Search Results (1,844)

The increasing prevalence of multidrug-resistant (MDR) Campylobacter species poses a serious threat to food safety and public health, highlighting the urgent need for natural antimicrobial alternatives to conventional antibiotics. This study investigated the antibacterial potential and mechanism of action of seven essential oils (EOs), Cymbopogon citratus, Mentha pulegium, Artemisia absinthium, Myrtus communis, Thymus algeriensis, Thymus capitatus, and Eucalyptus globulus, against multidrug-resistant Campylobacter jejuni and Campylobacter coli. The antimicrobial activity was first assessed by the agar disk diffusion and broth microdilution methods to determine inhibition zones, minimum inhibitory concentrations (MICs), and minimum bactericidal concentrations (MBCs). The most active EOs were further evaluated through time–kill kinetics, cell lysis, salt tolerance, and membrane integrity assays to elucidate their bactericidal mechanisms. Results showed that E. globulus, T. algeriensis, and M. communis exhibited the strongest inhibitory effects, particularly against C. jejuni, with MIC values ranging from 3.125% to 6.25%, while C. coli was more resistant. Time–kill and lysis experiments demonstrated rapid bacterial reduction and significant decreases in optical density, indicating cell disruption. Additionally, EO treatments reduced salt tolerance and induced leakage of cytoplasmic materials, confirming membrane damage. Overall, these findings suggest that selected essential oils exert potent antimicrobial effects through membrane disruption and osmotic imbalance, offering promising natural strategies to control MDR Campylobacter in food systems. The application of such bioactive compounds could contribute significantly to improving food quality, extending shelf life, and enhancing food safety. Full article

Background/Objectives: Bacterial biofilms formed by Escherichia coli pose a significant challenge in veterinary medicine due to their intrinsic resistance to antibiotics. Antimicrobial peptides (AMPs) represent a promising alternative. AMPs exert their bactericidal activity by binding to negatively charged phospholipids in bacterial membranes via electrostatic interactions, leading to membrane disruption and rapid cell lysis. Methods: In vitro assays including MIC determination, biofilm eradication testing (crystal violet, colony counts, and CLSM), swimming motility, and EPS quantification were performed. CRISPR/Cas9 was used to construct and complement a kduD mutant. A transposon mutagenesis library was screened for biofilm-defective mutants. In an in vivo murine excisional wound infection model treated with the mouse cathelicidin-related antimicrobial peptide (CRAMP-34), wound closure and bacterial burden were monitored. Gene expression changes were analyzed via RT-qPCR. Results: CRAMP-34 effectively eradicated pre-formed biofilms of a clinically relevant, porcine-origin E. coli strain and promoted wound healing in the murine infection model. We conducted a genome-wide transposon mutagenesis screen, which identified kduD as a critical gene for robust biofilm formation. Functional characterization revealed that kduD deletion drastically impairs flagellar motility and alters exopolysaccharide production, leading to defective biofilm architecture without affecting growth. Notably, the anti-biofilm activity of CRAMP-34 phenocopied aspects of the kduD deletion, including motility inhibition and transcriptional repression of a common set of biofilm-related genes. Conclusions: This research highlights CRAMP-34 as a potent anti-biofilm agent and unveils kduD as a previously unrecognized regulator of E. coli biofilm development, which is also targeted by CRAMP-34. Full article

Nanoplastics are persistent environmental pollutants with potential risks to human health. Due to their small size, nanoplastics are internalized by macrophages, potentially altering their function. In this study we found that, in macrophages, 50 nm polystyrene nanoplastics were predominantly present in endosomes, lysosomes, and in the endoplasmic reticulum. Internalization of polystyrene nanoplastics increased the bactericidal activity of macrophages, which was inhibited by the NADPH oxidase inhibitor diphenyleneiodonium. Consistently, measurements of cellular and mitochondrial reactive oxygen species by flow cytometry revealed that polystyrene nanoplastics induced reactive oxygen species production in macrophages. In contrast, internalization of polystyrene nanoplastics reduced the levels of nitric oxide released by macrophages in response to E. coli. Internalization of polystyrene nanoplastics followed by the addition of E. coli induced high expression levels of the aconitate decarboxylase 1 gene. In the absence of this gene, killing of E. coli by macrophages exposed to polystyrene nanoplastics was significantly attenuated with respect to control macrophages, indicating a role for the mitochondrial metabolite itaconate in the increased bactericidal activity of macrophages exposed to polystyrene nanoplastics. Collectively, our results indicate that exposure of macrophages to polystyrene nanoplastics increases their bactericidal activity through the production of reactive oxygen species and of itaconate. Full article

