Microbiome最新文献

Background: Bacterial antiphage defense systems play essential roles in microbial ecology, yet their dynamics within urban wastewater systems (UWS) remain poorly characterized.

Results: In this study, we performed comprehensive metagenomic and plasmidome analyses on 78 wastewater samples collected during two seasons and four sampling points across UWS from three European countries. We observed a significant reduction in the abundance, diversity, and mobility potential of defense systems during biological treatment. However, these reductions were not directly correlated with changes in microbial abundance. Defense systems were significantly enriched on plasmids, particularly conjugative plasmids, where their gene density was approximately twice as high as on chromosomes and remained relatively stable across compartments. In contrast to chromosomal defense systems, plasmid-borne systems exhibited more frequent co-localization with a wide range of mobile genetic elements (MGEs)-associated genes, thereby facilitating multilayered dissemination networks. Furthermore, we detected a strong correlation between phage abundance and host defense system profiles, indicating ongoing phage-host co-evolutionary dynamics in these environments.

Conclusions: In summary, our results demonstrate that UWS reduce the abundance and diversity of bacterial defense system genes. However, plasmid-associated defense systems can persist through shared mobile genetic reservoirs. These findings underscore the critical role of plasmids in bacterial immunity and provide new insights into defense system dynamics within urban wastewater environments.

Background: Bovine metritis is associated with uterine microbiota dysbiosis, characterized by the proliferation of Gram-negative anaerobes, including Fusobacterium necrophorum, Bacteroides pyogenes, and Porphyromonas levii. However, the mechanisms by which these opportunistic pathogens proliferate together and contribute to disease remain unclear. This study aimed to identify the interactions among these bacteria and to elucidate their role in the development of metritis.

Methods: F. necrophorum, B. pyogenes, and P. levii were isolated from the uteri of cows with metritis and cultured anaerobically in chopped meat carbohydrate broth. Bacterial growth, coaggregation, biofilm formation, endotoxin production, protease activity, adhesion to bovine endometrial epithelial (BEND) cells, and cytotoxicity were evaluated under single-, dual-, and triple-species culture conditions.

Results: Among the three species, F. necrophorum grew faster and acted as a key species that coaggregated with B. pyogenes and P. levii, promoting multi-species biofilm formation and increasing bacterial adhesion to BEND cells. The growth of B. pyogenes was enhanced by metabolites from P. levii, whereas the growth of P. levii was delayed by metabolites from F. necrophorum. The multi-species biofilm formed by these three bacterial species generated the highest biomass, with P. levii predominantly occupying the basal layer and F. necrophorum and B. pyogenes co-localizing in the upper layer. This spatial arrangement likely reflects the strong biofilm-forming ability of P. levii, which rapidly produces matrix and provides a scaffold for cohabiting species. Endotoxin levels were highest in both F. necrophorum and P. levii, and protease activity was highest in P. levii under mono-culture conditions. However, no synergistic effects were observed for either parameter under co-culture conditions. Interestingly, co-culture with B. pyogenes lowered the endotoxin levels of the other bacteria and attenuated the cytotoxicity of P. levii.

Conclusions: Our findings suggest that these opportunistic uterine pathogens interact synergistically to promote bacterial persistence in the uterus rather than exacerbating disease severity, which likely contributes to uterine microbiota dysbiosis and chronic inflammation. Video Abstract.

Background: Over the past decade, emerging evidence has shed light on the role of the gut microbiota in the interface between diet and brain health. Olive oil, particularly virgin olive oil, a key component and major fat source in the Mediterranean diet, has exhibited widespread healthful benefits, including improvements in gut microbiota and cognitive health. Despite insights from preclinical studies into the relationship between virgin olive oil consumption, gut microbiota, and cognitive function, human research in this area remains limited. Therefore, our study aims to investigate the interplay between total olive oil consumption and its subtypes, gut microbiota, and changes in cognitive function in older adults who were cognitively healthy at baseline but at high risk of cognitive decline.

Methods: In this prospective cohort study, we assessed a total of 656 participants aged 55 to 75y (mean age 65.0 ± 4.9y, 47.9% women) with overweight/obesity and metabolic syndrome who provided stool samples and completed a validated semi-quantitative food frequency questionnaire at baseline and a comprehensive battery of neuropsychological tests at baseline and at a 2-y follow-up.

