Search Results (1,799)

Background: Shiga toxin (Stx), produced by enterohemorrhagic Escherichia coli (EHEC), is a highly potent exotoxin responsible for severe complications such as hemolytic uremic syndrome (HUS). Among its isoforms, Stx2 exhibits stronger cytotoxicity and poses greater clinical risk, yet no effective therapy currently exists. Methods: In this study, two human monoclonal antibodies, YG12-1 and YG12-2, were identified from a phage display library and systematically characterized using an integrated modeling–validation workflow. Results: Structural modeling with ImmuneBuilder and Rosetta revealed that YG12-2 possessed a longer CDRH3 topology, more short-range hydrogen bonds, and stronger electrostatic complementarity, corresponding to lower binding energy and higher apparent affinity in ELISA and SPR. Although YG12-2 had a better affinity, YG12-1 shows better protective activity in a murine model of acute peritoneal infection. This paradox highlights a non-linear relationship between structural affinity and biological efficacy, emphasizing the importance of functional epitope accessibility and pharmacokinetic behavior in determining neutralization outcomes. Conlusions: Overall, these results indicated that targeting Stx2 with YG12-1 and YG12-2 could serve as a promising protective strategy against E. coli O157:H7 infection. Full article

Background: Chronic diabetic wounds, particularly diabetic foot ulcers (DFUs), are prone to recurrent infection and delayed healing, resulting in substantial morbidity, mortality, and economic burden. Multifunctional wound dressings that combine antibacterial, antioxidant, conductive, and self-healing properties may help to address the complex microenvironment of chronic diabetic wounds. Methods: In this study, ε-poly-L-lysine and amino-terminated polyethylene glycol were grafted onto carboxylated single-walled carbon nanotubes (SWCNTs) via amide coupling to obtain ε-PL-CNT-PEG. Aminated chondroitin sulfate (CS-ADH) and a catechol–metal coordination complex of protocatechualdehyde and Fe³⁺ (PA@Fe) were then used to construct a dynamic covalently cross-linked hydrogel network through Schiff-base chemistry. The obtained hydrogels (Gel0–3, Gel4) were characterized for photothermal performance, rheological behavior, microstructure, swelling/degradation, adhesiveness, antioxidant capacity, electrical conductivity, cytocompatibility, hemocompatibility, and antibacterial activity in the presence and absence of near-infrared (NIR, 808 nm) irradiation. Results: ε-PL-CNT-PEG showed good aqueous dispersibility, NIR-induced photothermal conversion, and improved cytocompatibility after surface modification. Incorporation of ε-PL-CNT-PEG into the PA@Fe/CS-ADH network yielded conductive hydrogels with porous microstructures and storage modulus (G′) higher than loss modulus (G′′) over the tested frequency range, indicating stable gel-like behavior. The hydrogels exhibited self-healing under alternating strain and macroscopic rejoining after cutting. Swelling and degradation studies demonstrated pH-dependent degradation, with faster degradation in mildly acidic conditions (pH 5.0), mimicking infected chronic diabetic wounds. The hydrogels adhered to diverse substrates and tolerated joint movements. Gel4 showed notable DPPH• and H₂O₂ scavenging (≈65% and ≈60%, respectively, within several hours). The electrical conductivity was 0.19 ± 0.0X mS/cm for Gel0–3 and 0.21 ± 0.0Y mS/cm for Gel4 (mean ± SD, n = 3), falling within the range reported for human skin. In vitro, NIH3T3 cells maintained >90% viability in the presence of hydrogel extracts, and hemolysis ratios remained below 5%. Hydrogels containing ε-PL-CNT-PEG displayed enhanced antibacterial effects against Escherichia coli and Staphylococcus aureus, and NIR irradiation further reduced bacterial survival, with some formulations achieving near-complete inhibition under low-power (0.2–0.3 W/cm²) 808 nm irradiation. Conclusions: A dynamic, conductive hydrogel based on PA@Fe, CS-ADH, and ε-PL-CNT-PEG was successfully developed. The hydrogel combines photothermal antibacterial activity, antioxidant capacity, electrical conductivity, self-healing behavior, adhesiveness, cytocompatibility, and hemocompatibility. These properties suggest potential for application as a wound dressing for chronic diabetic wounds, including diabetic foot ulcers, although further in vivo studies are required to validate therapeutic efficacy. Full article

