Distinguishing feature of gut microbiota in Tibetan highland coronary artery disease patients and its link with diet.

The prevalence of coronary artery disease (CAD) in Tibetan Highlanders is lower than that in plain-living individuals, but the mechanism still unclear. Gut microbiota (GM) disorder is considered one of the potential factors involved in the pathogenesis of CAD, but the GM characteristics of Tibetan Highlanders suffering from CAD are unknown. We sequenced the V3-V4 region of the 16S ribosomal RNA of gut bacteria from fecal samples from Tibetan and Han CAD patients and healthy individuals inhabiting the Qinghai-Tibet Plateau, as well as from Han CAD patients and healthy individuals living at sea level, and we analyzed the GM characteristics of these subjects by bioinformatics analysis. The results showed that Tibetan Highlanders suffering from CAD had higher GM α-diversity, with differently distributed cluster compared with healthy Tibetan Highlanders and Han CAD patients living at high and low altitudes. Genera Catenibacterium, Clostridium_sensu_stricto, Holdemanella, and Ruminococcus 2 were enriched in Tibetan Highlanders suffering from CAD compared with healthy Tibetan Highlanders and Han CAD patients living at high- and low-altitudes. Prevotella was enriched in Tibetan Highlanders suffering from CAD compared with Han CAD patients living at high- and low-altitudes. Moreover, Catenibacterium was positively correlated with Prevotella. Additionally, Catenibacterium, Holdemanella, and Prevotella were positively correlated with fermented dairy product, carbohydrate and fiber intake by the subjects, while Clostridium_sensu_stricto was negatively correlated with protein intake by the subjects. In conclusion, our study indicated that Tibetan Highlanders suffering from CAD showed distinct GM, which was linked to their unique dietary characteristics and might associated with CAD.

Gut Microbiota Serves a Predictable Outcome of Short-Term Low-Carbohydrate Diet (LCD) Intervention for Patients with Obesity.

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.

Ruminococcus bovis sp. nov., a novel species of amylolytic Ruminococcus isolated from the rumen of a dairy cow.

This study describes JE7A12T (=ATCC TSD-225T=NCTC 14479T), an isolate from the ruminal content of a dairy cow. Phenotypic and genotypic traits of the isolate were explored. JE7A12T was found to be a strictly anaerobic, catalase-negative, oxidase-negative, coccoid bacterium that grows in chains. The API 50 CH carbon source assay detected fermentation of d-glucose, d-fructose, d-galactose, glycogen and starch. HPLC showed acetate to be the major fermentation product as a result of carbohydrate fermentation. Phylogenetic analysis of JE7A12T based on 16S rRNA nucleotide sequence and amino acid sequences from the whole genome indicated a divergent lineage from the closest neighbours in the genus Ruminococcus. The results of 16S rRNA sequence comparison, whole genome average nucleotide identity (ANI) and DNA G+C content data indicate that JE7A12T represents a novel species which we propose the name Ruminococcus bovis with JE7A12T as the type strain.

Ruminococcoides bili gen. nov., sp. nov., a bile-resistant bacterium from human bile with autolytic behavior.

A strictly anaerobic, resistant starch-degrading, bile-tolerant, autolytic strain, IPLA60002T, belonging to the family Ruminococcaceae, was isolated from a human bile sample of a liver donor without hepatobiliary disease. Cells were Gram-stain-positive cocci, and 16S rRNA gene and whole genome analyses showed that Ruminococcus bromii was the phylogenetically closest related species to the novel strain IPLA60002T, though with average nucleotide identity values below 90 %. Biochemically, the new isolate has metabolic features similar to those described previously for gut R. bromii strains, including the ability to degrade a range of different starches. The new isolate, however, produces lactate and shows distinct resistance to the presence of bile salts. Additionally, the novel bile isolate displays an autolytic phenotype after growing in different media. Strain IPLA60002T is phylogenetically distinct from other species within the genus Ruminococcus. Therefore, we propose on the basis of phylogenetic, genomic and metabolic data that the novel IPLA60002T strain isolated from human bile be given the name Ruminococcoides bili gen. nov., sp. nov., within the new proposed genus Ruminococcoides and the family Ruminococcaceae. Strain IPLA60002T (=DSM 110008T=LMG 31505T) is proposed as the type strain of Ruminococcoides bili.

