Search Results (8,388)

Botrytis cinerea, the causative agent of gray mold, is a major fungal pathogen affecting a wide range of economically important crops. To identify sustainable alternatives to chemical fungicides, this study characterized the biocontrol potential of two bacterial strains, Serratia quinivorans NFX21 and Pseudomonas thivervalensis NFX104, through genomic analysis and functional assays targeting key stages of fungal growth and plant infection. The NFX21 and NFX104 strains significantly inhibited B. cinerea mycelial growth (~35%) and strongly suppressed conidial germination with performances comparable to the reference biocontrol strain Bacillus amyloliquefaciens QST 713. In tomato detached-leaf and whole-plant pot assays, application of NFX21 and NFX104 significantly reduced gray mold incidence and lesion severity relative to nontreated infected plants (53–64%, detached leaves; 12–13%, whole-plant assays), achieving disease control levels similar to those obtained with the commercial biofungicide Serenade ASO^®. Whole-genome sequencing allowed the taxonomic assignment of the NFX strains and revealed a rich repertoire of biosynthetic gene clusters and antifungal determinants. The NFX21 genome contained genes associated with N-acyl-homoserine lactone-mediated quorum-sensing and production of lipopeptides, siderophores, and extracellular lytic enzymes. The NFX104 genome harbored clusters involved in the biosynthesis of multiple siderophores, 2,4-diacetylphloroglucinol and hydrogen cyanide. Moreover, both the NFX21 and NFX104 genomes contained additional low-homology clusters that potentially encode for novel unexplored metabolites. Collectively, these results support the translational potential of NFX21 and NFX104 as biocontrol candidates for sustainable, integrated management of gray mold caused by B. cinerea. Full article

The global rise in antimicrobial resistance has spurred increased interest in alternative antimicrobial agents, particularly essential oils (EOs). These oils are complex mixtures of volatile compounds that exhibit documented biological activity. This study evaluated antimicrobial and antibiofilm effects of selected EOs against clinically relevant bacterial and fungal pathogens. Antimicrobial activity against planktonic cells was assessed using disc diffusion assays with DMSO-diluted EO solutions against Escherichia coli (E.coli), Staphylococcus aureus (S.aureus), Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Antibiofilm activity of E. coli and S. aureus was examined using ethanol-based EO formulations, with biofilm viability quantified by colony forming unit (CFU) enumeration. Cinnamon (Cinnamomum verum) oil showed the strongest and most consistent activity, inhibiting planktonic and biofilm models. Tea tree (Melaleuca alternifolia), lemongrass (Cymbopogon citratus), rosemary (Rosmarinus officinalis), rose (Rosa damascena), and jasmine (Jasminum officinale) oils showed significant planktonic antimicrobial effects, while jasmine oil (Jasminum officinale) demonstrated pronounced antibiofilm activity against S. aureus, including strong biofilm eradication in several replicates. In contrast, chamomile (Matricaria chamomilla) and sandalwood (Santalum austocaledonicum) oils showed limited or no activity. These findings highlight differences between planktonic and biofilm responses, emphasizing the importance of incorporating biofilm models into antimicrobial evaluation. Overall, Cinnamomum verum and Jasminum officinale oils may serve as complementary antimicrobial agents, warranting further investigation. Full article

Diabetic wounds infected with multidrug-resistant bacteria represent a major clinical challenge due to delayed healing and limited therapeutic options. In this study, we evaluated the therapeutic efficacy and biosafety of a biopolymeric skin patch loaded with the predatory bacterium Bdellovibrio bacteriovorus HD100 in a murine model of diabetic wounds infected with Pseudomonas aeruginosa. In vitro assays demonstrated that B. bacteriovorus HD100 reduced P. aeruginosa populations by approximately 3 log units within 48 h. In vivo, diabetic mice treated with the B. bacteriovorus-loaded patch achieved complete wound closure within $12\pm 1$ days, compared with $16\pm 1$ days in mice treated with conventional antibiotic therapy (piperacillin/tazobactam, 16 mg/kg; single dose). Non-diabetic mice treated with biopolymeric patches, with or without the predatory bacterium, exhibited complete wound closure within 9–10 days. Molecular analysis by PCR revealed no detectable dissemination of B. bacteriovorus DNA to internal organs (liver, spleen, kidney, or brain), indicating the systemic biosafety of topical application. Overall, these results demonstrate that B. bacteriovorus-based skin patches significantly accelerate wound closure in infected diabetic wounds and represent a promising localized biological alternative to conventional antibiotic therapy. Full article