Due to the indiscriminate use of antimicrobial drugs in the treatment of infectious diseases, human pathogenic bacteria have developed resistance to many commercially available antibiotics. Medicinal plants such as Convolvulus arvensis represent a renewable resource for the development of alternative therapeutic agents. This study aimed to evaluate the antibacterial activity of silver nanoparticles (AgNPs) biosynthesized from C. arvensis against two clinical antibiotic-resistant bacterial isolates. The pathogenic isolates were identified as Staphylococcus aureus MRSA and Escherichia coli ESBL using 16S rRNA gene sequencing. Silver nanoparticles were synthesized via a green synthesis approach, and their physicochemical properties were characterized using UV–Vis spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, zeta potential, and dynamic light scattering (DLS). The synthesized C. arvensis–AgNPs exhibited a surface plasmon resonance peak at 475 nm and predominantly spherical morphology with particle sizes ranging from 102.34 to 210.82 nm. FTIR analysis indicated the presence of O–H, C–O, C–N, C–H, and amide functional groups. The nanoparticles showed a zeta potential of −18.9 mV and an average hydrodynamic diameter of 63 nm. The antibacterial activity of the biosynthesized AgNPs was evaluated against methicillin-resistant S. aureus (MRSA and ATCC 29213) and E. coli (ESBL and ATCC 25922) using agar diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. Inhibition zones ranged from 10 to 13 mm, with MIC and MBC values of 12.5–25 µg/mL and 25–50 µg/mL, respectively. In addition, the nanoparticles exhibited antioxidant activity (DPPH assay, IC₅₀ = 0.71 mg/mL) and anti-inflammatory effects as determined by protein denaturation inhibition. No cytotoxic effects were observed in the MCF-7 cell line at the MIC level. These findings suggest that C. arvensis–AgNPs have potential as natural antimicrobial, antioxidant, and anti-inflammatory agents. Full article

Field-effect transistor (FET) biosensors enable label-free and real-time electrical transduction; however, their practical deployment is often constrained by the need for bulky benchtop instrumentation to provide stable biasing, low-noise readout, and data processing. Here, we report a portable extended-gate FET (EG-FET) integrated sensing system that consolidates the sensing interface, analog front-end conditioning, embedded acquisition/control, and user-side visualization into an end-to-end prototype suitable for on-site operation. The system couples a screen-printed Au extended-gate electrode to a MOSFET and employs a low-noise signal-conditioning chain with microcontroller-based digitization and real-time data streaming to a host graphical interface. As a proof-of-concept, enterohemorrhagic Escherichia coli O157:H7 was selected as the target. A bacteria-specific immunosensing interface was constructed on the Au extended gate via covalent immobilization of monoclonal antibodies. Measurements in buffered samples produced concentration-dependent current responses, and a linear calibration was experimentally validated over 10⁴–10¹⁰ CFU/mL. In specificity evaluation against three common foodborne pathogens (Staphylococcus aureus, Salmonella typhimurium, and Listeria monocytogenes), the sensor showed a maximum interference response of only 13% relative to the target signal (ΔI/ΔImax) with statistical significance (p < 0.001). Our work establishes a practical hardware–software architecture that mitigates reliance on benchtop instruments and provides a scalable route toward portable EG-FET sensing for rapid, point-of-need detection of foodborne pathogens and other biomarkers. Full article

D-tagatose is a high-value, low-calorie sweetener that can be produced from dairy lactose via a two-step enzymatic route: lactose hydrolysis to galactose followed by galactose isomerization to tagatose. Here, we combined genomics, in silico structural analysis, and biochemical assays to evaluate the lactose-to-tagatose conversion potential of an Antarctic isolate, L47, identified as Ewingella americana (NCBI accession SAMN54554459). Genome mining revealed one L-arabinose isomerase gene (araA) and three β-galactosidase genes (bgaA, bglY, lacZ), an uncommon combination in a single bacterium. Recombinant AraA was produced in Escherichia coli and biochemically characterized, showing Mn²⁺ dependence and measurable D-galactose isomerization, reaching ~18% tagatose from 100 mM galactose after 48 h under the tested conditions. In contrast, the β-galactosidases were predominantly recovered as insoluble aggregates in E. coli; therefore, β-galactosidase activity was assessed using washed inclusion-body preparations. Under these conditions, BgaA displayed the most consistent o-NPG hydrolyzing activity, whereas BglY and LacZ did not yield reproducible activity. Overall, our results identify BgaA as the most tractable lactose-hydrolyzing candidate from L47 in the current workflow and indicate that AraA performance is the principal bottleneck toward an efficient lactose-to-tagatose process, motivating future optimization at the enzyme and process levels. Full article