Infected wounds form a complex microenvironment that creates difficulties for drug delivery. In this study, a composite fiber membrane based on polyethylene oxide (PEO) was prepared. The intention was to achieve on-demand drug release and integrate multiple functions by adjusting the material composition. The membrane uses PEO as the main framework and contains chitosan (CS) and ascorbic acid (Asc). CS leads to an increase in fiber diameter, while Asc makes the fibers thinner. The two components act together to influence the microstructure. In vitro drug release experiments showed that changing the CS content in the PEO matrix can affect the initial release rate and the duration of sustained release. The membrane also shows sensitivity to pH. Under slightly acidic conditions, drug release becomes faster, which is similar to the state of infected wounds. In addition, the membrane maintains antioxidant activity and can inhibit Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). These results suggest that PEO-based composite fibers may be useful in drug delivery and tissue repair. Full article

The growing demand for biodegradable and functional packaging has driven research toward polysaccharide-based materials with improved performance. In this study, sodium alginate films were modified using natural deep eutectic solvents (NADES) and acorn polyphenolic extract to enhance their antimicrobial, mechanical, and thermal properties. The films were acquired by solvent casting and characterized through mechanical, spectroscopic, thermal, and microbiological analyses. Both NADES and the polyphenolic extract enhanced tensile strength and flexibility through additional hydrogen bonding within the alginate network, while the extract also introduced antioxidant functionality. Among all tested formulations, the A4E2 film exhibited the most balanced performance. FTIR spectra revealed hydrogen bonding between the film components, and thermogravimetric analysis showed an approximately 15 °C (F-EXT) and 20 °C (F-DES) shift in the main DTG degradation peak, indicating enhanced thermal stability. Controlled-release experiments demonstrated the gradual diffusion of phenolic compounds in aqueous, acidic, and fatty simulants, with an initial release phase within the first 6 h followed by sustained release up to 48 h, confirming the films’ suitability for various food environments. The combined modification reduced the growth of Escherichia coli and Staphylococcus aureus by 30–35%, with inhibition zone diameters reaching 27.52 ± 2.87 mm and 25.68 ± 1.52 mm, respectively, evidencing synergistic antimicrobial activity. These results highlight the potential of NADES- and extract-modified alginate films as sustainable materials for active food packaging applications. Full article

Polysaccharide-based wound dressings face challenges in mechanical properties and effective wound repair for infected wound surfaces. This study presents a novel polyvinyl alcohol (PVA)/Salecan (Sal) composite hydrogel dressing with high toughness, biocompatibility, and wound healing capabilities, developed using an interpenetrating polymer network strategy. The primary network was formed through electrostatic interactions between polydopamine (PDA) and biocompatible polysaccharide Salecan, followed by incorporation of AgNO₃, which was in situ reduced to silver nanoparticles within the hydrogel. PVA was introduced as a secondary matrix, further reinforcing the hydrogel network through cyclic freeze–thawing. The resulting hydrogel exhibited a tensile strength of 0.31 MPa, an elongation at break of 158.9%, and a toughness of 31.16 J·m⁻², demonstrating enhanced mechanical performance compared to both Salecan/PDA and previously reported Salecan/Fe³⁺ hydrogel. Co-culture experiments showed the hydrogel’s strong antibacterial effects, inhibiting 80.1% of Escherichia coli (E. coli) and 99.5% of Staphylococcus aureus (S. aureus). Fibroblast culture tests confirmed its excellent cytocompatibility. In vivo studies on infected wounds showed nearly complete healing in the S. aureus + hydrogel group within 12 days. Quantitative immunohistochemical analysis of CD31 revealed that hydrogel treatment significantly upregulated CD31 expression, indicating enhanced neovascularization. Complementary Western blot analysis further demonstrated that hydrogel-treated groups exhibited a marked downregulation of pro-inflammatory factors alongside CD31 upregulation. In summary, the PVA/Sal-based hydrogel represents a valuable strategy for reducing inflammation and promoting regeneration in the management of infected wounds. Full article