Background: To evaluate the potential of cefiderocol as a topical ophthalmic antibiotic by determining the susceptibility of keratitis isolates from an extensive panel of Gram-negative bacterial species to this siderophore-cephalosporin class antibiotic. Methods: Minimum Inhibitory Concentrations (MICs) of cefiderocol were determined by the broth dilution method using iron-depleted, cation-adjusted Mueller–Hinton broth. The following Gram-negative bacteria were included: Acinetobacter baumannii (n = 13), Achromobacter xylosoxidans (n = 14), Escherichia coli (n = 15), Klebsiella aerogenes (n = 14), Klebsiella pneumoniae (n = 13), Klebsiella oxytoca (n = 14), Moraxella spp. (n = 15), Proteus mirabilis (n = 13), Pseudomonas aeruginosa (n = 17), Serratia marcescens (n = 14) and Stenotrophomonas maltophilia (n = 12). MIC₉₀ values were calculated for each of the species. Results: MIC₉₀ values (µg/mL): A. baumannii (0.5), A. xylosoxidans (0.25), E. coli (0.5), K. aerogenes (1.0), K. oxytoca (0.5), K. pneumoniae (0.5), Moraxella spp. (0.5), P. mirabilis (0.25), P. aeruginosa (0.5), S. marcescens (0.5), and S. maltophilia (0.25). In total, 100% of the isolates were determined to be susceptible to cefiderocol in vitro except for A. xylosoxidans and Moraxella spp., for which there are no established breakpoints for cefiderocol. Conclusions: Cefiderocol demonstrated in vitro activity against the tested panel of Gram-negative keratitis isolates. The results of this study suggest cefiderocol may be useful for the treatment of keratitis caused by numerous Gram-negative pathogens. Further development of cefiderocol for the topical treatment of Gram-negative keratitis is indicated. Full article

Spontaneous fermentation processes can promote uncontrolled microbial growth and increase the risk of foodborne contamination, making the characterization of artisanal beverages essential for consumer safety. This study investigated the microbial composition of quinoa-based rejuvelac, a homemade fermented drink often perceived as a functional food, with the objective of identifying potential microbiological hazards associated with its preparation. High-throughput sequencing of the 16S rRNA V3–V4 region was combined with shotgun metagenomics to profile bacterial communities and recover metagenome-assembled genomes. The analysis revealed a strong dominance of Pseudomonadales, mainly Pseudomonas, Acinetobacter, Enterobacter and Burkholderiales, while lactic acid bacteria typically responsible for stable and safe fermentations were not detected. Shotgun metagenomics recovered medium- to high-quality genomes from Burkholderiaceae and Clostridiales, supporting the overrepresentation of non-beneficial taxa and indicating deviations from expected fermentation microbiota. These results show that the spontaneous preparation of rejuvelac may favor bacterial groups associated with environmental contamination rather than fermentative pathways, underscoring the importance of hygiene practices, controlled starter cultures and monitoring strategies to mitigate microbiological risk. The study highlights the need for improved safety standards in artisanal fermented foods to prevent unintended microbial contamination and protect consumers. Full article

Pseudomonas aeruginosa is a major opportunistic pathogen whose adaptive capacity limits the long-term efficacy of antibiotic therapy. Beyond classical resistance mechanisms, antibiotics may also act as stress signals that alter bacterial physiology and evolutionary trajectories. A central element of this response is the SOS regulatory network, controlled by the RecA–LexA system. Although well studied in Escherichia coli, SOS signaling in P. aeruginosa shows distinct regulatory features that remain incompletely understood. This review summarizes experimental and clinical evidence on antibiotic-induced SOS responses in P. aeruginosa, focusing on fluoroquinolones and other genotoxic agents. Fluoroquinolone exposure consistently induces SOS activation and RecA-dependent signaling, affecting short-term antibiotic susceptibility. However, the available evidence does not support a universal role for SOS activation as a major driver of long-term resistance evolution under most tested conditions. Its relationship with antibiotic-induced mutagenesis remains variable: some studies implicate low-fidelity DNA polymerases, whereas others report mutagenesis independent of canonical RecA–LexA control. Beyond mutagenesis, SOS activation may affect integron dynamics, virulence, and biofilm-associated phenotypes. Overall, in P. aeruginosa, the SOS response appears to be a context-dependent modulator of stress adaptation rather than a universal determinant of resistance evolution. Full article

