Archives of Microbiology最新文献

Bacterial laccases remain comparatively undercharacterized, particularly regarding the factors that influence their induction. In contrast, fungal laccases have been considerably researched and are known to be expressed under diverse physiological and environmental conditions. Existing literature provides limited insight into the environmental triggers associated with the expression of bacterial laccase genes. Our study evaluated Bacillus licheniformis CotA laccase activity in the presence of known fungal laccase inducers as well as oxidative stress and found no significant effect on induction. Comparative analysis between nutrient-rich and sporulation-promoting conditions revealed a ~ 4-5-fold increase in CotA activity and a ~ 4-fold increase in cotA gene expression during sporulation. Moreover, CotA was linked to the biosynthesis of a melanin-like pigment, as pigment yield correlated with laccase activity and decreased upon inhibitor treatment. Notably, sodium azide reduced pigment formation without inhibiting sporulation, indicating that CotA contributes to the pigmentation process rather than to spore development itself. These results showcase that CotA expression in B. licheniformis is primarily sporulation dependent.

Emerging evidence indicates that certain plant pathogens-once thought to be restricted to the plant kingdom-can opportunistically infect humans, particularly those who are immunocompromised. This paradigm-shifting recognition of cross-kingdom pathogenicity underscores complex microbial adaptability and highlights an underexplored public health concern. This review is a compilation of current knowledge on bacterial (Pantoea, Burkholderia, Agrobacterium), fungal (Fusarium, Aspergillus, Curvularia), and viral (e.g., TMV, PMMoV) plant pathogens implicated in human disease. Shared eukaryotic cellular architecture and overlapping molecular mechanisms may facilitate pathogen spillover across kingdoms. Furthermore, human pathogens for instance Salmonella and Escherichia coli have been detected in the rhizosphere and phyllosphere, raising additional concerns for food safety and agricultural practices. As globalization, climate change, and immunosuppressive health conditions intensify, the likelihood of such rare but significant infections may increase. A proactive, integrative "One Health" approach-encompassing plant, human, and environmental health-is essential to anticipate, monitor, and mitigate the potential risks posed by cross-kingdom microbial transmission.

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Virophages, identified when scientists discovered Sputnik, a double-stranded DNA (dsDNA) viruses that form a unique group of viral entities that can parasitize giant viruses. They rely on these giant viruses for replication and inhibiting them from spreading inside eukaryotic hosts. This review seeks to bring together current knowledge on dsDNA virophages. It details how they work, explains their roles in the host, giant virus, and virophage system, and evaluates their potential as new antiviral treatments. Mechanistically, virophages disrupt the giant by replication through competitive resource depletion inside the viral factory. It modifies viral gene expression, and disrupts progeny formation, thus supporting the survivability of the host cell. In addition to these intracellular effects, virophages participate in ecological processes, such as controlling microbial communities and facilitating nutrient recycling. The therapeutic potential of virophages is hypothesized in the context of diseases where the giant viruses have been detected (e.g., hospital-acquired pneumonia), though causal roles remain debated. Furthermore, their possible use as genetic vectors is being fully investigated. However, there are several challenges to overcome before clinical translation is possible: restricted host range, risks of immune activation, and difficulties in scalable production. Future research should focus on the discovery of new virophage species, their mechanism of actions, and bioengineering strategies to improve their antiviral characteristics.

Human metapneumovirus (HMPV) is a major respiratory pathogen belonging to the Pneumoviridae family that primarily affects children, the elderly, and immunocompromised individuals. Since its discovery in 2001, HMPV has been recognized as a significant cause of acute respiratory infections (ARIs) worldwide, exhibiting seasonal peaks and recurring outbreaks. In recent years, the virus has shown an unusual resurgence, particularly in the post-COVID-19 era, emphasizing the need for renewed clinical and epidemiological attention. This review provides a comprehensive overview of HMPV, encompassing its epidemiology, virion structure, replication mechanisms, host-pathogen interaction, clinical manifestations, diagnostic strategies, and current therapeutic approaches. Special attention is given to recent epidemiological trends, molecular insights derived from structural studies of viral proteins, and the challenges faced in developing vaccines and antiviral agents. Additionally, the review discusses the potential of plant-derived bioactive compounds as alternative or complementary therapeutic options. By consolidating the latest global data and highlighting existing knowledge gaps, the work aims to facilitate a better understanding of HMPV pathogenesis and guide future research directions for improved surveillance, diagnosis, and management of HMPV infections.

