Current Microbiology最新文献

To enhance stability and antimicrobial efficacy of antimicrobial peptide (AMP) epinecidin-1, we previously engineered three variants - GK-epi-1, Variant-1 and Variant-2-by substituting alanine and histidine residues with lysine. Our current study focuses on the antifungal capabilities of Epinecidin-1 and its variants against the clinical isolates of Candida spp. (Candida albicans, C. tropicalis, C. krusei & C. glabrata) and Aspergillus flavus. Computational docking studies are evidenced, the peptides had strong affinity against all fungal receptor examined which indicates their efficacy to interact with the Candida cell membrane receptors (Exo-B-(1,3)-Glucanase, Secreted aspartic proteinase (SAP) 1 & N-terminal domain adhesin: Als 9 - 2). Minimum Inhibitory Concentration (MIC), Minimum Fungicidal Concentration (MFC) and antibiofilm assays revealed its potent antifungal activity, particularly in disrupting biofilm formation. Effects of peptides on hyphal growth inhibition activity and Scanning Electron Microscopy (SEM) confirmed that the mechanism of action involves pore formation, hyphal disruption and induction of reactive oxygen species in Candida cell membrane. The antifungal spectrum was extended to A. flavus, a known ocular pathogen, where combination therapy using sub-inhibitory concentrations of Epinecidin-1 and its variant peptides with Amphotericin B and Miconazole showed enhanced synergistic effects, reducing required dosages for effective pathogen control.

Oil contamination poses serious environmental challenges, particularly in hyper-arid desert ecosystems; yet, microbial responses to oil pollution and biostimulation in desert soils remain insufficiently explored. This study explored the microbial community dynamics and hydrocarbon degradation potential to oil contamination and biostimulation in desert soils collected from sites in southern Israel polluted in 1975 and 2014. Laboratory-based biostimulation experiments were conducted over 1.5 years, involving the addition of water (20% or 50% gravimetric saturation), nutrients, and biosurfactants. Results revealed that biostimulation treatments reduced microbial diversity but enriched populations capable of hydrocarbon degradation. Proteobacteria and Actinobacteria were the dominant phyla, comprising 68% to 78% of the total microbial community across both contamination timelines. The relative abundance of Chloroflexi was higher in biostimulated contaminated soils, showing an increase of 41% to 227% compared to untreated contaminated soils. Differential abundance analysis identified distinct taxa of hydrocarbon degraders associated with untreated contaminated soils (e.g., Pseudomonas, Alkanindiges, Bacillus, and Mycobacterium) and biostimulated contaminated soils (e.g., Pseudomonas, Flavobacterium, Pseudoxanthomonas, unclassified Microbacteriaceae, Solimonadaceae, and Gammaproteobacteria). Further, soil hydrophobicity and total petroleum hydrocarbon suggested a positive relationship with the abundance of the nahAc gene, a key marker of hydrocarbon degradation. These findings exhibit that targeted biostimulation with water, nutrients, and biosurfactants accelerates oil biodegradation while selectively reshaping microbial communities toward hydrocarbon degrading taxa in hyper-arid desert soils. This study points to the potential development of effective management and remediation strategies for oil-contaminated desert environments.