Biogenic nanoparticles have recently emerged as promising bacterial growth inhibitors, requiring low concentrations and not producing harmful byproducts. However, knowledge gaps remain regarding how different extraction techniques affect nanoparticle synthesis, thereby influencing their replicability and scalability across various applications. To address these knowledge gaps, this study compared six extracts derived from Moringa oleifera biomass for the synthesis of iron oxide nanoparticles. Multivariate statistical analyses correlated extraction methods with biomolecule content (polyphenols, flavonoids, carbohydrates, proteins), iron percentage, and E. coli growth inhibition. All extracts showed varying concentrations of biomolecules, and different extraction methods were preferable for specific components. Flavonoids were best extracted by salting-out, while infusion methods were better for obtaining carbohydrates. Higher percentages of iron (22.77%) were linked to the presence of polyphenols and flavonoids. Nanoparticles prepared using salting-out and infusion extraction from leaf biomass displayed the highest efficiency in inhibiting E. coli growth, up to a dilution factor of 4. The outcomes of this research study provide an in-depth understanding of the role of specific biomolecules in biogenic nanoparticle synthesis, confirming that both synthesis yield and application effectiveness depend on the extract preparation method. Full article

Contamination of agricultural products such as maize by fungi is a significant concern worldwide, as it can compromise food safety and quality. In recent years, the use of microorganisms as natural food preservatives has gained interest. Probiotic lactic acid bacteria (LAB) and their metabolites are considered a promising strategy to reduce fungal growth and limit other food contaminants. This study aimed to characterize, screen and compare the probiotic properties and antifungal activity of LAB of maize origin. A total of 23 LAB isolates obtained from untreated maize grains were identified through 16S rRNA gene sequencing as Weissella viridenscens (34.7%), Pediococcus pentosaceus (34.7%), Enterococcus durans (17.4%), Leuconostoc citreum (9%), and Enterococcus faecium (4.3%). All isolates demonstrated acid, phenol, and bile salt tolerance; surface hydrophobicity; and antagonistic activity against selected bacterial foodborne pathogens. Notably, Enterococcus sp. showed the strongest inhibitory activity against Escherichia coli ATCC 5211 (21 mm inhibition zone) and Staphylococcus aureus (17 mm inhibition zone), whereas Pediococcus sp. exhibited the highest antagonistic effect against Listeria monocytogenes (18.7 mm inhibition zone). Furthermore, E. durans and P. pentosaceus demonstrated the strongest antifungal activity, effectively inhibiting the growth of Alternaria tenuissima (F22FR) and Fusarium oxysporum (F44FR), respectively. Overall, all the LAB strains isolated from this study showed considerable potential for use in the food industry as probiotics, starter cultures for functional food fermentations, bio-preservatives and biocontrol agents against toxigenic fungi and pathogenic bacteria, with E. durans standing out for its exceptional performance. Future research will explore the ability of these isolates and/or their enzymes to degrade mycotoxins commonly found in maize, a staple food in many African countries. Full article

This study prepared carbon dots (CDs) from agricultural waste pineapple peel via an eco-friendly microwave method, optimizing their performance through copper ion and chitosan doping. Multiple characterization techniques and performance tests were employed for systematic analysis. Antioxidant assays revealed that PP-CDs have excellent concentration-dependent free radical scavenging activity: the DPPH IC₅₀ values of Pineapple Peel Carbon Dots (PP-CDs), Copper-Doped Pineapple Peel Carbon Dots (Cu-PP-CDs) and Chitosan-Doped Pineapple Peel Carbon Dots (CS-PP-CDs) are 0.79, 0.95 and 0.98 mg/mL, while their ABTS IC₅₀ values are 0.22, 0.40 and 0.26 mg/mL, respectively. Antibacterial tests showed modified CDs have enhanced activity: Cu-PP-CDs exhibit inhibition zones of 23.1 ± 0.13 mm (E. coli) and 17.3 ± 0.05 mm (S. aureus) with MICs of 2.5 and 5.0 mg/mL, while CS-PP-CDs have respective zones of 12.8 ± 0.08 mm and 16.3 ± 0.12 mm with a 5.0 mg/mL MIC for both strains. All CDs present a quasi-spherical morphology and emit yellow fluorescence under UV excitation, with PP-CDs showing the strongest intensity. This study provides technical support for high-value utilization of pineapple peel and development of multifunctional CDs, which have food field potential but face large-scale production and toxicological evaluation challenges. Full article