Cyclic dinucleotides (CDNs), such as cyclic di-AMP (c-di-AMP) and cyclic di-GMP (c-di-GMP), are key second messengers that regulate fundamental bacterial processes, including cell wall synthesis, biofilm formation, antibiotic resistance, stress response, and virulence. These pathways are particularly relevant in major pathogens like Mycobacterium tuberculosis. Increasing evidence highlights the pathogenic potential of non-tuberculous mycobacteria (NTM), originally environmental species that are emerging as significant human pathogens. Understanding the evolution of CDN signaling may therefore provide critical insights into this transition. Our comparative genomic analysis revealed that the c-di-AMP synthase disA is present as a single copy in nearly all mycobacterial genomes, except within the genus Mycolicibacter.The corresponding phosphodiesterases, pde and ataC, are variably distributed, with pathogenic mycobacteria showing a preference for pde over ataC. In contrast to the relatively conserved c-di-AMP system, the c-di-GMP pathway comprising diguanylate cyclases (DGCs) and phosphodiesterases (PDEs), exhibits remarkable variation in gene presence/absence and domain architecture across the Mycobacteriaceae family. This diversity suggests multiple independent gene gain and loss events throughout evolution, often accompanied by the acquisition of accessory domains. Evolutionary analyses reveal a clear dichotomy between the two CDN signaling systems. The c-di-AMP pathway, governed by disA, which is under strong purifying selection similar to core housekeeping genes, and pde, which shows low genetic variability, underscores its conserved and essential role in maintaining core cellular physiology. In contrast, the c-di-GMP system is markedly more heterogeneous, consistent with its function in environmental sensing and adaptation. Together, these findings highlight a sharp evolutionary split in CDN signaling within the Mycobacteriaceae family, c-di-AMP serves as an indispensable regulator of core physiological processes, whereas c-di-GMP confers flexibility for niche-specific adaptation and survival.

Endophytes, the microorganisms inhabiting internal plant tissues without causing harm, have emerged as critical players at the intersection of biotechnology and nanoscience. Beyond their ecological functions, these are prolific producers of bioactive metabolites with antimicrobial, antioxidant, anticancer and stress-alleviating properties. Recent advances highlight their ability to act as natural bio-factories for the green synthesis of metallic, metal oxide, and carbon-based nanoparticles, where microbial metabolites mediate bio-reduction, capping, and stabilisation. This review offers a critical overview of research published in the past decade, identified through major scientific databases, highlighting key studies on endophyte-mediated nanoparticle synthesis, characterisation, and applications. Inclusion focused on peer-reviewed articles addressing biomedical, agricultural, and environmental applications, while descriptive reports lacking mechanistic or functional insight were excluded. Key findings reveal that endophyte-derived nanoparticles exhibit enhanced bioactivity, including potent antimicrobial effects against multidrug-resistant pathogens, targeted anticancer efficacy, and agricultural benefits such as improved nutrient uptake, pathogen resistance, and abiotic stress tolerance. However, major knowledge gaps persist regarding mechanistic pathways, phytotoxicity, long-term safety, and scalability. Comparative analysis with plant-mediated, bacterial-mediated and chemically synthesised further highlights the unique advantages of endophytes but also underscores the limited integration of omics-based insights and the absence of standardised protocols. By providing both a descriptive overview and a critical evaluation, this review advances understanding of endophyte-mediated nanotechnology as a sustainable platform for global health and food security. It emphasises the need for interdisciplinary research, regulatory clarity, and systematic toxicological evaluation to translate laboratory findings into real-world applications.

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C-phycocyanin (C-PC) is a high-value blue phycobiliprotein extensively utilized as a natural colorant and multifunctional bioactive compound. This study employed a polyphasic framework to characterize eleven native cyanobacterial isolates (NTBN series) from temple ponds in Tamil Nadu, India, with the aim of quantifying extractable C-PC and correlating pigment yield with molecular traits of the C-PC β-subunit. All isolates were cultivated under identical, non-optimized conditions (BG-11 medium, 25 ± 2 °C, 16:8 h light: dark, ~ 50 µmol photons m⁻² s⁻¹, 21 days, n = 3). Crude pigments were extracted and quantified spectrophotometrically, while cpcB sequences were subjected to homology modeling and physicochemical profiling (GRAVY, aliphatic index, instability index). Among the isolates, NTBN-07 and NTBN-15 exhibited the highest extractable C-PC content. Strains with lower GRAVY values (greater hydrophilicity) and moderate aliphatic indices consistently showed higher pigment productivity, as supported by multivariate analyses (heatmap and PCA). Homology models revealed conserved chromophore-binding residues with subtle tertiary conformational variations potentially influencing pigment stability and extractability. Although several native isolates yielded more C-PC than the laboratory reference Synechocystis sp. PCC 6803 under uniform, non-optimized conditions, their yields remained lower than those reported for optimized Arthrospira cultures. Study limitations include the use of crude extracts and reliance on in silico predictions pending protein-level validation. Overall, this work identifies temple-pond cyanobacteria as promising native bioresources for predictive strain selection, downstream process optimization, and sustainable pigment biotechnology.

