Salmonella infection has emerged as a global health threat, causing death, disability, and socioeconomic disruption worldwide. The rapid and sensitive detection of Salmonella is of great significance in guaranteeing food safety. Herein, we developed a colorimetric/fluorescent dual-mode method based on a DNA-nanotriangle programmed multivalent aptamer for the sensitive detection of Salmonella. In this system, aptamers are precisely controlled and assembled on a DNA nanotriangle structure to fabricate a multivalent aptamer (NTri-Multi-Apt) with enhanced binding affinity and specificity toward Salmonella. The NTri-Multi-Apt was designed to carry many streptavidin-HRPs for colorimetric read-outs and a large load of Sybr green I in the dsDNA scaffold for the output of a fluorescent signal. Therefore, combined with the magnetic separation of aptamers and the prefabricated NTri-Multi-Apt, the dual-mode approach achieved simple and sensitive detection, with LODs of 316 and 60 CFU/mL for colorimetric and fluorescent detection, respectively. Notably, the fluorescent mode provided a self-calibrated and fivefold-improved sensitivity over colorimetric detection. Systematic results also revealed that the proposed dual-mode method exhibited high specificity and applicability for milk, egg white, and chicken meat samples, serving as a promising tool for real bacterial sample testing. As a result, the innovative dual-mode detection method showed new insights for the detection of other pathogens.
Casein (CN) is a common allergen that is challenging to avoid in modern foods. The effect of cold argon plasma (CAP) on reducing CN antigenicity was investigated, focusing on alterations in epitope structure and sequence. CAP mainly contains hydroxyl radicals (∙OH). After a 12-min CAP treatment, the result of ELISA demonstrated an 80.46 % reduction in antigenicity. Transmission electron microscopy and electrophoresis revealed that certain CN aggregated, while multispectral analysis indicated that part of CN was fragmented into smaller peptides. The predictive 3D model suggested the disruption of linear epitopes located in the α-helix region might contribute to the reduced allergenicity. The peptide sequences were compared to the linear epitopes predicted by immunoinformatics approaches, revealing some reduction or breakage of key allergic sequences. Meanwhile, amino acids with aromatic side chains and hydrophobic groups were susceptible to CAP-induced modifications. This investigation demonstrated CAP could be beneficial for processing hypoallergenic foods.
Cold argon plasma (CAP) effectively modifies casein (CN) structures by cleaving peptide chains and altering allergenic epitopes. This study assessed the allergenicity of CAP-treated CN in KU812 cells and BALB/c mouse models, supported by a multiomics approach integrating 16S rDNA sequencing, serum metabolomics, and jejunal transcriptomics. CAP treatment reduced CN allergenicity, evidenced by decreased KU812 cell degranulation, alleviated allergic responses in mice, and a Th1/Th2 balance shift toward Th1 dominance. Furthermore, CAP-treated CN restored the gut microbiota equilibrium, increasing the number of beneficial bacteria. Multiomics analysis highlighted its impact on lipid metabolism pathways, with Zbp1 and Hbb-bt identified as potential regulators of allergic responses. These findings underscore the potential of cold argon plasma as an innovative strategy to reduce food allergenicity through multifaceted physiological mechanisms, offering promising therapeutic applications in food allergy management.
Lactiplantibacillus plantarum NUC08, a novel probiotic strain, has demonstrated potential for synergistic fermentation with starter cultures. This study investigates its functional properties in fermented milk and examines how mulberry fruit extract (MFE), rich in bioactive compounds, may influence its fermentation performance. MFE significantly boosted LAB growth, improved texture and rheological properties, and enhanced antioxidant capacity in the probiotic yogurt. GC-MS analysis revealed that MFE enriched the flavor profile by increasing key flavor-related metabolites, contributing to superior sensory qualities. Furthermore, the combination of L. plantarum NUC08 and MFE led to distinct shifts in metabolic pathways, as shown by LC-MS analysis, amplifying the regulatory effects on antioxidant activity. These findings demonstrate the synergy between MFE and L. plantarum NUC08, where MFE enhances the growth and functionality of L. plantarum NUC08, improving the yogurt's physicochemical properties, antioxidant capacity, and flavor, with potential for functional dairy product development.
Lipoteichoic acid synthase (LtaS) is crucial for the biosynthesis of lipoteichoic acid (LTA) in lactic acid bacteria (LAB), where LTA plays a key role in bacterial adhesion, immune modulation, and maintaining cell integrity. This study explores the regulation of LtaS activity in Lactiplantibacillus plantarum, examining the effects of factors such as temperature, pH, and metal ions on enzyme activity. Molecular docking was used to identify critical amino acids at the enzyme's active site, and site-directed mutagenesis confirmed the role of five key residues (Glu-259, Thr-303, Asn-353, Arg-360, and His-420) in LtaS activity. Among them, Thr-303 plays a pivotal role, followed by Glu-259 and His-420. Conservation analysis revealed that these active-site residues are highly conserved across LAB species. These findings provide valuable insights into the functional properties of LtaS, offering potential for enhancing the efficacy of LAB-based probiotics and improving their therapeutic benefits in health applications.