Search Results (856)

Rapidly increasing manufacturing waste intensifies the need for highly efficient and economically feasible waste-to-resource technologies. This research presented an upcycling strategy that transforms silver (Ag)-bearing waste into functional silver oxide nanoparticles (Ag₂O NPs) for potential use in biomedical applications. A two-step process of silver purification and the bio–sonochemical synthesis of Ag₂O NPs was employed. First, the sequential purification of Ag via melt-refining and electrorefining was utilized to efficiently achieve a silver purity of ≥99.90%. This purification encouraged the recycling of various forms of Ag-bearing waste. Subsequently, the purified Ag was prepared as the precursor for the bio–sonochemical synthesis of Ag₂O NPs, using Cannabis sativa SUT CBD12 flower extract as a natural reducing agent. The optimal conditions were adapted from a preliminary test using AgNO₃ as the precursor. At initial concentrations of 0.01 M Ag solution, 1 mM PVP solution, and 10 g dried weight of Cannabis sativa SUT CBD12 added to 100 mL DI water, the optimal condition was obtained at the capping agent:reducing agent:precursor volume ratio of 0.6:0.006:1, pH 10–12, under a short sonication time of 2 min. The purified Ag (waste-derived) and AgNO₃-derived Ag₂O NPs shared similar spherical shapes and sizes of ~100–130 nm. The Ag₂O NPs showed antibacterial effectiveness against S. aureus (ZOI of 26–29 mm) and E. coli (ZOI of 16–20 mm). Preliminary observations into the incorporation of Ag₂O NPs into polycaprolactone (PCL) to produce electrospun PCL/Ag₂O NPs nano fabrics shows a bead-free morphology, raising the possibility of a potential use in wound dressing. Following these preliminary explorations into potential uses and emission controls, a circular design maximizing the use of recycled resources is emphasized. Full article

Objectives: Increasing antimicrobial resistance among foodborne pathogens, particularly extended-spectrum β-lactamase (ESBL) and plasmid-mediated AmpC β-lactamase (pAmpC) production, has become a major public health concern worldwide. This study aimed to determine the presence of Salmonella Enteritidis, Salmonella Typhimurium, and Escherichia coli O157:H7 in bovine carcasses and to evaluate their antibiotic resistance profiles together with ESBL and pAmpC resistance characteristics. Methods: A total of 300 bovine carcasses were examined for the presence of Salmonella spp. and E. coli O157:H7 using culture-based isolation methods following ISO 6579-1 and FDA guidelines, respectively. The isolates were confirmed by molecular methods, and stx1, stx2, eae, and hly were investigated in E. coli O157:H7 isolates. Antimicrobial susceptibility testing was performed according to EUCAST guidelines. ESBL and pAmpC production were determined phenotypically and subsequently characterized by molecular methods. Results: A total of 25 Salmonella spp. (32% S. Enteritidis and 68% S. Typhimurium) and 20 E. coli O157:H7 isolates were recovered from different bovine carcasses. stx2 was the most frequently detected virulence gene. Of the 31 phenotypically ESBL-positive isolates, 29 carried at least one ESBL-associated gene. The predominant ESBL gene was bla_CTX-M (79.3%), followed by bla_TEM and bla_SHV (37.9%). Among CTX-M gene groups, CTX-M-25 was the most prevalent (94.4%). Phenotypic pAmpC production was detected in 13 isolates, while 17 isolates carried at least one pAmpC-associated gene, with FOX identified as the predominant gene group. All isolates were resistant to pefloxacin, followed by gentamicin (93.3%) and cefoxitin (55.5%). Multidrug resistance was detected in 34 (75.6%) isolates. Conclusions: The detection of ESBL-producing, pAmpC-positive, and multidrug-resistant Salmonella spp. and Escherichia coli O157:H7 isolates in bovine carcasses indicates the presence of antimicrobial-resistant foodborne pathogens in the beef production chain. These findings highlight the need for continued monitoring of antimicrobial resistance and effective control measures at the slaughterhouse level. Full article

