu5Ac, from mucins. Here, we unravelled the metabolism pathway of 2,7-anhydro-Neu5Ac in R. gnavus that is underpinned by the exquisite specificity of the sialic transporter for 2,7-anhydro-Neu5Ac and by the action of an oxidoreductase that converts 2,7-anhydro-Neu5Ac into Neu5Ac, which then becomes a substrate of a Neu5Ac-specific aldolase. Having generated an R. gnavus nan-cluster deletion mutant that lost the ability to grow on sialylated substrates, we showed that-in gnotobiotic mice colonized with R. gnavus wild-type (WT) and mutant strains-the fitness of the nan mutant was significantly impaired, with a reduced ability to colonize the mucus layer. Overall, we revealed a unique sialic acid pathway in bacteria that has important implications for the spatial adaptation of mucin-foraging gut symbionts in health and disease.
Asunto(s)
Adaptación Fisiológica , Microbioma Gastrointestinal/fisiología , Moco/metabolismo , Ácido N-Acetilneuramínico/metabolismo , Ruminococcus/metabolismo , Animales , Clostridiales , Glicoproteínas , Humanos , Redes y Vías Metabólicas/genética , Redes y Vías Metabólicas/fisiología , Ratones , Ratones Endogámicos C57BL , Mucinas/metabolismo , Ácido N-Acetilneuramínico/análogos & derivados , Neuraminidasa , Oxo-Ácido-Liasas/metabolismo , Polisacáridos/metabolismo , Proteínas Recombinantes , Ruminococcus/enzimología , Ruminococcus/genéticaRESUMEN
IgA is prominently secreted at mucosal surfaces and coats a fraction of the commensal microbiota, a process that is critical for intestinal homeostasis. However, the mechanisms of IgA induction and the molecular targets of these antibodies remain poorly understood, particularly in humans. Here, we demonstrate that microbiota from a subset of human individuals encode two protein "superantigens" expressed on the surface of commensal bacteria of the family Lachnospiraceae such as Ruminococcus gnavus that bind IgA variable regions and stimulate potent IgA responses in mice. These superantigens stimulate B cells expressing human VH3 or murine VH5/6/7 variable regions and subsequently bind their antibodies, allowing these microbial organisms to become highly coated with IgA in vivo. These findings demonstrate a previously unappreciated role for commensal superantigens in host-microbiota interactions. Furthermore, as superantigen-expressing strains show an uneven distribution across human populations, they should be systematically considered in studies evaluating human B cell responses and microbiota during homeostasis and disease.
Asunto(s)
Linfocitos B/inmunología , Microbioma Gastrointestinal/fisiología , Superantígenos/inmunología , Animales , Clostridiales/metabolismo , Ensayo de Inmunoadsorción Enzimática , Firmicutes/metabolismo , Citometría de Flujo , Humanos , Lacticaseibacillus rhamnosus/metabolismo , Listeria monocytogenes/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos NOD , Ratones Noqueados , Factor 88 de Diferenciación Mieloide/genética , Factor 88 de Diferenciación Mieloide/metabolismo , Ruminococcus/metabolismoRESUMEN
Gut microbiome community dynamics are maintained by complex microbe-microbe and microbe-host interactions, which can be disturbed by stress. In vivo studies on the dynamics and manipulation of those interactions are costly and slow, but can be accelerated using in vitro fermentation. Herein, in vitro fermentation was used to determine how an acute stressor, a sudden change in diet, impacts inter-bacterial species competition for resistant starch-supplemented medium (RSM). Fermentation vessels were seeded with fecal samples collected from 10 individuals consuming a habitual diet or U.S. military rations for 21 days. Lactobacillus spp. growth in response to RSM was attenuated following ration consumption, whereas growth of Ruminococcus bromii was enhanced. These differences were not evident in the pre-fermentation samples. Findings demonstrate how incorporating in vitro fermentation into clinical studies can increase understanding of stress-induced changes in nutrient-microbiome dynamics, and suggest that sudden changes in diet may impact inter-species competition for substrates.