Frontiers in Microbiology最新文献

The Caucasus region, including Georgia, is an important intersection for migratory waterbirds, offering potential for avian influenza virus (AIV) transmission between populations from different geographic areas. In 2022 and 2023, wild ducks were sampled during autumn migration events in Georgia to study the genetic relationships and molecular characteristics of influenza strains. Sequencing and phylogenetic analysis were used to compare the sampled strains to reference sequences from Africa, Asia, and Europe, allowing assessment of genetic relationships and virus transmission between migratory birds. Protein language modeling identified potential co-infections. Of 225 duck samples, 128 tested positive for the influenza M gene. 55 influenza-positive samples underwent whole-genome sequencing, revealing significant diversity. Analysis of the hemagglutinin (HA) segment showed notable differences among subtypes. Most samples were H6N1 and H6N6, but co-infections with combinations like H6H3, N8N1, N6H9, N2N6, and H9H6/N1N2 were also identified. These findings demonstrate the high variability of influenza viruses in migratory waterbirds in Georgia, including a notable rate of co-infections. Some samples exhibited uncommon genetic characteristics compared to other strains from the same year, suggesting Georgia's role as a mixing vessel for influenza viruses. This facilitates reassortment during co-infections and contributes to the genetic diversity observed across flyways.

As a pivotal defense system within the female lower genital tract, the healthy vaginal microecosystem, dominated by Lactobacillus, safeguards against pathogenic microorganisms and maintains overall reproductive health through producing antimicrobial substances and sustaining an acidic environment. However, this intricate ecosystem is susceptible to a variety of adverse factors that trigger vaginal microbiota (VMB) dysbiosis, which further precipitate vaginal infections and gynecological disorders. Based on rigorous clinical evidence, this review systematically summarizes current mechanistic understanding of Lactobacillus-mediated VMB homeostasis. It evaluates the therapeutic potential of probiotics in both pharmaceutical and dietary supplement forms, and discusses the clinical necessity and existing challenges in developing live biotherapeutic products (LBPs) targeting the vaginal microecology. By integrating perspectives from both basic research and translational medicine, this work provides a theoretical foundation for developing targeted microbiota modulation strategies, thereby advancing precision medicine approaches for the management of vaginal dysbiosis.

Introduction: The Kabru Glacier, located in the Sikkim Himalayan region at an altitude of 7,318-7,412 m above sea level (a.s.l), forms part of the Kanchenjunga range in the Eastern Himalaya. Glaciers in this region are predominantly summer-fed and highly sensitive to climatic fluctuations. Despite their ecological significance, glaciers of the Sikkim Himalaya remain largely unexplored from a microbiological perspective due to harsh weather conditions and limited accessibility. In this context, the present study investigates the bacterial diversity across different depths (upper, middle, and bottom) of ice core samples collected from the Kabru Glacier.

Methods: Bacterial diversity was examined using a combination of culture-dependent and culture-independent approaches. In addition, antibiotic resistance profiles and metal tolerance characteristics of the isolated bacteria were evaluated to gain further insight into their adaptive potential.

Results and discussion: Culture-dependent analysis revealed a comparatively high bacterial load in the Kabru Glacier, suggesting that the biodiversity-rich Himalayan surroundings may influence the microbial community structure. Phenotypic characterization showed a predominance of Gram-positive bacteria (62.6%) over Gram-negative bacteria (37.3%). Growth profile analyses indicated optimal growth temperatures of 15°C and 20°C, with variable tolerance to salinity and pH, reflecting adaptive responses to environmental stress. Elemental analysis of ice core samples revealed higher concentrations (ppb range) of Na, Mg, K, Ca, Mn, Li, and Zn compared to other elements. Phylogenetic analysis based on 16S rRNA gene sequencing identified members of the phyla Pseudomonadota, Bacillota, and Actinomycetota. Consistently, culture-independent 16S rRNA amplicon sequencing also demonstrated the dominance of these phyla. Alpha diversity indices corroborated trends observed in the culture-dependent analysis, supporting the complementary reliability of both methodologies in elucidating bacterial community structure. Furthermore, antibiotic susceptibility testing revealed resistance to cefixime (CFM) and metronidazole (MET), along with elevated tolerance to heavy metals such as CuSO₄, ZnCl₂, and NiCl₂, while showing lower tolerance to HgCl₂.

