Colorectal cancer (CRC) is a digestive tract malignant tumor with a relatively high incidence and mortality rate worldwide. The occurrence and development of CRC are closely associated with disturbances in the gut microbiota. Paraclostridium tenue (synonym Eubacterium tenue) is generally considered a harmless commensal and can be isolated from fecal samples of healthy adults. However, whether this bacterium is a beneficial organism with an antitumor effect is unknown. This study systematically evaluated the anti-CRC effects of P. tenue strain Pt517 on CRC cells in vitro and in the CT26 syngeneic mouse model. Pt517 culture supernatant (Pt517CS) inhibited the proliferation, colony formation, and migration ability of CRC cells; induced cell apoptosis; and altered cell cycle distribution. Daily intragastric administration of Pt517 significantly inhibited tumor growth in mice; increased the expression levels of TNF-α, INF-γ, and CD8 in tumor tissues; and decreased the levels of IL-6, IL-10, and TGF-β. Pt517 intervention significantly modulated the gut microbiota composition with increased relative abundance of Parabacteroides goldsteinii, Lachnospiraceae, and Enterorhabdus caecimuris B7. The long-chain fatty acids (LCFAs), stearic acid and palmitic acid, were increased in the serum of treatment group mice and detected in Pt517CS. Functional verification indicated that stearic acid and palmitic acid directly inhibited the proliferation of CT26 cells in a dose-dependent manner, suggesting that Pt517 might exert its anti-CRC effect by secreting LCFAs. These findings indicate that P. tenue Pt517 is a potential new candidate for the microbial treatment of CRC, which warrants further validation for its safety and efficacy before clinical translation.

Background/Objectives: Eubacterium limosum El1405 is a novel probiotic candidate strain that has been shown to exert prominent anti-inflammatory and anti-tumor bioactivities, with potential antibacterial activity against pathogenic bacteria. This study aimed to systematically evaluate the safety of E. limosum El1405 and its probiotic functions and protective effects against pathogenic bacterial infection. Methods: The safety of E. limosum El1405 was assessed through in vitro assays of hemolytic and gelatinase activities and a 28-day subchronic oral toxicity mouse model. In the mouse model, three different doses (low, medium, and high) of E. limosum El1405 were tested, and physiological status, visceral histopathology, hematological profiles, serum biochemistry, and cytokines were measured. The antibacterial activity of the strain against pathogenic bacteria was determined in vitro. A Salmonella Typhimurium -infected mouse model was used to assess its potential to protect against infection. Results: In vitro safety assays confirmed that E. limosum El1405 possessed no hemolytic or gelatinase activity. In the 28-day subchronic oral toxicity test, low, medium, and high doses of El1405 caused no significant alterations in mouse body weight, visceral index, organ histopathology, hematological parameters, serum biochemistry, or cytokine levels. The strain exhibited antibacterial activity against S. Typhimurium in vitro. In S. Typhimurium-infected mice, El1405 intervention effectively mitigated S. Typhimurium-induced damage, reduced visceral bacterial loads, decreased pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) in the ileum and serum, and elevated the anti-inflammatory cytokine IL-10. Conclusions:E. limosum El1405 displays a favorable safety profile and promising probiotic effects, including antibacterial capacity and anti-inflammatory protective effects against S. Typhimurium infection, supporting further exploration and development of E. limosum El1405 as a novel functional probiotic strain for clinical and health applications.

Background: Metabolic-dysfunction-associated steatotic liver disease (MASLD) is the most prevalent chronic liver disorder globally. Probiotic supplementation has shown promise in its prevention and treatment. Although Weissella viridescens, a lactic acid bacterium with immunomodulatory effects, has antibacterial and anti-inflammatory activities, there is a lack of direct evidence for its role in alleviating MASLD. This study aimed to investigate the protective effects of W. viridescens strain Wv2365, isolated from healthy human feces, in a high-fat diet (HFD)-induced rat model of MASLD. Methods: Rats were randomly assigned to a normal chow diet (NC), high-fat diet (HFD), and HFD supplemented with W. viridescens Wv2365 (Wv2365) groups. All groups were fed their respective diets for 8 weeks. During this period, the NC and HFD groups received a daily oral gavage of PBS, while the Wv2365 group received a daily oral gavage of Wv2365. Results: Wv2365 supplementation significantly reduced HFD-induced body weight gain, improved NAFLD activity scores, alleviated hepatic injury, and restored lipid metabolism. A liver transcriptomic analysis revealed the downregulation of inflammation-related pathways, along with decreased serum levels of TNF-α, IL-1β, IL-6, MCP-1, and LPS. Wv2365 also activated the Nrf2/HO-1 antioxidant pathway, enhanced hepatic antioxidant enzyme activities and reduced malondialdehyde levels. A gut microbiota analysis showed the enrichment of beneficial genera, including Butyricicoccus, Akkermansia, and Blautia. Serum metabolomic profiling revealed increased levels of metabolites including indole-3-propionic acid, indoleacrylic acid, and glycolithocholic acid. Conclusions: Wv2365 attenuates hepatic injury, oxidative stress, and inflammation in a rat model of high-fat-diet-induced MASLD, supporting its potential as a probiotic candidate for the modulation of MASLD.