Objectives: Multidrug-resistant (MDR) Pseudomonas aeruginosa represents a major clinical challenge, driven in part by resistance–nodulation–division (RND) efflux pumps that reduce intracellular antibiotic concentrations and limit the efficacy of many antibacterial agents, including fluoroquinolones. The aim of this study was to identify and characterize TXA11114 as a small-molecule efflux pump inhibitor (EPI) capable of restoring the activity of the fluoroquinolone levofloxacin against MDR P. aeruginosa. Methods: The antibacterial activity of the TXA11114–levofloxacin combination was evaluated using minimum inhibitory concentration (MIC) assays against panels of clinical isolates. Mechanistic studies included levofloxacin accumulation assays, ethidium bromide accumulation assays, outer-membrane permeability measurements, and whole-genome sequencing of mutants with altered potentiation phenotypes. In vivo efficacy was evaluated in murine thigh and lung infection models, while preliminary safety and drug-like properties were assessed using cytotoxicity assays and in vitro ADME profiling. Results: The TXA11114–levofloxacin combination produced > 1 log₁₀ CFU reductions in bacterial burden in murine thigh and lung infection models, exceeding the activity of levofloxacin monotherapy. TXA11114 markedly potentiated levofloxacin activity, producing substantial reductions in levofloxacin MIC values across multiple MDR clinical isolates, and also enhanced the activity of several additional efflux pump substrates, including β-lactams, tetracyclines, chloramphenicol, and trimethoprim–sulfamethoxazole. Mechanistic experiments demonstrated increased intracellular accumulation of efflux substrates without evidence of nonspecific membrane disruption, and mutations in ompH were associated with altered potentiation phenotypes. Conclusions: The TXA11114–levofloxacin combination produced significantly greater bacterial reductions than levofloxacin monotherapy in murine infection models. Levofloxacin was selected because fluoroquinolone resistance in P. aeruginosa is frequently driven by efflux-mediated mechanisms. While this study focused on levofloxacin potentiation, future work will evaluate additional efflux pump substrates and further define the molecular target of TXA11114. Full article

Controlled environment agriculture (CEA) relies on hydroponic systems to achieve high yields, yet optimizing plant performance remains a challenge. Beneficial endophytic bacteria offer a sustainable solution by promoting growth and nutrient uptake. Here, we investigated the mechanistic basis of growth enhancement in lettuce (Lactuca sativa) inoculated with Pseudomonas psychrotolerans IALR632 in a nutrient film technique (NFT) system. Growth measurements showed significant increases in shoot and root biomass and leaf greenness. RNA-seq profiling at 4, 10, and 15 days after transplanting revealed dynamic transcriptional reprogramming, with 38, 796, and 7642 differentially expressed genes, respectively. MapMan and GO analyses indicated up-regulation of pathways related to cell wall remodeling, lipid metabolism, nitrogen assimilation, and stress adaptation, alongside modulation of ethylene signaling. Root bacterial microbiome through 16S metabarcoding sequencing demonstrated distinct community shifts, confirmed by analysis of similarity (ANOSIM) (R = 1, p = 0.028), with enrichment of genera linked to nutrient cycling and plant growth promotion. These findings provide integrated molecular and ecological evidence that IALR632 enhances lettuce growth by coordinating host gene expression and rhizobiome restructuring, offering a mechanistic framework for microbial inoculant strategies in hydroponic horticulture. Full article