Conclusion: Collectively, these findings suggest that bacterial diversity in the Kabru Glacier is shaped by multiple environmental parameters. The occurrence of antibiotic-resistant and metal-tolerant bacteria underscores the need for further comprehensive investigations to better understand microbial adaptation and potential ecological implications in high-altitude glacial ecosystems.

To enhance sustainable soil fertility and efficient phosphorus (P) management, phosphate-solubilizing bacteria (PSB) play a central role in solubilizing soil mineral phosphorus by releasing organic acids and acidifying micro-niches. Thus far, the influence of spatial P heterogeneity on bacterial eco-physiological adaptations to P-limited, alkaline soils remains poorly understood. This study examined how soil edaphic factors vary across major wheat-growing regions, assessing their influence on the abundance and functional properties of culturable PSB. Soil available P was the strongest predictor of culturable bacterial abundance, with a threshold of P < 6.3 mg kg^-1 dry soil driving major variations. At low P levels, organic matter played a key role, while at higher P levels, potassium (K ≥ 123) and pH further shaped bacterial abundance. Low-P soil PSB (L _PSB ) secreted elevated levels of organic acids such as malic, succinic, gibberellic and citric acid, but low levels of indole acetic acid. A clear trade-off was observed between P solubilization and growth-related traits: L _PSB invested more in acquiring resources (e.g., producing siderophores and organic acids) and less in synthesizing phytohormones. A net house study showed that L _PSB contribute to plant growth. Plants with 70% phosphate fertilization (P₇₀) and PSB inoculation reached the yield levels comparable to those with 100% fertilization without the PSB, indicating the potential of PSB to reduce dependency on fertilizers. This was associated with a significant increase in wheat biomass (24.3%), yield (28.53%) and P use efficiency (31.66%) by L _PSB inoculation compared to the control P₇₀. Our findings emphasize the importance of microbial functional plasticity in enhancing P use efficiency in P-limited soil, offering a basis for developing climate-smart bioformulations to improve sustainable crop productivity.

This study examined the microbial community structure, functional potential, and resistance determinants in uranium (U)- and nickel (Ni)-contaminated soils from the Savannah River Site (SRS), a former nuclear materials production and waste collection facility operated by the U. S. Department of Energy (DOE). Soil cores were collected from the Steed Pond area, where long-term discharge of acidic wastewater resulted in spatially variable contamination levels. Concentrations of U and Ni in the collected samples ranged from 0.22-10.44 g kg^-1 and 0.79-2.28 g kg^-1, respectively. Shotgun metagenomic and high-throughput quantitative PCR (HT-qPCR) analyses revealed bacterial communities dominated by Pseudomonadota, Actinomycetota, and Acidobacteriota, with enrichment of taxa affiliated with genera known to include diazotrophic members (e.g., Bradyrhizobium and Burkholderia), alongside increased abundance of nitrogen fixation-related functional genes. Carbon and nitrogen cycle genes were generally well represented across samples, with selective shifts observed in acetate assimilation genes (acsA/acsE) and comparatively low abundance of hydrazine oxidoreductase (hzo), indicating pathway-specific variation rather than broad metabolic suppression. A total of 117 resistance-associated genes were identified, comprising 93 antibiotic-resistance genes (ARGs), 3 metal-resistance genes (MRGs), and 21 mobile genetic elements (MGEs). Strong positive correlations among ARGs, MRGs, and MGEs indicate co-selection and horizontal gene transfer, forming a genetically mobile resistome. Collectively, these findings demonstrate that long-term U-Ni contamination selects for metabolically versatile, diazotroph-enriched, and genetically mobile microbiomes. Such communities exhibit both resistance proliferation and bioremediation potential, providing key insights into microbial adaptation and ecosystem recovery in legacy nuclear-contaminated soils.

Introduction: Obesity-related diabetes is a significant global health concern, underscored by perturbations in iron metabolism and gut microbiota composition. This study investigates the mechanistic role of Chia Seed Oil (CSO), rich in omega-3 fatty acids, in suppressing iron metabolism pathologies and promoting gut microbiota alterations to mitigate obesity-related diabetes.

Methods: Using a high-fat diet-induced obesity model in male C57BL/6J mice, we aimed to explore the effects of CSO supplementation on metabolic outcomes, iron status, and gut microbiota diversity.

Results: Our findings suggest that CSO effectively regulates iron metabolism, evidenced by altered serum ferritin levels, hepcidin, and transferrin saturation, while promoting a diverse gut microbiota profile.

