Search Results (1,238)

Salmonellosis is a global foodborne pathogen with zoonotic importance that seriously threatens livestock breeding and human health. Due to the implementation of an anti-resistance policy, probiotics as an alternative to antibiotics have attracted widespread attention. In this study, the widely used probiotic Escherichia coli Nissle 1917 (EcN) was selected to study its protective effect on mice infected with Salmonella typhimurium. Two mice groups (n = 15) were treated with either EcN and PBS. Flow cytometry showed that the frequency of mature dendritic cells in the Peyer’s patch was significantly increased compared to the PBS group. Previous administration of EcN protected against challenge with Salmonella typhimurium infection as an increased survival rate of the mice, a decreased degree of pathological changes, and the number of live bacteria in the spleen and liver were recorded compared to the control group. The results of 16S rRNA high-throughput sequencing of fecal microbial flora showed that EcN could reduce the abundance of microorganisms in the intestine and reduce the proportion of Lactobacillus, while Ruminococcaceae sp., Rikenella sp. and Bifidobacterium sp. disappeared. In contrast, the abundance of Bacteroides increased, which reduced the effect of Salmonella typhimurium on the distribution of intestinal microorganisms. Our results demonstrated that EcN has a protective effect against Salmonella typhimurium infection and may act as a candidate probiotic bacterium to apply in the future. Full article

Salmonella infects a wide range of hosts, causing gastroenteritis or systemic infection in humans and animals, highlighting the urgent need for a deeper understanding of its pathogenesis. SpvC, a critical virulence determinant of salmonella, facilitates bacterial dissemination. Gasdermin D (GSDMD) is the only gasdermin known to protect mice against acute Salmonella enteritis. Our preliminary findings indicated that SpvC counteracts GSDMD-mediated antibacterial effects to enhance bacterial dissemination, although its functional relevance to epithelial-derived GSDMD and the underlying mechanisms remain unclear. To address this, Gsdmd^−/− C57BL/6J and wild-type mice were infected with Salmonella Typhimurium (S. Typhimurium) wild-type strain and spvC deletion mutant. Our results demonstrate that SpvC compromises intestinal epithelial barrier integrity, overcoming GSDMD-mediated protection against systemic infection. Specifically, through bioinformatics analysis, LC-MS/MS, and in vivo experiments with Caco-2 cell monolayers and site-directed spvC mutants, we identified SEC23B as a novel target of SpvC. This interaction disrupts the intestinal epithelial barrier through the autophagy–pyroptosis pathway. This study identifies SEC23B as a unique cellular target of SpvC involved in GSDMD activation during S. Typhimurium systemic infection. It also reveals a novel mechanism by which Salmonella evades host defense mechanisms. Full article

Unpasteurized fruit juices in developing countries pose significant public health risks due to potential contamination with foodborne pathogens, particularly in rural areas where reliable energy for thermal processing is lacking. This study evaluates the natural acidity of passion fruit juice as a non-thermal strategy to inactivate Salmonella ser. Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes. Pathogens were inoculated into passion fruit juice at pH 2.9, 3.4, and 3.9, and their survival was monitored at 25 °C (room temperature) and 5 °C (refrigerated). Log-linear and Weibull models were used to predict inactivation kinetics, targeting a 5-log reduction in accordance with FDA requirements. At pH 2.9 and 5 °C, S. Typhimurium and E. coli achieved a 5-log reduction within 8 h, while L. monocytogenes required 24 h to achieve the same reduction level. The Weibull model provided a superior fit (R² > 0.94) at pH 2.9 and 3.4, accurately capturing the nonlinear inactivation dynamics. Increasing pH to 3.9 significantly slowed inactivation, underscoring the critical role of low pH. These findings suggest that the inherent acidity of passion fruit juice provides a practical, energy-independent method for controlling pathogenic bacteria in developing regions, preserving nutritional quality without thermal processing. Full article