Detection of cell-free microbial DNA using a contaminant-controlled analysis framework.

BACKGROUND: The human microbiome plays an important role in cancer. Accumulating evidence indicates that commensal microbiome-derived DNA may be represented in minute quantities in the cell-free DNA of human blood and could possibly be harnessed as a new cancer biomarker. However, there has been limited use of rigorous experimental controls to account for contamination, which invariably affects low-biomass microbiome studies. RESULTS: We apply a combination of 16S-rRNA-gene sequencing and droplet digital PCR to determine if the specific detection of cell-free microbial DNA (cfmDNA) is possible in metastatic melanoma patients. Compared to matched stool and saliva samples, the absolute concentration of cfmDNA is low but significantly above the levels detected from negative controls. The microbial community of plasma is strongly influenced by laboratory and reagent contaminants introduced during the DNA extraction and sequencing processes. Through the application of an in silico decontamination strategy including the filtering of amplicon sequence variants (ASVs) with batch dependent abundances and those with a higher prevalence in negative controls, we identify known gut commensal bacteria, such as Faecalibacterium, Bacteroides and Ruminococcus, and also other uncharacterised ASVs. We analyse additional plasma samples, highlighting the potential of this framework to identify differences in cfmDNA between healthy and cancer patients. CONCLUSIONS: Together, these observations indicate that plasma can harbour a low yet detectable level of cfmDNA. The results highlight the importance of accounting for contamination and provide an analytical decontamination framework to allow the accurate detection of cfmDNA for future biomarker studies in cancer and other diseases.

Identification of gut microbiota signatures in symptomatic dermographism.

Symptomatic dermographism (SD) is a recurrent inflammatory skin disease related to immunity; however, the details remain elusive. In view of the important role of gut microbiota in immune regulation, the purpose of this study is to investigate the alterations of gut microbiota in SD and explore the potential bacterial biomarkers for diagnosis. A case-control study including SD patients and normal controls (NCs) was carried out. Gut microbiota of the participants was analysed by the 16S rDNA sequencing of faecal samples. The linear discriminant analysis effect size and the receiver operating characteristic curve (ROC) analysis were used to identify the bacterial biomarkers. Forty-four participants were included in this study. The alpha-diversity and beta-diversity of gut microbiota differed significantly between SD patients and NCs. The abundance of Verrucomicrobia, Ruminococcaceae and their subordinate taxa were reduced in SD patients, while Enterobacteriales and its subordinate taxon exhibited higher relative abundance compared with NCs. Subdoligranulum and Ruminococcus bromii showed a potential diagnostic value for SD, and Prevotella stercorea was negatively relevant to duration of SD. Furthermore, the pyruvate, butyric acid and histamine metabolism pathway were likely to be involved in the pathogenesis of SD. Our results revealed that the gut microbiota of SD patients experienced obvious changes, and Verrucomicrobia, Ruminococcaceae and Enterobacteriales were microbiota signatures for SD.

Modulation of rumen fermentation and microbial community through increasing dietary cation-anion difference in Chinese Holstein dairy cows under heat stress conditions.

AIMS: The effect of increasing dietary cation-anion difference (DCAD) on rumen fermentation and ruminal microbial community in dairy cows under heat stress (HS) conditions were evaluated. METHODS AND RESULTS: This study was performed as a two-period cross-over design during the summer season, with eight lactating dairy cows randomly distributed to either a control DCAD diet (CON: 33·5 mEq/100 g DM) or high DCAD diet (HDCAD: 50·8 mEq/100 g DM). Throughout the present study, the temperature and humidity index (THI; 80·2 ± 4·29) was generally elevated above the threshold (THI = 72) that is reported to cause HS in lactating dairy cows. Rumen liquid samples were collected on 15 and 21 d during each 21 d-period. The absolute concentration of ruminal total volatile fatty acid (TVFA) in HDCAD treatment was significantly (P < 0·05) higher than those in the control, whilst the ruminal pH, NH3 -N, and VFA molar percentages were unaffected through increasing DCAD. Furthermore, the copy numbers of the cellulolytic bacteria Ruminococcus albus and Ruminococcus flavefaciens in rumen fluid significantly (P < 0·05) rose along with the increment of DCAD. Although the Alpha diversity indexes and the bacterial microbiota structure were unaffected, increasing DCAD significantly (P < 0·05) enriched the phylum Fibrobacteres and genus Fibrobacter in the microflora of rumen fluid, whilst the genera Flexilinea and Dubosiella were the most differentially abundant taxa in the control. CONCLUSIONS: Increasing DCAD under HS conditions resulted in a greater concentration of total VFA without affecting rumen bacteria diversity or structure, although the enrichment of some cellulolytic/hemicellulolytic bacteria was observed. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study provides information on the modulation of rumen fermentation and microbial community through the increment of DCAD in Holstein dairy cows under HS conditions.