Gut microbiota play a key role in ameliorating colorectal cancer (CRC). Eubacterium limosum is a potential probiotic with anti-CRC functions. However, the mechanistic basis of its anti-CRC effect remains largely unknown. In vitro, we detected the effects of the E. limosum strain El1405 on cell proliferation, colony formation, cell cycle, and apoptosis of CRC cells, and found that El1405CS specifically suppressed cell proliferation by altering cell cycle distribution and inducing apoptosis. In the CT26 syngeneic mouse model, daily gavage with live El1405, inactivated El1405, culture supernatant of El1405, and El1405-derived indole derivatives, including indole-3-lactic acid (ILA), indole-3-acetic acid (IAA), L-arginine, and butyrate, inhibited tumor growth. Analysis of the 16S rRNA gene sequences revealed that El1405 altered the microbiota compositions within tumors, primarily reducing the abundance of Enterobacter, Pseudomonas, and Staphylococcus. Staphylococcus succinus isolated from the tumors of CT26 syngeneic mice promoted abdominal metastasis of tumors. Moreover, El1405 intervention significantly increased the levels of TNF-α, INF-γ, and CD8 in the tumor microenvironment, while decreasing the levels of CD4, IL-6, IL-10, and TGF-β. Metabolomic analysis indicated that El1405 induced antitumor effects through changing the serum metabolome of mice by producing indole derivatives such as ILA and IAA. Furthermore, 16S rRNA gene sequencing demonstrated that El1405 intervention changed the composition of intestinal flora, significantly increasing the abundance of Roseburia and Eubacterium while decreasing the abundance of Staphylococcus and Enterococcus. These findings suggest that E. limosum El1405 is a potential probiotic candidate for the prevention of CRC.

ABSTRACT The commensal bacterium Alistipes shahii is a core microbe of the human gut microbiome and its abundance is negatively correlated with inflammatory bowel diseases (IBDs). However, its fundamental role in regulating inflammatory response remains unknown. Using a dextran sulfate sodium (DSS)-induced colitis mouse model, we examined the effect of A. shahii strain As360 intervention on host inflammatory response and found that A. shahii As360 alleviated disease activity index, colon shortening, and colonic histopathological lesion. The levels of tight junction proteins (mainly ZO1 and claudin-1) were decreased in DSS-induced colitis mice, whereas the levels of these proteins were elevated in colitis mice with A. shahii As360 treatment. In addition, A. shahii As360 treatment led to alterations in cytokine release, especially an increase of IL10. It also led to reduced expressions of mtor and Nlrp3 and increased expression of mTOR inhibitor Ddit4 at the transcriptional level. 16S rRNA amplicon sequencing found that Bacteroides, a producer of short-chain fatty acids (SCFAs), was enriched in the fecal samples of mice with A. shahii treatment. Metabolic analyses found that, following A. shahii As360 treatment, the SCFAs in the fecal content was increased whereas lactic acid was decreased in the cecal content. These findings suggest that supplementation with A. shahii As360 is a promising strategy to prevent colitis.IMPORTANCEAs one of the core microbes and keystone species in the human gut, Alistipes shahii has the potential to inhibit inflammation and improve inflammatory bowel diseases (IBDs) conditions. In this study, we experimentally demonstrated that oral administration of A. shahii As360 alleviated symptoms of colitis, altered the release of cellular inflammatory factors, reduced the intestinal epithelial barrier damage, and changed gut microbiota and fecal metabolites. These findings provide a deeper understanding of the beneficial effects of A. shahii and its perspective for better strategies to prevent IBD.

