Search Results (1,038)

Rapid and accurate serotyping of Salmonella (S.) enterica subsp. enterica serovars is essential for effective public health surveillance, outbreak control, and food safety management. Traditional serotyping, although considered the gold standard, is time-consuming, technically demanding, and costly. This study aimed to evaluate the applicability of artificial intelligence (AI)-enhanced Fourier-transform infrared (FT-IR) spectroscopy using an IR Biotyper (Bruker Daltonics, Bremen, Germany) for the rapid and accurate serotyping of Salmonella enterica subsp. enterica isolates in Croatia. Materials and Methods: A total of 143 isolates representing different S. enterica serovars of human and food origin were analysed using the IR Biotyper. Each strain was tested in three biological and at least three technical replicates. The obtained results were compared with traditional serotyping according to the Kauffmann–White–Le Minor scheme. Isolate identification at the genus level was further confirmed by MALDI-TOF mass spectrometry. Results: The IR Biotyper demonstrated high reproducibility and complete concordance with standard serotyping methods, enabling accurate differentiation of the most prevalent S. enterica serovars in Croatia. Conclusions: Our findings demonstrate the applicability of FT-IR in routine laboratory work, with the potential to reduce typing time, reduce the number of strains, and lower overall costs required for epidemiological surveillance within the One Health approach. Full article

A new Schiff base, (E)-2-(((1,10-phenanthrolin-5-yl)imino)methyl)-4,6-di-tert-butylphenol (Fen-IHB), was designed to incorporate an intramolecular hydrogen bond (IHB) between the phenolic OH and the azomethine nitrogen with the goal of modulating its physicochemical and biological properties. Fen-IHB was synthesized by condensation of 5-amino-1,10-phenanthroline with 3,5-di-tert-butyl-2-hydroxybenzaldehyde and exhaustively characterized by HR-ESI-MS, FTIR, 1D/2D NMR (¹H, ¹³C, DEPT-45, HH-COSY, CH-COSY, D₂O exchange), and UV–Vis spectroscopy. Cyclic voltammetry in anhydrous CH₃CN revealed a single irreversible cathodic peak at −1.43 V (vs. Ag/Ag⁺), which is consistent with the intramolecular reductive coupling of the azomethine moiety. Density functional theory (DFT) calculations, including MEP mapping, Fukui functions, dual descriptor analysis, and Fukui potentials with dual descriptor potential, identified the exocyclic azomethine carbon as the principal nucleophilic site and the phenolic ring (hydroxyl oxygen and adjacent carbons) as the main electrophilic region. Noncovalent interaction (NCI) analysis further confirmed the strength and geometry of the intramolecular hydrogen bond (IHB). In vitro antimicrobial assays indicated that Fen-IHB was inactive against Gram-negative facultative anaerobes (Salmonella enterica serovar Typhimurium and Typhi, Escherichia coli) and strictly anaerobic Gram-positive species (Clostridioides difficile, Roseburia inulinivorans, Blautia coccoides), as any growth inhibition was indistinguishable from the DMSO control. Conversely, Fen-IHB displayed measurable activity against Gram-positive aerobes and aerotolerant anaerobes, including Bacillus subtilis, Streptococcus pyogenes, Enterococcus faecalis, Staphylococcus aureus, and Staphylococcus haemolyticus. Overall, these comprehensive characterization results confirm the distinctive chemical and electronic properties of Fen-IHB, underlining the crucial role of the intramolecular hydrogen bond and electronic descriptors in defining its reactivity profile and selective biological activity. Full article

This study aimed to optimize the total phenolic content (TPC) and antioxidant activity (AA) of acerola (Malpighia emarginata) by-product extracts obtained by probe-type ultrasound-assisted extraction and assess the composition and antibacterial activity of the extract obtained under optimized conditions. A Box–Behnken experimental design was applied to evaluate the effects of ultrasonic power (350 to 650 W), ethanol concentration (20% to 80% v v⁻¹), and extraction time (20 to 60 min) on TPC and AA. The optimal extraction conditions were 650 W, 50% (v v⁻¹) ethanol, and 20 min, which yielded the highest values of TPC (3.36 g gallic acid equivalent 100 g⁻¹) and AA through the DPPH radical scavenging method (4.97 mM Trolox equivalents 100 g⁻¹) and a ferric reducing antioxidant power assay (11.35 mM Trolox equivalents 100 g⁻¹). Organic acids, phenolic acids, flavonoids, and alkaloids were identified in the optimized extract, including malic acid, protocatechuic acid, resorcylic acid, and rutin. The optimized extract (2.89–11.32 mg mL⁻¹) inhibited the growth of Listeria monocytogenes, Shigella sonnei, Salmonella enterica subsp. enterica Typhi, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli. Acerola by-products represent a promising source of extracts with the potential to replace synthetic additives, contributing to the circular economy of agroindustries. Full article

