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Microbiomes play a pivotal role in sustaining plant function and broader ecosystem processes. Leguminous plants host vast populations of intracellular bacteria within specialized root organs known as nodules. The intricate mutualism between legumes and rhizobia ensures a stable supply of biologically fixed nitrogen (N) essential for plant growth. While rhizobia remain the central actors in this symbiosis, recent discoveries reveal the presence of non-rhizobial endophytes within nodules, suggesting a complex interplay shaped by host selection and compatibility with rhizobial partners. Understanding the structure and dynamics of crop nodule-associated microbial communities is thus critical for optimizing host responses to rhizobia and for leveraging beneficial plant–microbe interactions. This review explores the dualistic nature—both facilitative and inhibitory—of the nodule microbiome in relation to nodulation. We examine the diversity of soil bacteria that stimulate nodulation and those that ultimately colonize nodule tissues, questioning whether these functional groups overlap. Furthermore, we discuss the molecular dialogs and counter-signaling mechanisms that regulate endophyte ingress into nodules, and evaluate how nodule endophytes contribute to plant performance and soil fertility. Full article

In nature, a significant number of plant species form symbiotic associations with microorganisms, with arbuscular mycorrhizal fungi (AMF) and endophytic fungi being two prevalent groups of these partners. However, the ability to establish such symbioses with AMF and endophytic fungi is limited to a small fraction of native grass species. Nitrogen is a crucial nutrient for plant growth, yet it is often a limiting factor, underscoring the importance of understanding how plants acquire it. AMF enhance plant growth by improving nitrogen uptake efficiency, but the combined effects of endophytic fungi and AMF on plant physiology and ecology remain underexplored. To address this knowledge gap, in the present study, we conducted an indoor randomized block experiment to investigate the influence of endophytic fungi and AMF infection on the physiological and ecological attributes of Festuca rubra under various nitrogen regimes. The findings indicated that AMF inoculation significantly affected the total carbon content of F. rubra and the total sulfur concentration in its underground tissues across different nitrogen conditions. Additionally, dual colonization by AMF and endophytic fungi had a significant impact on the underground total nitrogen content of the plants. Furthermore, the complex interactions among AMF, endophytic fungi, and nitrogen availability emerged as critical determinants influencing underground total carbon content, transpiration rates, intercellular carbon dioxide concentrations, and the activity of soil extracellular enzymes in F. rubra. The activity of soil extracellular enzymes and pH significantly affected the structure and diversity of rhizosphere bacterial, fungal, and archaeal communities. AMF enhanced the richness of rhizosphere bacterial communities under low-nitrogen conditions, whereas endophytic fungi infection increased bacterial diversity. Soil extracellular enzyme activity and pH were closely related to the community structures and diversities of rhizosphere bacteria, fungi, and archaea. This study clarifies the effects of AMF and endophytic fungi infection on the physiological and ecological characteristics of F. rubra, significantly contributing to our understanding of the synergistic mechanisms governing the interactions among AMF, endophytic fungi, and their host plants. Full article

Segmented filamentous bacteria (SFB) are host-specific, immune-modulating microorganisms that colonize the small intestine of various vertebrate species, playing a crucial role in stimulating immune maturation during early life. Previous research on the genomes of SFB from humans, rats, and mice has revealed significant differences among SFB strains associated with various hosts, suggesting that their evolution is closely linked to their relationships with specific hosts. However, the genome of SFB from chickens has not been extensively investigated. In this study, we present the metagenomic reconstruction of an SFB genome derived from the ileum of layer Lohmann Select Leghorn (LSL) chickens. We utilized Hi-C sequencing techniques to assemble the LSL-SFB and annotate the avian SFB from both turkeys and chickens. Our reference-guided consensus assembly, followed by Hi-C scaffolding, produced a high-quality genome for LSL-SFB. Our pangenomic analysis revealed substantial conservation of core gene clusters among mammalian SFB strains, but we also identified a distinct repertoire of genes in chicken and turkey SFB. Furthermore, metabolic network analysis indicated a reduced capacity for biosynthesis, signifying an increased reliance on the host, as shown by the absence of key biosynthetic and utilization pathways. We also discovered a unique flagellin subunit (fliC-2) in chicken SFB from different genetic lines and confirmed its interaction with the chicken flagellin receptor, Toll-like receptor five. This study provides the first high-quality genome and annotation of LSL-SFB, alongside that of turkeys, offering valuable insights into the mechanisms of host specificity and adaptation. Understanding the interactions between host-specific SFB and their hosts, as well as their role in promoting immune maturation, is essential for improving intestinal health. Full article

