Frontiers in Microbiology最新文献

Introduction: Arbuscular mycorrhizal fungi (AMF) and plant rhizosphere microbes reportedly enhance plant tolerance to abiotic stresses and promote plant growth in contaminated soils. Soil salinization represents a severe environmental problem. Although the influence of AMF in the phytoremediation of saline-alkali soils has been fully demonstrated, the underlying interactive mechanisms between AMF and rhizosphere microbes are still unclear.

Methods: A greenhouse pot experiment was conducted to explore the effects of AMF (Claroideoglomus etunicatum) on tall fescue growth promotion and the rhizosphere microbial community in saline-alkali soils. We aimed to investigate the mechanism of AMF affecting plant growth under saline-alkali stress conditions via interactions with rhizosphere microbes.

Results: We found that AMF significantly increased plant shoot, root, and total biomass in saline-alkali stress soil. AMF significantly increased the diversity of bacterial and fungal communities and altered their composition. For bacteria, the AMF inoculation treatment (M+) showed higher relative abundance of Proteobacteria, Actinobacteriota, and Firmicutes and lower relative abundance of Acidobacteriota and Chloroflexi compared to the no-AMF application treatment (M-). For fungi, the M+ treatment showed lower relative abundance of Ascomycota and higher relative abundance of Mortierellomycota compared to the M- treatment. Furthermore, structural equation modeling (SEM) revealed that AMF promoted plant growth under saline-alkali stress conditions mainly by regulating the diversity of bacterial communities in the rhizosphere soil.

Discussion: This study provides a theoretical basis for improving plant adaptation to saline-alkali stress through soil microbial management practices.

Pancreatic cancer (PC) is a lethal malignancy with limited early detection strategies and poor therapeutic response. Emerging evidence implicates the gut microbiota in carcinogenesis, yet whether microbial alterations are causal or secondary remains uncertain. In this study, we integrated cross-sectional 16S rDNA sequencing, two-sample Mendelian randomization (MR), and mediation analysis to investigate the causal role of gut microbiota in PC risk. We profiled fecal microbiota in a Beijing-based cohort of 26 newly diagnosed PC patients and 9 healthy controls, revealing significant dysbiosis characterized by reduced microbial diversity, depletion of butyrate-producing genera (e.g., Faecalibacterium), and enrichment of pro-inflammatory taxa such as Olsenella. Using European GWAS summary data, MR analysis identified 17 gut microbial taxa causally associated with PC risk, including Olsenella and Pauljensenia sp000411415. Notably, higher abundance of Pauljensenia sp000411415 was associated with increased PC risk, an effect partially mediated by reduced circulating levels of octanoylcarnitine (C8) and glutarylcarnitine (C5-DC)-metabolites independently linked to lower PC risk. Population-matched MR in East Asian cohorts validated several causal associations, enhancing ancestral relevance. Our findings support a causal role for specific gut microbes in pancreatic carcinogenesis and highlight a Pauljensenia-acylcarnitine axis whereby microbial suppression of protective metabolites may contribute to disease development. This integrative approach bridges microbial dysbiosis with functional mechanisms, offering novel insights for microbiome-informed strategies in PC prevention and early detection.

Introduction: The search for sustainable agricultural strategies has highlighted the importance of plant-microbe interactions within soil ecosystems. In particular, extracellular metabolites produced by soil bacteria represent a promising, yet underexplored, source of bioactive compounds capable of modulating plant germination and early development.

Methods: This study evaluated the biostimulant potential of extracellular metabolites present in bacterial cell-free supernatants on the germination and early growth of Hibiscus sabdariffa and Prosopis juliflora under controlled laboratory conditions. Two native bacterial strains isolated from soils of Nuevo León, Mexico, were identified as Lysinibacillus xylanilyticus and Bacillus cereus using MALDI-TOF mass spectrometry. Supernatants obtained after cultivation in Luria-Bertani (LB) medium were applied directly to seeds, and germination and growth parameters were recorded. Phytochemical screening of the supernatants was also performed.

Results: The L. xylanilyticus supernatant significantly enhanced seed germination (96.66 ± 5.77%; p < 0.0001) and promoted early growth in both plant species, increasing shoot length, leaf width, and fresh biomass. In contrast, the B. cereus supernatant inhibited H. sabdariffa germination (30 ± 10%; p = 0.0146) and showed limited effects on P. juliflora. Notably, a 50:50 mixture of both supernatants completely inhibited H. sabdariffa germination while significantly stimulating P. juliflora germination (90 ± 10%; p = 0.0130). Phytochemical analysis revealed low concentrations of carbohydrates and coumarins, suggesting that the observed effects were likely mediated by other, unidentified bioactive metabolites.