Background/Objectives: Neutrophils express the receptor for advanced glycation end products (RAGE), yet its role in antibacterial responses remains incompletely defined. This study aims to elucidate the dual functionality of RAGE as a membrane-bound signaling sensor and a source of soluble RAGE (sRAGE) in human neutrophils challenged with Salmonella typhimurium, a clinically relevant Gram-negative pathogen. Methods: Human peripheral neutrophils from healthy donors were isolated and stimulated with S. typhimurium, LPS, or fMLP. Calcium flux, ROS/RNS production, and phagocytosis were assessed using fluorescent probes and spectroscopy. RAGE expression and localization were analyzed by immunofluorescence microscopy and flow cytometry. Soluble RAGE in supernatants was quantified by ELISA, and its molecular forms were characterized by Western blotting. Results: Resting neutrophils exhibited minimal surface RAGE but a substantial intracellular pool. RAGE inhibition with FPS-ZM1 attenuated bacteria-induced Ca²⁺ mobilization, oxidative burst, nitrosative output, and phagocytosis, with the most pronounced defect at the pathogen-attachment stage—consistent with impaired cytoskeletal remodeling. Upon activation, neutrophils rapidly released sRAGE (peak at ~10 min) via combined metalloprotease-dependent shedding and regulated secretion of pre-formed intracellular stores. Paradoxically, FPS-ZM1 amplified sRAGE release while suppressing membrane-proximal signaling. Conclusions: Neutrophil RAGE functions as a dynamic, multi-compartmental regulator: membrane-associated RAGE licenses effector responses to Gram-negative bacteria, while concomitant sRAGE release provides a fast negative-feedback loop to limit excessive inflammation. This self-limiting circuit balances antimicrobial defense with tissue protection, and its dysregulation may contribute to pathological outcomes in acute and chronic infections. Full article

Background/Objectives: Calcium phosphate cement (CPC) is extensively utilised in bone repair owing to its biocompatibility, osteoconductivity, and compositional similarity to native bone. Functionalisation of CPC with palm tocotrienol may enhance its regenerative potential. However, the incorporation of phytochemicals requires safety evaluation to exclude potential genotoxic risks. This study investigated the mutagenic potential of CPC and tocotrienol-enriched CPC (CPC-T3) using the bacterial reverse mutation assay. Methods: Mutagenicity was evaluated in five bacterial strains, including Salmonella typhimurium TA100, TA98, TA1535, TA1537, and Escherichia coli WP2 trp uvrA, under both non-metabolic and metabolic activation conditions. Revertant colonies were quantified at multiple concentrations and mutagenicity ratios were calculated relative to the negative control. Results: Across all strains and metabolic conditions, neither CPC nor CPC-T3 induced reproducible or concentration-dependent increases in revertant colony numbers. Although isolated elevations were detected at certain concentrations, these findings lacked dose–response relationships and did not meet the criteria for a positive mutagenic response according to Organisation for Economic Co-operation and Development (OECD) Test Guideline No. 471. The performance of negative and positive controls confirmed the validity and sensitivity of the assay. Notably, the inclusion of palm tocotrienol did not alter the overall mutagenicity profile of CPC. Conclusions: CPC and CPC-T3 demonstrated no evidence of mutagenic activity under the conditions of the bacterial reverse mutation assay. These findings represent preliminary genotoxicity screening. Further mammalian genotoxicity and in vivo studies are warranted to support future translational development as implantable medical devices. Full article

Salmonella enterica is a significant Gram-negative bacterium possessing over 2500 serovars capable of affecting both animals and humans and disseminating widely due to its adaptability, genetic diversity, and ability to form biofilms. Different serovars, such as S. enterica Typhimurium (ST), Enteritidis (SE), and Infantis (SI), display varying traits and survival strategies in harsh environments. Biofilms, composed of proteins, lipids, and DNA, enable bacteria to survive stresses such as pH changes, nutrient shortages, temperature fluctuations, and disinfectants. Evaluating disinfectants on inert surfaces is crucial for understanding their effectiveness and impact on poultry. This study assessed the efficacy of chlorine dioxide (ClO₂) disinfectant against ST, SE, and SI growth, biofilm formation, and biofilm removal at varying concentrations in vitro. Results showed serotype-dependent and condition-specific responses, with SE and SI being more affected than ST, which may be associated with differences in oxidative stress response mechanisms, highlighting the need for tailored disinfection protocols. Full article

Novel biobased materials and processing techniques are actively developed for sustainable coatings. This study investigated the potential mutagenicity of novel materials and derived dispersions used for biobased paper and wood coatings using a pilot 384-well test. The standard Ames test was performed for selected materials to compare and validate the results with the non-standard 384-well test. Salmonella Typhimurium strains (TA100 and TA98) were used for testing. Experimental dispersions were prepared using suberin and betulin extracted from outer birch bark. The test set of seven samples (n = 7) included commercial reference samples and additives. Both test methods were suitable for these samples but also highlighted method-specific differences and challenges. For suberin-derived materials and betulin at 0.5–1% concentration, neither of the tests indicated mutagenicity. In the case of some industrial samples, the 384-well test and the standard Ames test gave clearly contradictory results. These can be explained by the test limitations, such as the sample color or compositional instability of dispersions. To summarize, this study indicated the need to test the novel coating materials with multiple concentrations, and several bacterial strains carrying different types of genetic mutations, as well as to use complementary genotoxicity tests for a more accurate toxicity profile. Full article

