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Mikrochimica Acta Jun 2024A one-shot CO laser-based strategy to generate conductive reduced graphene oxide (rGO) decorated with nanoceria (nCe) is proposed. The 2D/0D rGO-nCe films, integrated as...
A one-shot CO laser-based strategy to generate conductive reduced graphene oxide (rGO) decorated with nanoceria (nCe) is proposed. The 2D/0D rGO-nCe films, integrated as catalytic sensing layers in paper-based sensors, were employed for on-site monitoring of indoor fogging treatments against Listeria monocytogenes (Lm), a ubiquitous pathogenic bacterium. The rGO-nCe laser-assisted synthesis was optimized to preserve the rGO film morphological and electron-transfer features and simultaneously integrate catalytic nCe. The films were characterized by microscopical (SEM), spectroscopical (EDX, Raman, and FTIR), and electrochemical techniques. The most performing film was integrated into a nitrocellulose substrate, and the complete sensor was assembled via a combination of xurography and stencil printing. The rGO-nCe sensor's catalytic activity was proved toward the detection of HO, obtaining sensitive determination (LOD = 0.3 µM) and an extended linear range (0.5-1500 µM). Eventually, the rGO-nCe sensor was challenged for the real-time continuous monitoring of hydrogen peroxide aerosol during no-touch fogging treatment conducted following the EU's recommendation for biocidal product use. Treatment effectiveness was proved toward three Lm strains characterized by different origins, i.e., type strain ATCC 7644, clinical strain 338, and food strain 641/6II. The sensor allows for discrimination and quantification treatments at different environmental biocidal amounts and fogging times, and correlates with the microbiological inhibition, promoting the proposed sensor as a useful tool to modulate and monitor no-touch treatments.
Topics: Graphite; Hydrogen Peroxide; Lasers; Paper; Listeria monocytogenes; Disinfection; Cerium; Limit of Detection; Electrochemical Techniques; Catalysis
PubMed: 38822891
DOI: 10.1007/s00604-024-06427-9 -
British Journal of Hospital Medicine... May 2024We present an unusual case of rhomboencephalitis in a young, healthy patient. Although meningitis is usually associated with immunodeficiency, rhomboencephalitis is...
We present an unusual case of rhomboencephalitis in a young, healthy patient. Although meningitis is usually associated with immunodeficiency, rhomboencephalitis is more commonly seen in immunocompetent patients. The wide differential for rhomboencephalitis can create a diagnostic challenge. Without prompt pathogen identification and appropriate antibiotic regimen, central nervous system infections can be fatal. Cerebro-Spinal Fluid (CSF) Polymerase Chain Reaction (PCR) aided a prompt diagnosis and adjustment of therapy to achieve a good patient outcome.
Topics: Humans; Listeria monocytogenes; Immunocompetence; Listeriosis; Anti-Bacterial Agents; Male; Rhombencephalon; Magnetic Resonance Imaging; Meningitis, Listeria; Adult; Encephalitis; Polymerase Chain Reaction
PubMed: 38815971
DOI: 10.12968/hmed.2023.0453 -
International Journal of Biological... Jun 2024Carbon dots (CDs) were derived using eggplant peel by a hydrothermal approach and incorporated into the carboxymethyl cellulose (CMC) and gelatin (Gel) blend to develop...
Carbon dots (CDs) were derived using eggplant peel by a hydrothermal approach and incorporated into the carboxymethyl cellulose (CMC) and gelatin (Gel) blend to develop sustainable and functional packaging films for fruit preservation. The CD was uniformly dispersed within the CMC/Gel blend to form a dense and continuous film and fashioned a strong interaction with the polymer chain, increasing the tensile strength of the film by 5.0-16.0 %. Also, with the impregnation of CDs, the UV-blocking potential of the CMC/Gel film was greatly improved to the extent of blocking 94.3 % of UV-B and 72.5 % of UV-A, while the water vapor permeability slightly decreased (by 2.7-5.4 %), and the water contact angle of the film marginally expand (by 6.2-19.1 %). The CMC/Gel film with 3 wt% of CD added depicted strong antioxidant efficacy of 100 % against ABTS and 59.1 % against DPPH and displayed strong antibacterial action that inhibited the progress of Listeria monocytogenes and Escherichia coli by 99.8 %. In addition, when table grapes were packaged using a CMC/Gel composite film containing CD and stored at 4 °C for 24 days, the fruits packed with the composite film maintained excellent external quality and extended the shelf life.