IntroductionInflammatory bowel disease (IBD) is a chronic inflammatory condition of the intestine, for which no cure currently exists. The gut microbiota play a critical role in ameliorating IBD, and Eubacterium limosum has emerged as a potential probiotic with anti-inflammatory properties. However, the specific anti-inflammatory effects of E. limosum and the underlying mechanisms remain largely unexplored.MethodsThe E. limosum strain El1405 was utilized to evaluate its effects on dextran sodium sulfate (DSS)-induced murine colitis. The structural changes in intestinal microbiota were assessed using 16S rRNA gene sequencing. Inflammatory cytokines in the colon and serum were measured via enzyme-linked immunosorbent assay, while metabolomics was employed to analyze metabolites present in both the colon and serum.ResultsThe supplementation with E. limosum El1405 significantly reduced the disease activity index, colon shortening, and colonic histopathological lesions. El1405 reshaped the intestinal microbiota community structure, resulting in a significant increase in the abundance of Bacteroides acidifaciens, Bacteroides thetaiotaomicron, Mucispirillum schaedleri, Phocaeicola vulgatus (formerly Bacteroides vulgatus), and Akkermansia muciniphila, while concurrently decreasing the abundance of Escherichia coli and Enterococcus faecalis. The E. limosum intervention downregulated IL-17 signaling and reduced levels of inflammatory cytokines associated with IL-17 signaling, including IL-6, IL-17, TNF-α, IL-21, IL-22, and GM-CSF. E. limosum could induce anti-inflammatory effects by altering the serum metabolome of mice, especially producing anti-inflammatory metabolites such as indole-3-acetic acid and indole-3-lactic acid.DiscussionThis study demonstrated the beneficial effects of E. limosum El1405 on DSS-induced colitis in mice, by modulating gut microbiota, reducing inflammatory cytokines in the colon and serum, and increasing anti-inflammatory metabolites in the serum. All contribute to the downregulation of IL-17 signaling and the alleviation of colitis. E. limosum supplementation may represent a promising probiotic candidate for IBD prevention.

Inflammatory bowel disease (IBD) is a chronic condition with no cure. Probiotics may offer a new strategy for the treatment of IBD. Weissella confusa has been shown to have antibacterial, anti-inflammatory, and antioxidant beneficial effects in animal models. However, the anti-inflammatory effect of W. confusa at host cellular level and their effect on the gut microbiota are unclear. This study aimed to investigate the effects of W. confusa Wc1982 on inflammation and gut microbiota alterations in a dextran sulfate sodium (DSS) induced colitis mouse model. Female C57BL/6J mice were randomly divided into control, DSS, and Wc1982 groups (n = 6/group). The Wc1982 group was given continuous gavage of W. confusa Wc1982 for 14 days with the last 7 days also treated with 3% DSS. Disease phenotypes including daily body weight, disease activity index (DAI), colon length and histological changes were evaluated. The composition of colon flora, α-diversity and β-diversity were analyzed by 16S rRNA sequencing. The colonic gene expression profile was analyzed by RNA-seq, and serum and colonic proinflammatory cytokines were assessed by enzyme-linked immunosorbent assay. Analysis of variance (ANOVA) was used to analyze the differences among groups, and Spearman rank test was used to calculate the correlation between species relative abundance and pro-inflammatory markers. Compared with DSS group, W. confusa Wc1982 significantly improved the disease phenotypes of colitis mice including decreased DAI and pathological score and reduced colon shortening, decreased colonic IL-17, IL-6, and TNF-α levels and serum lipopolysaccharide (p < 0.05), and downregulated the expression of key genes of IL-17 pathway (Lcn2, Mmp3, Mmp13, Ptgs2; p < 0.05). W. confusa Wc1982 modified the gut microbiota community of colitis mice, with increased α-diversity, increased abundance of W. confusa and Akkermansia muciniphila, and decreased abundance of Enterococcus faecalis and Escherichia coli (all p < 0.05). Supplementation with W. confusa Wc1982 offers a promising strategy for alleviating colitis.