The development of functional polymer films on porous paper substrates is inherently constrained by substrate-induced defects that hinder film continuity and barrier performance. In this study, process-controlled amylose–Poly(Vinyl alcohol) (PVA) coatings incorporating ZnO nanoparticles (ZnO NPs) were fabricated via aqueous deposition to investigate the process-structure-property relationship governing oxygen barrier behavior on paper. The moisture resistance of the coating was also evaluated. Single-layer coatings exhibited severe barrier failure due to insufficient film formation and pervasive pinhole defects. In contrast, systematic multi-layer deposition enabled the formation of continuous polymer films. A pronounced non-linear reduction in oxygen transmission rate was observed once the dry coating thickness exceeded approximately 5 µm. Under these conditions, the oxygen transmission rate decreased to approximately 15 cc/m²·day·atm at 20 °C and 65% relative humidity. This transition was correlated with the elimination of substrate-induced defects, as confirmed by morphological analysis. In addition to enhanced barrier performance, ZnO NP-loaded coatings demonstrated strong and broad-spectrum antimicrobial activity against both Escherichia coli and Staphylococcus aureus, indicating their multifunctional potential for active packaging applications. Supporting evaluations further indicated adequate mechanical flexibility and high repulpability, highlighting the suitability of the coating for sustainable paper-based packaging. Overall, this work identifies a quantitative critical film thickness that serves as process-specific design guideline for engineering high-performance functional polymer coatings on porous paper substrates. Full article

Fungal secondary metabolites are valuable sources of natural antioxidants and antimicrobials. This study evaluated the submerged fermentation of Penicillium crustosum OR889307 supplemented with lemon peel as a co-substrate to enhance the production of bioactive compounds. Lemon peel was selected for its phenolic precursors and sustainable availability as an agro-industrial byproduct. Crude extracts, aqueous and organic fractions, and molecular-weight partitions were assessed for antioxidant activity using the DPPH assay and for antimicrobial activity against Escherichia coli, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa, and Candida albicans. Semi-purified extracts from co-substrate fermentations exhibited enhanced bioactivity, showing MIC values of 185 µg/mL against P. aeruginosa and 225 µg/mL against MRSA, along with strong ABTS radical-scavenging capacity (238.95 ± 2.17 µmol TE). RP-HPLC-ESI-MS profiling revealed phenolic acids, flavanones, flavonols, and lignans, including ferulic acid 4-O-glucoside, bisdemethoxycurcumin, secoisolariciresinol, and quercetin 3-O-xylosyl-glucuronide. These findings demonstrate that lemon peel supplementation promotes the biosynthesis of antimicrobial and antioxidant metabolites by P. crustosum. This approach supports sustainable agro-waste valorization and offers a promising strategy for obtaining natural bioactive compounds with potential applications in food preservation and health-related formulations. Full article

Background/Objectives. Lactiplantibacillus plantarum CRL681 has previously demonstrated a strong antagonistic effect against Escherichia coli O157:H7 in food matrices; however, the molecular mechanisms underlying this activity remain poorly understood. Since initial interactions between beneficial bacteria and pathogens occur mainly at the cell surface and in the extracellular environment, the characterization of the bacterial secretome is essential for elucidating these mechanisms. In this study, the secretome of L. plantarum CRL681 was comprehensively characterized using an integrated in silico and in vitro approach. Methods. The exoproteome and surfaceome were analyzed by LC-MS/MS under pure culture conditions and during co-culture with E. coli O157:H7. Identified proteins were functionally annotated, classified according to subcellular localization and secretion pathways, and evaluated through protein–protein interaction network analysis. Results. A total of 275 proteins were proposed as components of the CRL681 secretome, including proteins involved in cell surface remodeling, metabolism and nutrient transport, stress response, adhesion, and genetic information processing. Co-culture with EHEC induced significant changes in the expression of proteins associated with energy metabolism, transport systems, and redox homeostasis, indicating a metabolic and physiological adaptation of L. plantarum CRL681 under competitive conditions. Notably, several peptidoglycan hydrolases, ribosomal proteins with reported antimicrobial activity, and moonlighting proteins related to adhesion were identified. Conclusions. Overall, these findings suggest that the antagonistic activity of L. plantarum CRL681 against E. coli O157:H7 would be mediated by synergistic mechanisms involving metabolic adaptation, stress resistance, surface adhesion, and the production of non-bacteriocin antimicrobial proteins, supporting its potential application as a bioprotective and functional probiotic strain. Full article