Antimicrobial resistance represents a major global challenge for healthcare systems, particularly in urinary tract infections (UTIs), where empirical antibiotic therapy is frequently required. Acute pyelonephritis (AP) remains a severe condition, requiring prompt diagnosis and treatment. Local epidemiological data are essential for optimizing therapeutic strategies. The aim of this study was to analyze the pathogen distribution and antimicrobial resistance (AMR) patterns in patients with complicated AP. An observational, analytical study on community-acquired and hospital-acquired AP was conducted on patients admitted with complicated AP between January 2021 and December 2025. After applying the inclusions and exclusions criteria, 553 urinary isolates with complicated AP were analyzed to determine pathogen distribution and phenotypic AMR patterns derived from antimicrobial susceptibility testing. A total of 109 (19.7%) AMR isolates presented resistance phenotype. Resistant phenotypes were more frequently observed among male gender; age did not reach statistical significance. This study highlights the continued predominance of Escherichia coli in complicated AP while demonstrating a significant AMR burden among non-Escherichia coli pathogens, particularly Klebsiella and Pseudomonas species. These findings emphasize the importance of local epidemiological surveillance and culture-guided antibiotic therapy in the management of complicated UTIs. Full article

Despite the importance of surface microbiota in postharvest quality, the effects of mechanical damage on microbial succession in Hypsizygus marmoreus during refrigerated storage remain insufficiently understood. In this study, 16S rRNA gene and ITS amplicon sequencing were used to characterize the bacterial and fungal communities on intact and mechanically damaged H. marmoreus during 15 days of storage at 4 °C. Storage time, rather than mechanical damage, was the main driver of whole-community variation, although mechanical damage accelerated visible spoilage assessed qualitatively. Bacterial communities showed pronounced temporal turnover, shifting from early Firmicutes-rich assemblages to late-stage Proteobacteria-dominated communities, especially Pseudomonas. In contrast, fungal communities remained largely dominated by Ascomycota throughout storage, although mechanically damaged mushrooms showed a greater late-stage occurrence of opportunistic yeasts such as Candida. Predicted functional and phenotypic analyses further suggested late-stage increases in Gram-negative, aerobic, biofilm-forming, stress-tolerant, and potentially pathogenic bacterial traits. Because these traits were inferred from 16S rRNA gene-based prediction rather than measured directly, they should be interpreted cautiously. Overall, the results suggest that maintaining the physical integrity of H. marmoreus during postharvest handling may help preserve quality and delay the emergence of spoilage-associated microbial traits during refrigerated storage. Full article

Quorum sensing (QS) represents a promising target for anti-virulence therapy; however, effective pharmacological intervention requires a detailed understanding of regulatory network architecture and environmental context. In Klebsiella pneumoniae, the orphan LuxR-type receptor SdiA lacks a cognate LuxI synthase and instead detects exogenous acyl-homoserine lactones (AHLs), positioning it as an inter-species signal integrator. Here, we demonstrate that SdiA functions as a context-dependent regulator whose impact on biofilm formation and virulence gene expression is gated by environmental AHL availability. Using isogenic ΔluxS, ΔsdiA, and ΔluxSΔsdiA mutants in a clinical bloodstream isolate, we show that under AHL-limited conditions, SdiA promotes baseline biofilm development, whereas in the presence of exogenous C6-HSL, it restrains excessive biofilm maturation. Two-way ANOVA confirmed significant genotype, treatment, and interaction effects, establishing that SdiA-mediated regulation is signal contingent. We further investigated the halogenated thiolactone meta-bromo-thiolactone (mBTL), previously described as a QS inhibitor in Pseudomonas aeruginosa. In K. pneumoniae, mBTL acts as a context-selective modulator rather than a simple inhibitor. Under AHL-limited conditions, mBTL phenocopied ΔsdiA, reducing biofilm formation and inducing overlapping transcriptional profiles. In contrast, under AHL-replete conditions, mBTL opposed SdiA-dependent gene expression, consistent with competitive antagonism of ligand-bound receptor. RNA-seq analysis revealed substantial concordance between ΔsdiA and WT + mBTL under AHL-free conditions, with the inversion of transcriptional directionality in the presence of C6-HSL. The findings redefine SdiA as a conditional quorum-sensing integrator and identify mBTL as a ligand-context-dependent modulator of LuxR-type signaling. Our results highlight the necessity of evaluating anti-virulence compounds across relevant signal environments and introduce receptor state-selective modulation as a strategic framework for targeting hybrid quorum-sensing systems in polymicrobial pathogens. Full article