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a highly prevalent chronic liver condition linked to obesity and metabolic imbalance. Alterations in the gut microbiota are increasingly recognized as contributors to its progression. Alistipes putredinis, a core member of the human gut microbiota, has been linked with metabolic health, but its functional role in MASLD remains unclear. Methods: This study evaluated the potential of A. putredinis strain Ap77, isolated from the stool of a healthy adult, to mitigate MASLD-related alterations in a high-fat diet (HFD)-induced rat model. Animals were divided into normal chow (NC), HFD, and HFD plus Ap77 groups and received daily oral gavage of Ap77 or PBS for 8 weeks. Results: Ap77 supplementation attenuated the body weight increase associated with high-fat diet consumption. It also reduced hepatic triglyceride levels and fat mass and improved liver histology. Transcriptomic analysis revealed suppression of inflammation-associated pathways. Correspondingly, the concentrations of IL-1β, IL-6, and TNF-α in both the liver and serum were reduced. Ap77 supplementation was associated with an increased abundance of health-associated bacterial genera, such as Lachnospiraceae UCG_010, Akkermansia, and Flavonifractor, as well as elevated serum levels of butyrate, indole-3-propionic acid, and indoleacrylic acid. Notably, correlation analysis revealed that Lachnospiraceae UCG_010 was positively associated with these metabolites. Conclusions:A. putredinis Ap77 alleviates hepatic steatosis and inflammation in MASLD, potentially by reshaping gut microbiota and suppressing inflammation-related signaling pathways.

Background: Some lactobacilli strains have been documented to cause bacteremia and sepsis in immunocompromised or critically ill hospitalized patients, challenging the universally presumed safety of lactobacilli. Therefore, strain-specific risk assessments are required for the use of Lactobacillus as a probiotic. Lactobacillus xujianguonis, a novel Lactobacillus species isolated from Marmota himalayana, has probiotic potential but lacks safety data. Objective: To evaluate the preclinical safety of L. xujianguonis for food-grade use. Methods: Systematic safety assessment includes in vitro studies and oral toxicity studies. In vitro studies encompassed gastrointestinal tolerance, auto-aggregation and pathogen inhibition, antibiotic susceptibility, and hemolysis/gelatinase activity assays. Oral toxicity studies contained acute single-dose and repeated-dose 28-day oral toxicity studies in mice based on the OECD toxicity study guidelines. Results: L. xujianguonis strains HT111-2 and 06-2 demonstrated certain probiotic traits, including high acid/bile tolerance, strong auto-aggregation, and antimicrobial activity against common human gastrointestinal pathogens. In vitro safety assessments showed susceptibility to nine antibiotics and absence of hemolytic/gelatinase activity. Acute oral exposure (1 × 1011 CFU/kg) induced no mortality, clinical abnormalities, or organ toxicity. Subchronic 28-day administration (multiple doses) showed absence of adverse clinical signs with body weight stability and no hematological, biochemical, or histopathological deviations in C57BL/6 mice. Inflammatory and immunological markers remained unaffected. Histological staining results and transcriptional level validation revealed no evidence of intestinal tissue damage. Conclusions: This study provides preliminary evidence of the safety of L. xujianguonis, supporting its advancement to functional research.

Weissella viridescens has been proposed as a probiotic candidate, but strain-level multi-omics evidence remains limited. The complete genome of the human-derived W. viridescens strain Wv2365 was sequenced through a hybrid assembly of Illumina and PacBio sequencing reads and compared with eight publicly available W. viridescens genomes. Pangenome analysis and functional annotation were performed, and metabolites were profiled by broadly targeted metabolomic analysis. In addition, the acid and bile tolerance, auto-aggregation and cell surface hydrophobicity, and antioxidant activity of the strain, as well as both in silico and phenotypic safety, were assessed. Wv2365 carries a single chromosome of 1.57 Mb with 41.3% G+C content. The species has an open pangenome with 803 core genes. Genomic and metabolomic features converged on carbohydrate and amino acid metabolism, including glycolysis/tricarboxylic acid (TCA) cycle and arginine pathways, and a carbohydrate-active enzyme (CAZyme) repertoire dominated by glycosyltransferases. In vitro, Wv2365 tolerated pH 3.0 and 0.3% bile, showed auto-aggregation, surface hydrophobicity, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging. The strain was susceptible to 10 antibiotics tested except for its intrinsic vancomycin non-susceptibility and was non-hemolytic and gelatinase negative. No acquired antimicrobial resistance or virulence genes were found in the genome. These findings indicate that W. viridescens Wv2365 is safe with probiotic traits relevant to gastrointestinal survival, colonization, and redox balance.