Invasive pulmonary fungal infections remain a major cause of morbidity and mortality among immunocompromised and critically ill patients. Rapid and accurate diagnosis is crucial for improving outcomes, yet conventional methods such as culture and histopathology suffer from limited sensitivity and slow turnaround times. Recently, significant progress has been made in the development and standardization of serological and molecular biomarkers that enhance the early detection of the key pulmonary fungal diseases, particularly invasive pulmonary aspergillosis and pneumocystosis. Diagnostic tools for mucormycosis, however, remain scarce. PCR tools have strong potential to significantly improve early detection, but they are not yet widely implemented, and standardized commercial assays remain limited. Accessible antigen-based tests with robust performance are highly anticipated and expected to become available soon. This review summarizes the current evidence regarding the optimal use of galactomannan, β-D-glucan and PCR-based assays, emphasizing how their performance varies according to the pathogen, the type of specimen and the host population. Specific challenges, such as differentiating colonization from infection in non-HIV Pneumocystis pneumonia or interpreting galactomannan and PCR in patients receiving mold-active prophylaxis, are highlighted. We also discuss how combining biomarkers can enhance diagnostic accuracy and support timely therapeutic decisions. A clear understanding of the strengths, limitations and appropriate interpretation of these diagnostic tools is crucial in an era of increasing host complexity, shifting fungal epidemiology, and expanding antifungal options. Full article

Soil-borne oomycetes, such as Phytophthora and Pythium species, are highly destructive pathogens responsible for severe diseases in crops, ornamentals, and natural ecosystems. These pathogens can persist in soil for many years, making them particularly difficult to control. To establish infection, they deploy a diverse arsenal of effector proteins that manipulate host immune responses, disrupt vital cellular functions, and may influence the rhizosphere microbiome to facilitate successful colonization. Phytophthora relies heavily on RxLR effectors to disrupt intracellular immunity, while Pythium species predominantly deploy necrosis-inducing NLPs and cell wall-degrading enzymes, with no confirmed canonical RxLR effectors, suggesting distinct evolutionary strategies. This review aims to explore the detailed mechanisms of plant-pathogen interaction. In recent years, significant progress has been made in understanding the molecular dialogue between pathogens and their hosts, particularly how pathogenic species such as Phytophthora and Pythium manipulate plant immunity through effector secretion, and how plants counteract by activating defense mechanisms at molecular, cellular, and biochemical levels, including changes in hormone signaling, reactive oxygen species (ROS) dynamics, and defense gene expression. The review also outlines emerging disease management strategies and integrative approaches guided by effector biology and microbiome insights. Full article

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by barrier dysfunction and susceptibility to Staphylococcus aureus colonization. Biofilm formation modifies antibiotic resistance and the host immune response. This longitudinal study analyzed antimicrobial susceptibility and biofilm formation in 136 S. aureus isolates obtained over 18 months from lesional, nonlesional, and nasal samples of 26 pediatric patients with moderate-to-severe AD. Antimicrobial susceptibility testing was determined by the disk diffusion method, and biofilm production was quantified using a crystal violet microtiter assay. Clinical parameters, including disease severity, treatment response, and the administration of dilute bleach baths, were evaluated in relation to bacterial characteristics. Overall, 60.2% of isolates exhibited moderate-to-strong biofilm production, significantly associated with severe AD at baseline (p = 0.01), lack of clinical improvement (p = 0.04), and persistent moderate-to-severe disease (p = 0.01). Resistance rates for penicillin, gentamicin, clindamycin, and erythromycin exceeded 15%. Isolates from patients using dilute bleach baths showed greater resistance to ciprofloxacin (p < 0.0001) and exhibited constitutive or inducible macrolide–lincosamide–streptogramin B (MLS_B) resistance, with ermA detected in 80% of inducible cases. In conclusion, S. aureus biofilm formation is linked to disease severity and treatment failure in pediatric AD, underscoring the importance of culture-guided, targeted therapeutic strategies. Full article