Most traditional photocatalysts exist in powder form and have the disadvantage of being difficult to recycle and causing secondary pollution to the environment after use. To overcome this drawback, this study combined natural biopolymer (silk fibroin (SF)) with a previously developed titanium-based photocatalytic material P/Ag/Ag₂O/Ag₃PO₄/TiO₂ (PAgT) and fabricated a novel SF/PAgT fiber membrane via electrospinning. During the synthesis process, through adjusting the mass concentration of the PAgT dopant (0–0.30 g/mL), a series of photocatalytic fiber membranes were prepared. The morphology and structure of the as-prepared membranes were characterized by various analytical methods, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), contact angle (CA) and thermogravimetric analysis (TGA). The SEM images confirmed that the SF/PAgT composite membrane possessed a protrusive and spindle-shaped structure. FT-IR results verified that the primary structure of SF in all the as-prepared SF/PAgT membranes belonged to the Silk II type. The binding of SF with the PAgT photocatalyst did not disrupt the chemical structure and original properties of SF. Moreover, the XRD and CA measurements indicated that the SF/PAgT-4 fiber membrane exhibited the stronger diffraction peaks of anatase TiO₂ crystal structure and enhanced hydrophilicity. The experimental results clarified that the PAgT photocatalyst was successfully loaded onto the SF fiber membrane by electrospinning. To evaluate the performance of the developed visible-light-driven photocatalytic fiber membranes, Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were selected as representative bacteria strains. The results demonstrated that SF/PAgT-4 exhibited the optimal antibacterial activity and can completely inactivate 10⁷ CFU/mL of E. coli and S. aureus within just 30 min and 60 min treatment, respectively, indicating the optimal doping mass concentration of PAgT during the synthesis process was 0.20 g/mL. Furthermore, the scavenger study proved that during the photocatalytic disinfection process by SF/PAgT-4, all three radicals, including ·OH, h⁺ and ·O₂⁻, participated in the current photocatalytic disinfection system. They were capable of attacking the bacterial cells, causing the cell membrane injury, thereby leading to the intracellular component leakage and inducing extensive bacterial inactivation. Hence, by virtue of its excellent recyclability (during five cycles) and thermal stability (below 250 °C), the developed SF/PAgT-4 fiber membrane holds immense potential for highly efficient and sustainable utilization in practical water treatment applications. Full article

Background: Hydrogel membranes are highly effective biomaterials with huge potential for advanced wound management, offering the dual advantage of maintaining a beneficial moist environment while serving as a localized reservoir for antibacterial agents. Zinc oxide nanoparticles (ZnO NPs) are particularly notable in this regard, possessing potent antibacterial capabilities and intrinsic tissue-healing properties. Methods: In this study, we report the successful fabrication of a novel locust bean gum (LBG) hydrogel encapsulated with ZnO NPs, utilizing AlCl₃ as a cross-linking agent. The synthesized nanocomposite hydrogels were structurally and chemically characterized using Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR) followed by in vivo studies using experimental animals by creating wound model. Results: Physicochemical evaluations revealed a concentration and pH-dependent swelling profile, achieving a maximum swelling capacity of 97% at pH 9. In vitro kinetic studies depicted a highly desirable initial burst release of the active therapeutic, subsequently followed by a continuous, sustained release phase that was strictly governed by non-Fickian diffusion mechanics. Furthermore, the optimized formulations achieved excellent entrapment efficiencies (>95%) and substantial free-radical scavenging antioxidant potential (>86%). Biological assessments confirmed the safety and efficacy of the nanocomposites. The formulations exhibited zero cellular toxicity against fibroblast cell lines and demonstrated complete biocompatibility during tissue histopathological evaluations. Significant antimicrobial activity was also observed, as demonstrated by reduction in the Minimum Inhibitory Concentration (MIC) against critical pathogens, including S. aureus, E. coli, P. aeruginosa, and resistant MRSA strains. Crucially, in vivo studies using experimental animal models demonstrated accelerated tissue remodeling, achieving complete wound healing by day 11 and vastly outperforming the control groups. Finally, in silico molecular docking simulations corroborated these empirical findings, revealing strong and favorable binding interactions of the nanocomposite with key target proteins to elucidate its underlying antibacterial mechanisms. Conclusions: Collectively, these results establish the ZnO-loaded LBG hydrogel as a safe, multifunctional, and highly efficient topical drug delivery platform for cutaneous wound healing. Full article