Ethnopharmacological relevance. Withania somnifera (L.) Dunal, widely used in traditional medical systems such as Ayurveda, Unani, and Middle Eastern folk medicine, is valued for its adaptogenic, anti-inflammatory, neuroprotective, antimicrobial, and anticancer properties. These activities are primarily attributed to withanolides, with Withaferin A recognized as one of the most bioactive constituents. Although traditional preparations often rely on the root, leaf use provides a more sustainable alternative and may yield significant quantities of active metabolites. Identifying efficient, modern extraction technologies that can enhance the recovery of bioactive compounds from leaves is essential for developing effective, standardized ethnopharmacological formulations. Materials and methods. Plants of W. somnifera grown from seeds were subjected to different environmental conditions (control, drought, cold, yeast extract treatment). Leaves were extracted using Pressurized Cyclic Solid–Liquid Extraction (PCSLE) with hydroalcoholic solvents and compared with conventional infusion of dried leaves. Extracts were fractionated with solvents of varying polarity and analyzed by TLC, HPLC, and NMR for quantification of Withaferin A. Expression levels of key withanolide-biosynthetic genes (CAS, SMT1, DWARF1, CYP71, CYP76) were assessed using qRT-PCR. Antimicrobial activity of pure Withaferin A, aqueous extract, and hydroalcoholic PCSLE extract was evaluated through MIC and MBC assays against Gram-positive and Gram-negative strains. Cytotoxic activity was measured via MTT assays in six human cancer cell lines after 3, 6, and 24 h of treatment. Results. PCSLE yielded substantially higher levels of Withaferin A than traditional infusion, especially in medium-polarity fractions (chloroform and ethyl acetate), with concentrations reaching 0.70% in fresh leaf mass (4.8% dry weight), compared to 0.11% obtained by infusion. Gene expression analysis revealed that 24-week-old plants exhibited the highest transcription of withanolide-biosynthetic genes, and drought stress significantly upregulated CAS, SMT1, DWARF1, CYP71, and CYP716, indicating enhanced metabolic flux toward withanolide production. Hydroalcoholic PCSLE extracts showed broad-spectrum antimicrobial activity, with MIC and MBC values comparable to pure Withaferin A and demonstrating bactericidal effects against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes. The aqueous extract showed activity only against Gram-positive strains. Cytotoxicity assays demonstrated an optimistic, dose-dependent reduction in cell viability across all tumour cell lines treated with the hydroalcoholic PCSLE extract, closely mirroring the activity of pure Withaferin A and consistently exceeding the effect of the aqueous extract. IC50 values confirmed the high bioactive content of PCSLE extracts and suggested mechanisms like those known for Withaferin A. Conclusions. PCSLE proved to be a highly efficient extraction technology for obtaining leaf extracts rich in Withaferin A, outperforming conventional extraction methods while exploiting sustainable plant tissue. Developmental stage and drought stress significantly modulated the expression of genes involved in withanolide biosynthesis, highlighting agronomic strategies capable of enhancing metabolite production. Hydroalcoholic PCSLE extracts exhibited antimicrobial and cytotoxic activities comparable to pure Withaferin A, supporting their relevance as promising therapeutic candidates. These findings advocate for the use of W. somnifera leaves as a sustainable source of bioactive compounds and demonstrate that advanced extraction technologies can contribute to the development of innovative ethnopharmacological preparations for antimicrobial and anticancer applications. Full article

