Archives of Microbiology最新文献

Bacteriophages are re-emerging as a viable approach to tackle bacterial infections in response to increasing antibiotic resistance. Addressing the global challenge of non-typhoidal salmonellosis, this study details the isolation and characterization of six phages targeting Salmonella Enteritidis and Salmonella Typhimurium. Isolated Salmonella Phages vB_ntSalM-cftriSP1, vB_ntSalS-cftriSP2, vB_ntSalS-cftriSP3, vB_ntSalS-cftriSP4, vB_ntSalS-cftriSP5 and vB_ntSalP-cftriSP6 showed latent periods ranging from 20 to 40 min, with respective burst sizes of 100, 66, 218, 190, 42 and 103 PFU/CFU in one-step growth analysis. In vitro lytic activity demonstrated that at multiplicities of infection (MOI) of 1, 10, and 100, each phage consistently inhibited Salmonella growth. The phages exhibited a broad host range, distinct morphology, stability, lytic activity, genomic characteristics, and anti-biofilm activity. Morphological and genomic analyses classified the phages into the families Ackermannviridae, Casjensviridae, and Autotranscriptaviridae, with double-stranded DNA genomes ranging from 41,389 bp to 51,048 bp and an overall GC content of 38.25 to 44.23%. Predicted coding DNA sequences (CDS) were linked to biological processes, cellular components, and molecular functions. Mass spectrometric analysis identified key structural proteins, with the corresponding genes distributed throughout the genomes. Comparative genomic analysis revealed notable similarity to Salmonella phages Slyngel, SE1 in P22, and S149. Furthermore, treatment with the isolated phages significantly disrupted pre-formed S. enterica biofilms, as evidenced by a reduction in viable cell counts. Collectively, these findings demonstrate that the newly characterized phages hold strong potential as effective biocontrol agents for preventing and mitigating biofilm-associated Salmonella contamination and its associated public health risks.

Fungal infections are rapidly emerging as a serious global concern, impacting both the agriculture and healthcare sectors. While fungi play essential roles in geochemical cycles, certain species have become significant threats to human health and agricultural productivity. The rise of resistant and opportunistic fungal pathogens has led to increased mortality rates in humans and severe crop losses. It draws scientific attention to the urgent need for sustainable alternatives of antifungals. The growing resistance in fungal strains has further intensified the innovation in antifungal strategies. Existing antifungal agents are limited in scope and efficacy, particularly against resistant strains. In this context, endophytic nanotechnology offers a promising solution. Endophyte derived nanoparticles present a sustainable, eco-friendly, and effective strategy to combat fungal infections. This review comprehensively discusses the role of endophyte derived nanoparticles in addressing fungal diseases in both agriculture and healthcare. It also highlights the biosynthesis mechanisms, modes of antifungal action, and key studies demonstrating the efficacy of endophyte-mediated nanoparticles. This emerging technology provides a valuable foundation for the development of next-generation antifungal agents with enhanced specificity, reduced toxicity, and minimal environmental impact. By integrating microbiology, nanoscience, and biotechnology, endophytic nanotechnology emerges as a dual-action, eco-friendly, and effective strategy for managing fungal infections across agricultural and clinical domains.

Endophytes establish persistent symbiotic relationships within healthy plant tissues, with certain strains demonstrating robust lignocellulose degradation capabilities, positioning them as promising biocatalysts for efficient biomass conversion. These endophytes present significant advantages in sustainable straw utilization, biosynthesis of valuable bioactive compounds, advancement of bioenergy production technologies, and the development of bio-fertilizers. This review systematically evaluates recent advancements in lignocellulose-degrading endophytes (LDE) research, addressing critical scientific aspects including strain selection, identification, host and strain distribution characteristics, enzymatic system properties, and industrial applications. Strain screening incorporates comprehensive phenotypic, enzymatic, and genomic analyses, while identification relies on integrated morphological, metabolic, and molecular genetic markers. The primary LDE producers are predominantly Ascomycota fungi and Proteobacteria bacteria, which preferentially colonize dicotyledonous plants through diverse symbiotic mechanisms. Lignocellulose degradation is mediated by a sophisticated enzymatic system, whose activity can be enhanced through carbon source induction and strain optimization strategies. Co-cultivation systems have demonstrated synergistic effects in improving degradation efficiency. Furthermore, endophytic metabolites exhibit broad applicability, facilitating lignocellulose breakdown in agricultural residues to yield high-value natural products and renewable energy sources, et al. The degradation efficiency of endophytes is intrinsically linked to their evolutionary adaptations and functional genomic modules. Recent studies indicate that a “dual carbon” strategy has significantly enhanced research on LDE, thereby promoting sustainable agricultural residue conversion and contributing to carbon neutrality objectives.