Shiga toxin–producing Escherichia coli (STEC) are important zoonotic pathogens that can disseminate through environmental water systems, yet data from Southern Italy remain scarce. The aim of this study was to investigate the occurrence and genetic characteristics of STEC isolated from surface water samples collected from rivers and lakes in the Apulia region (Southern Italy). A total of 120 samples were processed according to ISO/TS 13136:2012, followed by whole genome sequencing (WGS) for isolate confirmation and characterization. Overall, 20% of the samples were stx-positive in screening. STEC strains were isolated from 4.2% of stx-positive enrichments, corresponding to one sample out of a total of 120 (0.8%). The isolate was identified as O139:H1, carrying the stx2e subtype and belonging to sequence type ST1. Genomic analysis revealed multiple virulence-associated determinants, including the complete F18 fimbrial operon (fedA-F), hlyA, csgA, gad, chuA, yehA-D, and ompT, along with stress-resistance and tellurite-resistance genes. The strain was susceptible to all antibiotics tested. The genomic profile suggests a swine-associated lineage with multiple environmental persistence traits but limited antimicrobial resistance. The detection of a swine-associated STEC strain in surface waters highlights potential environmental dissemination pathways and underscores the importance of continued monitoring within integrated water–livestock surveillance frameworks. Full article

Microbiologically induced concrete corrosion (MICC) poses a severe challenge to the long-term durability of infrastructure, particularly in sewer networks and marine environments, which is driven by microbial metabolic activities that attack cement hydrates (Ca(OH)₂, C-S-H) mainly caused by biogenic sulfuric acid (from sulfur-oxidizing bacteria) or organic acids (from fungi), converting them into expansive gypsum and ettringite, and then cause cracking and spalling. This article reviews advances in mechanisms, key microorganisms, and protection strategies of MICC to enhance our understanding of MICC and provide a guideline for effective protection. The corrosion mechanisms differ by environment: sewers exhibit three-stage pH-driven succession, marine biofilms can either accelerate or inhibit corrosion, while fungi dominate in agricultural and historical settings. Core functional microorganisms involved in MICC include sulfur-oxidizing bacteria (SOB), sulfate-reducing bacteria (SRB), and acid-producing fungi (AF), following pH-dependent succession, while indicator microorganisms for protection efficacy include typical SOB, SRB, and AF that are involved in MICC, as well as general antimicrobial indicator strains (e.g., Escherichia coli and Staphylococcus aureus) which are used only to assess broad antimicrobial activity and do not represent MICC-specific resistance. Multi-scale deterioration proceeds from microstructural decalcification and pore coarsening to macroscopic mass loss and compressive strength reduction. Protection strategies are categorized into: (i) corrosion-resistant materials (e.g., calcium aluminate cement and alkali-activated materials), (ii) antimicrobial additives (e.g., nano-ZnO and Cu₂O), (iii) surface coatings (e.g., superhydrophobic coatings and electrodeposited Cu/Cu₂O layers), and (iv) ecological regulation. However, significant gaps remain between laboratory efficacy and field performance, highlighting the need for long-term validation, multi-scale characterization, intelligent responsive materials, eco-compatible protection systems, and standardized microbial exposure systems. Full article