Salmonella infection in poultry remains a major concern due to its economic impact and public health risks. Synbiotics have emerged as a natural strategy to improve gut health and resistance to enteric pathogens. This study evaluated the immune response and early protective effects of a synbiotic in broiler chickens using a reduced in vivo model of Salmonella Typhimurium infection. A total of 44 broiler chickens were randomly assigned to four dietary treatments: control (CT), control plus synbiotic (CT + Syn), challenged (ST), and challenged plus synbiotic (ST + Syn). Birds were challenged at 7 days of age and euthanized at day 12 for sample collection. Synbiotic supplementation reduced bacterial colonization and adhesion in the ileum, as assessed by intestinal content isolation and immunofluorescence analysis. Additionally, the synbiotics mitigated lesion severity in the intestine, liver, and heart, increased anti-inflammatory IL-10 expression, and reduced pro-inflammatory cytokines IL-1β and TNF-α. Ileal histomorphometry showed increased epithelial height in the ST + Syn birds, while intestinal permeability was not affected. Improved body weight was also observed compared to the challenged birds without supplementation. In conclusion, synbiotic supplementation provided early protection against S. Typhimurium infection by modulating immune responses, preserving intestinal morphology, and supporting weight gain in broiler chickens. Full article

The rise in global consumption of fresh vegetables is a response to their nutrient-dense composition and low caloric content—key factors for optimising human metabolic health. This study evaluated the Quantitative Microbial Risk Assessment (QMRA) of Helicobacter pylori and enteric pathogens in fresh vegetables within the central highlands of Peru. The research integrated conventional microbiology, qPCR, and Monte Carlo simulations. The results revealed a high prevalence of Escherichia coli (83.7%), with a heterogeneous distribution where Huancayo presented the highest prevalence (95.5%) and Chupaca the lowest (68.2%). In contrast, pathogens such as H. pylori and Campylobacter jejuni showed marginal prevalences of 2.33% and 3.49%, respectively, with detections restricted to leafy and root vegetables at specific points of sale. Although biochemical tests indicated the presumptive presence of Helicobacter pylori, the qPCR results were negative, possibly due to the bacteria’s viable but non-culturable (VBNC) state. The QMRA model showed a highly skewed annual infection risk distribution, with E. coli presenting the highest risk: median Pann = 1.000 and 84.3% of simulations exceeding the WHO tolerable threshold of 10⁻⁴. For Salmonella Typhimurium and Shigella flexneri, 22.4% and 9.1% of simulations exceeded the same threshold, respectively. The results underscore the urgent need to implement traceability programs and improve agricultural practices across the evaluated provinces. Full article

Developing eco-friendly metal oxide nanoparticles (NPs) with plant-based reducing and stabilizing agents offers a sustainable alternative to traditional chemical methods. Nonetheless, the detailed mechanisms by which phytochemicals influence NPs formation, antimicrobial properties, and cytocompatibility remain poorly understood, especially in systems mediated by Vaccinium. This study aimed to synthesize TiO₂ NPs and ZnO NPs using Vaccinium corymbosum (blueberry) extract, analyze their structural and surface characteristics, assess their antimicrobial effectiveness and cytotoxicity, and explore potential molecular mechanisms through computational docking. ZnO NPs were produced via alkaline precipitation (pH 12) from ZnCl₂, while food-grade TiO₂ was mixed with blueberry extract. A comprehensive characterization was carried out using techniques like X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, transmission and scanning electron microscopy (TEM/SEM), dynamic light scattering (DLS), and high-performance liquid chromatography (HPLC) for polyphenol profiling. The antimicrobial activity was tested against Escherichia coli and Salmonella Typhimurium, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined. Cytotoxicity was assessed using Gallus gallus domesticus leukocytes and Artemia salina bioassays, and molecular docking simulations were performed to examine polyphenol interactions with the bacterial DNA gyrase subunit B (GyrB). XRD analysis confirmed the presence of wurtzite ZnO (with a crystallite size of 18.2 nm) and anatase TiO₂ (12.8 nm after functionalization). HPLC identified key polyphenols, including quercetin, cyanidin, malvidin, and cyanidin-3-glucoside, with patterns indicating stronger adsorption onto TiO₂ NPs surfaces. ZnO NPs showed higher antimicrobial effectiveness (>90% inhibition at 2 mg/mL; MIC 0.5–1 mg/mL) compared to TiO₂ (72% inhibition at 16 mg/mL; MIC 8–16 mg/mL). Cytotoxicity results indicated concentration-dependent effects. Molecular docking simulations revealed favorable binding energies (−6.2 to −8.4 kcal/mol) for blueberry polyphenols with GyrB, suggesting potential synergistic antimicrobial effects and ROS production. The study highlights a successful green synthesis of bioactive TiO₂ NPs and ZnO NPs using Vaccinium corymbosum extract, where polyphenol surface functionalization enhances both colloidal stability and biological activity. This comparative research offers mechanistic insights into how polyphenol-coated NPs work and supports the development of eco-friendly antimicrobial oxide nanomaterials. Full article

