Listeria monocytogenes and Staphylococcus aureus are prevalent foodborne pathogens responsible for poisoning humans with food. The present study was devoted to the establishment of a method based on dual polymerase spiral reaction (dual-PSR) and melting curve analysis for concurrent identification L. monocytogenes and S. aureus. Specifically, the primer pairs were aimed at the conserved hlyA gene of L. monocytogenes and that of S. aureus (nuc). These reactions were carried out isothermally at 65 degrees C for 45 min within the same reaction vessel, and the amplified products were analyzed in a melting curve. Different average temperatures of melting allow the discrimination in the dual-PSR assay between the two target bacteria. The limits of simultaneous determination of L. monocytogenes and S. aureus in artificially contaminated fresh-cut fruit samples were 1 x 10-4 ng of genomic DNA and 1 x 102 CFU/g, respectively. This method is characterized by its expeditious nature and simultaneous detection capability, and it promises to be a valuable technology for the monitoring of pathogenic microorganisms around health and quality control of foodstuffs within that industry.

Listeria monocytogenes and Salmonella are common pathogens in milk products that cause foodborne illness. Rapid and accurate detection is essential for effective control of their infections. In this study, the bioinformatics method was used to screen highly specific primers for L. monocytogenes ( AX10_RS05385 ) and Salmonella ( SEEPA511_RS03120 ), which were combined to construct a dual qPCR system. On this basis, propidium monoazide (PMA) was used to compensate the inability of qPCR to distinguish between viable and non-viable cells. The addition of sodium deoxycholate (SD) was utilized to maximally improve the inhibition efficiency of PMA. The gold nanoparticles (AuNPs) enhanced about 20% fluorescence signal of the qPCR system, thereby establishing a rapid, highly specific, and sensitive AuNPs-SD-PMA-qPCR detection technology. This method could accurately detect as low as 5 x 10 1 CFU/g L. monocytogenes and Salmonella in milk products after 6 h enrichment. Therefore, the AuNPs-SD-PMA-qPCR provided significant application value for simultaneous detection of viable L. monocytogenes and Salmonella in food.

Type 2 diabetes mellitus is accompanied by hyperglycaemia, liver dysfunction and intestinal dysbiosis. Bioactive peptides, as functional food, ameliorate type 2 diabetes mellitus by preventing oxidative damage to the liver. Bacillus amyloliquefaciens fmb50 was used in our earlier studies to create the lipopeptide surfactin, which was shown to alleviate type 2 diabetes mellitus by regulating the intestinal flora. In this study, high-fat diet/streptozotocin-induced type 2 diabetes mellitus mice were treated with surfactin from B. amyloliquefaciens fmb50 for 12 weeks. Faecal metabolomics profiling was analysed to explore the antihyperglycaemic mechanism of surfactin in type 2 diabetes mellitus mice. The results suggested that 32 differential metabolites were identified from faeces, suggesting that surfactin administration partly exerted an antihyperglycaemic effect in type 2 diabetes mellitus mice. Finally, surfactin was shown in further experiments to lower serum and liver triacylglycerides, reduce liver fat accumulation, inhibit adipocyte hypertrophy and reverse liver, pancreas, adipose tissue and colon tissue damage in type 2 diabetes mellitus mice. These findings suggest that early surfactin supplementation might delay the development of type 2 diabetes mellitus. Graphical abstract Potential mechanism by which surfactin relieves T2DM. Green arrows pointing down indicate decreased parameters or metabolites in the M group, and green arrows pointing up indicate increased parameters or metabolites in the M group. Red arrows pointing down indicate decreased parameters or metabolites in the T2DM group, and red arrows indicate pointing up increased parameters or metabolites in the T2DM group.