Two Gram-stain-positive, oxidase-negative, non-motile, facultative anaerobic, α-hemolytic, coccus-shaped bacteria (zg-86T and zg-70) were isolated from the respiratory tracts of marmots (Marmota Himalayana) on the Qinghai-Tibet Plateau of China. Phylogenetic analysis of the 16S rRNA gene and 545 core genes revealed that these two strains belong to the Streptococcus genus. These strains were most closely related to Streptococcus respiraculi HTS25T, Streptococcus cuniculi CCUG 65085T, and Streptococcus marmotae HTS5T. The average nucleotide identity (ANI) and digital DNA‒DNA hybridization (dDDH) were below the threshold for species delineation. The predominant cellular fatty acids (CFAs) in this novel species were C16:0, C18:0, and C18:1ω9c, whereas the primary polar lipids were phosphatidylglycerol (PG), phosphatidylethanolamine (PE) and an unknown phosphoglycolipid (PGL). The optimal growth conditions for the strains were 37 °C, pH 7.0, and 0.5

Four anaerobic, Gram-stain-positive, non-motile, non-sporulating rod-shaped bacterial strains (R7T, R21, R22 and R25T) were isolated from the intestinal contents of plateau pika (Ochotona curzoniae) collected from the Qinghai-Tibet Plateau, PR China. The four isolates grew at between 25 and 42 °C (optimally at 35-37 °C), and with 0.3-3.3% NaCl (w/v) [optimum, 1.3% (w/v)]. Adding l-arginine to the medium could promote their growth. Strains R7T and R21 were most closely related to Adlercreutzia caecimuris B7T (97.48% 16S rRNA gene sequence similarity). Strains R25T and R22 were most closely related to Adlercreutzia equolifaciens DSM 19450T (98.25% 16S rRNA gene sequence similarity). The genome sequences of R7T and R25T were 2.89 and 2.90 Mb in size with 63.6 and 62.8 mol% DNA G+C contents, respectively. Phylogenetic analysis based on 16S rRNA gene sequences and core genes revealed that R7T and R21 were most closely related to A. caecimuris B7T and Adlercreutzia mucosicola DSM 19490T, whereas R25T and R22 were most closely related to A. equolifaciens DSM 19450T and Adlercreutzia rubneri ResAG-91T. R7T, R25T and the closely related species had average nucleotide identity (ANI) values of 81.9-83.2% as well as digital DNA-DNA hybridisation (dDDH) values between 27.3 and 27.9%, which clearly indicated that they represent two novel species within the genus Adlercreutzia. For R7T and R25T, meso-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan, and the whole cell sugars included galactose, glucose and ribose. On the basis of these results, we propose that strains R7T and R25T represent two novel species of the genus Adlercreutzia, namely Adlercreutzia wanghongyangiae sp. nov. and Adlercreutzia shanghongiae sp. nov., respectively. The type strains are R7T (=GDMCC 1.4459T=KCTC 25860T) and R25T (=GDMCC 1.4458T=KCTC 25861T).

ABSTRACT Prevotella copri is the dominant species of the Prevotella genus in the gut, which is genomically heterogeneous and difficult to isolate; hence, scarce research was carried out for this species. This study aimed to investigate the effect of P. copri on hyperglycemia. Thirty-nine strains were isolated from healthy individuals, and three strains (HF2123, HF1478, and HF2130) that had the highest glucose consumption were selected to evaluate the effects of P. copri supplementation on hyperglycemia. Microbiomics and non-target metabolomics were used to uncover the underlying mechanisms. Oral administration of P. copri in diabetic db/db mice increased the expression and secretion of glucagon-like peptide-1 (GLP-1), significantly improved hyperglycemia, insulin resistance, and lipid accumulation, and alleviated the pathological morphology in the pancreas, liver, and colon. P. copri changed the composition of the gut microbiota of diabetic db/db mice, which was characterized by increasing the ratio of Bacteroidetes to Firmicutes and increasing the relative abundance of genera Bacteroides , Akkermansia , and Faecalibacterium . After intervention with P. copri , fecal metabolic profiling showed that fumaric acid and homocysteine contents decreased, and glutamine contents increased. Furthermore, amino acid metabolism and cAMP/PKA signaling pathways were enriched. Our findings indicate that P. copri improved glucose metabolism abnormalities in diabetic db/db mice. Especially, one of the P. copri strains, HF2130, has shown superior performance in improving hyperglycemia, which may have the potential as a probiotic against hyperglycemia. IMPORTANCE As a core member of the human intestinal ecosystem, Prevotelal copri has been associated with glucose metabolic homeostasis in previous studies. However, these results have often been derived from metagenomic studies, and the experimental studies have been based solely on the type of strain DSM 18205 T . Therefore, more experimental evidence from additional isolates is needed to validate the results according to their high genomic heterogeneity. In this study, we isolated different branches of strains and demonstrated that P. copri could improve the metabolic profile of hyperglycemic mice by modulating microbial activity. This finding supports the causal contribution of P. copri in host glucose metabolism.