The formation of biofilms by Salmonella is of considerable interest to the food production and medical industries. This study investigated the effects of a carrier medium (Luria–Bertani, Mueller–Hinton II, Brain Heart Infusion or chicken meat juice), temperature (14 °C, 23 °C or 37 °C) and surface type (adhesive, non-adhesive or suspension plate) on biofilm formation in 16 different Salmonella isolates belonging to the serovars S. Enteritidis (five isolates), S. Infantis (five isolates) and S. Typhimurium (six isolates). Chicken meat juice was found to have a moderate yet balanced supportive effect, while Mueller–Hinton II (MH-II) medium drastically supported biofilm formation at low temperatures, albeit with significant variation among the isolates. Temperature and medium also affected the antibacterial, biofilm inhibitory and destructive effects of essential oils. At 14 °C and 23 °C, 35% of essential oils exhibited antibacterial activity against Salmonella serovars at a concentration of 0.1%, as determined by the drop plate method. Ajowan, thyme, orange, clove and oregano EOs completely inhibited biofilm formation at a concentration of 0.1%. More than half of the 60 essential oils tested reduced the optical density of mature biofilms (OD: 0.15–0.36) to below 0.05; ajowan, lime, palmarosa, thyme, oregano and clove were the most effective, exhibiting antibacterial, biofilm inhibitory and biofilm destructive effects on all of the investigated Salmonella isolates. Full article

Zinc oxide promotes poultry growth, but it tends to agglomerate. This necessitates high doses and leads to environmental contamination from unabsorbed, excreted zinc. Undigested zinc is excreted and can enter the food chain, increasing the probability of zinc residues in edible poultry tissues (muscle, liver, and eggs) and raising concerns for consumer safety. MOF-supported single-atom zinc catalysts (SAC) resolve agglomeration by atomic anchoring, enhancing bioavailability. High-temperature/high-pressure fixation of Zn²⁺ surfaces was confirmed by XRD, while FESEM revealed the corresponding surface morphology, collectively verifying SAC formation. SAC exhibited potent antimicrobial efficacy against key pathogens such as Salmonella typhimurium, Escherichia coli, and Staphylococcus aureus (MIC of 3.125 mg/mL, MBC of 25 mg/mL). Co-culture experiments further demonstrated that the antibacterial performance of SAC remained stable over a temperature range of 20–80 °C and a pH range of 2–8, thus exhibiting excellent thermal stability and gastrointestinal tolerance. In 7-day-old chicks, SAC alleviated S. typhimurium-induced inflammation, reduced bacterial adherence, upregulated claudin-1, preserved gut homeostasis, ameliorated tissue lesions, and increased the abundance of Lactobacillus in the cecum, demonstrating promising potential for poultry infection control. Full article

We evaluated the antimicrobial and antioxidant capabilities of a bacteriocin purified from a recently identified marine Lactococcus lactis (L. lactis) NAN6399 strain, a lactic acid bacterium recovered from Mediterranean coastal waters near Alexandria, Egypt, and identified by combined API 50 CHL phenotypic profiling and 16S rRNA gene sequencing. Bacteriocin purification was achieved by sequential ammonium sulfate precipitation and reverse-phase high-performance liquid chromatography (RP-HPLC). The purified bioactive fraction had an approximate molecular weight of 20 kDa by SDS-PAGE and a 106-amino-acid N-terminal sequence that, upon BLAST alignment, returned 98.1% overall identity to the Lactococcin 972 family bacteriocin AAK06118.1 from L. lactis IL1403, with divergence confined exclusively to the terminal two C-terminal residues. This sequence is structurally and functionally distinct from canonical Lcn972 (L. lactis IPLA 972): the two peptides share an identical 25-residue signal peptide but diverge entirely in their mature bioactive domains, which exhibit only 9.1% sequence identity. Canonical Lcn972 operates through Lipid II-mediated septum disruption and inhibits only Lactococcus species; the NAN6399 peptide, correctly designated as a novel member of the Lcn972-like peptide family, demonstrated broad-spectrum antimicrobial efficacy against multiple indicator organisms (Staphylococcus aureus, Salmonella typhimurium, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterococcus faecalis), producing inhibition zones of up to 30 mm and minimum inhibitory concentration (MIC) values as low as 1.25 μg/mL against S. aureus. Antioxidant capacity was assessed using the DPPH radical scavenging assay, with the purified preparation achieving 73.14 ± 0.34% inhibition. Collectively, these data establish L. lactis NAN6399 as the producer of a bifunctional Lcn972-family bacteriocin with both antimicrobial and antioxidant potential, provide the first experimental characterization of the antimicrobial activity of this Lcn972-family branch, and highlight marine LAB as a productive reservoir for novel bioactive peptide discovery. Full article