Results: Results from the multivariable linear regression models showed that higher consumption of virgin olive oil was associated with improved cognitive function over a 2-y follow-up, and a more diverse gut microbiota overall structure at baseline. Conversely, increased consumption of common olive oil is linked to lower alpha diversity of the microbial communities, and accelerated cognitive decline. Mediation analysis suggests that gut microbiota and particularly the Adlercreutzia, may serve as a mediator taxon in the association between virgin olive oil consumption and positive changes in general cognitive function.

Conclusions: Higher consumption of virgin olive oil was associated with cognitive preservation, possibly mediated by favorable alterations in gut microbiota composition. Our study provides novel insights into the complex interplay between different types of olive oil consumption, gut microbiota, and changes in cognitive function. These findings underscore the potential of microbiota-targeted dietary strategies to promote cognitive health in aging populations, though further high-quality and clinical cohort studies are required. Video Abstract.

Background: Urban wastewater systems (UWSs) act as reservoirs and conduits for the dissemination of antibiotic resistance genes (ARGs), with plasmids playing a central role in their spread. Despite their significance, the diversity and persistence of plasmids in UWSs remain underexplored.

Results: This study applies a multi-omics approach, including metagenomic and direct plasmidome sequencing, high-throughput qPCR array, and whole genome sequencing of plasmid isolates, to comprehensively profile the microbial plasmidome and resistome on 78 samples across UWSs in Denmark, Spain, and the UK. We successfully uncovered an extensive plasmid and ARG diversity that could not be fully captured by a single method, especially identified 78,574 plasmids, including 20,925 plasmids previously unreported. We also observed that plasmids carried a disproportionate share of clinically relevant ARGs, particularly beta-lactamase resistance genes; most importantly, they were preferentially located on transmissible plasmids. Furtherly, plasmids harbor ARG can enhance their persistence in wastewater ecosystems, especially harboring multiple types of ARGs. Moreover, Bacteroides emerged as a unique persistent ARG reservoir not only for harboring and disseminating diverse resistance genes especially in residential-relevant areas, but also emerged as a major driver of antimicrobial resistance dynamics across different wastewater treatment processes.

Conclusions: Overall, this work provides the first attempt at a holistic description of the UWSs' resistome, its structure, dynamics, and mobility and significantly expands the current knowledge. Video Abstract.

Background: Slaughterhouses and meat cutting plants represent potential hotspots for the spread and transfer of spoilage and pathogenic, including antimicrobial resistant, bacteria to meat and meat products. Here, we characterise the progression of the microbiome and resistome of two pork cuts (loin and sirloin) at different stages of processing, from the slaughter line to the end of shelf-life. To this end, we analysed samples from facility surfaces, carcasses, and meat cuts using whole metagenome sequencing.

Results: The taxonomic and antimicrobial resistance gene (ARG) profiles of carcasses and meat cuts were significantly influenced by the point of sampling and the processing room. The facility surfaces were found to be the main source of some abundant genera, such as Anoxybacillus, Acinetobacter, Pseudomonas, and Brochothrix, in carcasses and meat cuts. A total of 1,291 metagenome-assembled genomes were reconstructed, corresponding to the most prevalent species identified in the taxonomic analysis at the read level. A reduction in bacterial and ARGs richness and diversity was observed for carcasses and meat cuts along the production chain, which suggests that processing procedures are effective in reducing bacterial and ARGs loads. Nonetheless, an increase in the ARGs load was observed at two sampling points: the carcass after evisceration and the sirloin at the end of its shelf-life (in this case linked to the increase of a single gene, tet(L)). The ARGs most frequently detected were those associated with resistance to tetracyclines, aminoglycosides, and lincosamides. Acinetobacter (in processing environments and carcass/meat samples) and Staphylococcus (in carcasses and meat) were identified as the main genera associated with the ARGs found.

Conclusions: Overall, our results provide the most detailed metagenomics-based perspective on the microbial successions of pig carcasses and fresh meat cuts during slaughtering, processing, and commercialisation. The observations made suggest that selection pressures imposed by processing steps and contact with facility surfaces contribute to shaping the microbiome and resistome of the two pork products throughout their production line and shelf-life. Video Abstract.

Background: Phytate is the primary phosphorus storage molecule of plants and plays a major role in animal nutrition. To enhance phosphate availability and absorption in livestock, and to reduce eutrophication by liquid manure, bacterial phytases are often added to animal feed. The dephosphorylated form of phytate, the polyol myo-inositol (myo-Ins) with multiple functions in eukaryotes, is metabolized by approximately 30% of all bacterial species.