Background: Lipopolysaccharide (LPS) functions as a Toll-like receptor 4 (TLR4) agonist that triggers innate immunity; however, structural variations between pathogenic and commensal bacteria distinctly influence its immunostimulatory profile. This study evaluated the immunostimulatory activity of LPS derived from the commensal bacterium Hafnia alvei and explored its potential as an exploratory vaccine adjuvant. Methods: Cytokine induction was evaluated in immune cells across diverse host species, and receptor activation was assessed via reporter assays. To investigate in vivo immunogenicity and preliminary tolerability, H. alvei LPS was formulated into a prototype oil-in-water (O/W) emulsion utilizing ovalbumin (OVA) as a model antigen. Results: LPS from H. alvei strain BA2000346 exhibited immunostimulatory activity comparable to that of Escherichia coli, while inducing greater TNF-α expression than pathogenic Salmonella and Pseudomonas strains. Distinct from E. coli LPS, it demonstrated the capacity to activate both TLR4 and the mannose-recognizing Dectin-2 receptor in reporter systems. This cytokine induction was consistent across various strains and host species. Furthermore, the prototype O/W emulsion formulation enhanced antigen-specific humoral and cellular immune responses while demonstrating preliminary tolerability based on body-weight monitoring and visual clinical observation. Conclusions: H. alvei-derived LPS exhibits TLR4 and Dectin-2 agonist activity in vitro. When synergized with an O/W emulsion delivery system, it provides a preliminary indication of cross-species stimulatory potential and supports further investigation as a hypothesis-generating platform for future vaccine adjuvant development. Full article

This study evaluates the microbiological quality of drinking water in the urban area of Guaranda through an integrated approach combining culture-based methods, biochemical characterization, and polymerase chain reaction (PCR) analysis. A total of 50 drinking water samples were collected from strategically selected points within the urban distribution system following Ecuadorian technical standards. Microbiological analyses included the detection of total and fecal coliforms, as well as the isolation and identification of Escherichia coli O157:H7, Salmonella spp., and Listeria monocytogenes. Culture-based analyses revealed that 22% of samples were positive for total coliforms and 4% for fecal coliforms. In selective culture media, contamination rates reached 18% for E. coli O157:H7, 8% for Salmonella spp., and 46% for Listeria monocytogenes. However, biochemical profiling showed substantial inconsistencies with the expected phenotypic characteristics of these pathogens, particularly in oxidase and citrate tests, suggesting possible false-positive identifications in complex environmental matrices. PCR assays confirmed lower detection frequencies, identifying E. coli O157:H7 and Salmonella spp. in 2% of samples each, and Listeria monocytogenes in 10% of samples. Agarose gel electrophoresis validated the amplification of specific DNA fragments of 212 bp, 244 bp, and 388 bp, respectively. The findings demonstrate significant discrepancies between conventional phenotypic methods and molecular techniques, highlighting the limitations of culture-based identification when used alone. This study emphasizes the importance of integrating molecular diagnostics into routine water quality monitoring programs to improve the reliability of pathogen detection and support more effective public health risk management in urban drinking water systems. Full article