Snail mucus is increasingly investigated as a biologically compatible source of multifunctional biomolecules for pharmaceutical and dermatological use. However, the chemical profile and biological activities of mucus from the Moroccan endemic terrestrial snail Otala tingitana remain poorly characterized. In addition, the influence of heliciculture diet on the composition and functional properties of the mucus remains unclear. Here, O. tingitana was reared for 140 days under controlled conditions and fed a basal flour diet or the same diet supplemented with 3% Rosmarinus officinalis, Origanum compactum, or Thymus zygis subsp. zygis. Mucus from wild snails was included for comparison. Mucus samples were chemically profiled by GC–MS and evaluated for antibacterial activity, antioxidant capacity, wound-healing efficacy in mice, and histological anti-inflammatory effects, and evaluated semi-quantitatively based on the degree of inflammatory cell infiltration. GC–MS identified 13 compounds and demonstrated clear diet-dependent shifts in dominant components. All mucus samples exhibited broad-spectrum antibacterial activity against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella Typhimurium (inhibition zones 10.31–14.30 mm; MIC 120–240 µg/mL), with predominantly bactericidal profiles (MBC/MIC < 4) and significantly enhanced activity in plant-supplemented groups (p < 0.05). Antioxidant performance improved markedly with medicinal-plant supplementation, reaching low IC₅₀ values (best ≈ 1.18 mg/mL) compared with basal-diet mucus. In vivo, topical application accelerated wound closure, achieving complete healing in <21 days, versus 28 days in untreated controls. In addition, histological assessment showed faster resolution of inflammatory cell infiltration in treated groups. Collectively, these findings provide the first integrated evidence that O. tingitana mucus possesses antibacterial, antioxidant, wound-healing, and anti-inflammatory activities, and that heliciculture diet is a practical lever to optimize its bioactive profile. Further studies should prioritize standardized manufacturing, contaminant control, and safety/toxicology assessment before translational development. Full article

Salmonella in gut habitats have traditionally been thought to conserve energy for growth via fermentation. However, recent reports indicate that ingested Salmonella can stimulate host-derived nitrate accumulation in the mucosal microenvironment, thereby enabling growth through nitrate respiration. Sodium tungstate is an effective treatment that inhibits the growth of certain nitrate-respiring bacteria, including Escherichia coli, Paracoccus and Proteus, when cultured under gut simulating conditions or within the gut of experimentally treated mice. This inhibitory effect is hypothesized to occur by inactivation of molybdenum-containing enzymes required for nitrate metabolism. Information is lacking on whether tungstate can inhibit the growth of Salmonella, particularly in the presence of culturable gut microbiota. Therefore, the objectives of this study were to evaluate the effects of sodium tungstate on Salmonella during pure culture or when cultured with freshly collected bovine rumen microbiota and to assess its impact on fermentation as well as nitrate and nitrite metabolism within the rumen microbial cultures. Our results indicate that 50 mM sodium tungstate treatment, whether alone or in combination with 5 mM nitrate, markedly increased the growth of Salmonella serovars Newport, Dublin and Typhimurium during pure culture. Moreover, during in vitro incubation, increased growth of experimentally inoculated S. Newport as well as wildtype E. coli and lactic acid bacteria was observed with ruminal microbiota treated with 100 mM tungstate when compared to non-tungstate-treated controls. Effects of tungstate on nitrate and nitrite metabolism were as expected during pure and mixed culture. When cultured with reduced tungsten rather than tungstate, the latter being bound to four oxygen atoms, an inhibitory effect on the growth of S. Newport was observed and effects on nitrate and nitrite metabolism were consistent with those observed with tungstate. These results suggest that, under conditions used in the present experiments, tungstate may have served as a source of oxygen for respiration above that achieved with nitrate alone. While this hypothesis has yet to be proven, it is supported by an adverse effect of tungstate, whether alone or in combination with 5 mM nitrate, on methane and volatile fatty acid production by the ruminal microbiota when compared to untreated or nitrate-only-treated microbiota. Full article