Analysis of Gut Microbiome and Metabolite Characteristics in Patients with Slow Transit Constipation.

BACKGROUND: Slow transit constipation (STC) is a type of functional constipation in which colon transit time is extended as a result of a reduction in the high amplitude of colon contraction activity. The utility of gut microbiome and metabolite characteristics in patients with STC is rarely studied. Short-chain fatty acids (SCFAs) enhance colonic fluid and sodium absorption and thus may aggravate the symptoms of STC. However, the content and role of SCFAs in constipation patients are not clear. We speculate that gut microbiome and SCFAs in the colon of STC patients may be abnormal and linked to the underlying mechanism of STC. METHODS: This observational study is registered at ClinicalTrials.gov (NCT02984969). The high-throughput sequencing was used to analyze the diversity and composition of fecal microbial communities. Gas chromatography-mass spectrometry (GC-MS) was used to determine the properties and concentrations of the SCFAs in the two groups. RESULTS: The Shannon diversity and Simpson diversity of the gut microbiome were significantly greater in the STC group than the control group. The two groups also showed significant differences in the species composition of the gut microbiome at different classification levels. The results of GC-MS showed that the acetate concentrations in the STC group were significantly reduced compared with the control group, but the other five types of SCFAs and total SCFAs showed no significant difference between groups. ROC curve analyses revealed that the AUC of Acetate (AUC = 0.758) was higher than Propionate (AUC = 0.660). The largest AUC of gut microbiome for predicting STC was Prevotella (AUC = 0.807). Correlation analysis showed a positive correlation between the concentration of Ruminococcus and Disease history (rs = 0.519). Meanwhile, a positive correlation between the concentration of Roseburia and Acetate (rs = 0.606) or Butyrate (rs = 0.543) was found. CONCLUSION: We found significant differences between the STC and control groups in the main components of the gut microbiome, with greater diversity in the STC group and differences between the groups in species composition at different classification levels. These different microbiome and metabolite may be valuable biomarkers for STC.

Mgll Knockout Mouse Resistance to Diet-Induced Dysmetabolism Is Associated with Altered Gut Microbiota.

Monoglyceride lipase (MGLL) regulates metabolism by catabolizing monoacylglycerols (MAGs), including the endocannabinoid 2-arachidonoyl glycerol (2-AG) and some of its bioactive congeners, to the corresponding free fatty acids. Mgll knockout mice (Mgll-/-) exhibit elevated tissue levels of MAGs in association with resistance to the metabolic and cardiovascular perturbations induced by a high fat diet (HFD). The gut microbiome and its metabolic function are disrupted in obesity in a manner modulated by 2-arachidonoyl glycerol (2-AG's) main receptors, the cannabinoid CB1 receptors. We therefore hypothesized that Mgll-/- mice have an altered microbiome, that responds differently to diet-induced obesity from that of wild-type (WT) mice. We subjected mice to HFD and assessed changes in the microbiomes after 8 and 22 weeks. As expected, Mgll-/- mice showed decreased adiposity, improved insulin sensitivity, and altered circulating incretin/adipokine levels in response to HFD. Mgll-/- mice on a chow diet exhibited significantly higher levels of Hydrogenoanaerobacterium, Roseburia, and Ruminococcus than WT mice. The relative abundance of the Lactobacillaceae and Coriobacteriaceae and of the Lactobacillus, Enterorhabdus, Clostridium_XlVa, and Falsiporphyromonas genera was significantly altered by HFD in WT but not Mgll-/- mice. Differently abundant families were also associated with changes in circulating adipokine and incretin levels in HFD-fed mice. Some gut microbiota family alterations could be reproduced by supplementing 2-AG or MAGs in culturomics experiments carried out with WT mouse fecal samples. We suggest that the altered microbiome of Mgll-/- mice contributes to their obesity resistant phenotype, and results in part from increased levels of 2-AG and MAGs.

