Staphylococcus aureus (S. aureus) is a major foodborne pathogen. Amid escalating antibiotic selection pressure, the prevalence of multidrug-resistant S. aureus strains throughout the food chain has risen continuously, posing grave threats to food safety and public health. Constituting the core regulatory framework mediating antibiotic resistance in foodborne S. aureus, signaling pathway regulatory systems are highly responsive to the food matrix and processing conditions, rendering them a critical starting pointing for deciphering bacterial resistance mechanism and designing targeted control strategies. This review systematically summarizes the current contamination status and hazard characteristics of foodborne drug-resistant S. aureus, with focus on the key signaling pathways (including quorum sensing and two-component signal transduction systems) and their roles in mediating the development of antibiotic resistance. Finally, it recapitulates signaling pathway-based targeted control strategies for S. aureus in the food chain, aiming to provide theoretical support for the development of targeted control techniques.

Curing fish roes with high concentrations of sodium chloride is needed to ensure the taste and storage quality of caviar during its production. To solve the problem of the use of high concentrations of sodium salt during the processing of Oncorhynchus masou caviar, one-factor-at-a-time method, Plackett-Burman (PB) design, steepest ascent design and response surface methodology were used to optimize the formulation of low-sodium salt substitutes based on total bacterial count. The results showed that potassium lactate, potassium chloride and magnesium chloride substitution at 17.64%, 14.61% and 34.36%, respectively had the smallest negative effect on caviar quality and could improve the pH value, water activity and color difference of caviar and inhibit microbial growth in it. Therefore, the use of the low-sodium salt formulation for the preparation of caviar can improve the product quality and safety, indicating its great application potential.

Foods may be contaminated by foodborne pathogens during production, processing, transportation, storage, and consumption, resulting in hidden safety hazards. Currently, many sterilization methods are available to control foodborne pathogens including thermal processing, irradiation, electrolyzed water and plasma. But they have some disadvantages in terms of food sensory quality, large-scale application, and safe production. Lactic acid bacteria are widely used as starter cultures and preservatives in foods because of their versatile biolgical activity, and they also can antagonize foodborne pathogens in foods. In this article, the antibacterial mechanism of lactic acid bacteria is expounded from the perspectives of competitive effect, interference with the bacterial virulence signal system and antibacterial metabolites, and the latest application of lactic acid bacteria against foodborne pathogens in dairy products, meat products, and fruit and vegetable products is reviewed. We hope that this review could provide a new idea for the control of foodborne pathogens and the development of lactic acid bacteria preparations.

In order to prepare dipeptidyl peptidase Ⅳ (DPP-Ⅳ) inhibitory peptide, sturgeon skin collagen was hydrolyzed by protease. A combination of one-factor-at-a-time method and response surface methodology was used optimize the preparation conditions based on percentage of DPP-Ⅳ inhibition. The optimal enzymatic hydrolysis conditions were determined as follows: temperature 50 ℃, solid-to-liquid ratio 1:100 (g/mL), pH 6.12, enzyme dosage 10170.35 U/g, and enzymatic hydrolysis time 12.12 h. The hydrolysate prepared under the optimized conditions was separated and purified by sequential ultrafiltration, gel filtration chromatography and reverse-phase high performance liquid chromatography (RP-HPLC). As identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), the amino acid composition of the purified peptide with DPP-Ⅳ inhibitory activity was GPSGLDGAK, and its half-maximum inhibitory concentration (IC₅₀) value was (61.27 ± 1.16) μmol/L. The results of this study can provide a reference for the production of new bioactive components from sturgeon skin.

The present study aimed to express soluble recombinant class Ⅱa bacteriocin in Escherichia coli. The plantaricin LPL-1 gene was cloned into an arabinose promoter, and the C-terminus was fused with the his-tag sequence for expression. The inhibitory activity of recombinant plantaricin LPL-1 against Listeria monocytogenes 54002 was used as the response variable. A novel cell factory, E. coil (ΔtrxB + Δgor + ahpC^M), suitable for class Ⅱa bacteriocin expression was established by CRISPR gene editing technology. It was derived from E. coil BW25331 by deleting the thioredoxin reductase (trxB) gene and glutathione reductase (gor) gene and mutating the gene encoding peroxidase (ahpC). The recombinant plantaricin LPL-1 was purified by affinity chromatography, and its physicochemical properties were analyzed. The purified plantaricin LPL-1 possessed wide pH stability (2–11), high thermal stability (60–100 ℃), and surfactant stability. The recombinant bacteriocin has wide potential for food industrial applications.

The nutritional value of Huso dauricus caviar was explored in terms of amino acids, fatty acids, mineral elements and vitamins, and its sensory quality and antioxidant capacity were evaluated. The results showed that Huso dauricus caviar has a protein content of 25.6%, a fat content of 18.9%, an ash content of 2.6%, a moisture content of 51.5% and a carbohydrate content of 1.4%. In total, 19 amino acids were detected and quantified, and the results showed that the ratio of essential amino acids to total amino acids was 42.85%, and the ratio of essential amino acids to non-essential amino acids was 74.98%, which are in accordance with the levels recommended by the FAO/WHO. A total of 36 fatty acids were detected in this caviar, among which eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) altogether accounted for 2.24% of the fresh mass, and n-3 and n-6 polyunsaturated fatty acids 2.65% and 6.70%, respectively, indicating it to be a food rich in polyunsaturated fatty acids. The caviar was rich in trace elements including Fe (25.9 mg/kg) and Zn (20 mg/kg) and a variety of vitamins including fat-soluble vitamins A, D and E, and water-soluble vitamin B and biotin. The results of sensory evaluation showed that Huso dauricus caviar was intact and full roes with a bright color and had a compact texture and a good taste. In addition, the caviar had a good antioxidant capacity, with total antioxidant capacity (TAC) of (1.473 ± 0.102) mmol/g, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity of (58.603 ± 1.481)%, hydroxyl radical scavenging capacity of (183.909 ± 5.952) U/mg and total superoxide dismutase (SOD) activity of (27.633 ± 1.809) U/mg. In conclusion, Huso dauricus caviar is rich in nutrients with a well-balanced nutritional composition and has health benefits.