Topics: Gelatin; Carboxymethylcellulose Sodium; Food Packaging; Fruit; Solanum melongena; Carbon; Anti-Bacterial Agents; Antioxidants; Permeability; Listeria monocytogenes; Escherichia coli; Quantum Dots
PubMed: 38815951
DOI: 10.1016/j.ijbiomac.2024.132715 -
Food Chemistry Oct 2024Owing to their lack of outer skin, Chinese bayberries are highly susceptible to mechanical damage during picking, which accelerates bacterial invasion and rotting,...
Owing to their lack of outer skin, Chinese bayberries are highly susceptible to mechanical damage during picking, which accelerates bacterial invasion and rotting, shortening their shelf life. In this study, montmorillonite (MMT) was used to absorb an aqueous sodium chlorite solution embedded in a carboxymethyl cellulose sodium hydrogel after freeze drying, and the hydrogel was crosslinked by Al ions. Al hydrolyzed to produce H, creating an acidic environment within the hydrogel and reacting with NaClO to slowly release ClO. We prepared a ClO slow-release hydrogel gasket with 0.5 wt% MMT-NaClO and investigated its storage effect on postharvest Chinese bayberries. Its inhibition rates against Escherichia coli and Listeria monocytogenes were 98.84% and 98.96%, respectively. The results showed that the gasket preserved the appearance and nutritional properties of the berries. The antibacterial hydrogel reduced hardness loss by 26.57% and ascorbic acid loss by 46.36%. This new storage method could also be applicable to other fruits and vegetables.
Topics: Anti-Bacterial Agents; Bentonite; Carboxymethylcellulose Sodium; Escherichia coli; Food Preservation; Fruit; Hydrogels; Listeria monocytogenes; Myrica
PubMed: 38815326
DOI: 10.1016/j.foodchem.2024.139799 -
Frontiers in Bioscience (Landmark... May 2024, a Gram-positive bacterium, is a prominent foodborne pathogen that causes listeriosis and poses substantial health hazards worldwide. The continuing risk of listeriosis...
BACKGROUND
, a Gram-positive bacterium, is a prominent foodborne pathogen that causes listeriosis and poses substantial health hazards worldwide. The continuing risk of listeriosis outbreaks underlies the importance of designing an effective prevention strategy and developing a robust immune response by reverse vaccinology approaches. This study aimed to provide a critical approach for developing a potent multiepitope vaccine against this foodborne disease.
METHODS
A chimeric peptide construct containing 5 B-cell epitopes, 16 major histocompatibility complex I (MHC-I) epitopes, and 18 MHC-II epitopes were used to create a subunit vaccination against . The vaccine safety was evaluated by several online methods, and molecular docking was performed using ClusPro to determine the binding affinity. Immune simulation was performed using the C-ImmSimm server to demonstrate the immune response.
RESULTS
The results validated the antigenicity, non-allergenicity, and nontoxicity of the chimeric peptide construct, confirming its suitability as a subunit vaccine. Molecular docking showed a good score of 1276.5 and molecular dynamics simulations confirmed the construct's efficacy, demonstrating its promise as a good candidate for listeriosis prophylaxis. The population coverage was as high as 91.04% with a good immune response, indicating good antigen presentation with dendritic cells and production of memory cells.
CONCLUSIONS
The findings of this study highlight the potential of the designed chimeric peptide construct as an effective subunit vaccine against , paving the way for future advances in preventive methods and vaccine design.
Topics: Listeria monocytogenes; Molecular Docking Simulation; Bacterial Vaccines; Vaccines, Subunit; Listeriosis; Computational Biology; Epitopes, B-Lymphocyte; Humans; Epitopes; Molecular Dynamics Simulation; Animals; Foodborne Diseases; Immunoinformatics
PubMed: 38812301
DOI: 10.31083/j.fbl2905176 -
Scientific Reports May 2024Current knowledge about effects of disturbance on the fate of invaders in complex microbial ecosystems is still in its infancy. In order to investigate this issue, we...