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen of public health concern, requiring a One Health approach to clarify its transmission and distribution. However, its prevalence and genomic characteristics in livestock and companion animals remain underexplored in low-income countries. We investigated prevalence and genomic features of STEC in animals in western Ghana, representing the first genomic report of STEC in Ghana. Fecal samples (97) were collected from goats (n = 33), sheep (n = 33), dogs (n = 30), and a cat (n = 1), with STEC detected in 12.1% of goats and sheep samples. Whole-genome sequencing identified serotypes O38:H26, O43:H2, and O157:H7. stx1c and stx2b genes were detected in O38:H26 and O43:H2, whereas stx2c and key virulence genes (chuA, eae, esp, nle, tir, and toxB) were exclusively found in O157:H7. Phylogenetic analysis revealed that O38:H26 isolates form a cluster closely related to clinical strains from the UK. O43:H2 isolates exhibited diverse stx profiles, linking animal, environmental, and clinical strains from North America and the UK. O157:H7 isolates were genetically similar to European clinical and food-derived strains, suggesting that goats and sheep are important STEC reservoirs in Ghana, offering data for public health risk assessment and effective One Health-based control strategies. Full article

The development of eco-friendly antimicrobial materials is essential for addressing antibiotic resistance, while reducing environmental impact. In this study, bio-derived anionic and cationic cellulose nanofibers (a-CNF and c-CNF) were employed as templating matrices for the in situ hydrothermal synthesis of cellulose/ZnO nanohybrids. Physicochemical characterization confirmed efficient cellulose functionalization and high-quality nanofibrillation, as well as the formation of uniformly dispersed ZnO nanoparticles (≈10–20 nm) strongly integrated within the cellulose network. The ZnO content was 30 and 20 wt. % for a-CNF/ZnO and c-CNF/ZnO, respectively. Antibacterial evaluation against Escherichia coli and Staphylococcus aureus revealed enhanced activity for both hybrids, with c-CNF/ZnO displaying the lowest MIC/MBC values (50/100 μg/mL). Antiviral assays revealed complete feline calicivirus inactivation at 100 μg/mL for c-CNF/ZnO, while moderate activity was observed against bovine coronavirus, highlighting the role of surface charge. Cytotoxicity assays on mammalian cells demonstrated high biocompatibility at antimicrobial concentrations. Life cycle assessment showed that c-CNF/ZnO exhibits a lower overall environmental burden than a-CNF/ZnO, with electricity demand being the main contributor, indicating clear opportunities for further reductions through process optimization and scale-up. Overall, these results demonstrate that CNF/ZnO nanohybrids effectively combine renewable biopolymers with ZnO antimicrobial functionality, offering a sustainable and safe platform for biomedical and environmental applications. Full article

Globally, large quantities of animal waste and human sewage sludge are generated annually. Their application as soil amendments can enhance soil quality and support a circular economy. However, these wastes may harbour pathogenic bacteria, posing contamination risks to soil and water and potential transmission to animals and humans. This study investigated the survival of five bacterial pathogens during six months of storage in five types of organic waste and following their subsequent application to soil. During storage, T₉₀ values ranged as follows: Salmonella Typhimurium (2.3–17.7 days), Campylobacter jejuni (0 to 23.9 days), Escherichia coli O157:H7 (4.3 to 57.8 days), and Listeria monocytogenes (1.9 to 170.4 days). In soil, T₉₀ values were S. Typhimurium (4.2 to 17.4 days), C. jejuni (4.8 to 26.8 days), E. coli O157:H7 (4.3 to 52.9 days), and L. monocytogenes (2 to 83.7 days). Clostridium sporogenes remained stable throughout both experiments, preventing T₉₀ calculation. Contrary to our initial hypothesis that soil microbiota would accelerate pathogen decline, T₉₀ values were higher during storage in 11 cases and higher in soil in nine scenarios. These findings highlight the need for pre-treatment strategies for animal waste and biosolids before land spreading to consistently mitigate risks of pathogen transmission and environmental contamination. Full article

