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ABSTRACT 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 β1,4-galactosidase activities. There was a lack of detectable sulfatase and weak β1,3-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. IMPORTANCE An 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.

An anaerobic isolate, strain AT7T, was cultivated from a stool sample of a morbidly obese French woman using a microbial culturomics approach. The 16S rRNA gene sequence analysis showed that strain AT7T exhibited 96% nucleotide sequence similarity with Ruminococcus torques strain JCM 6553T (= ATCC 27756T = VPI B2-51T), currently the closest related species with a validly published name. The strain was observed to be a Gram-stain positive, non-motile, asporogenous and coccobacillary-shaped bacterium. It was found to be catalase positive and oxidase negative. Its major fatty acids were identified as C16:0 (54%) and C18:1n9 (30%). The draft genome of strain AT7T is 3,069,882 bp long with 42.4% G+C content. 2925 genes were predicted, including 2867 protein-coding genes and 58 RNAs. Based on phenotypic, biochemical, phylogenetic and genomic evidence, we propose the creation of the new genus Mediterraneibacter and species, Mediterraneibacter massiliensis, that contains strain AT7T (= CSUR P2086T = DSM 100837T), and the reclassification of Ruminococcus faecis, Ruminococcus lactaris, Ruminococcus torques, Ruminococcus gnavus, Clostridium glycyrrhizinilyticum as Mediterraneibacter faecis comb. nov., with type strain Eg2T (= KCTC 5757T = JCM15917T), Mediterraneibacter lactaris comb. nov., with type strain ATCC 29176T (= VPI X6-29T), Mediterraneibacter torques comb. nov., with type strain ATCC 27756T (= VPI B2-51T), Mediterraneibacter gnavus comb. nov., with type strain ATCC 29149T (= VPI C7-9T) and Mediterraneibacter glycyrrhizinilyticus comb. nov., with type strain ZM35T (= JCM 13368T = DSM 17593T), respectively.

Epidemiological studies have identified increased colorectal cancer (CRC) risk with high red meat (HRM) intakes, whereas dietary fibre intake appears to be protective. In the present study, we examined whether a HRM diet increased rectal O6-methyl-2-deoxyguanosine (O6MeG) adduct levels in healthy human subjects, and whether butyrylated high-amylose maize starch (HAMSB) was protective. A group of twenty-three individuals consumed 300 g/d of cooked red meat without (HRM diet) or with 40 g/d of HAMSB (HRM+HAMSB diet) over 4-week periods separated by a 4-week washout in a randomised cross-over design. Stool and rectal biopsy samples were collected for biochemical, microbial and immunohistochemical analyses at baseline and at the end of each 4-week intervention period. The HRM diet increased rectal O6MeG adducts relative to its baseline by 21 % (P< 0·01), whereas the addition of HAMSB to the HRM diet prevented this increase. Epithelial proliferation increased with both the HRM (P< 0·001) and HRM+HAMSB (P< 0·05) diets when compared with their respective baseline levels, but was lower following the HRM+HAMSB diet compared with the HRM diet (P< 0·05). Relative to its baseline, the HRM+HAMSB diet increased the excretion of SCFA by over 20 % (P< 0·05) and increased the absolute abundances of the Clostridium coccoides group (P< 0·05), the Clostridium leptum group (P< 0·05), Lactobacillus spp. (P< 0·01), Parabacteroides distasonis (P< 0·001) and Ruminococcus bromii (P< 0·05), but lowered Ruminococcus torques (P< 0·05) and the proportions of Ruminococcus gnavus, Ruminococcus torques and Escherichia coli (P< 0·01). HRM consumption could increase the risk of CRC through increased formation of colorectal epithelial O6MeG adducts. HAMSB consumption prevented red meat-induced adduct formation, which may be associated with increased stool SCFA levels and/or changes in the microbiota composition.