Metagenomic insights into the diversity of carbohydrate-degrading enzymes in the yak fecal microbial community.

BACKGROUND: Yaks are able to utilize the gastrointestinal microbiota to digest plant materials. Although the cellulolytic bacteria in the yak rumen have been reported, there is still limited information on the diversity of the major microorganisms and putative carbohydrate-metabolizing enzymes for the degradation of complex lignocellulosic biomass in its gut ecosystem. RESULTS: Here, this study aimed to decode biomass-degrading genes and genomes in the yak fecal microbiota using deep metagenome sequencing. A comprehensive catalog comprising 4.5 million microbial genes from the yak feces were established based on metagenomic assemblies from 92 Gb sequencing data. We identified a full spectrum of genes encoding carbohydrate-active enzymes, three-quarters of which were assigned to highly diversified enzyme families involved in the breakdown of complex dietary carbohydrates, including 120 families of glycoside hydrolases, 25 families of polysaccharide lyases, and 15 families of carbohydrate esterases. Inference of taxonomic assignments to the carbohydrate-degrading genes revealed the major microbial contributors were Bacteroidaceae, Ruminococcaceae, Rikenellaceae, Clostridiaceae, and Prevotellaceae. Furthermore, 68 prokaryotic genomes were reconstructed and the genes encoding glycoside hydrolases involved in plant-derived polysaccharide degradation were identified in these uncultured genomes, many of which were novel species with lignocellulolytic capability. CONCLUSIONS: Our findings shed light on a great diversity of carbohydrate-degrading enzymes in the yak gut microbial community and uncultured species, which provides a useful genetic resource for future studies on the discovery of novel enzymes for industrial applications.

Structural and functional changes of gut microbiota in ovariectomized rats and their correlations with altered bone mass.

As a critical factor involved in the maintenance of physiological homeostasis, the gut microbiota (GM) reportedly plays a key role in bone development. To date, the association between the GM and steroid deficiency-induced osteoporosis remains poorly understood. Forty female Sprague Dawley rats were divided into an ovariectomy (OVX) or control group. We performed 16S rRNA and metagenome sequencing, to compare diversity, taxonomic differences, and functional genes. The GM composition did not change in the control group and the number of operational taxonomic units increased significantly following ovariectomy. Alpha diversity, determined by ACE estimator, CHAO estimator, the Shannon index, and the Simpson index showed an increasing trend after ovariectomy. Samples in the OVX group were well clustered both pre- and post-ovariectomy, as demonstrated by principal coordinate 1 (PC1) and PC2. Functional genes of GM, including those involved in synthesis and metabolism of carbohydrates and nucleotides, microbial structure, and heme, as well as hemin uptake and utilization, increased at the early stage of osteoporosis. We observed that Ruminococcus flavefaciens exhibited the greatest variation in abundance among the GM and this was also associated with osteoclastic indicators and the estrobolome. Specific changes in fecal microbiota are associated with the pathogenesis of steroid deficiency-induced osteoporosis.

Prebiotic Effects of Partially Hydrolyzed Guar Gum on the Composition and Function of the Human Microbiota-Results from the PAGODA Trial.