Results: Here, we employed a culturomics approach to identify possible metabolic interactions between phytase-producing and myo-Ins degrading bacteria in intestinal samples from pigs. Selective cultivation revealed an unexpectedly high abundance of myo-Ins degrading bacteria, suggesting substantial phytate dephosphorylation in the pig gut. Phytase activity assays performed on gut isolates showed a high degree of variability, suggesting the presence of a diverse set of phytases yet to be characterized. Furthermore, using supernatants of phytase-positive gut strains cultivated in the presence of phytate, we observed cross-feeding of myo-Ins from phytase producers to phytase-negative strains, including the pathogen Salmonella enterica serovar Typhimurium.

Conclusions: The data demonstrate that a wide range of commensal bacteria can potentially benefit from phytase activity by utilizing myo-Ins, released through phytate hydrolysis, as a growth substrate. Video Abstract.

Background: The gut microbiota plays an essential role in mucosal immunity, with secretory immunoglobulin A (IgA) acting as a key effector in neutralizing pathogens and maintaining host-microbiota homeostasis. IgA production occurs via T cell-dependent (TD) and -independent pathways, with T follicular helper (Tfh) cells driving high-affinity, antigen-specific IgA responses. However, the specific microbial taxa and metabolites that regulate Tfh-mediated IgA responses under steady-state conditions remain poorly understood. This study investigated how gut microbiota-derived signals shape Tfh responses and IgA production, with implications for enhancing mucosal vaccine efficacy.

Results: We demonstrate that Peyer's patches (PP)-derived Tfh cells exhibit superior IgA-inducing capacity compared to splenic Tfh cells. RNA sequencing revealed distinct transcriptional profiles in PP-Tfh cells, including upregulation of the genes associated with Tfh differentiation and activation (Bcl6, Cd40lg, Maf), T-B cell interactions (Il21, Sh2d1a, Fyn), and migration (Ccr6, Cxcr5). Functionally, PP-Tfh cells formed larger T-B cell contact areas and induced significantly higher IgA secretion in co-culture than their splenic counterparts. Microbiota depletion experiments revealed that eliminating neomycin-depleted bacteria reduced fecal IgA levels and diminished PP-Tfh cell frequencies. Fecal microbiota transplantation from neomycin-treated mice restored both IgA production and Tfh responses in germ-free (GF) mice. Bioinformatic analysis (PICRUSt2 and LEfSe) identified butyrate-producing Lachnospiraceae and Ruminococcaceae as key drivers of the Tfh-IgA axis. Butyrate supplementation enhanced Tfh differentiation and IgA⁺ germinal center B cell development in vitro and increased fecal IgA levels in vivo. Mechanistically, butyrate promoted IgA production via GPR43 signaling, as its effect was lost in co-cultures with Gpr43^⁻/⁻ Tfh cells. Moreover, treatment with tributyrin, a butyrate prodrug, enhanced vaccine-induced IgA and protected mice against Salmonella Typhimurium infection, reducing bacterial burden and tissue damage. These findings define a functional microbiota-Tfh-IgA axis sustained by neomycin-depleted, butyrate-producing bacteria.

Conclusions: Our study underscores the crucial role of the gut microbiota, particularly neomycin-depleted butyrate producing taxa, in regulating PP-Tfh cell function and IgA production. Butyrate emerges as a metabolite linking microbial metabolism to Tfh differentiation and IgA class switching. Together, these findings establish a microbiota-metabolite-Tfh cell axis essential for mucosal immune homeostasis and suggest novel strategies for enhancing vaccine efficacy and protection against enteric infections. Video Abstract.

Background: Aerobiome diversity is extensive; however, species-level community structure remains poorly resolved. Likewise, microbiomes of public transit systems are of public interest due to their importance for health, though few studies have focused on these ecosystems whilst utilising shotgun metagenomics. Aerosol studies have focused predominantly on individual cities, with limited between-city comparisons suggesting specific community structures. Longitudinal studies show aerobiome diversity as dynamic, fluctuating during seasonal and daily cycles, though interannual cycles remains to be considered. Further, a bacterial bias has limited fungal aerobiome studies, with few considering both fractions collectively. As such, the objective of this study was to examine spatial and temporal patterns in the species diversity of public transit aerobiomes, with an emphasis on bacteria and fungi.