Some bacterial species within the Enterobacteriaceae family possess different types of fimbrial (pili) adhesins that promote adherence to cells and colonization of host tissues. One of the well-characterized fimbrial systems is the pap operon, which encodes P fimbriae, a key virulence factor in urinary and systemic infections. One of the key regulators of P fimbriae is the transcriptional regulator PapB which plays a pivotal role as a master switch, not only by directing phase-variable expression of its own operon but also by influencing expression of heterologous fimbrial systems. This review explores the structural organization, biogenesis, and multi-tiered regulatory control of P fimbriae, with emphasis on PapB and homologous regulatory proteins such as SfaB, FocB, PixB, and PefB. Comparative genomics and phylogenetic analyses reveal that regulators belonging to the PapB family are evolutionarily conserved across π-fimbrial systems and also regulate other types of fimbriae. These regulators respond to epigenetic changes, host-derived signals, and global transcriptional cues to control levels of production of specific fimbriae in a bacterial population to dynamically modulate bacterial adhesion in different environmental niches. Optimally, understanding these mechanisms could lead to novel approaches to perturb PapB-family proteins and abrogate production of some types of fimbriae as a targeted strategy to prevent bacterial infections dependent on adherence mediated by PapB family regulators. Full article

Mexican culture offers a great variety of traditional maize-based fermented foods that are beneficial for human health. Atole agrio (sour atole), prepared from blue maize (Zea mays) in the state of Veracruz, has been scarcely studied as a potential functional food. The purpose of this study was to select endogenous potentially probiotic lactic acid bacteria (LAB) from freshly fermented blue maize atole agrio. Samples of spontaneously fermented atole agrio were used for the isolation of LAB on MRS agar. The abilities to tolerate acidic pH, bile salts, and sodium chloride, as well as surface hydrophobicity and aggregation capabilities, were used as criteria for probiotic potential. Selected LAB were identified using MALDI-TOF-MS. Finally, safety-related characterizations, such as hemolytic activity and antibiotic susceptibility, were performed. In the initial stages of fermentation, the presence of fungi, yeasts, coliform organisms, and LAB were detected, and in the final fermentation process, where the blue atole agrio reached a pH of 4, 49 isolates of LAB were obtained. Sixteen isolates showed high tolerance to pH 2, and seven of them showed tolerance to 3% bile salts and 4% sodium chloride. The seven isolates were identified as Pediococcus pentosaceus. Although the seven isolates showed low hydrophobicity to hexadecane and chloroform, they had medium autoaggregation and coaggregation with pathogens. The seven isolates showed notable antibacterial properties against Staphylococcus aureus, Salmonella enterica serovar Typhimurium, Escherichia coli, and Listeria monocytogenes, as well as good amylolytic capacity. All the P. pentosaceus strains were non-hemolytic, sensible to clindamycin and resistant to the other 11 antibiotics tested. Only subtle differences were found among the seven isolates, which can be considered potential candidates for probiotics. The freshly fermented blue maize atole agrio can be considered a functional food containing potentially probiotic LAB and the antioxidant phenolic compounds present in blue maize. Full article

The efficacy of peracetic acid (0.05%, 0.5%, and 1%), sodium hypochlorite (0.2%, 0.6%, and 1%), and benzalkonium chloride (0.3%, 1.15%, and 2%) was evaluated against Staphylococcus aureus (ATCC 6538), Salmonella enterica serovar Typhimurium, (ATCC 14028), Enterococcus hirae (ATCC 8043), Pseudomonas aeruginosa (ATCC 9027), Escherichia coli (ATCC 9027), and Listeria monocytogenes (ATCC 35152) using stainless steel discs, following European Committee for Standardization (CEN) guidelines. According to CEN, a sanitizer must achieve at least a 5 Log₁₀ CFU reduction to be considered effective. Peracetic acid at 1% demonstrated the highest inactivation capacity, reducing all tested strains by more than 7 Log₁₀ CFU/mL. P. aeruginosa (ATCC 9027) showed high tolerance to sodium hypochlorite and benzalkonium chloride, with reductions below 2 Log₁₀ CFU/mL even at maximum concentrations. Both sodium hypochlorite and benzalkonium chloride, at their highest tested concentrations, effectively inactivated S. aureus, S. typhimurium, E. hirae, L. monocytogenes, and E. coli, achieving reductions greater than 7 Log₁₀ CFU/mL. Overall, sanitizers were effective only at intermediate or maximum concentrations recommended by the manufacturers, suggesting that minimum label concentrations should be avoided to ensure microbiological control. Full article