Current knowledge about effects of disturbance on the fate of invaders in complex microbial ecosystems is still in its infancy. In order to investigate this issue, we compared the fate of Klebsiella pneumoniae (Kp) and Listeria monocytogenes (Lm) in soil microcosms. We then used environmental disturbances (freeze-thaw or heat cycles) to compare the fate of both invaders and manipulate soil microbial diversity. Population dynamics of the two pathogens was assessed over 50 days of invasion while microbial diversity was measured at times 0, 20 and 40 days. The outcome of invasion was strain-dependent and the response of the two invaders to disturbance differed. Resistance to Kp invasion was higher under the conditions where resident microbial diversity was the highest while a significant drop of diversity was linked to a higher persistence. In contrast, Lm faced stronger resistance to invasion in heat-treated microcosms where diversity was the lowest. Our results show that diversity is not a universal proxy of resistance to microbial invasion, indicating the need to properly assess other intrinsic properties of the invader, such as its metabolic repertoire, or the array of interactions between the invader and resident communities.
Topics: Soil Microbiology; Listeria monocytogenes; Humans; Microbiota; Klebsiella pneumoniae; Temperature; Biodiversity
PubMed: 38811807
DOI: 10.1038/s41598-024-63284-5 -
Comparative Biochemistry and... May 2024Cathelicidins are important antimicrobial peptides in various vertebrate species where they are crucial parts of the innate immune system. The current understanding of...
Cathelicidins are important antimicrobial peptides in various vertebrate species where they are crucial parts of the innate immune system. The current understanding of amphibian cathelicidins is limited, particularly with regard to their immunomodulatory effects. To address this knowledge gap, we produced the cDNA sequence of the cathelicidin gene from a skin transcriptome of the Chinese spiny frog Quasipaa spinosa. The amino acid sequence of the Quasipaa spinosa cathelicidin (QS-CATH) was predicted to consist of a signal peptide, a cathelin domain, and a mature peptide. Comparative analysis of the QS-CATH amino acid sequence with that of other amphibian cathelicidins revealed high variability in the functional mature peptide among amphibians, whereas the cathelin domain was conserved. The QS-CATH gene was expressed in several tissues, with the highest level of expression in the spleen. Upregulation of QS-CATH after Aeromonas hydrophila infection occurred in the kidney, gut, spleen, skin, and liver. Chemically synthesized QS-CATH exhibited pronounced antibacterial activity against Shigella flexneri, Staphylococcus warneri, Escherichia coli, Salmonella enterica, and Listeria monocytogenes. Furthermore, QS-CATH disrupted the cell membrane integrity of S. flexneri, as evidenced by a lactate dehydrogenase release assay, and it hydrolyzed the genomic DNA of S. flexneri. Additionally, QS-CATH elicited chemotaxis and modulated the expression of inflammatory cytokine genes in RAW264.7 mouse leukemic monocyte/macrophage cells. These findings confirm the antimicrobial effects of amphibian cathelicidin and its ability to influence immune cell function. This will expedite the potential utilization of amphibian antimicrobial peptides as therapeutic agents.
PubMed: 38810897
DOI: 10.1016/j.cbpc.2024.109943 -
Science Advances May 2024Infusion of C-labeled metabolites provides a gold standard for understanding the metabolic processes used by T cells during immune responses in vivo. Through infusion of...
Infusion of C-labeled metabolites provides a gold standard for understanding the metabolic processes used by T cells during immune responses in vivo. Through infusion of C-labeled metabolites (glucose, glutamine, and acetate) in -infected mice, we demonstrate that CD8 T effector (Teff) cells use metabolites for specific pathways during specific phases of activation. Highly proliferative early Teff cells in vivo shunt glucose primarily toward nucleotide synthesis and leverage glutamine anaplerosis in the tricarboxylic acid (TCA) cycle to support adenosine triphosphate and de novo pyrimidine synthesis. In addition, early Teff cells rely on glutamic-oxaloacetic transaminase 1 (Got1)-which regulates de novo aspartate synthesis-for effector cell expansion in vivo. CD8 Teff cells change fuel preference over the course of infection, switching from glutamine- to acetate-dependent TCA cycle metabolism late in infection. This study provides insights into the dynamics of Teff metabolism, illuminating distinct pathways of fuel consumption associated with CD8 Teff cell function in vivo.
Topics: Glutamine; Animals; CD8-Positive T-Lymphocytes; Acetates; Mice; Carbon Isotopes; Listeriosis; Listeria monocytogenes; Citric Acid Cycle; Glucose; Mice, Inbred C57BL
PubMed: 38809979
DOI: 10.1126/sciadv.adj1431 -
Applied and Environmental Microbiology Jun 2024The foodborne pathogen is differentiated into four distinct lineages which differ in their virulence. It remains unknown, however, whether the four lineages also differ...