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Rhizobial technology has become a transformative tool for environmentally friendly and sustainable agriculture. Rhizobia are key nitrogen-fixing bacteria that enhance soil fertility and reduce reliance on synthetic nitrogen fertilisers. In addition to nitrogen fixation, they act as effective plant growth promoters by producing phytohormones, mobilising nutrients, and improving root development. Advances in bioinoculant engineering now support efficient symbiotic associations in both leguminous and non-leguminous crops, offering a green strategy to boost agricultural productivity. Rhizobia also help plants withstand abiotic and biotic stresses, and many strains display strong biocontrol abilities by producing antimicrobial compounds and suppressing phytopathogens. However, their field performance can be inconsistent due to poor survival during storage, competition with native microbes, environmental conditions, and limited farmer awareness. To overcome these challenges, strategies such as co-inoculation with compatible microbes, encapsulated formulations, genetic enhancement, improved agronomic practices, pathogen management, and farmer awareness are being developed to increase inoculant stability and effectiveness. Overall, rhizobial technology serves as a cornerstone of smart, sustainable farming, supporting food security, environmental protection, and the restoration of soil health for future green agriculture.

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Heterocyst differentiation in certain filamentous cyanobacteria is a multifaceted process essential for nitrogen fixation, orchestrated by a sophisticated regulatory network that encompasses several key stages. These include induction, pattern differentiation, commitment, extracellular layer formation, cell-cell communication, and ultimately, nitrogen fixation and metabolism. Key regulators like NtcA and HetR control heterocyst development, while proteins such as PatS, HetN, and PatA modulate pattern formation. Certain non-coding RNAs, such as NsiR1, Yfr1, and NsiR4, also regulate gene expression and contribute to the shutdown of CO₂ fixation in differentiating heterocysts. Meanwhile, the heterocysts’ unique envelope protects nitrogenase from oxygen, enabling nitrogen fixation. Genetic engineering approaches, including CRISPR-Cas systems, have been employed to increase heterocyst frequency and enhance the production of compounds such as ethanol, butanol and H₂. By manipulating genes responsible for heterocyst differentiation, scientists can optimize nitrogen fixation, develop efficient biofertilizers, and unlock opportunities for a more sustainable future in agriculture and biotechnology. This review addresses the current understanding of the regulatory networks and molecular mechanisms that influence the development and function of heterocysts, providing insights into the biology and potential applications of these specialized cells through gene manipulations.

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The frequency of new and re-emerging viral infections is rising, driven by shifts in environmental conditions and altered interactions between hosts, vectors, and pathogens. New treatments may be developed through a better understanding of the molecular processes underlying viral replication. The low-density lipoprotein receptor (LDLR) serves as a critical entry portal for a diverse range of infectious agents, facilitating the initiation and perpetuation of their infection cycles. Furthermore, numerous viruses, such as the dengue virus and the hepatitis C virus (HCV), depend on host cholesterol (CHO) for replication and spread. Consequently, targeting the LDLR with pharmacological agents presents a promising therapeutic strategy for a broad spectrum of viral infections, including those caused by human immunodeficiency virus (HIV), HCV, and severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2). In addition, human metapneumovirus (HMPV) is a leading cause of respiratory infections in young children, underscoring the need for effective treatments. This research investigates the role of the LDLR in HMPV and other emerging viruses. A key finding is that HMPV infection depends on LDLR-mediated pathways, as evidenced by the rapid recovery observed after exogenous CHO administration. Therefore, understanding the mechanism of LDLR in viral entry and replication is crucial and presents a promising avenue for developing novel antiviral therapies.