To address the low-value recycling dilemma of waste polyvinyl butyral (PVB) and cater to the demand for sustainable multifunctional active food packaging, this study developed a facile and cost-effective solution blow spinning approach. Continuous, smooth, and bead-free nanofiber membranes were prepared by optimizing the solution blow spinning process parameters. Zinc oxide nanoparticles (ZnO NPs) were incorporated into the PVB nanofiber membrane with vacuum impregnation. The results demonstrated that ZnO NPs significantly enhanced the tensile strength, thermal stability, and the UV absorption of PVB fiber membranes. ZnO/PVB fiber membranes exhibited antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Practical preservation tests showed that ZnO/PVB fiber membranes effectively inhibited cherry tomatoes’ microbial spoilage and water loss, extending the shelf life of tomatoes to 13 days. These findings validate the potential of ZnO/PVB composite nanofiber membranes as active food packaging and provide a feasible technical pathway for the low-cost, efficient utilization of recycled PVB. Full article

The use of natural antimicrobials and advanced sensor technologies is increasingly explored to improve the safety and quality of dairy products like cheese. The current work evaluated the effect of sodium alginate edible films enriched with oregano essential oil (EO) on the microbial spoilage of Feta cheese and the fate of Escherichia coli O157:H7 and Listeria monocytogenes during storage. Samples were inoculated with approximately a 4 log CFU/g of pathogens and subsequently wrapped with edible films containing EO or left without, serving as controls. Samples were stored under aerobic and vacuum conditions at 4 and 12 °C. Microbiological analyses, pH, and sensory attributes were monitored during storage, while multispectral imaging (MSI) devices were used for rapid, non-invasive quality assessment. EO films moderately suppressed spoilage and pathogen survival, particularly under aerobic conditions. The MSI spectral data coupled with machine learning models provided reasonable results for the estimation of yeast and mould populations, with the best models coming from aerobic conditions, from benchtop-MSI data, with R² = 0.726 and RMSE = 0.426 from the Neural Networks model, and R² = 0.661 and RMSE = 0.696 from the LARS model. The results highlight the combined potential of natural antimicrobial films and MSI-based sensors for extending Feta cheese shelf life and enabling rapid, non-destructive monitoring, respectively. Full article

Torularhodin is the monocyclic C40 carotenoid with the β-ring and a terminal carboxyl group at the acyclic part, with long conjugated double bonds, only synthesized in fungi called red (oleaginous) yeasts, e.g., the genera Rhodotorula and Sporobolomyces. This unique red pigment with strong antioxidant properties is promising for use in food additives, nutritional supplements, and cosmetics. We aimed to produce torularhodin in Escherichia coli through the identification of the biosynthesis genes needed for its heterologous production, while no genes oxidizing torulene to torularhodin had been reported. The Rhodotorula toruloides crtI (CAR1) and crtYB (CAR2) genes, which were chemically synthesized, proved to lead to the complete conversion of phytoene into torulene when they were introduced into an E. coli cell that carried the Pantoea ananatis crtE and Haematococcus pluvialis IDI genes. We found that the Planococcus maritimus genes coding for C30 carotenoid terminal oxidase (crtP/crtNb/cruO) and aldehyde dehydrogenase (aldH/crtNc), through their introduction into the E. coli transformant synthesizing torulene, mediated the efficient oxidations of torulene to torularhodin, and resulted in the production of torularhodin as the dominant carotenoid. This is the first report of torularhodin production in a heterologous host. We also identified the aldH/crtNc gene in R. toruloides. Full article

This work presents the results of the synthesis and investigation of new antibacterial composite materials based on acrylonitrile–butadiene–styrene (ABS) copolymer and o-, m-, p-carboxyphenylmaleimides (CPhMI). The composites were obtained by thermal mixing with varying contents of different CPhMI isomers in the polymer matrix. The structural and thermal characteristics of the synthesized materials were investigated using IR and UV spectroscopy, as well as thermogravimetric (TGA) and differential thermal analysis (DTA). The results indicate that the o-isomer imparts the highest thermal stability, while the p-isomer shows slightly lower stability. In terms of processability, the m-isomer exhibits the highest melt flow, the p-isomer an intermediate level, and the o-isomer the lowest. The antibacterial activity of the composites was evaluated by the agar diffusion method against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) microorganisms. All synthesized samples exhibited strong antibacterial activity against S. aureus and E. coli at a concentration of 0.5 wt%, confirming their potential for application in medical devices, as well as in sanitary polymer coatings and packaging. Full article