Plant endophytes, often termed the “second genome”, critically shape host adaptability. However, the complexity of their interactions, regulated by microbial traits, host species, and environment, has limited both our understanding of symbiosis and the application of beneficial endophytes. The symbiosis between locoweeds (Oxytropis and Astragalus species) and the endophyte Alternaria sect. Undifilum, which produces the neurotoxin swainsonine, serves as an ideal model for investigating these relationships. Through extensive national surveys (2021–2023) across China’s major locoweed habitats, combining field sampling with cultivation, molecular, quantitative, and modeling approaches, a central question emerged: To what extent are the distribution and function of this symbiosis shaped by the contemporary environment versus host evolutionary history? The results showed that: (1) Among 32 surveyed species of Oxytropis, Astragalus, and Sphaerophysa, the endophyte Alternaria sect. Undifilum colonized 11 species. In colonized plants, endophyte loads ranged from 0.02 to 58.87 pg/ng total DNA, and swainsonine concentrations varied from 0.00003% to 1.00%. (2) Environmental factors, rather than host phylogeny, were the key driver governing the geographical distribution and expression of the symbiosis. (3) Low temperature and drought stress regulated the symbiotic relationship and chemical defense through both direct effects on the symbionts and indirect pathways involving grazing pressure. This study demonstrates that the environment is the core force dominating the geographical pattern and functional expression of the locoweed–endophyte symbiosis at ecological scales. These findings provide new perspectives for understanding the general principles of plant–endophyte symbiosis and establish a scientific foundation for predicting and utilizing endophyte resources in changing environments. Full article

Rheumatoid nodules are the most common extra-articular manifestation of rheumatoid arthritis. Long-term immunomodulatory therapies, including corticosteroids, used in the management of rheumatoid arthritis are associated with a higher risk of infections. Leishmaniasis is a neglected protozoal infection that may arise in these patients. Cutaneous presentation is the most common and is characterized by a wide spectrum of clinical manifestations and courses, depending on the interplay between species involved and the host’s immune response. Here, we report the rare and intriguing case of a patient with long-standing rheumatoid arthritis, chronically treated with systemic prednisone, whose rheumatoid nodules were colonized by Leishmania major. In this context, therapeutic strategies must be tailored to species and patient factors. This report expands the differential diagnosis of rheumatoid nodule, highlighting the importance of considering opportunistic infections in exuberant presentations, particularly in immunosuppressed patients coming from or travelling in endemic regions. Intracellular pathogens may exploit the localized immunological niche represented by the rheumatoid nodule of an immunocompromised host to survive and replicate undisturbed. It also underscores the value of the clinico-pathological correlation and the importance of integrating molecular analyses to identify unexpected microorganisms that can be hidden by concomitant disease, avoiding misdiagnosis, ensuring timely treatment, and improving patients outcomes. Full article

This study systematically characterized functional compartmentalization along the intestinal tract of New Zealand rabbits by analyzing mucosal tissue and luminal contents from distinct segments, including the duodenum, jejunum, ileum, cecum, and colon, using RNA-seq and 16S rRNA sequencing. Transcriptomic analysis revealed that differentially expressed genes identified between the small and large intestines were mainly enriched in digestion, absorption, and immune functions. Genes associated with the transport of amino acids, sugars, vitamins, and bile salts showed significantly higher expression in the small intestine, whereas genes related to water absorption, short-chain fatty acids (SCFAs), nucleotides, and metal ion transport were preferentially expressed in the large intestine. From an immunological perspective, genes involved in fungal responses were enriched in the small intestine, while bacterial response pathways and pattern recognition receptor (PRR) signaling genes were upregulated in the large intestine. Microbiota analysis demonstrated significantly greater diversity and abundance in the large intestine compared with the small intestine. Specifically, Proteobacteria and Actinobacteria were enriched in the small intestine, whereas Firmicutes, Verrucomicrobia, and Bacteroidetes dominated the large intestine. Correlation analysis further identified significant associations between gut microbiota composition and host genes involved in nutrient digestion and absorption. Together, these findings provide transcriptome-based evidence for regional specialization of nutrient transport, immune responses, and microbial ecology along the rabbit intestine. Full article