Two novel strain pairs (HM61T/HM23 T /HM23 and S- 34T/S- 58) T /S- 58) were isolated from soil and the faeces of Tibetan antelope ( Pantholops hodgsonii) ) collected at the Qinghai- Tibet Plateau of PR China. All four new isolates were aerobic, non- motile, Gram- stain- positive, catalase- positive, oxidase- negative, and short rod- shaped bacteria. The results of phylogenetic analysis based on the full- length 16S rRNA genes and 283 core genomic genes indicated that the four strains were separated into two independent branches belonging to the genus Nocardioides. . Strains HM61T T and HM23 were most closely related to Nocardioides pelophilus THG T63T T (98.58 and 98.65 % 16S rRNA gene sequence similarity). Strains S- 34T T and S- 58 were most closely related to Nocardioides okcheonensis MMS20-HV4-12T T (98.89 and 98.89 % 16S rRNA gene sequence similarity). The G+C contents of the genomic DNA of strains HM61T T and S- 34T T were 70.6 and 72.5 mol%, respectively. Strains HM61T, T , S-34T T and the type strains of closely related species in the analysis had average nucleotide identity values of 75.4-90.5 % as well as digital DNA-DNA hybridization values between 20.1 and 40.8 %, which clearly indicated that the four isolates represent two novel species within the genus Nocardioides. . The chemotaxonomic characteristics of strains HM61T T and S- 34T T were consistent with the genus Nocardioides. . The major fatty acids of all four strains were iso-C 16:0 , C 17: 1 omega 8 c or C 18:1 omega 9 c . For strains HM61T T and S- 34T, T , MK-8(H4) 4 ) was the predominant respiratory quinone, ll-2,6- diaminopimelic acid was the diagnostic diamino acid in the cell- wall peptidoglycan, and the polar lipids profiles were composed of diphosphatidylglycerol and phosphatidylglycerol. Based on phylogenetic, phenotypic, and chemotaxonomic data, we propose that strains HM61T T and S- 34T T represent two novel species of the genus Nocardioides, , respectively, with the names Nocardioides bizhenqiangii sp. nov. and Nocardioides renjunii sp. nov. The type strains are HM61T T (=GDMCC 4.343T=JCM T =JCM 36399T) T ) and S- 34T T (=CGMCC 4.7664T=JCM T =JCM 33792T). T ).

Objective:The purpose of this study was to investigate the bacterial communities of biting midges and ticks collected from three sites in the Poyang Lake area, namely, Qunlu Practice Base, Peach Blossom Garden, and Huangtong Animal Husbandry, and whether vectors carry any bacterial pathogens that may cause diseases to humans, to provide scientific basis for prospective pathogen discovery and disease prevention and control.Methods:Using a metataxonomics approach in concert with full-length 16S rRNA gene sequencing and operational phylogenetic unit (OPU) analysis, we characterized the species-level microbial community structure of two important vector species, biting midges and ticks, including 33 arthropod samples comprising 3,885 individuals, collected around Poyang Lake.Results:A total of 662 OPUs were classified in biting midges, including 195 known species and 373 potentially new species, and 618 OPUs were classified in ticks, including 217 known species and 326 potentially new species. Surprisingly, OPUs with potentially pathogenicity were detected in both arthropod vectors, with 66 known species of biting midges reported to carry potential pathogens, including Asaia lannensis and Rickettsia bellii, compared to 50 in ticks, such as Acinetobacter lwoffii and Staphylococcus sciuri. We found that Proteobacteria was the most dominant group in both midges and ticks. Furthermore, the outcomes demonstrated that the microbiota of midges and ticks tend to be governed by a few highly abundant bacteria. Pantoea sp7 was predominant in biting midges, while Coxiella sp1 was enriched in ticks. Meanwhile, Coxiella spp., which may be essential for the survival of Haemaphysalis longicornis Neumann, were detected in all tick samples. The identification of dominant species and pathogens of biting midges and ticks in this study serves to broaden our knowledge associated to microbes of arthropod vectors.Conclusion:Biting midges and ticks carry large numbers of known and potentially novel bacteria, and carry a wide range of potentially pathogenic bacteria, which may pose a risk of infection to humans and animals. The microbial communities of midges and ticks tend to be dominated by a few highly abundant bacteria.