Prophylactic or therapeutic antibiotic use along with chemotherapy treatment potentially has a long-standing adverse effect on the resident gut microbiota. We have established a case-control cohort of 32 pediatric and adolescent acute lymphoblastic leukemia (ALL) patients and 25 healthy siblings (sibling controls) to assess the effect of chemotherapy as well as antibiotic prophylaxis on the gut microbiota. We observe that the microbiota diversity and richness of the ALL group is significantly lower than that of the control group at diagnosis and during chemotherapy. The microbiota diversity is even lower in antibiotics-exposed ALL patients. Although the gut microbial diversity tends to stabilize after 1-year post-chemotherapy, their abundances were altered because of chemotherapy and prophylactic antibiotic treatments. Specifically, the abundances of mucolytic gram-positive anaerobic bacteria, including Ruminococcus gnavus and Ruminococcus torques, tended to increase during the chemotherapy regimen and continued to be elevated 1 year beyond the initiation of chemotherapy. This dysbiosis may contribute to the development of gastrointestinal complications in ALL children following chemotherapy. These findings set the stage to further understand the role of the gut microbiome dynamics in ALL patients and their potential role in alleviating some of the adverse side effects of chemotherapy and antibiotics use in immunocompromised children.

Ruminococcus torques is an anaerobic, Gram-positive gut bacterium that has been associated with gastrointestinal diseases including irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). Its mucolytic effect disrupts the integrity of the intestinal barriers, which are involved in dysbiosis and pathogenicity. Recent clinical evidence has also reported its involvement in extraintestinal infections like pneumonia, keratitis, bacteremia and ocular infection in immunocompromised individuals. Although, R. torques has emerged as a clinically more significant pathogen, no vaccine is yet approved against it, highlighting the urgent need for novel prophylaxis strategies. The primary objective of this investigation was to employ bioinformatics and immunoinformatics strategies in the construction of a candidate multi-epitope vaccine. The complete proteome of Ruminococcus torques strain ATCC 27,756 was obtained and subjected to a series of analyses to find strong B- and T-cell epitopes with high antigenicity, non-allergenicity and non-toxicity. Key proteins such as cell division protein FtsX, single-stranded DNA binding protein and probable peptidoglycan glycosyltransferase FtsW were identified as the final target candidates. A multi-epitope vaccine was designed by linking the selected epitopes with the assistance of suitable spacers and adjuvant. The three-dimensional structure of the vaccine was modeled, refined and validated by in-silico approach. Furthermore, the protein-protein molecular docking was conducted to define probable binding poses on the multi-epitope vaccine against the Toll-like receptor (TLR4) protein. The stability of the vaccine-receptor complex was further validated by molecular dynamics simulation. In silico cloning of the vaccine construct yielded a GC content of 49.29% and a Codon Adaptation Index (CAI) of 0.875 indicating maximum expression potential in the host system. Although computational analyses provide valuable insights, experimental validation is required to confirm the immunogenicity and protective efficacy of the vaccine proposed.

Background Recent advances in microbiome-targeted therapies have uncovered immunomodulatory bacterial taxa with strain-specific therapeutic potential; however, the microbial signatures driving exclusive enteral nutrition (EEN) efficacy, particularly protective microbiota, and their mechanistic links to therapeutic outcomes remain uncharacterized in pediatric inflammatory bowel disease (IBD). Elucidating these microbial determinants and their functional pathways is critical for advancing targeted probiotic strategies in children. Methods A cohort of treatment-naïve pediatric Crohn's disease (CD) patients and age-matched healthy controls (HC) were enrolled. Fecal samples were collected from both HC and CD patients during active phase and remission following EEN therapy. Metagenomic sequencing, qPCR validation, and targeted bile acid (BA) analysis were conducted to identify candidate protective strains and potential impacts on BA homeostasis. Mechanistic investigations were conducted using dextran sulfate sodium (DSS)- and trinitrobenzene sulfonic acid (TNBS)-induced colitis model in male mice. Results The relative abundance of Ruminococcus torques ( R. torques ) demonstrated significant depletion in active CD cases ( p  = 0.02) compared to HC, which was restored after EEN treatment at remission status ( p  < 0.001). Its level was negatively correlated with the disease severity index (PCDAI r =-0.64; CDEIS r =-0.70) and positively correlated with the secondary to primary BA ratio ( r  = 0.27). In murine models, R. torques supplementation attenuated colitis severity through enhancing epithelial integrity (claudin-3, 3.3-fold; occludin, 7.5-fold), suppressing pro-inflammatory mediators (TNF-α, -44%; IL-6, -71%), regulating BA metabolism (secondary/unconjugated BAs, 29%) and autophagy pathway (LC3-II/LC3-I ratio, -1.8-fold). Conclusions Our findings demonstrated R. torques as a novel microbial therapeutic candidate for IBD management. The anti-colitis mechanisms involve the modulation of BA metabolic homeostasis, epithelial barrier reinforcement, and inflammation resolution.