This study evaluated activities of crude extracts from different parts of the tree of heaven (Ailanthus altissima (Mill.) Swingle) collected in Slovenia and Hungary, using effect-directed analyses based on hyphenation of high-performance thin-layer chromatography (HPTLC) and nine in vitro assays performed in situ on chromatographic plates after the separation. HPTLC separation combined with a set of four antibacterial assays, two antifungal assays, and three enzyme inhibitor assays to evaluate the extracts of 14 plant parts: young shoots, young leaves, mature leaves, yellow leaves, petioles of leaves, petioles of male inflorescences, petioles of fruits, female inflorescences, male inflorescences, mature male inflorescences, bark of 1–2-year branches, bark of 2-year branches, bark of tree trunk, and bark of roots. Antibacterial activities against Gram-positive bacteria (Bacillus subtilis, Rhodococcus fascians) and Gram-negative bacteria (Aliivibrio fischeri, Pseudomonas syringae pv. maculicola (Psm)), as well as inhibition of enzymes α-glucosidase, lipase, and acetylcholinesterase, were observed for all extracts. Extracts differed in their antifungal activities. Extracts of young shoots, mature leaves, petioles of leaves, and bark of roots showed antifungal activity against plant pathogens Fusarium avenaceum and Bipolaris sorokiniana. Extracts of yellow leaves, male inflorescences, bark of 1–2-year branches, and bark of tree trunks were only active against F. avenaceum, whereas extracts of young leaves were only active against B. sorokiniana. This study is the first to report that A. altissima extracts exhibit (1) antifungal activity against F. avenaceum and B. sorokiniana; (2) antibacterial activity against A. fischeri, Psm, R. fascians, and B. subtilis (except leaves, bark of branches and bark of tree trunks); and (3) inhibitory activity toward lipase, α-glucosidase (except bark of tree trunks), and acetylcholinesterase (except bark of tree trunks). Full article

The rhizosphere is a critical interface linking plants and soil; however, the mechanisms by which parasitic plants affect host growth through rhizosphere microecological changes remain unclear. This study systematically elucidates how Monochasma savatieri, a hemiparasitic plant, promotes blueberry growth by reshaping rhizosphere microecology. Pot experiments showed that parasitism significantly enhanced urease, sucrase, and soil nitrate reductase activities, improving organic matter decomposition and nutrient transformation efficiency. Concurrently, soil total nitrogen (TN), total phosphorus (TP), and total potassium (TK), along with alkali-hydrolyzable nitrogen (AN) and available potassium (AK), decreased, suggesting enhanced nutrient absorption by roots. At the microbial level, parasitism altered community composition and diversity, enriching functional taxa such as Nitrosomonas, OLB5, and Serendipita. Functionally, pathways related to stress resistance (necroptosis and glutamatergic synapses) were activated, whereas those linked to pathogen colonization (Pseudomonas aeruginosa biofilm formation and tryptophan metabolism) were suppressed. These modifications reduced harmful microbial competition, optimized nutrient cycling and signaling networks, and established a favorable rhizosphere microenvironment for root health. By integrating soil enzyme activity, nutrient dynamics, and microbial functions, M. savatieri systemically improves the rhizosphere microenvironment, ultimately enhancing blueberry growth. This study provides theoretical support for intercropping and management of parasitic plants with blueberries. Full article

Triphenyl phosphate (TPHP), a typical organophosphate flame retardant, has been listed as an emerging pollutant, yet its biodegradation remains poorly studied. Herein, an efficient TPHP-degrading marine bacterium, Pseudomonas abyssi RL-WG04, was isolated from mangrove sediments, which could degrade 95.22% of 100 mg/L TPHP within 120 h. RL-WG04 exhibited good tolerance to varied environmental conditions, maintaining over 70% TPHP degradation percentages (100 mg/L, 7 d) across 20–50 °C, pH 7.0–9.0, and salinity 2.0–4.0% (NaCl, w/v). Organic solvents (p-xylene, biphenyl, toluene and ethyl acetate, 0.5% v/v) had a negligible impact, whereas metal ions (Mn²⁺, Fe³⁺, Ca²⁺, Cu²⁺, Mg²⁺, Zn²⁺, and Co²⁺) strongly inhibited degradation, especially at 1 mM. Under optimized conditions, TPHP degradation by RL-WG04 followed the improved Gompertz model (R² = 0.99927). Metabolite identification indicated that RL-WG04 transformed TPHP into phenol but failed to utilize phenol for growth because of the phenol 2-monooxygenase deficiency. Nevertheless, the constructed consortia of RL-WG04 and Pseudomonas sp. RL-LY03 (phenol-degrading bacterium) achieved complete TPHP degradation and cell proliferation. Additionally, RL-WG04 could efficiently remove TPHP (25 mg/kg) from clay and sandy mangrove sediments with 100% and 90.04% removal percentages, respectively. Overall, this work provides novel insights into the fate of TPHP and a potential approach for its remediation. Full article