Graphical abstract

A polyphasic workflow illustrating the gene-to-function analysis of cyanobacteria isolated from temple ponds. The schematic integrates sampling, cpcB gene amplification, protein modeling, pigment yield analysis, and structure–function correlations to identify high-yielding strains such as Synechococcus elongatus. These strains are proposed as promising candidates for biotechnological applications, including natural pigment and antioxidant production.

Environmental pollution stands as one of the most pressing challenges of our time, resulting in various harmful effects on ecosystems. Bioremediation emerges as a critical strategy in addressing this issue. This review is essential for enhancing our understanding of the mechanisms through which pollutants induce toxicity and the adaptive strategies that organisms employ to mitigate these contaminants. The article explores a range of mathematical models, including isotherm models, kinetic models, and thermodynamic principles, while integrating biological factors. It provides a comprehensive discussion of these mathematical frameworks and quantum principles as they relate to biological systems and processes. Additionally, it examines the molecular interactions between pollutants and organisms, framed within the context of quantum mechanical phenomena such as quantum tunneling, quantum coherence, and Cooper pair quantum entanglement. Furthermore, the article delves into the significance of pore structures, layer formation, changes in entropy, and the order of reactions, all while maintaining a biological perspective. It critically discusses the interplay of activation energy, adsorption, desorption, and the formation of boundary layers. Ultimately, the objective is to elucidate the mechanisms influenced by quantum mechanical phenomena through the application of various mathematical models, complemented by a biological viewpoint. These insights may act as a catalyst for innovative solutions to combat environmental pollution on a global scale.

Salmonella utilizes multiple virulence factors to adhere to, invade, and replicate within host cells, ensuring systemic dissemination. Among these, the outer membrane protein PagN functions as both an adhesin and invasin, playing a central role in early infection stages and in establishing persistent intracellular populations. PagN expression is controlled by the PhoP/PhoQ two-component system and is specifically induced under host-related environmental conditions such as acidic pH, low magnesium concentration, and the presence of antimicrobial peptides—conditions typically encountered within the Salmonella-containing vacuole. Structural and functional studies demonstrate that PagN binds to host cell heparan sulfate proteoglycans and β1 integrins, mediating receptor-dependent invasion through a zipper-like mechanism independent of type III secretion systems. Deletion of pagN results in attenuated virulence and reduced bacterial replication in vivo, while its conservation across serovars underscores its critical role in Salmonella pathogenesis. Importantly, PagN elicits strong humoral and cellular immune responses in experimental models, supporting its potential as a promising vaccine antigen and diagnostic biomarker for broad-spectrum Salmonella detection and control.

Camellia oleifera and Elaeocarpus decipiens are significant economic crops in South China. However, their production is severely impacted by diseases caused by Colletotrichum gloeosporioides or Pseudocryphonectria elaeocarpicola, respectively. The phyllosphere microbiota of diseased plants represents an underexplored reservoir of functional microorganisms with bioactive potential. However, no prior studies have investigated antagonistic microorganisms from these communities against both pathogens. In this study, 45 fungal strains were isolated from six species of diseased plants in southern China. Their ability to produce secondary metabolites was evaluated using high-performance liquid chromatography (HPLC), leading to the selection of 20 strains with complex and unique chromatographic profiles as bioactive candidates. Dual-culture assays revealed that nine strains exhibited significant antagonism against C. gloeosporioides, producing extracellular antifungal metabolites with maximum antagonistic index of 218.64 ± 26.36% and inhibition rate of 57.92 ± 0.77%. Eight strains showed marked antagonistic activity against P. elaeocarpicola, also secreting antifungal compounds, with maximum antagonistic index of 106.66 ± 16.83 and inhibition rate of 74.99 ± 0.23%. Notably, strains DP13, DP14, and DP16 strongly inhibited both pathogens. Phylogenetic analysis identified the nine highly antagonistic strains as Diaporthe sp. (DP13), Chaetomium globosum (DP14), Muyocopron dipterocarpi (DP15), Muyocopron lithocarpi (DP16), Fusarium equiseti (DP20), Neopestalotiopsis sp. (DP28), Fusarium lateritium (DP32, DP33), and Diaporthe heliconiae (DP43). This study provides insights into exploring functional microorganisms from diseased phyllosphere microbiota and offers valuable resources for eco-friendly management of camellia anthracnose and Elaeocarpus blight, with DP13, DP14, and DP16 as promising broad-spectrum biocontrol candidates.