Discussion: The study elucidates the potential of CSO as a therapeutic agent in managing obesity-associated metabolic disorders by restoring iron homeostasis and fostering gut health. These results highlight the interconnectedness of dietary fat, iron metabolism, and microbiome dynamics in the pathophysiology of obesity-related diabetes, suggesting a multifaceted approach to treatment strategies.

Microbial interactions are pivotal components of Earth's ecosystems, driving essential processes that sustain life, regulate environmental conditions, and ensure ecosystem resilience. A comprehensive understanding of these relationships is imperative for leveraging their potential in environmental solutions and biotechnological innovations. In this study, we explore the intricate bacterial interplay between three key players involved in biomass degradation: Clostridium acetobutylicum (Gram-positive), Escherichia coli, and Nitratidesulfovibrio vulgaris Hildenborough (Gram-negative) using synthetic reconstituted consortium. N. vulgaris independently cooperates with both C. acetobutylicum and E. coli through thigh physical interactions and transfer of biological material to ensure its survival. These interactions are dependent of nutritional starvation and provokes with a rise of hydrogen production in the consortium C. acetobutylicum/N. vulgaris. However, prior studies showed that E. coli does not exchange cytoplasmic material with C. acetobutylicum. To probe the stability of these microbial interactions and the hydrogen production, we monitored growth and metabolic kinetics in pure and co-cultures. Our findings reveal a surprising shift: N. vulgaris emerges as an unexpected mediator and protector, reshaping the relationship between E. coli and C. acetobutylicum. This study highlights the underestimated influence of minority species like N. vulgaris in microbial communities, shedding a new light on their ecological and functional roles.

Studying airborne viruses in remote environments like the sub-Antarctic island of South Georgia offers key insights into viral ecology, diversity, and their role in shaping ecosystems through microbial and nutrient interactions. We analyzed airborne viral community composition at two sites in South Georgia. Sampling took place using multiple methodologies, with the data produced subjected to viral metagenomics. The Coriolis μ device (wet collection) was the most effective, yielding 30 viral scaffolds. Two-thirds of the scaffolds were only obtained from the coastal location, indicating that location influences airborne viral diversity. Protein-based clustering of 39 viral operational taxonomic units (vOTUs) revealed similarities of 15 with known marine viruses, suggesting oceanic influence on the airborne viral community. Protein homologs related to UV damage protection and photosynthesis from two airborne vOTUs were widely distributed across major oceans, suggesting their potential role in supporting the resilience of marine microorganisms under changing climate conditions. Some vOTUs had protein similarities to viruses infecting extremophiles, indicating viral adaptations to harsh environments. This study provides a baseline for understanding the complexity and sustainability of airborne viral communities in remote ecosystems. It underscores the need for continued monitoring to assess how these communities respond to shifting atmospheric and ecological conditions.

Propionic acid is a common food preservative, but many microbes, including the important biocontrol agent Bacillus thuringiensis, can metabolize it via the 2-methylcitrate cycle. However, the accumulation of cycle intermediates, such as 2-methylcitrate, can be toxic, and the overall physiological effects of this toxicity on B. thuringiensis are unclear. In this study, we investigated the toxic effects of 2-methylcitrate on B. thuringiensis and its corresponding cellular responses by characterizing the prpD deletion mutant ΔprpD, which lacks the 2-methylcitrate dehydratase. We found that the accumulation of 2-methylcitrate in the ΔprpD mutant led to a sharp decline in biomass, extensive cell lysis and death during the stationary phase. Comparative transcriptomic analysis revealed that this toxicity is associated with severe overall metabolic imbalance, characterized by a significant transcriptional dichotomy: concerted downregulation of nearly all glycolytic pathway genes and simultaneous upregulation of TCA cycle genes. This transcriptional decoupling of central carbon metabolism is the root cause of the observed lethal phenotype. Furthermore, we identified and characterized an internal promoter located within the prp operon that specifically drives prpD expression. This internal promoter rapidly and efficiently clears toxic intermediates, representing a complex regulatory adaptation mechanism to combat the harmful effects of propionic acid metabolism. Our findings provide a comprehensive transcriptional view of the toxicity of 2-methylcitrate and reveal a unique bacterial metabolic detoxification strategy, highlighting the value of PrpD as a potential anti-bacterial target.