Macrophages play a crucial role in regulating immune responses, inflammation, and tissue repair. Depending on environmental cues, they polarize into pro-inflammatory M1 or anti-inflammatory, pro-regenerative M2 phenotypes. Extracellular vesicles (EVs) derived from mesenchymal stem/stromal cells (MSCs) have emerged as key mediators of intercellular communication and immune modulation. This study investigates the effects of matrix-bound vesicles (MBVs) and small extracellular vesicles (sEVs) derived from human umbilical cord MSCs (UC-MSCs) on human monocyte-derived macrophages (MDMs) in vitro. Both MBVs and sEVs reduced pro-inflammatory activation of M1 macrophages, downregulating the expression of CXCL10 and CD86 while increasing the M2 marker CD206. MBVs exerted a stronger suppressive effect on M1 MDM phenotype markers as well as on STAT1, STAT2, and IRF9 mRNA levels in M1 macrophages, indicating the inhibition of the JAK/STAT1 signaling pathway involved in the pro-inflammatory activation of macrophages. Functionally, both vesicle types enhanced phagocytosis of FITC-labeled E. coli by M1 and M0_GM macrophages, promoting a shift toward an M2-like phenotype. Moreover, MBVs and sEVs attenuated reactive oxygen species (ROS) production, with sEVs showing a more pronounced effect both on ROS generation and on the expression of NOX2 complex subunits (p47^phox, p67^phox) in M1 macrophages. These findings demonstrate that MBVs and sEVs from UC-MSCs possess distinct yet complementary immunomodulatory and antioxidant properties on MDMs, suggesting their potential as promising cell-free therapeutic agents for inflammatory and degenerative diseases. Full article

This study presents the development of a smart packaging material utilizing garlic-derived nitrogen-doped carbon dots (CDs) integrated into a whey protein–starch (WP-S) emulsion. The research aimed to create a real-time, non-invasive biosensor capable of detecting microbial spoilage. The synthesized CDs demonstrated strong pH-sensitive photoluminescence, exhibiting distinct changes in CIE coordinates and fluorescence intensity in response to varying pH values. The WP-S-CDs emulsion was tested against E. coli, S. aureus, and C. albicans. The results showed that the composite film provided a clear colorimetric shift and fluorescence quenching, both of which are directly correlated with microbial metabolic activity. The physical and electronic properties of the composite were investigated to understand the sensing mechanism. Scanning electron microscopy (SEM) of the dried film revealed that the WP-S-CDs system formed a more porous structure with larger pore sizes (3.63–8.18 µm) compared to the control WP-S film (1.62–6.52 µm), which facilitated the rapid diffusion of microbial metabolites. Additionally, density functional theory (DFT) calculations demonstrated that the incorporation of CDs significantly enhanced the composite’s electronic properties by reducing its band gap and increasing its dipole moment, thereby heightening its reactivity and sensitivity to spoilage byproducts. In a practical application on apples, the WP-S-CDs coating produced a visible red spot, confirming its function as a dynamic sensor. The material also showed a dual-action antimicrobial effect, synergistically inhibiting C. albicans while exhibiting an antagonistic effect against bacteria. These findings validate the potential of the WP-S-CDs emulsion as a powerful, multi-faceted intelligent packaging system for food quality monitoring. Full article

Plant essential oils have gained attention for their green and safe characteristics in recent years. However, negative effects on sensory attributes caused by high concentrations hinder their application in foods. The synergistic antibacterial activity and mechanism of basil (BEO) and ginger (GEO) essential oils against Escherichia coli and Staphylococcus aureus were investigated in this study. The preservative effect on braised beef, a Chinese traditional meat product, of combined BEO and GEO was also studied. Both BEO and GEO displayed notable antibacterial activity when applied individually against E. coli and S. aureus. Moreover, the combination of BEO and GEO exhibited synergistic activity, with a fractional inhibitory concentration index of 0.75. The BEO + GEO combination reduced bacterial metabolism, ruptured bacterial membranes, reduced membrane potential, and destructed intracellular enzymes and the membrane integrity of E. coli and S. aureus. The application of BEO + GEO in braised beef could effectively maintain its quality and prolong its shelf life by inhibiting bacterial growth, preventing texture changes and color deterioration. The combination of BEO and GEO exhibited a synergistic antibacterial activity, providing effective preservation of braised beef. The findings contribute valuable insights into the development of natural antibacterial preservatives for meat products. Full article