This study investigated alterations in the gut microbiota signature and microbial metabolites in children with metabolic dysfunction-associated steatotic liver disease (MASLD). We found that an increased abundance of Ruminococcus torques was associated with increased levels of deoxycholic acid and the progression of MASLD, suggesting that R. torques may serve as a novel clinical target in pediatric MASLD.

Subsequent to the publication of the above article, it has been noticed that the designation of the type strain is not correct. The strain referred to throughout the article as strain AT7T should be designated as strain Marseille-P2086T (= CSUR P2086T = DSM 100837T). The corrected for protologue for the species Mediterraneibacter massiliensis, represented by strain Marseille-P2086T as type strain, is given below.

The bacterial species diversity of three colonic tissue samples from elderly people was investigated by sequence analysis of randomly cloned eubacterial 16S rDNA. The majority of sequences (87%) clustered within three bacterial groups: (1) Bacteroides; (2) low G+C content Gram-positives related to Clostridium coccoides (cluster XIVa); (3) Gram-positives related to Clostridium leptum (cluster IV). These groups have been shown to dominate the human faecal flora. Only 25% of sequences were closely related (> 97%) to current species type strains, and 28% were less than 97% related to any database entry. 19% of sequences were most closely related to recently isolated butyrate-producing bacteria belonging to clusters XIVa and IV, with a further 18% of the sequences most closely related to Ruminococcus obeum and Ruminococcus torques (members of cluster XIVa). These results provide the first molecular information on the microbial diversity present in human colonic samples.

Recently, several studies explored associations between type 1 diabetes (T1DM) and microbiota. The aim of our study was to assess the colonic microbiota structure according to the metabolic control in T1DM patients treated with insulin pumps. We studied 89 T1DM patients (50.6% women) at the median age of 25 (IQR, 22–29) years. Pielou’s evenness (p = 0.02), and Shannon’s (p = 0.04) and Simpson’s diversity indexes (p = 0.01), were higher in patients with glycosylated hemoglobin (HbA1c) ≥ 53 mmol/mol (7%). There were no differences in beta diversity between groups. A linear discriminant analysis effect size (LEfSe) algorithm showed that one family (Ruminococcaceae) was enriched in patients with HbA1c < 53 mmol/mol, whereas one family (Streptococcaceae) and four species (Ruminococcus torques, unclassified species of Lactococcus, Eubacteroim dolichum, and Coprobacillus cateniformis) were enriched in patients with HbA1c ≥ 53 mmol/mol. We found that at class level, the following pathways according to Kyoto Encyclopedia of Genes and Genomes were enriched in patients with HbA1c < 53 mmol/mol: bacterial motility proteins, secretion system, bacterial secretion system, ribosome biogenesis, translation proteins, and lipid biosynthesis, whereas in patients with HbA1c ≥ 53 mmol/mol, the galactose metabolism, oxidative phosphorylation, phosphotransferase system, fructose, and mannose metabolism were enriched. Observed differences in alpha diversity, metabolic pathways, and associations between bacteria and HbA1c in colonic flora need further investigation.