This study investigates whether fecal microbiota transplantation (FMT) can alleviate gut microbiota dysbiosis induced by a high-fat diet (HFD) through modulation of fatty acid metabolism, competition for nutrients, production of short-chain fatty acids (SCFAs), and restoration of mucus layer integrity. To elucidate the mechanisms by which FMT regulates colonic microbial function and host metabolic responses, 80 male Bal b/c mice were randomly assigned to four experimental groups (n = 20 per group): Normal Diet Group (NDG), High-Fat Diet Group (HDG), Restrictive Diet Group (RDG), and HDG recipients of NDG-derived fecal microbiota (FMT group). The intervention lasted for 12 weeks, during which body weight was monitored biweekly. At the end of the experiment, tissue and fecal samples were collected to assess digestive enzyme activities, intestinal histomorphology, gene expression related to gut barrier function, and gut microbiota composition via 16S rRNA gene sequencing. Results showed that mice in the HDG exhibited significantly higher final body weight and greater weight gain compared to those in the NDG and RDG (p < 0.05). Notably, FMT treatment markedly attenuated HFD-induced weight gain (p < 0.05), reducing it to levels comparable with the NDG (p > 0.05). While HFD significantly elevated the activities of α-amylase and trypsin (p < 0.05), FMT supplementation effectively suppressed these enzymatic activities (p < 0.05). Moreover, FMT ameliorated HFD-induced intestinal architectural damage, as evidenced by significant increases in villus height and the villus height-to-crypt depth ratio (V/C) (p < 0.05). At the molecular level, FMT significantly downregulated the expression of pro-inflammatory cytokines (IL-1β, IL-1α, TNF-α) and upregulated key tight junction proteins (Occludin, Claudin-1, ZO-1) and mucin-2 (MUC2) relative to the HDG (p < 0.05). 16S rRNA analysis demonstrated that FMT substantially increased the abundance of beneficial genera such as Lactobacillus and Bifidobacterium while reducing opportunistic pathogens including Romboutsia (p < 0.05). Furthermore, alpha diversity indices (Chao1 and ACE) were significantly higher in the FMT group than in all other groups (p < 0.05), indicating enhanced microbial richness and community stability. Functional prediction using PICRUSt2 revealed that FMT-enriched metabolic pathways (particularly those associated with SCFA production) and enhanced gut barrier-related functions. Collectively, this study deepens our understanding of host–microbe interactions under HFD-induced metabolic stress and provides mechanistic insights into how FMT restores gut homeostasis, highlighting its potential as a therapeutic strategy for diet-induced dysbiosis and associated metabolic disorders. Full article

To investigate whether Echinacea purpurea polysaccharides (EPP) alleviate inflammatory bowel disease (IBD) by modulating gut microbiota, we utilized a mixed antibiotic (ABX)-induced gut dysbiosis model and a co-housing model in rats. ABX treatment severely reduces microbial richness and functional diversity, decreasing SCFA-producing bacteria and impairing the anti-inflammatory effect of SCFA-mediated EPP. Without ABX, EPP significantly ameliorates IBD symptoms and colonic pathology damage in rats, reduces the levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) (p < 0.05), inhibits the activation of the TRAF6/NF-κB signaling pathways, and reverses gut microbiota imbalance by partially restoring Bacteroidetes abundance and reducing Firmicutes levels. Among co-housed rats, the EPP-treated group exhibited significantly lower Disease Activity Index (DAI) scores, serum levels of pro-inflammatory factors, and colonic expression of pro-inflammatory pathway-related gene (TRAF6, STAT3) (p < 0.05) without ABX. 16S rRNA gene sequencing revealed a significant reduction in Firmicutes abundance (p < 0.05) alongside significant increases in Bacteroidetes and Actinobacteria abundances, accompanied by elevated levels of acetic acid and propionic acid (p < 0.05). These findings suggest recipient mice restored microbial function and acquired IBD-regulating ability post-microbial exchange. EPP alleviates IBD-related pathological injury by inhibiting the JAK2/STAT3 and TRAF6/NF-κB signaling pathways, with its therapeutic mechanism intricately linked to the microbiota–metabolite–host axis. Full article

Ectomycorrhizal (ECM) symbiosis is a fundamental mutualism crucial for forest eco-system health. Its establishment is governed by sophisticated molecular dialogue preceding physical colonization. This review synthesizes this pre-colonization crosstalk, beginning with reciprocal signal exchange where root exudates trigger fungal growth, and fungal lipochitooligosaccharides activate host symbiotic programming, often via the common symbiosis pathway. Successful colonization requires fungi to navigate plant immunity. They employ effectors, notably mycorrhiza-induced small secreted proteins (MiSSPs), to suppress defenses, e.g., by stabilizing jasmonate signaling repressors or inhibiting apoplastic proteases, establishing a localized “mycorrhiza-induced resistance.” Concurrent structural adaptations, including fungal hydrophobins, expansins, and cell wall-modifying enzymes like chitin deacetylase, facilitate adhesion and apoplastic penetration. While this sequential model integrates immune suppression with structural remodeling, current understanding is predominantly derived from a limited set of model systems. Significant knowledge gaps persist regarding species-specific determinants in non-model fungi and hosts, the influence of environmental variability and microbiome interactions, and methodological challenges in capturing early signaling in situ. This review’s main contributions are: providing a synthesized sequential model of molecular crosstalk; elucidating the dual fungal strategy of simultaneous immune suppression and structural remodeling; and identifying crucial knowledge gaps regarding non-model systems and species-specific determinants, establishing a research roadmap with implications for forest management and ecosystem sustainability. Full article