Discussion: These findings demonstrate that extracellular metabolites produced by soil-derived bacteria exert species-specific and measurable biological effects on seed germination and early plant growth. The contrasting responses observed between plant species and supernatant combinations underscore the complexity of plant-microbe chemical interactions. Overall, this study highlights the potential of bacterial extracellular metabolites as microbiome-based tools for sustainable agriculture and ecological restoration.

Sulfate-reducing microorganisms (SRM) can contribute to souring and to the corrosion of infrastructure built to support many industrial operations, including in aquatic environments. While chemicals such as biocides can effectively treat planktonic cells, less is known about biocide efficacy for treating established biofilms potentially plaguing infrastructure. We used a biofilm flow cell system to examine the efficacy of sodium nitroprusside (SNP, a nitrosating compound proposed as a "green" biocide) and alkyl dimethyl benzyl ammonium chloride (ADBAC), a membrane-disrupting biocide used across many sectors, to mitigate existing SRM biofilms. Biofilms were treated with various amounts of SNP (15-750 ppm) or ADBAC (25-500 ppm) for 10-14 h. Biofilm responses were tracked by measuring sulfide concentrations and were also analyzed for microbial community composition and by microscopy. Planktonic SRM cultures were inhibited by 15 ppm SNP, while biofilms were only transiently inhibited by 15-750 ppm SNP. Planktonic cultures were inhibited by 10 ppm ADBAC, but 50 ppm ADBAC did not suppress sulfide production in existing biofilms. ADBAC added at 100 ppm to the biofilms showed transient inhibition while the 250 and 500 ppm treatments completely inhibited sulfidogenesis. Two-photon microscopy showed primarily viable cells following the 50 ppm ADBAC treatments, a mix of viable and non-viable cells following the 100 ppm ADBAC treatment, and non-viable cells following the 250 and 500 ppm ADBAC treatments, confirmed by quantitative analysis of the images. 16S rRNA gene sequencing showed the prevalence of Desulfobulbus and either Desulfomicrobium or Pseudomonas in active biofilms, with these taxa differentially persisting after many of the biocide treatments. The results revealed that higher doses of biocides are needed to effectively treat existing SRM biofilms compared to planktonic cells, and that biocide dosing may only be transiently effective. Studying the effects of chemical treatments on sessile rather than planktonic communities in aquatic environments may lead to more effective treatment strategies to mitigate problematic biofilms plaguing infrastructure degradation across many industries.

Post-transcriptional regulation is the predominant mode of gene expression control in Trypanosoma brucei, yet the underlying regulatory elements and proteins remain poorly defined. AU- and GU-rich elements (AREs and GREs) are common post-transcriptional regulatory motifs. To investigate their roles in T. brucei, we analyzed transcriptomic datasets and extracted 5,840 genes with defined 5' and 3' untranslated regions (UTRs), including 327 that are developmentally regulated between the parasite's two life stages. Computational analysis revealed that AU- and GU-rich elements are widespread and enriched in the 3'UTRs of developmentally regulated mRNAs as well as in transcripts with long half-lives. Functional assays demonstrated regulatory activity of AREs and GREs within the 3'UTRs of five representative genes (ICP, TOP2, MCC-β, PK, and KREPB6), with differential effects on reporter expression. Notably, the GREs in the ICP and TOP2 3'UTRs destabilized reporter transcripts in procyclic-form trypanosomes but enhanced expression in bloodstream forms. RNA pulldown assays further identified DRBD2 as a potential GRE-binding protein, and DRBD2 knockdown reduced ICP mRNA abundance in procyclic trypanosomes. Collectively, these findings demonstrate that AREs and GREs are critical regulatory elements in T. brucei, exhibiting gene-specific and context-dependent functions. Elucidating their regulatory roles and identifying additional binding proteins will provide new insights into the mechanisms of post-transcriptional control in this parasite.

Introduction: Aspergillus fumigatus has been designated by the World Health Organization (WHO) as a critical fungal pathogen. Its spores are commonly present in the air and are inhaled daily. Azoles are the first-line treatment for Aspergillus infections, but the emergence of resistance is a growing concern. However, limited data exist on the occurrence of azole-resistant A. fumigatus in the outdoor environment in Spain.

Methods: This study aimed to investigate the prevalence of azole-resistant A. fumigatus isolates in outdoor air at two distinct locations in Madrid. We characterized the isolates using TRESPERG genotyping and examined the underlying molecular mechanisms responsible for azole resistance development.

Results: Azole-resistant A. fumigatus isolates were found in 55% of the 20 air samples collected. Among the 200 A. fumigatus isolates analyzed, 38.5% were azole resistant and were classified into 10 different genotypes. Notably, the TR34/L98H mutation in Cyp51A was found in 77% of the resistant isolates, while 23% showed no mutations in the screened targets (cyp51A, cyp51B, or hmg1).

Discussion: This study revealed a high prevalence of azole-resistant A. fumigatus in outdoor environmental air, with the TR34/L98H mutation being the main mechanism of azole resistance. A close genetic relationship was observed among the resistant isolates. This research underscores the need for continued monitoring of environmental azole-resistant A. fumigatus isolates and highlights the importance of understanding genetic diversity and resistance mechanisms to develop effective strategies for fungal infection control.

