A novel strategy to enhance photocatalytic killing of foodborne pathogenic bacteria by modification of non-metallic monomeric black phosphorus with Elaeagnus mollis polysaccharides

New antibacterial agents are needed to overcome the challenges of microbial food contamination. In this study, we investigated the potential of Elaeagnus mollis polysaccharide (EMP) to modify black phosphorus (BP) for use as a bactericide for foodborne pathogenic bacteria. The resulting compound (EMP-BP) displayed enhanced stability and activity compared with BP. EMP-BP exhibited an increased antibacterial activity (bactericidal efficiency of 99.999 % after 60 min of light exposure) compared to EMP and BP. Further studies revealed that photocatalytically generated reactive oxygen species (ROS) and active polysaccharides acted collectively on the cell membrane, leading to cell deformation and death. Furthermore, EMP-BP inhibited biofilm formation and reduced expression of virulence factors of Staphylococcus aureus, and material hemolysis and cytotoxicity tests prove that the material had good biocompatibility. In addition, bacteria treated with EMP-BP remained highly sensitive to antibiotics and did not develop significant resistance. In summary, we report an environmentally friendly method for controlling pathogenic foodborne bacteria that is efficient and apparently safe.

Effect of Ultrasound-Assisted Solvent Enzymatic Extraction on Fatty Acid Profiles, Physicochemical Properties, Bioactive Compounds, and Antioxidant Activity of Elaeagnus mollis Oil

Elaeagnus mollis oil extracted from the nuts of Elaeagnus mollis Diels can be used in food and pharmaceutical applications due to its excellent nutritional value. An ultrasound-assisted solvent enzymatic extraction (UASEE) method was used to extract oil from Elaeagnus mollis Diels with n-hexane solvent (1:11.6 g/mL) and 1.1% (w/w) mixed enzymes (neutral protease:hemicellulase:pectinase = 1:1:1, w/w/w). The physicochemical properties, fatty acid profile, bioactive compounds, antioxidant activity, morphology, and thermal stability of UASEE oil were investigated and compared with soxhlet extraction (SE) oil and cold pressing (CP) oil. The UASEE oil exhibited a higher content of unsaturated fatty acids (93.96 ± 0.28%), total tocopherols and tocotrienols (147.32 ± 2.19 mg/100 g), total phytosterols (261.78 ± 5.74 mg/100 g), squalene (96.75 ± 0.31 mg/100 g), total phenolic content (84.76 ± 2.37 mg GAE/kg), and antioxidant activity (12.52 ± 0.28 mg/mL) than SE and CP oil. The lower peroxide value and acid value in UASEE oil indicated its better quality and lower likelihood of rancidity. The oil obtained using UASEE had higher thermal stability as well, as indicated by thermogravimetric analysis. Scanning electron microscopy (SEM) showed that the UASEE process causes damage to cell walls, and the leakage of substances in the cells facilitates extraction in the following step. Thus, UASEE is a promising processing method for the extraction of Elaeagnus mollis oil.