Chagas disease (CD), caused by Trypanosoma cruzi, is a neglected tropical illness affecting 6–8 million people in Latin America. Reaching scholarly consensus on the host response to T. cruzi infection remains a significant challenge, primarily due to substantial heterogeneity in outcomes driven by both the choice of animal model and the infecting parasite’s discrete typing unit (DTU). This variability complicates the evaluation and comparison of new therapeutic compounds against existing drugs, namely benznidazole and nifurtimox. This study provides a comprehensive, kinetic, multifaceted characterization of the acute infection using the highly virulent T. cruzi Y strain (TcII) in outbred Swiss mice. Here, crucial infection parameters are presented, including the optimal infective dose, the parasitemia dynamics, tissue damage markers, hematological profiles, cytokine production (Th1/Th2/Th17/Th22), and molecular parasite identification in target organs (heart, colon, esophagus, spleen, and liver) across the span of the infection. The novelty of this study lies in the kinetic integration of these parameters within a defined model; rather than presenting isolated data points, we demonstrate how the biochemical, physiological, and clinical signs and immunological responses, with the resulting organ involvement, evolve and interact over time. To complete the report, a necropsy evaluation was performed at the end of the acute, fatal infection, and it is presented here. This study fulfills a long-standing recommendation from diverse drug discovery groups for the creation of a definitive reference model to standardize preclinical testing for anti-Chagasic agents. Full article

The application of essential oils and plant extracts as natural food preservatives has gained increasing interest; however, their potential impacts on gut health and host physiology remain unknown. This study evaluated the effects of synergistic combinations of peppermint essential oil (EO) + thyme EO and peppermint EO + feijoa peel extract on gut microbiota composition and colonic morphology in a rat model. Sprague–Dawley rats were orally given the synergistic combinations daily for 28 days, and their effects were assessed using 16S rRNA gene sequencing of the caecum microbiota and histological analysis of proximal colon tissues. Alpha diversity metrics showed no significant differences (p > 0.05) between treatment and control groups, and beta diversity indicated no treatment-related shift in the bacterial communities. Taxonomic profiling at the phylum, family, and genus levels showed comparable relative abundances of dominant microbial taxa across all treatments, with no evidence of dysbiosis. Histological examination of proximal colon tissues revealed no significant changes in crypt depth between treated and control groups, confirming the absence of adverse morphological effects on the intestinal epithelium. The results of this study indicate that synergistic combinations of peppermint EO, thyme EO, and feijoa peel extract do not adversely affect the gut microbiota composition and colonic morphology in rats, thereby supporting their application as preservatives in foods. Full article

A novel lytic bacteriophage, XAN_XB1, was isolated from hospital wastewater through host bacterial enrichment and evaluated for its potential in controlling multidrug-resistant Stenotrophomonas maltophilia infections. Transmission electron microscopy revealed that XAN_XB1 has a long tail, possessing an icosahedral head of ~80 nm in diameter and a tail measuring ~150 nm in length. It produced clear plaques of 0.5–1 mm on host bacterial lawns. Host range analysis demonstrated its ability to infect multiple multidrug-resistant S. maltophilia isolates. Biological characterization showed that the phage is chloroform-insensitive, retains strong lytic activity across a wide temperature (4–60 °C) and pH (3.0–10.0) range, and achieves more rapid host suppression under higher multiplicity of infection (MOI). Whole-genome sequencing determined a ~47 kb double-stranded DNA genome encoding 71 predicted open reading frames, with no known virulence or antibiotic resistance genes. Phylogenetic analysis of MCP and terminase large subunit sequences placed XAN_XB1 in a unique Caudoviricetes, with ANI values below the 95% ICTV threshold verifying its status as a novel phage species. The XAN_XB1 therapy significantly alleviates S. maltophilia infection-induced severe pulmonary inflammatory lesions, high mortality, elevated serum inflammatory factors and massive pulmonary bacterial colonization in male BALB/c mice, confirming its favorable therapeutic effect on such infections. Collectively, these results reveal that is an efficacious candidate for therapeutic development against S. maltophilia infections. Full article