Results: Air samples taken over a 3-year period (2017-2019) from six global cities were subjected to shotgun metagenomic sequencing. Improved classification databases, notably for fungi, applying stringent parameters for trimming, exogenous contamination removal and classification yielded high species-level resolution. Microbial diversity varied substantially among cities, while human and environmental factors, recorded in parallel, were of secondary significance. Bacteria dominated the public transit aerobiome with increased presence in cities with higher population densities. All aerobiomes had complex compositions, consisting of hundreds to thousands of species. Interannual variation had limited significance on the public transit aerobiome diversity and community structure.

Conclusions: Cities were the most important factor contributing to diversity and community structure, demonstrating specific bacterial and fungal signatures. Further, possible correlation between geographical distance and genetic signatures of aerobiomes is suggested. Bacteria are the most abundant constituent of public transit aerobiomes, though no single species is globally dominant, conversely indicating a large inter-city variation in community structure. The presence of a ubiquitous global species core is rejected, though an aerobiome sub-core is confirmed. For the first time, local public transit aerobiome cores are presented for each city and related to ecological niches. Further, the importance of a robust bioinformatics analysis pipeline to identify and remove exogenous contaminants for studying low-biomass samples is highlighted. Lastly, a core and sub-core definition of contaminant aerobiome species with taxon tables, to facilitate future environmental studies, is presented. Video Abstract.

Background: The canine microbiome is a vastly understudied area relative to the importance of dogs in society, particularly given the potential importance of the microbiome in veterinary medicine. This has led to a large knowledge gap in the basic taxonomy and functions of the canine gut microbiome and an overreliance on human databases for canine-specific research. Using a broad sample set, long read sequencing, short read sequencing, and metagenomic assembly approaches, we have produced the most comprehensive microbiome resource in all companion animal research.

Results: Here, we describe the recovery of 240 core species that account for > 80% of the canine gut microbiome when tested on an independent validation dataset. We uncovered > 900 new canine-specific strains, 89 novel species, and 10 novel genera, providing a dramatic increase in previous knowledge of the canine microbiome and allowing for mapping rates of up to 95%, a 70% increase on historic mapping rates of ~ 25% using publicly available resources. Through detailed annotation of function, we demonstrate the potential importance of the novel species and genera to health and nutrition and provide evidence of new canine-adapted strains of existing genera and species previously unknown to inhabit canines that provide important metabolic function to the canine host. We discovered the canine microbiome has an expansive ability to metabolize carbohydrates, providing insight into how canines process diverse carbohydrates given their known limited host genomic potential. We uncovered a range of species with abilities to produce butyrate, propionate, and vitamins, highlighting the importance of the canine microbiome to host nutrition. We describe two novel Peptacetobacter species that could regulate host bile acid metabolism, an important finding in the context of chronic GI disease in pets. We demonstrated all new species and genera had no known virulence, suggesting they are commensal and, finally, provided a baseline for antimicrobial resistance in the microbiota species of healthy pets.

Conclusions: This work gives entirely new perspectives on the functional capabilities of the canine gut microbiome, suggesting the canine microbiome is distinct, presumably having evolved to its host, diet, and environment over several millennia. Video Abstract.

Background: The nasal microbiome, a dynamic assemblage of commensals and opportunistic pathogens, is crucial to human health.

Results: Using cross-sectional data from 1,608 adults and longitudinal sampling of 149 individuals over 8-22 months, we identified nine nasal community state types (CSTs), defined by bacterial density and indicator taxa, with varying stability and transition patterns. Core taxa such as Staphylococcus epidermidis and Cutibacterium acnes were highly stable, while opportunistic pathogens like Staphylococcus aureus and Moraxella catarrhalis had shorter residence times. Interactions between Dolosigranulum pigrum and Corynebacterium pseudodiphtheriticum/propinquum were linked to reduced S. aureus colonization. Host factors, including age and biological sex, significantly shaped microbiome dynamics: men exhibited higher bacterial densities and pathogen colonization, while women showed more stable commensal-dominated CSTs. Aging was associated with shifts in CST frequencies, with declining S. aureus and increasing Enterobacterales.

Conclusions: These findings reveal potential strategies by modulating nasal microbiome dynamics to reduce pathogen colonization and improve health. Video Abstract.