(1) Background: Alterations in the structural composition of the human gut microbiota have been identified in various disease entities along with exciting mechanistic clues by reductionist gnotobiotic modeling. Improving health by beneficially modulating an altered microbiota is a promising treatment approach. Prebiotics, substrates selectively used by host microorganisms conferring a health benefit, are broadly used for dietary and clinical interventions. Herein, we sought to investigate the microbiota-modelling effects of the soluble fiber, partially hydrolyzed guar gum (PHGG). (2) Methods: We performed a 9 week clinical trial in 20 healthy volunteers that included three weeks of a lead-in period, followed by three weeks of an intervention phase, wherein study subjects received 5 g PHGG up to three times per day, and concluding with a three-week washout period. A stool diary was kept on a daily basis, and clinical data along with serum/plasma and stool samples were collected on a weekly basis. PHGG-induced alterations of the gut microbiota were studied by 16S metagenomics of the V1-V3 and V3-V4 regions. To gain functional insight, we further studied stool metabolites using nuclear magnetic resonance (NMR) spectroscopy. (3) Results: In healthy subjects, PHGG had significant effects on stool frequency and consistency. These effects were paralleled by changes in α- (species evenness) and ß-diversity (Bray-Curtis distances), along with increasing abundances of metabolites including butyrate, acetate and various amino acids. On a taxonomic level, PHGG intake was associated with a bloom in Ruminococcus, Fusicatenibacter, Faecalibacterium and Bacteroides and a reduction in Roseburia, Lachnospiracea and Blautia. The majority of effects disappeared after stopping the prebiotic and most effects tended to be more pronounced in male participants. (4) Conclusions: Herein, we describe novel aspects of the prebiotic PHGG on compositional and functional properties of the healthy human microbiota.

Gut enterotypes are stable during Bifidobacterium and Lactobacillus probiotic supplementation.

The human gut microbiome has been classified into three distinct enterotypes (Bacteroides, Prevotella, and Ruminococcus). The relationship between probiotics and gut enterotype is not yet clear. Cayenne pepper is effective in vitro as a prebiotic for Bifidobacteria and Lactobacilli, so cayenne ingestion with probiotics may lead to more profound gut microbial shifts. We aimed to determine whether probiotics (with or without cayenne pepper) alter gut bacterial community composition and if these changes are associated with the original gut enterotype of the individual. A total of 27 adult participants provided three fecal samples: prior to probiotic treatment (baseline), post probiotic treatment (probiotic), and post probiotic plus cayenne pepper treatment (probiotic + cayenne). DNA was extracted, amplified, and the V4 region sequenced on the Illumina MiSeq platform using V2 chemistry. Sequence reads were processed in mothur and assigned using the SILVA reference by phylotype. Three enterotypes characterized the study population-Bacteroides (B; n = 6), Prevotella (P; n = 11), and Ruminoccocus (R; n = 10). There was no significant increase in probiotic genera in fecal samples after treatment periods. Alpha diversity scores were significantly lower in B-type but not in P- or R-type individuals after probiotic treatment. For the majority of individuals, their enterotype remained constant regardless of probiotic (and cayenne) treatment. This suggests that baseline gut community characteristics and enterotype classification influence responsiveness to probiotic treatment, but that enterotype is stable across administration of prebiotic and probiotics. PRACTICAL APPLICATION: A person's gut microbial community influences their responsiveness to probiotics and prebiotic ingredients. Consumers must understand that it is difficult to shift their gut microbiota even with simultaneous administration of prebiotic and probiotic. Greater understanding of these phenomena will enable consumers to choose the most efficacious products for their needs.

Dysbiosis-Induced Secondary Bile Acid Deficiency Promotes Intestinal Inflammation.

Secondary bile acids (SBAs) are derived from primary bile acids (PBAs) in a process reliant on biosynthetic capabilities possessed by few microbes. To evaluate the role of BAs in intestinal inflammation, we performed metabolomic, microbiome, metagenomic, and transcriptomic profiling of stool from ileal pouches (surgically created resevoirs) in colectomy-treated patients with ulcerative colitis (UC) versus controls (familial adenomatous polyposis [FAP]). We show that relative to FAP, UC pouches have reduced levels of lithocholic acid and deoxycholic acid (normally the most abundant gut SBAs), genes required to convert PBAs to SBAs, and Ruminococcaceae (one of few taxa known to include SBA-producing bacteria). In three murine colitis models, SBA supplementation reduces intestinal inflammation. This anti-inflammatory effect is in part dependent on the TGR5 bile acid receptor. These data suggest that dysbiosis induces SBA deficiency in inflammatory-prone UC patients, which promotes a pro-inflammatory state within the intestine that may be treated by SBA restoration.

Ruminococcus gnavus bacteremia, an uncommon presentation of a common member of the human gut microbiota: case report and literature review.