The lack of improved sanitation in rural areas of developing countries, including South Africa, exacerbates open defecation, leading to the significant contamination of water sources by human and animal waste. This study aimed to establish the association of Campylobacter jejuni, Salmonella enterica serovar Typhimurium, Shigella flexneri, and Yersinia enterocolitica in open defecation sites and animal waste with the contamination of water sources in Vhembe District, South Africa. A total of 1032 water samples and 111 faecal samples from the Collins Chabane and Thulamela municipalities were analysed using qPCR. Regression models were used to assess associations, with S. Typhimurium (19–60%) and S. flexneri (11–44%) being the most prevalent bacteria in faecal matter and water, showing detection rates of 4–100% and 5–100%, respectively. Strong associations were found during the wet season between faecal waste and water contamination for S. flexneri (R² = 0.7, p = 0.005) and S. Typhimurium (R² = 0.619, p = 0.091). Urgent measures are needed to address the contamination of rural water sources due to open defecation and livestock waste. Full article

This study aimed to develop innovative functional gummy candies enriched with protein hydrolysates derived from porcine liver, enhancing their antioxidant and antimicrobial properties. First, the overall consumer acceptability (OA) was assessed to determine the most suitable combination of gummy matrix components. Selected combinations were then analyzed for antioxidant activity (ABTS•+, DPPH•), antimicrobial effects, microbiological safety, and physicochemical characteristics. The incorporation of liver hydrolysates significantly increased antioxidant capacity. The highest activity was observed in sample GC5Pa24Ag, hydrolyzed with papain for 24 h and formulated with agar, showing ABTS•+ and DPPH• scavenging activities of (67.6 ± 0.98 µmol/g) and (49.14 ± 1.00%), respectively (p ≤ 0.05). Pepsin hydrolyzed samples (GC2Pe3Gl, GC2Pe6Gl, GC2Pe24Gl) exhibited significantly larger inhibition zones against Listeria monocytogenes ATCC 13932, Escherichia coli ATCC 25922, and Salmonella enterica subsp. enterica serovar Typhimurium ATCC 14028 compared to the control (p < 0.05). Among all, GC5Pa24Ag demonstrated the broadest antimicrobial activity, with a 29.0 ± 0.2 mm inhibition zone against all tested pathogens. These findings suggest that porcine liver hydrolysates can be successfully incorporated into confectionery products to create functional gummies with potential health benefits, offering antioxidant protection and antimicrobial effects in a consumer-friendly form. Full article

The growing demand for natural preservatives has driven interest in essential oils (EOs) from medicinal and aromatic plants. This study examines the potential of EOs from six wild populations of Albanian Lamiaceae, specifically Origanum vulgare subsp. hirtum, Thymbra capitata, and Satureja montana species, to be utilized for food conservation, among other possible uses. The EOs were extracted by hydrodistillation, and their chemical profiles were analyzed through GC-MS. DPPH and ABTS assays were performed to evaluate antioxidant activity. The antimicrobial efficacy of the oils was assessed using the broth microdilution method against six common foodborne pathogens: Salmonella enterica serovar Enteritidis, Escherichia coli, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Micrococcus luteus, and one fungus, Candida albicans. The most potent EOs in terms of yield and biological activity, resulting from O. vulgare subsp. hirtum and T. capitata, were encapsulated in oil-in-water emulsions, which were characterized for particle size and zeta potential. The results show that the populations of O.vulgare subsp. hirtum and T. capitata taken in the study belong to carvacrol chemotypes, and their EOs show strong antioxidant activity and are effective against all tested microorganisms. Nanoemulsions prepared with these EOs showed promising stability, indicating their potential as natural preservatives in food applications. Full article