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Q fever is a globally prevalent zoonotic disease, with the exception of New Zealand and French Polynesia. This study aimed to investigate the presence of gene regions encoding Com1, porin P1, CB-MIP, and heat shock proteins in C. burnetii-positive tissue samples collected from the Veterinary Control Institutes in Erzurum, Samsun, Pendik, and Konya using PCR, and to produce the Com1 protein recombinantly from a selected local isolate. PCR analysis revealed the presence of heat shock protein genes in 82.3% of the positive samples, Porin P1 in 70.5%, CB-MIP in 94.1%, and Com1 in 88.2%. The com1 gene from one field isolate was successfully cloned using the Champion™ pET Directional TOPO^® Expression Kit, and the recombinant protein was expressed. The immunological activity of the resulting proteins, generated using three different primer combinations, was assessed via ELISA. Among the tested proteins, Protein Com1A demonstrated superior immunoreactivity compared to Proteins Com1B and Com1C. Considering the requirement for Biosafety Level 3 (BSL-3) laboratories for the cultivation of the bacterium, the successful recombinant expression of the immunodominant Com1 antigen offers a valuable tool for the development of diagnostic kits or vaccine candidates.

Quorum sensing (QS), a key bacterial cell-to-cell signaling process, regulates group behaviors including biofilm formation, virulence factor production, and antibiotic resistance among the ESKAPE pathogens especially in Pseudomonas aeruginosa and Klebsiella pneumoniae. This review presents a comprehensive comparative evaluation of QS systems, with emphasis on the Las, Rhl, and PQS systems in P. aeruginosa and AI-1, AI-2, and SdiA cascades in K. pneumoniae. We examine the varied and interconnected roles of QS-regulated genes in modulating biofilm development, virulence determinants, and antibiotic resistance through the upregulation of efflux pump expression in these pathogens. Through the identification of similarities and differences between QS systems and their impact on resistance, the review aims to guide future research and the development of novel therapeutic strategies to fight infections caused by P. aeruginosa and K. pneumoniae. Additionally, understanding QS networks may help guiding combination therapies and inform strategies to prevent the emergence of antimicrobial resistance.

Coal overburden spoils generated from opencast mining are often enriched with heavy metals such as nickel (Ni), copper (Cu), and chromium (Cr), posing long-term environmental risks. This study investigates the bioremediation potential of native, multi-metal-tolerant bacterial and fungal strains pre-isolated from coal overburden materials. Four bacterial and seven fungal isolates were selected based on metal tolerance and mutual compatibility. These were used to formulate four microbial consortia, which were immobilized in alginate beads and applied to coal overburden samples under controlled conditions. Consortium-4 (containing all selected isolates) achieved the highest removal efficiencies—Cr (60.52%), Cu (29.31%), and Ni (25.91%)—over 60 days, accompanied by a shift in pH from highly acidic to moderately acidic. Scanning electron microscopy (SEM) confirmed metal-induced morphological adaptations in the microbes. The findings highlight the effectiveness of indigenous microbial consortia as a sustainable and low-cost bioremediation strategy for heavy metal mitigation in coal mining environments.

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Antimicrobial resistance (AMR) poses a serious threat currently to human health and necessitates urgent discovery of novel antimicrobial agents. We hypothesized that the vast biodiversity of the marine environment represents a promising resource for isolating bacteria with potent antagonistic activity against multi-drug resistant pathogens. The primary objective was to purify and characterize the antibacterial protein fractions exhibiting antagonistic activity from marine bacteria. To accomplish this, the present study isolated, identified, and characterized antibacterial compounds produced by bacteria from samples collected at Narara beach, Gujarat, India. Thirty-four bacterial isolates were obtained and screened for antagonistic activity against two multidrug-resistant (MDR) pathogens, Salmonella paratyphi and Acinetobacter baumannii. One isolate, ISD30, identified as Marinobacter pelagius by morphological, biochemical and 16 S rRNA gene sequencing, showed significant antagonistic activity. The 16 S rRNA gene sequence was deposited to GenBank, with accession number: PQ097291. The bioactive compound from M. Pelagius (ISD30) was confirmed as proteinaceous and purified using Fast Protein Liquid Chromatography (FPLC) gel filtration. FPLC yielded two bioactive fractions, one among them exhibiting potent antagonistic activity against MDR pathogen S. paratyphi, but not A. baumannii. SDS-PAGE analysis estimated the protein’s molecular weight to be ~ 75 kDa. Upon analysis, the protein demonstrated a Minimum Inhibitory Concentration (MIC) of 70 µg/mL and thermal stability up to 70 °C. This study is the first report of an antibacterial protein from M. pelagius, with significant inhibitory activity against the MRD clinical pathogen S. paratyphi, highlighting the potential of marine Marinobacter species as a novel source for antimicrobial agents against MDR pathogens.