Case report: We present a case of a 66-year-old female diagnosed with R. gnavus bacteremia associated with fecal peritonits secondary to small-bowel herniation and perforation. Identification  as R. gnavus was delayed because of absence of this species in the MALDI-TOF MS database (Vitek MS, bioMérieux). Identification was provided by 16S rRNA gene sequencing. Review: R. gnavus, a Gram-positive, strictly anaerobic bacterium, is a member of the human gut microbiota. Dysbiosis in the gut microbiota, with increased amounts of R. gnavus, has been described in inflammatory bowel disease. R. gnavus has only been reported occasionally as the cause of infections. Hence the potential pathogenicity is not yet fully recognized, and data regarding the antimicrobial susceptibility profile are rare. Identification of anaerobic bacteria such as R. gnavus is greatly accelerated  as a result of the introduction of MALDI-TOF MS. However, as illustrated in this case report, an extensive and up-to-date MALDI-TOF MS database is necessary for providing an accurate identification.

Gut microbiota in Mexican patients with common variable immunodeficiency

Introduction: Common variable immunodeficiency (CVID) is the main symptomatic primary immunodeficiency and is associated with complex immune disorders. Gut microbiota interacts closely with the immune system, and intestinal dysbiosis is related to multiple diseases. Objective: To describe for the first time the composition of gut microbiota in Mexican patients with CVID. Methods: Fecal samples from five patients with CVID were collected and massive sequencing of the V3-V4 region of 16S rRNA gene was carried out using illumina technology. Results: Bacterial relative abundance was observed at all taxonomic levels. Firmicutes, Actinobacteria and Verrucomicrobia were the predominant phyla. The Clostridia class and the Clostridial order were the most common in their respective taxon; the Ruminococcaceae family predominated. A total of 166 genera were reported, with the most abundant being Faecalibacterium. Five species were identified, but only Bifidobacterium longum was present in all patients. Conclusions: Unlike healthy subjects' gut microbiota, where Firmicutes and Bacteroidetes predominate, the microbiota of the patients with CVID considered in this study was abundant in Firmicutes, Actinobacteria and Verrucomicrobia. The low presence of Bacteroidetes and high abundance of Firmicutes might indicate the existence of intestinal dysbiosis in these patients.

Faecal microbiota shift during weaning transition in piglets and evaluation of AO blood types as shaping factor for the bacterial community profile.

The host-microbiota interplay is recognized as a key factor for the homeostatic maintenance in animals. In pigs, the weaning transition represents a drastic changes event leading to high risk of gut dysbiosis, which in most cases results in economic losses for swine industry. The blood type antigens expressed on mucosal surfaces can act as receptors for bacterial adhesion and the hypothesis of possible associations between blood groups and intestinal microbial profiles has been tested in human with contrasting results. Nevertheless, no studies testing the blood type as possible shaping factor for gut microbiota are available for pigs. The results of our previous study suggested the porcine AO blood types system as a possible factor influencing the microbiota composition. In the present study, the changes in fecal microbiota of 12 piglets were followed from 7 days after birth to 2 weeks post-weaning, testing the hypothesis that blood types may impact on its structure. No effects attributable to the difference in blood groups were detected, however, the sampling site (faeces) and the low statistical power might have masked the hypothesized impact. The data clearly showed the rearrangement of the bacterial ecosystem triggered by weaning transition; mainly consisting of a shift from a Bacteroidaceae-Enterobacteriaceae dominated community, to a Prevotellaceae-Ruminococcaceae dominated community. The functional analysis by metagenomic predictions suggested a role of the high levels of long-chain fatty acid in swine milk as energy source for Enterobacteriaceae (E. coli), in suckling piglets. This study provides a first insight for further investigations; indicating the need for larger sample size, preferably derived from intestinal mucosa, to test the potential effect of blood groups on gut microbiota profiles, and for analyses aimed at assessing the long-chain fatty acids degradation activity within the intestinal microbiota of suckling piglets, with particular attention to the role of E. coli.

In silico prediction reveals the existence of potential bioactive neuropeptides produced by the human gut microbiota.