Background/Objectives: The consumption of liquid egg products is rising. While thermal pasteurization improves safety and shelf life, it can affect product quality. Furthermore, egg products continue to cause many foodborne illnesses, especially those caused by Salmonella enterica subspecies enterica serovar Enteritidis (Salmonella Enteritidis). Bacteriophages (or phages) are an effective alternative to specifically fight foodborne bacteria. This study aimed to evaluate (i) the stability of phage vB_SeEM_UALMA_PCSE1 (PCSE1) under different conditions of temperature and pH; (ii) the effect of multiplicity of infection (MOI) and temperature on phage efficacy; (iii) the bactericidal effect of phage PCSE1 against S. Enteritidis in liquid whole eggs compared to thermal pasteurization; and (iv) the effect of both treatments on the physicochemical and functional properties of liquid whole eggs. Methods: For this, stability tests, bacterial growth inhibition assays in culture media and liquid eggs, and physicochemical and functional analyses were conducted. Results: Phage PCSE1 was (i) stable at pH 7 and 8, and at 4, 25, and 37 °C for 56 days; (ii) effectively prevented S. Enteritidis growth in TSB (reduction of 1.8, 4.5, and 4.5 log colony-forming units (CFU)/mL at 4, 10, and 25 °C, respectively, relative to the bacterial control); (iii) controlled S. Enteritidis in liquid whole eggs at 25 °C (reduction of 5.8 log CFU/mL relative to the bacterial control) comparable to pasteurization (reduction of 5.2 log CFU/mL); and (iv) preserved eggs’ properties, contrarily to pasteurization. Conclusions: These findings suggest PCSE1 is a promising strategy to fight S. Enteritidis in liquid egg products, though further studies on shelf-life are needed. Full article

Green synthesis of gold nanoparticles (AuNPs) provides a significantly eco-friendly and low-impact counterpart to conventional chemical methods. In the present study, we synthesized gold nanoparticles using Schinus molle (P-AuNPs) aqueous extract as a reducing and stabilizing agent. The obtained nanoparticles were then stabilized by another biocompatible agent, the chiral amino acids L-cysteine (L-Cys-AuNPs) and D-cysteine (D-Cys-AuNPs), to estimate the potential of the surface modification for enhancing AuNPs surface chemistry and antimicrobial action. The synthesized gold nanoparticles were confirmed by UV-Vis spectroscopy, FTIR, XRD, and circular dichroism to validate their formation, crystalline structure, surface properties, and chirality. Physicochemical characterization confirmed the formation of crystalline AuNPs with size and morphology modulated by chiral functionalization. TEM and DLS analyses showed that L-cysteine-functionalized AuNPs were smaller and more uniform, while FTIR and circular dichroism spectroscopy confirmed surface binding and the induction of optical activity, respectively. L-Cys-AuNPs exhibited the highest antimicrobial efficacy against a broad spectrum of microorganisms, including Escherichia coli, Salmonella enterica, Listeria monocytogenes, Staphylococcus aureus, Staphylococcus epidermidis, and, notably, Candida albicans. L-Cys-AuNPs showed the lowest MIC and MBC values, highlighting the synergistic effect of chirality on biological performance. These findings suggest that L-cysteine surface engineering significantly enhances the therapeutic potential of AuNPs, particularly in combating drug-resistant fungal pathogens such as C. albicans. This research paves the way for the development of next-generation antimicrobial agents, reinforcing the relevance of green nanotechnology in the field of materials science and nanotechnology. Full article

Salmonella is one of the main causes of food-borne illness worldwide. In most cases, Salmonella contamination can be traced back to food processing plants and/or to cross-contamination during food preparation. To avoid food-borne diseases, food processing plants use sanitizers and biocidal to reduce bacterial contaminants below acceptable levels. Despite these preventive actions, Salmonella can survive and consequently affect human health. This study investigates the adaptive capacity of the main Salmonella enterica serotypes isolated from the poultry production line, focusing on their replication, antimicrobial resistance, and biofilm formation under stressors such as acidic conditions, oxidative environment, and high osmolarity. Using growth curve analysis, crystal violet staining, and microscopy, we assessed replication, biofilm formation, and antimicrobial resistance under acidic, oxidative, and osmotic stress conditions. Disinfectant tolerance was evaluated by determining the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of sodium hypochlorite. The antibiotic resistance was assessed using the Kirby–Bauer method. The results indicate that, in general, acidic and osmotic stress reduce the growth of Salmonella. However, no significant differences were observed specifically for serotypes Infantis, Heidelberg, and Corvallis. The S. Infantis isolates were the strongest biofilm producers and showed the highest prevalence of multidrug resistance (71%). Interestingly, S. Infantis forming biofilms required up to 8-fold higher concentrations of sodium hypochlorite for eradication. Furthermore, osmotic and oxidative stress significantly induced biofilm production in industrial S. Infantis isolates compared to a reference strain. Understanding how Salmonella responds to industrial stressors is vital for designing strategies to control the proliferation of these highly adapted, multi-resistant pathogens. Full article