Four Gram-stain-negative, oxidase-positive, non-motile, cocci-shaped bacteria strains (ZJ106T, ZJ104, ZJ785T and ZJ930) were isolated from marmot respiratory tracts. Phylogenetic analyses based on 16S rRNA genes, 53 ribosomal protein sequences and 441 core genes supported that all four strains belonged to the genus Neisseria with close relatives Neisseria weixii 10022T and Neisseria iguanae ATCC 51483T. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values were below the species-level thresholds (95-96 % for ANI, and 70 % for dDDH). The major fatty acids of all four strains were C16 : 1  ω7c /C16 : 1  ω6c, C16 : 0 and C18 : 1  ω9c. Major polar lipids were composed of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. MK-8 was the major menaquinone. Based on Virulence Factor Database analysis, the four strains were found to contain NspA and PorB H-factor binding proteins that promote evasion of host immunity. Strains ZJ106T and ZJ104 contained structures similar to the capsule synthesis manipulator of Neisseria meningitidis. Based on phenotypic and phylogenetic evidence, we propose that strains ZJ106T and ZJ785T represent two novel species of the genus Neisseria, respectively, with the names Neisseria lisongii sp. nov. and Neisseria yangbaofengii sp. nov. The type strains are ZJ106T (=GDMCC 1.3111T=JCM 35323T) and ZJ785T (=GDMCC 1.1998T=KCTC 82336T).

Six facultative anaerobic, Gram-stain-positive, oxidase-negative, rod-shaped bacteria (strains zg-B89T, zg-B12, zg-Y338T, zg-Y138, zg-Y908T and zg-Y766), were isolated from the intestinal contents of Marmota himalayana in Qinghai Province, PR China. The 16S rRNA gene sequence analysis showed that zg-B89T showed highest similarity to Cellulomonas iranensis NBRC 101100T (99.5 %), zg-Y338T to Cellulomonas cellasea DSM 20118T (98.7 %), and zg-Y908T to Cellulomonas flavigena DSM 20109T (99.0 %). Phylogenetic and phylogenomic analysis based on 16S rRNA gene and 881 core genes revealed that these six strains formed three separate clades in the genus Cellulomonas. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between these three novel species and all members of the genus Cellulomonas were below species thresholds (95-96 % for ANI and 70 % for dDDH). The DNA G+C contents of zg-B89T, zg-Y338T and zg-Y908T were 73.6, 72.9 and 74.5 %, respectively. Strains zg-B89T and zg-Y908T had anteiso-C15 : 0, C16 : 0 and anteiso-C15 : 1 A, and zg-Y338T had anteiso-C15 : 0, C16 : 0 and iso-C16 : 0 as the main fatty acids. All novel type strains had MK-9 (H4) as the predominant respiratory quinone, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside as the major polar lipids, and rhamnose, ribose and glucose as the cell-wall sugars. The peptidoglycan amino acids of zg-B89T, zg-Y338T and zg-Y908T contained ornithine, alanine, glutamic acid and aspartic acid (except for zg-Y338T). Based on genotypic, phenotypic, phylogenetic and biochemical properties, the six uncharacterized strains represent three novel species in the genus Cellulomonas, for which the names Cellulomonas xiejunii sp. nov. (type strain zg-B89T=GDMCC 1.2821T=KCTC 49756T), Cellulomonas chengniuliangii sp. nov. (type strain zg-Y338T=GDMCC 1.2829T=KCTC 49754T) and Cellulomonas wangsupingiae sp. nov. (type strain zg-Y908T=GDMCC 1.2820T=KCTC 49755T) are proposed, respectively.