This manuscript describes the development of a nano-sized synthetic smectic clay hydrogel (LAP) that enables controlled oxygen delivery, making it a promising candidate for treating skin wound infections and promoting healing. LAP is an ingredient in various dermatological products, including powders, creams and emulsions. We investigated the antibacterial effect of the LAP hydrogel by incorporating calcium peroxide (CPO), an oxygen-releasing agent, and measuring the size of the inhibitory halo. We found that CPO hydrogels in LAP showed a significant increase in oxygen release during the first five hours, especially at low CPO concentrations. For example, the hydrogel with 5% CPO showed a controlled release profile with a final percentage oxygen release of 2.47 ± 0.01% after 5 h. In contrast, the hydrogels with 10% and 20% CPO achieved lower final oxygen release values, 0.67 ± 0.01% and 0.75 ± 0.01%, respectively, suggesting that the encapsulation efficiency of LAP is higher at higher concentrations. LAP also proved to be an effective oxygen barrier and showed inherent antimicrobial activity. The research confirmed the antibacterial properties of the hydrogel, with inhibition sites observed against both E. coli and S. aureus. These results emphasize the potential of this hydrogel to serve as an effective tool for wound treatment by providing sustained oxygenation and fighting microbial infections. Full article

Background/Objectives: Colistin (polymyxin E) has re-emerged as a last-hope treatment against MDR Gram-negative pathogens due to the development of extensively drug-resistant Gram-negative bacteria. Unfortunately, rapid global resistance towards colistin has emerged, which represents a major public health concern. In this context (CBD), a lipophilic molecule derived from Cannabis sativa, exhibits antimicrobial activity mainly against Gram-positive bacteria but is generally ineffective against Gram-negative species. However, synergistic antibacterial activity between CBD and polymyxin B has been reported. The objective of this work is to analyze the colistin–CBD synergy against clinically relevant Gram-negative isolates displaying diverse mechanisms of colistin resistance and to explore the basis of the possible mechanism of action involved in the first steps of this synergy. Methods: Microbiological assays, minimal inhibitory concentration, cell culture, synergy tests by checker board and time kill, biofilm inhibition evaluation by crystal violet and MTT, SEM (scanning electron microscopy), molecules interaction analysis by nuclear magnetic resonance (NMR). Results: The colistin–CBD combination displayed synergy in colistin resistant Gram-negative bacteria and also disrupted preformed biofilms and killed bacteria within them. Time-kill assays revealed rapid bactericidal activity and SEM showed mild surface alterations on bacterial outer membranes after sublethal colistin monotherapy. Furthermore, a series of sequential treatment assays on colistin-resistant Escherichia coli showed that simultaneous exposure to both compounds was required for activity, as introducing a washing step between treatments abolished the antibacterial effect. In order to obtain deeper insight into this mechanism, NMR analyses were performed, revealing specific molecular interactions between CBD and colistin molecules. Conclusions: These results provide evidence for the first time that both molecules engage through a specific and structurally meaningful interaction and only display synergy when acting together on colistin-resistant bacteria. Full article

Poly(ethylene glycol) (PEG) and poly(2-hydroxy ethyl methacrylate) are polymers used for many biomedical applications due to their biocompatibility, non-toxicity, and antibiofouling properties. In this work, a new comb-like hydrogel based on 2-hydroxyethyl methacrylate (HEMA) grafted onto a polyethylene glycol network (net-PEG) was synthesized by gamma radiation from Co⁶⁰ in two steps. First, PEG (Mw = 20,000) was crosslinked at 30 kGy, and then HEMA was grafted, varying the concentration (5–20% v/v) and irradiation dose (2.5–15 kGy). Results of infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed the incorporation of HEMA onto net-PEG. Moreover, the properties of comb-like hydrogel (net-PEG)-g-HEMA were studied through swelling kinetics, drug loading and release, antimicrobial activity, and biocompatibility assays. The findings showed a different behavior in swelling kinetics and drug delivery depending on HEMA grafting. Comb-like hydrogel with 30 and 66% grafting could load more ciprofloxacin (2 mg g⁻¹) than net-PEG (1.5 mg g⁻¹) but only release 38 and 48% at 24 h, respectively. In addition, all drug-loaded hydrogels displayed inhibition for Gram-negative bacteria (E. coli) and a cell viability superior of 95% using mouse embryonic fibroblasts (BALT/T3). Comb-like hydrogel has potential application in the biomedical field such as in wound dressings or controlled drug delivery systems. Full article