The increasing demand for fresh fruits and vegetables has been accompanied by a rise in foodborne illness outbreaks linked to fresh produce. Traditional antimicrobial washing treatments, such as chlorine and peroxyacetic acid, have limitations in efficacy and pose environmental and worker health concerns. This study evaluated the effectiveness of organic acids (citric, malic, and lactic acid) and power ultrasound, individually and in combination, for the reduction in Salmonella enterica and Listeria monocytogenes on four fresh produce types: romaine lettuce, cucumber, tomato, and strawberry. Produce samples were inoculated with bacterial cocktails at 8–9 log CFU/unit and treated with organic acids at 2 or 5% for 2 or 5 min, with or without power ultrasound (40 kHz). Results showed that pathogen reductions varied based on the produce matrix with smoother surfaces such as tomato, exhibiting greater reductions than rougher surfaces (e.g., romaine lettuce and strawberry). Lactic and malic acids were the most effective treatments, with 5% lactic acid achieving a reduction of >5 log CFU/unit for S. enterica and 4.53 ± 0.71 log CFU/unit for L. monocytogenes on tomatoes. The combination of organic acids and power ultrasound demonstrated synergistic effects, further enhancing pathogen reduction by <1.87 log CFU/unit. For example, S. enterica on cucumbers was reduced by an additional 1.87 log CFU/unit when treated with 2% malic acid and power ultrasound for 2 min compared to malic acid alone. Similarly, L. monocytogenes on strawberries was further reduced by 1.84 log CFU/unit when treated with 5% malic acid and power ultrasound for 2 min. These findings suggest that organic acids, particularly malic and lactic acids, combined with power ultrasound, may serve as an effective hurdle technology for enhancing the microbial safety of fresh produce. Future research can include validating these treatments in an industrial processing environment. Full article

Antimicrobial food packaging with natural antimicrobials and biodegradable polymers presents an innovative solution to mitigate microbial contamination, prolong freshness, reduce food waste, and alleviate environmental burden. This study developed antimicrobial hemicellulose-based films by incorporating carvacrol (1% and 2%) as a natural antimicrobial agent through micro-emulsification produced by high-pressure homogenization (M-films). For comparison, films with the same formula were constructed using coarse emulsions (C-films) without high-pressure homogenization. These films were investigated for their antimicrobial efficacy, mechanical and barrier properties, and physicochemical attributes to explore their potential as sustainable antimicrobial packaging solutions. The M-films demonstrated superior antimicrobial activity, achieving reductions exceeding 4 Log CFU/mL against Listeria monocytogenes, Escherichia coli, and Salmonella enterica, compared to the C-films. High-pressure homogenization significantly reduced the emulsion’s particle size, from 11.59 to 2.55 μm, and considerably enhanced the M-film’s uniformity, hydrophobicity, and structural quality. Most importantly, the M-films exhibited lower oxygen transmission (35.14 cc/m²/day) and water vapor transmission rates (52.12 g/m²/day) than the C-films at 45.1 and 65.5 cc/m²/day, respectively, indicating superior protection against gas and moisture diffusion. Markedly improved mechanical properties, including foldability, toughness, and bubble-free surfaces, were also observed, making the M-films suitable for practical applications. This study highlights the potential of high-pressure homogenization as a method for enhancing the functional properties of hemicellulose-based films (i.e., M-films). The fabricated films offer a viable alternative to conventional plastic packaging, paving the way for safer and greener solutions tailored to modern industry needs. Full article

Background: The spread of ESBL-producing Enterobacteriaceae (ESBL-PE) strains in food poses a potential risk to human health. The aim of the study was to determine the occurrence of ESBL-PE and to investigate their distribution on foods. Methods: A total of 1000 food samples, including both raw and ready-to-eat products, was analyzed for the presence of ESBL-producing Enterobacteriaceae using chromogenic selective agar. Antibiotic resistance in the isolated strains was assessed using conventional methods, while whole-genome sequencing was employed to predict antimicrobial resistance and virulence genes. Results: The overall occurrence of ESBL-PE strains was 2.8%, with the highest contamination in raw meat samples (10%). A total of 31 multidrug-resistant (MDR) strains was isolated, mainly Escherichia coli, followed by Klebsiella pneumoniae, Salmonella enterica, and Enterobacter hormaechei. All strains exhibited high levels of resistance to at least four different β-lactam antibiotics, as well as to other antimicrobial classes including sulfonamides, tetracyclines, aminoglycosides, and quinolones. Whole-genome sequencing identified 63 antimicrobial resistance genes, with bla_CTX-M being the most prevalent ESBL gene. Twenty-eight (90%) isolates carried Inc plasmids, known vectors of multiple antimicrobial resistance genes, including those associated with ESBLs. Furthermore, several virulence genes were identified. Conclusions: The contamination of food with ESBL-PE represents a potential public health risk, underscoring the importance of the implementation of genomic surveillance to monitor and control the spread of antimicrobial resistance. Full article