Six Gram-stain-positive, facultative anaerobic, nonmotile and rod-shaped strains, designated zg-Y50T, zg-Y1362, zg-Y1379T, zg-Y869, zg-629T and zg-Y636, were isolated from the intestinal contents of Marmota himalayana in Qinghai Province, PR China. Strains zg-Y50T, zg-Y1379T and zg-629T exhibited the highest 16S rRNA gene sequence similarities of 99.2, 98.9 and 98.8 % to Aeromicrobium choanae 9 H-4T, Aeromicrobium ginsengisoli JCM 14732T and Aeromicrobium flavum TYLN1T, respectively. Phylogenetic and phylogenomic analyses based on the 16S rRNA gene and genomic sequences, respectively, revealed that the six strains formed three distinct clades within the genus Aeromicrobium. The genome sizes of strains zg-Y50T, zg-Y1379T and zg-629T were 3.1-3.7 Mb, with DNA G+C contents of 69.6-70.4 mol%. Average nucleotide identity and digital DNA-DNA hybridization values between each novel strain and available members of the genus Aeromicrobium were all below species thresholds. All novel strains contained MK-9 (H4) as the major menaquinone and diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol as the polar lipids. The predominant fatty acid of the six isolates was C18 : 1  ω9c. The cell-wall peptidoglycan contained ʟʟ-diaminopimelic acid as the diagnostic diamino acid. Based on the results from this polyphasic taxonomic study, three novel species in the genus Aeromicrobium are proposed, namely, Aeromicrobium duanguangcaii sp. nov. (zg-Y50T=GDMCC 1.2981T=KCTC 49764T), Aeromicrobium wangtongii sp. nov. (zg-Y1379T=GDMCC 1.2982T=KCTC 49765T) and Aeromicrobium senzhongii sp. nov. (zg-629T=CGMCC 1.17414T=JCM 33888T).

The great majority of microbial species remain uncultured, severely limiting their taxonomic characterization and biological understanding. The plateau pika ( Ochotona curzoniae ) is a small burrowing steppe lagomorph that is endemic to the Qinghai-Tibetan Plateau and is considered to be the keystone species in the maintenance of ecological stability.

As a core microbe of the human gut ecosystem, Bacteroides vulgatus has been linked to multiple aspects of metabolic disorders in a collection of associative studies, which, while indicative, warrants more direct experimental evidence to verify. In this study, we experimentally demonstrated that oral administration of B. vulgatus Bv46 ameliorated the serum lipid profile and systemic inflammation of high-fat diet-induced hyperlipidemic rats in a microbiome-regulated manner, which appears to be associated with changes of bile acid metabolism, short-chain fatty acid biosynthesis, and serum metabolomic profile. Hyperlipidemia is a risk factor and key indicator for cardiovascular diseases, and the gut microbiota is highly associated with hyperlipidemia. Bacteroides vulgatus is a prevalent mutualist across human populations and confers multiple health benefits such as immunoregulation, antiobesity, and coronary artery disease intervention. However, its role in antihyperlipidemia has not been systematically characterized. This study sought to identify the effect of B. vulgatus Bv46 on hyperlipidemia. Hyperlipidemic rats were modeled by feeding them a high-fat diet for 6 weeks. The effect of B. vulgatus Bv46 supplementation was evaluated by measuring anthropometric parameters, lipid and inflammation markers, and the liver pathology. Multi-omics was used to explore the underlying mechanisms. The ability of B. vulgatus Bv46 to produce bile salt hydrolase was confirmed by gene annotation and in vitro experiments. Oral administration of B. vulgatus Bv46 in hyperlipidemic rats significantly reduced the body weight gain, food efficiency, and liver index, improved the serum lipid profile, lowered the levels of serum inflammatory cytokines, promoted the loss of fecal bile acids (BAs), and extended the fecal pool of short-chain fatty acids (SCFAs), especially propionate and butyrate. B. vulgatus Bv46 induced compositional shifts of the gut microbial community of hyperlipidemic rats, characterized by a lower ratio of Firmicutes to Bacteroidetes with an increase of genera Bacteroides and Parabacteroides. After intervention, serum metabolite profiling exhibited an adaptation in amino acids and glycerophospholipid metabolism. Transcriptomics further detected altered biological processes, including primary bile acid biosynthesis and fatty acid metabolic process. Taken together, the findings suggest that B. vulgatus Bv46 could be a promising candidate for interventions against hyperlipidemia.IMPORTANCE As a core microbe of the human gut ecosystem, Bacteroides vulgatus has been linked to multiple aspects of metabolic disorders in a collection of associative studies, which, while indicative, warrants more direct experimental evidence to verify. In this study, we experimentally demonstrated that oral administration of B. vulgatus Bv46 ameliorated the serum lipid profile and systemic inflammation of high-fat diet-induced hyperlipidemic rats in a microbiome-regulated manner, which appears to be associated with changes of bile acid metabolism, short-chain fatty acid biosynthesis, and serum metabolomic profile. This finding supports the causal contribution of B. vulgatus in host metabolism and helps to form the basis of novel therapies for the treatment of hyperlipidemia.