Environmental pollution has emerged as a pervasive global health threat, yet its effects extend far beyond direct organ toxicity. Increasing evidence reveals that the gut microbiota serves as a central mediator of pollutant-induced physiological dysfunctions. This review integrates recent advances on how air pollutants, heavy metals, persistent organic pollutants, and emerging contaminants perturb microbial composition, metabolic activity, and host-microbe signaling. Pollutant exposure alters microbial-derived metabolites such as short-chain fatty acids, bile acids, and tryptophan derivatives, thereby impairing intestinal barrier integrity and immune homeostasis. These microbiota-driven disturbances trigger oxidative stress, chronic inflammation, and neuroendocrine dysregulation, contributing to metabolic disorders, immune imbalance, neurotoxicity, and carcinogenesis. Mechanistically, redox imbalance, activation of TLR4/NF-κB and NLRP3 pathways, and dysregulation of AhR signaling represent critical intersections linking environmental exposure to disease. By elucidating these molecular and ecological connections, this review underscores the gut microbiotaas a key target and therapeutic entry point for mitigating the health impacts of environmental pollution and guiding microbiota-based interventions for disease prevention.

Respiratory tract infections (RTIs) are among the most prevalent diseases in human society and pose a major global health threat, affecting millions annually. A wide range of pathogens, primarily viruses and bacteria, cause RTIs. These infections often present with similar symptoms, which limits effective clinical treatment. Extensive research has addressed RTIs, with ongoing discussion regarding their current status and advancements in detection technologies. Novel laboratory methods that offer rapid, sensitive, and specific results now supplement traditional diagnostic approaches. In this review, we summarize the infection characteristics and detection methods of common respiratory pathogens, evaluate the effectiveness and limitations of current detection methods, and aim to promote advancements in laboratory diagnosis and explore the potential of emerging technologies in this field.

Microplastic pollution fosters the development of distinct microbial biofilm communities, termed the plastisphere, that vary across environmental contexts. Here, we used 16S rRNA gene sequencing combined with machine learning (ML) approaches to explore plastisphere microbial diversity and the interactions between potential plastic-degrading bacteria (PDBs) and non-plastic-degrading bacteria (NDBs) across ocean, surface water, and wastewater habitats. Our findings reveal that wastewater plastispheres harbor the most diverse and compositionally even microbial communities, likely driven by complex nutrient loads, pollutant inputs, and high microbial seeding potential. Genus-level analysis of potential PDBs indicated habitat-specific taxa, including Pseudomonas, Acinetobacter, and Aquabacterium in wastewater, Flavobacterium and Alteromonas in ocean, and Psychrobacter and Novosphingobium in surface waters. Network analyses using Pearson's correlation and Random Forest modeling uncovered consistent co-occurrence patterns between potential PDBs and diverse NDB taxa such as Clostridium_sensu_stricto_5, Lachnospiraceae_UCG-001, and Cloacibacterium, suggesting potential facilitative interactions, including redox modulation, nutrient exchange, and biofilm support. ML tools proved effective in identifying key taxa and potential ecological interactions, but their application remains limited by taxonomic resolution, lack of functional validation, and insufficient integration of environmental metadata. These findings underscore the ecological complexity of plastisphere communities and the need for community-level approaches in plastic biodegradation research.

Spring viremia of carp (SVC), caused by spring viremia of carp virus (SVCV), is a highly contagious disease that poses a serious threat to cyprinid aquaculture and international trade, and it is listed as a notifiable disease by the World Organization for Animal Health (WOAH). Effective surveillance and control of SVCV rely on accurate and highly sensitive molecular diagnostic methods. However, several previously published RT-qPCR assays contain mismatches between primer/probe sequences and viral genomes, which may lead to false-negative results and reduced diagnostic reliability. In this study, a whole-genome comparison of 24 representative SVCV strains covering all four genotypes (SVCVa-d) was conducted, and a new primer-probe set (Cefas AR) targeting a highly conserved region of the L gene was designed. Reaction conditions were optimized, and the assay was rigorously validated in accordance with the WOAH Manual of Diagnostic Tests for Aquatic Animals. The developed RT-qPCR assay exhibited excellent analytical performance, with a limit of detection of 1.28 copies/μL, diagnostic sensitivities of 100% for cell-culture isolates and 96.6% for tissue samples, and a diagnostic specificity of 100%. In addition, the assay demonstrated strong reproducibility and consistency across nine independent laboratories. In conclusion, the WOAH-validated RT-qPCR assay developed in this study provides a highly sensitive, specific, and reliable tool for rapid screening, routine surveillance, and confirmatory diagnosis of SVCV, supporting sustainable aquaculture development and international aquatic animal health management.