This work reports on a large-scale potential neuropeptide activity screening in human gut microbiomes deposited in public databases. In our experimental approach, the sequences of the bioactive peptides collected in the MAHMI database, mainly predicted as immunomodulatory or antitumoral, were crossed with those of the neuroactive/digestive peptides. From 91,325,790 potential bioactive peptides, only 581 returned a match when crossed against the 5949 neuroactive peptides from the NeuroPep database and the 15 digestive hormones. Relevant bacterial taxa, such as Ruminococcus sp., Clostridium sp. were found among the main producers of the matching sequences, and many of the matches corresponded to adiponectin and the hormone produced by adipocites, which is involved in glucose homeostasis. These results show, for the first time, the presence of potentially bioactive peptides produced by gut microbiota members over the nervous cells, most notably, peptides with already predicted immunomodulatory or anti-inflammatory activity. Classical (Lactobacillus sp.) and next-generation (Faecalibacterium sp.) probiotics are shown to produce these peptides, which are proposed as a potential mechanism of action of psychobiotics. Our previous experimental results showed that many of these peptides were active when incubated with immune cells, such as dendritic cells, so their effect over the nervous system innervating the gut mucosa holds significant potential and should be explored.

Gut microbiota analysis and its significance in vasovagal syncope in children.

BACKGROUND: Vasovagal syncope (VVS) is common in children and greatly affect both physical and mental health. But the mechanisms have not been completely explained. This study was designed to analyze the gut microbiota in children with VVS and explore its clinical significance. METHODS: Fecal samples from 20 VVS children and 20 matched controls were collected, and the microbiota were analyzed by 16S rRNA gene sequencing. The diversity and microbiota compositions of the VVS cases and controls were compared with the independent sample t test or Mann-Whitney U test. The correlation between the predominant bacteria and clinical symptoms was analyzed using Pearson or Spearman correlation test. RESULTS: No significant differences in diversity were evident between VVS and controls (P > 0.05). At the family level, the relative abundance of Ruminococcaceae was significantly higher in VVS children than in controls (median [Q1, Q3]: 22.10% [16.89%, 27.36%] vs. 13.92% [10.31%, 20.18%], Z = -2.40, P < 0.05), and LEfSe analysis revealed Ruminococcaceae as a discriminative feature (linear discriminant analysis [LDA] score > 4, P < 0.05). The relative abundance of Ruminococcaceae in VVS patients was positively correlated with the frequency of syncope (r = 0.616, P < 0.01). In terms of its correlation with hemodynamics, we showed that relative abundance of Ruminococcaceae was negatively correlated with the systolic and diastolic pressure reduction at the positive response in head-up tilt test (HUTT; r = -0.489 and -0.448, all P < 0.05), but was positively correlated with the mean pressure drop and decline rate (r = 0.489 and 0.467, all P < 0.05) as well as diastolic pressure drop and decline rate at the HUTT positive response (r = 0.579 and 0.589, all P < 0.01) in VVS patients. CONCLUSION: Ruminococcaceae was the predominant gut bacteria and was associated with the clinical symptoms and hemodynamics of VVS, suggesting that gut microbiota might be involved in the development of VVS.

Gut microbiota in Mexican patients with common variable immunodeficiency.

INTRODUCTION: Common variable immunodeficiency (CVID) is the main symptomatic primary immunodeficiency and is associated with complex immune disorders. Gut microbiota interacts closely with the immune system, and intestinal dysbiosis is related to multiple diseases. OBJECTIVE: To describe for the first time the composition of gut microbiota in Mexican patients with CVID. METHODS: Fecal samples from five patients with CVID were collected and massive sequencing of the V3-V4 region of 16S rRNA gene was carried out using illumina technology. RESULTS: Bacterial relative abundance was observed at all taxonomic levels. Firmicutes, Actinobacteria and Verrucomicrobia were the predominant phyla. The Clostridia class and the Clostridial order were the most common in their respective taxon; the Ruminococcaceae family predominated. A total of 166 genera were reported, with the most abundant being Faecalibacterium. Five species were identified, but only Bifidobacterium longum was present in all patients. CONCLUSIONS: Unlike healthy subjects' gut microbiota, where Firmicutes and Bacteroidetes predominate, the microbiota of the patients with CVID considered in this study was abundant in Firmicutes, Actinobacteria and Verrucomicrobia. The low presence of Bacteroidetes and high abundance of Firmicutes might indicate the existence of intestinal dysbiosis in these patients.