The escalating threat of antimicrobial resistance (AMR) necessitates the development of innovative therapeutic approaches. This study reports the green synthesis of magnesium oxide nanoparticles (MgO-NPs) using Citrullus colocynthis extract, a medicinal plant rich in bioactive compounds, as a sustainable alternative to conventional antibiotics. The synthesized MgO-NPs were characterized by UV-Vis spectroscopy (absorption peak at 250 nm), XRD (cubic crystalline structure, 15-25 nm size), SEM-EDX (agglomerated spherical morphology, Mg/O ratio 2.6:1), and FTIR (Mg-O vibration at 860 cm^- 1). The nanoparticles exhibited potent, dose-dependent antibacterial activity against multidrug-resistant (MDR) Staphylococcus aureus [MIC: 35.3 ± 2.1 µg/ml (0.0353 ± 0.0021 mg/ml); MBC: 97.1 ± 3.5 µg/ml (0.0971 ± 0.0035 mg/ml)] and Escherichia coli [MIC: 47.5 ± 4.2 µg/ml (0.0475 ± 0.0042 mg/ml); MBC: 105.5 ± 6.8 µg/ml (0.1055 ± 0.0068 mg/ml)], with a bactericidal mode of action (MBC/MIC ≤ 4). Remarkably, MgO-NPs restored susceptibility to β-lactam antibiotics (ceftazidime and penicillin) in resistant strains, demonstrating synergistic effects. Antifungal activity of MgO-NPs against Candida albicans (17.3 ± 0.7 mm) and Aspergillus niger (14.4 ± 0.8 mm) at a concentration of 10 mg/ml was also observed. Phytochemical analysis revealed solvent-dependent bioactive constituents in C. colocynthis, with aqueous extracts rich in tannins/phenolics and methanolic extracts rich in flavonoids/terpenoids. This is the first report demonstrating the restoration of antibiotic susceptibility by MgO-NPs synthesized from C. colocynthis extract.

Myroides odoratimimus is an emerging opportunistic pathogen increasingly implicated in infections across human and animal populations. We previously reported the first outbreak of pneumonia in post-weaning piglets associated with M. odoratimimus, marking a significant shift in its recognized host range. The affected swine herd exhibited co-infection with Porcine Circovirus types 2 and 3 (PCV2 and PCV3), likely contributing to proliferative dermatitis and nephropathy syndrome (PDNS), reproductive abnormalities and immunosuppression. This study presents the genomic characterization of a multidrug-resistant strain (M. odoratimimus pgdne) isolated during the outbreak. Whole-genome sequencing revealed multiple antimicrobial resistance determinants-including the chromosomally encoded blaMUS-1 metallo-β-lactamase-and several virulence-associated factors. Genotype-phenotype correlation demonstrated strong concordance. Phylogenetic analysis (distance method, 1,000 bootstrap replicates) showed close relatedness with human isolates, suggesting zoonotic potential. These findings underscore the pathogenic capacity of M. odoratimimus in immunocompromised animal hosts and highlight its relevance to public health and thereby reinforces the need for integrated One Health-based surveillance and control strategies targeting emerging multidrug-resistant pathogens.

Ensuring plant resilience is crucial for maintaining global food security amidst a changing climate. Leveraging the multitude of microorganisms in different environmental conditions appears to be a promising and sustainable approach to boosting agricultural productivity. However, understanding the legacy of microbial bioinoculants in agroecosystems remains a challenging issue, thereby hampering their widespread applicability and acceptance. This review offers an in-depth insight into the intricacies of designing effective bioinoculants, orchestrated by an understanding of the ecological contexts that drive their success. Furthermore, this article emphasizes the importance of adopting a holistic approach to designing effective bioinoculants, thereby enhancing their application in agriculture.

The present study reports the presence of thymoquinone (TQ), a promising benzoquinone compound, in the lichen Dirinaria frostii (strain DF_MSCBU, NCBI-accession no. PP955960), collected from Similipal National Park, India. The extract of D. frostii was subjected to GCMS analysis and detected the presence of thymoquinone. Further, purification of the TQ fraction was carried out using HPLC against a standard thymoquinone reference. FTIR analysis identified the key functional groups. In addition, Nuclear Magnetic Resonance (¹H NMR and ¹³C NMR) spectroscopy was performed to determine the structure and composition of the molecule. The purified TQ was then used for antibacterial assays against pathogenic bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Vibrio cholerae following the MIC method showed pathogen inhibition at different incubation time, of both Gram +ve and Gram -ve bacteria. Thymoquinone showed significant bactericidal activity compared to the standard antibiotics azithromycin, streptomycin, and erythromycin in a dose-dependent manner. This study demonstrates occurrence of thymoquinone from D. frostii as a novel finding and opens new possibilities for its therapeutic applications in the future.