The (3aS, 6aR)-lactone serves as the key chiral intermediate for the synthesis of d-biotin. A promising approach involves the asymmetric hydrolysis of meso-dimethyl ester catalyzed by an esterase to yield the (4S, 5R)-monomethyl ester, which is subsequently reduced and cyclized to afford (3aS, 6aR)-lactone. This study first optimized the fermentation medium and culture conditions for the recombinant E. coli pET21a-EstSIT01 harboring the Microbacterium esterase gene, which exhibits high selectivity for the asymmetric synthesis of (4S, 5R)-monomethyl ester. Under optimal conditions (fermentation medium: glycerol 25 g/L, yeast extract 15 g/L, NaCl 10 g/L, MgSO₄•7H₂O 5 g/L; induction was initiated 2 h post-inoculation at 30 °C and pH 7.2), the enzyme activity increased 5.1-fold compared to the initial level, reaching 1072.7 U/L. Secondly, the reaction conditions for the whole-cell synthesis of (4S, 5R)-monomethyl ester catalyzed by EstSIT01 were optimized. The results indicated that organic solvents adversely affected enzyme stability, while high buffer salt concentration negatively impacted enzyme activity at elevated substrate concentrations. The optimal reaction strategy involved maintaining the pH of the aqueous reaction system at 7.5 by the controlled addition of aqueous ammonia to neutralize the (4S, 5R)-monomethyl ester produced during the reaction. Using 17.5 g/L cells and 200 mM substrate meso-dimethyl ester in deionized water, with the reaction pH mentioned at 7.5, complete conversion (100%) was achieved within 4 h at 30 °C. The space–time yield reached 441.6 g/L/d, exceeding the typical requirement for industrial biotransformation (>100 g/L/d), with 99.1% enantiomeric excess (ee) of (4S, 5R)-monomethyl ester. Finally, (4S, 5R)-monomethyl ester was reduced using sodium borohydride to synthesize (3aS, 6aR)-lactone with an ee value of 98.7%. The overall yield from meso-dimethyl ester to (3aS, 6aR)-lactone was 86.2%. These results demonstrate that this integrated chemo-enzymatic approach constitutes a greener method with promising potential for industrial application. Full article

This study investigates the simultaneous elimination of ethyl acetate (EA), a representative volatile organic compound (VOC), and Escherichia coli aerosols from indoor air using a continuous-flow dielectric barrier discharge (DBD) plasma reactor coupled with a photocatalytic luminous textile system (Cu/TiO₂-coated fibers). The effects of applied voltage, relative humidity, and air-flow rate on pollutant removal and disinfection performance were systematically evaluated. Optimal DBD operation at 18 kV, 1 m³ h⁻¹ airflow, and 70% relative humidity achieved single-process removal efficiencies of 77% for EA and 2 log reduction (CFU mL⁻¹) for E. coli. When photocatalysis was coupled with DBD plasma, a significant combined effect was observed, increasing EA degradation to 87% and bacterial inactivation to 3.8 log (CFU mL⁻¹). The coupling enhanced active-species generation, improved CO₂ selectivity (up to 53%), and reduced residual ozone concentration. Humidity positively affected microbial inactivation due to °OH radical formation but slightly decreased VOC degradation by limiting ozone regeneration. Results demonstrate the efficiency and scalability of the DBD–photocatalysis hybrid system for multi-pollutant indoor air purification, offering rapid, low-temperature treatment suitable for industrial-scale applications. Full article

This study investigated the behavior of Salmonella Typhimurium ATCC 14028, Escherichia coli O157:H7 and Listeria monocytogenes ATCC 13932 during the ripening of ‘Nduja, a traditional spreadable fermented sausage for which quantitative microbiological data remain limited. An experimental challenge test was conducted under pilot-plant conditions simulating artisanal production, with products inoculated with the three pathogens and monitored over a 28-day ripening period. Microbiological analyses were performed at defined time points, alongside pH and water activity measurements, and inactivation kinetics were modelled using linear and non-linear approaches. The results showed a pathogen-dependent response to the combined antimicrobial hurdles of the process. Salmonella Typhimurium was declined to levels below the detection limit by day 28 (–7.10 log CFU/g), while E. coli O157:H7 showed a progressive reduction (–3.61 log CFU/g) but persisted at detectable levels. L. monocytogenes exhibited the highest resistance, with only a limited reduction (–1.32 log CFU/g); however, no net growth was observed throughout the ripening period, indicating that the product environment did not support its growth. The ripening process was characterized by decreasing pH and water activity, driven by lactic acid bacteria growth, with no differences between inoculated and control samples. Non-linear models provided the best fit to the survival data, highlighting the presence of resistant subpopulations. Overall, the results suggest that ‘Nduja ripening creates conditions unfavorable for sustained pathogen proliferation, although the extent of microbial reduction differed among the investigated microorganisms. These findings provide useful data for the microbiological characterization of this traditional product and may support future risk assessment and process validation studies. Full article