The foodborne pathogen is differentiated into four distinct lineages which differ in their virulence. It remains unknown, however, whether the four lineages also differ with respect to their ability to persist in food processing facilities, their resistance to high pressure, a preservation method that is used commercially for control on ready-to-eat meats, and their ability to form biofilms. This study aimed to determine differences in the pressure resistance and biofilm formation of 59 isolates of representing lineages I and II. Furthermore, the genetic similarity of 9 isolates of that were obtained from a meat processing facility over a period of 1 year and of 20 isolates of from food processing facilities was analyzed to assess whether the ability of the lineages of to persist in these facilities differs. Analysis of 386 genomes with respect to the source of isolation revealed that genomes of lineage II are over-represented in meat isolates when compared with clinical isolates. Of the 38 strains of that persisted in food processing facilities (this study or published studies), 31 were assigned to lineage II. Isolates of lineage I were more resistant to treatments at 400 to 600 MPa. The thickness of biofilms did not differ between lineages. In conclusion, strains of lineage II are more likely to persist in food processing facilities while strains of lineage I are more resistant to high pressure.IMPORTANCE substantially contributes to the mortality of foodborne disease in developed countries. The virulence of strains of four lineages of differs, indicating that risks associated with the presence of are lineage specific. Our study extends the current knowledge by documentation that the lineage-level phylogeny of plays a role in the source of isolation, in the persistence in food processing facilities, and in the resistance to pathogen intervention technologies. In short, the control of risks associated with the presence of in food is also lineage specific. Understanding the route of contamination is an important factor to consider when designing improved control measures.
Topics: Listeria monocytogenes; Phylogeny; Food Microbiology; Food Handling; Biofilms; Food-Processing Industry; Meat Products
PubMed: 38809044
DOI: 10.1128/aem.00861-24 -
MBio May 2024Pathogenic bacteria rely on secreted virulence factors to cause disease in susceptible hosts. However, in Gram-positive bacteria, the mechanisms underlying secreted...
UNLABELLED
Pathogenic bacteria rely on secreted virulence factors to cause disease in susceptible hosts. However, in Gram-positive bacteria, the mechanisms underlying secreted protein activation and regulation post-membrane translocation remain largely unknown. Using proteomics, we identified several proteins that are dependent on the secreted chaperone PrsA2. We followed with phenotypic, biochemical, and biophysical assays and computational analyses to examine the regulation of a detected key secreted virulence factor, listeriolysin O (LLO), and its interaction with PrsA2 from the bacterial pathogen (). Critical to virulence is internalization by host cells and the subsequent action of the cholesterol-dependent pore-forming toxin, LLO, which enables bacterial escape from the host cell phagosome. Since is a Gram-positive organism, the space between the cell membrane and wall is solvent exposed. Therefore, we hypothesized that the drop from neutral to acidic pH as the pathogen is internalized into a phagosome is critical to regulating the interaction of PrsA2 with LLO. Here, we demonstrate that PrsA2 directly interacts with LLO in a pH-dependent manner. We show that PrsA2 protects and sequesters LLO under neutral pH conditions where LLO can be observed to aggregate. In addition, we identify molecular features of PrsA2 that are required for interaction and ultimately the folding and activity of LLO. Moreover, protein-complex modeling suggests that PrsA2 interacts with LLO via its cholesterol-binding domain. These findings highlight a mechanism by which a Gram-positive secretion chaperone regulates the secretion, stability, and folding of a pore-forming toxin under conditions relevant to host cell infection.
IMPORTANCE
is a ubiquitous food-borne pathogen that can cause severe disease to vulnerable populations. During infection, relies on a wide repertoire of secreted virulence factors including the LLO that enables the bacterium to invade the host and spread from cell to cell. After membrane translocation, secreted factors must become active in the challenging bacterial cell membrane-wall interface. However, the mechanisms required for secreted protein folding and function are largely unknown. encodes a chaperone, PrsA2, that is critical for the activity of secreted factors. Here, we show that PrsA2 directly associates and protects the major virulence factor, LLO, under conditions corresponding to the host cytosol, where LLO undergoes irreversible denaturation. Additionally, we identify molecular features of PrsA2 that enable its interaction with LLO. Together, our results suggest that and perhaps other Gram-positive bacteria utilize secreted chaperones to regulate the activity of pore-forming toxins during infection.
PubMed: 38809022
DOI: 10.1128/mbio.00743-24