The Ib-M1 peptide exhibits bactericidal activity against Escherichia coli O157:H7 and low toxicity in mammalian cells. The present study aimed to evaluate the effect of Ib-M1 on E. coli O157:H7 membrane permeabilization. For this purpose, the minimum inhibitory concentrations of Ib-M1 for E. coli O157:H7 and ML35 were measured. The permeability of the E. coli outer and inner membranes was determined by measuring N-phenyl-1-naphthylamine and O-nitrophenyl-β-galactosidase hydrolysis, respectively after bacterial exposure to antimicrobial peptides and control antibiotics. Morphological changes in antimicrobial-exposed E. coli O157:H7 were evaluated by scanning electron microscopy following treatment with antimicrobial peptides. Ib-M1 expressed activity against E. coli O157:H7 and ML35 at minimal inhibitory concentrations (MIC) of 2.9 ± 1.7 and 6.3 ± 0 μM, respectively. The peptide induced permeabilization of the outer membrane of E. coli O157:H7 at all concentrations evaluated and permeabilization of the inner membrane after 50 min at concentrations between 1× MIC and 8× MIC. The morphological changes induced by Ib-M1 led to significant alterations in bacterial shape including collapsed cells and pronounced surface roughness and invaginations. In conclusion, physiological and morphological evidence indicates that the Ib-M1 antimicrobial effect against E. coli O157:H7 is mediated by its permeabilizing action on the outer and inner bacterial membranes. Full article

Biofilm formation constitutes a major factor in antibiotic treatment failure, shielding bacteria from drugs and promoting persistence. This study demonstrates that the anti-biofilm action of clove oil enhances the efficacy of fosfomycin against Escherichia coli O157:H7 (E. coli O157). Using a luxS-eGFP reporter system, it was found that clove oil inhibited E. coli O157 biofilm formation by up to 80% via suppression of the LuxS/AI-2 quorum sensing (QS) system and bacterial motility. Crucially, this disruption was shown to correlate with a strong synergistic effect when combined with fosfomycin in vitro. In a murine peritoneal infection model, the combination therapy demonstrated superior efficacy compared to monotherapy. Specifically, bacterial loads in the liver, spleen, and small intestine were significantly reduced, and histopathological damage was alleviated. Mechanistically, these effects were linked to the downregulation of the QS. These findings indicate that clove oil acts as a potent adjuvant to fosfomycin by disrupting biofilms, offering a promising strategy against systemic infections caused by E. coli O157. 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

In this research work, Ag-doped and undoped TiO₂ nanocomposites were prepared through a sol–gel method, using diethanolamine as a solvent. From the evolution of various characterized techniques (XRD, FT-IR, SEM and TGA analysis), it was found that Ag-TiO₂ nanocomposites have a mixture of rutile and anatase phases of titania. The catalytic performance of the Ag-TiO₂ nanocomposites was evaluated for Eriochrome Black T (EBT) photodegradation. To determine the photocatalytic efficiency of the nanocomposites, different factors including pH (2–12), catalytic dose (2–12 mg), reaction time (0–180 min) and concentration (2–10 mg/L) were investigated. The calcined Ag-TiO₂ showed high degradation (94%) for EBT at a low pH for 0.01 g of catalyst using 10 mg/L of dye solution. The kinetic study revealed that the photocatalytic degradation process obeys pseudo second-order kinetics. To investigate antibacterial effects, different bacteria such as Enterococcous, Staph Avrius, serritia and Escherichia E. coli were utilized. A total of 200 mg of calcined Ag-TiO₂ nanocomposite showed optimum activities against bacterial strains. Full article