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Fruits and vegetables are susceptible to Listeria monocytogenes. In this study, the nano emulsion of oregano essential oil (OEO) prepared by ultrasonic (US) nanoemulsion method combined with US has a promising synergistic bactericidal effect on L. monocytogenes , with 255 W/cm2+0.06 μL/mL origano essential oil nanoemulsion (OEONE) completely kill the initial number of bacteria (8.67 ± 0.17 log CFU/mL) after 15 min of treatment. Compared to control, reactive oxygen species (ROS), malondialdehyde (MDA) detection, nucleic acid and protein release tests showed that US + OEONE intensified cell membrane lipid peroxidation and increased cell membrane permeability. Flow cytometry (FCM) once again demonstrated the damage to cell membrane integrity caused by US + OEONE treatment. The results of field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) indicate that US + OEONE treatment alter cell morphology. Also, this study provides evidence to support the use of US + OEONE as a practical preservation method to minimize the presence of L. monocytogenes on the surface of blueberries, and sensory evaluations indicate that US + OEONE-treated blueberries are acceptable. In addition, this method demonstrated the ability to retard microbial proliferation without affecting the color, texture, and antioxidant properties of blueberries during storage. These results indicate that the implementation of US + OEONE is expected to improve the microbial safety of fresh produce. [Display omitted] • Ultrasound (US) and oregano essential oil (OEONE) had a synergistic antibacterial efficacy. • US + OEONE significantly disrupted the permeability and integrity of cell membranes. • US + OEONE obviously altered the morphology and internal microstructure of cells. • US + OEONE caused bacterial oxidative stress and lipid peroxidation. • The treatment method of US + OEONE has promising application effect on blueberry preservation. [ABSTRACT FROM AUTHOR]

Eugenol is a natural active substance with high antibacterial activity, but its antibacterial activity against Vibrio vulnificus has not been extensively studied. The purpose of this study was to investigate the antibacterial and biofilm-clearing abilities and potential mechanisms of eugenol against V. vulnificus , and to provide knowledge for the use of eugenol to prevent oyster contamination. It was found that eugenol had an encouraging antibacterial effect on V. vulnificus with a minimum inhibitory concentration (MIC) of 0.2 mg/mL. The accumulation of reactive oxygen species (ROS) and the increase of malondialdehyde (MDA) content suggest that oxidative stress is involved in the bactericidal mechanism. Moreover, cell membrane hyperpolarization, changes in cell membrane integrity and morphology suggest that eugenol can reduce the permeability and integrity of cell membranes in V. vulnificus. In addition, eugenol produced a significant biofilm clearance effect on V. vulnificus , as evidenced by the reduced amount of biofilm and the reduction of polysaccharides and viable cells in the biofilm. Finally, eugenol was able to effectively inhibit the activity of V. vulnificus in artificially contaminated oyster at 4 °C and 25 °C. But sensory analysis showed that 0.10% eugenol was most acceptable to trained panelists. All of these highlight the great promise of eugenol as a natural bacteriostatic agent for the food industry. [Display omitted] • Antibacterial and anti-biofilm activities of eugenol against Vibrio vulnificus were investigated. • Under eugenol stress, the cell membrane permeability of V. vulnificus cells was enhanced, and the cell structure was damaged. • Eugenol effectively reduces biofilms formed by V. vulnificus on glass and stainless steel surfaces. • Eugenol has advantages in the control of oysters contaminated with V. vulnificus. [ABSTRACT FROM AUTHOR]

[Display omitted] • DDAB showed antibacterial effects toward S. aureus and P. aeruginosa , and caused membrane depolarization. • DDAB removed biofilms of S. aureus and P. aeruginosa , and destroyed biofilm microstructure. • DDAB combined with SAEW significantly decreased viable bacteria in biofilms compared with DDAB or SAEW alone. • DDAB combined with SAEW decreased polysaccharides, proteins and phospholipids in biofilms more than DDAB or SAEW alone. • The novel combination of DDAB and SAEW can remove biofilms in food processing environments. This project explored the antibacterial mechanism of didecyldimethylammonium bromide (DDAB) toward Staphylococcus aureus and Pseudomonas aeruginosa , and its removal effect on biofilms. Furthermore, we explored the effect of treatment by DDAB combined with slightly acidic electrolyzed water (SAEW) on biofilms of S. aureus or P. aeruginosa. First, DDAB has bacteriostatic and biofilm removal effects. Second, The effect of DDAB combined with SAEW on biofilm is more obvious than that of the two alone. DDAB at a concentration of 16 MIC combined with SAEW (ACC 30 mg/L, ORP 875 mV, pH 6.30) completely cleared the biofilm. In addition, the results of Confocal laser scanning microscopy (CLSM), Field emission scanning electron microscopy (FESEM) and Attenuated total reflection–Fourier-transform infrared spectroscopy (ATR-FTIR) showed that DDAB combined with SAEW could disrupt the structure of biofilms, reduce polysaccharides, proteins and phospholipids in biofilms. This method has the potential to be used in food production chains to control S. aureus and P. aeruginosa and their biofilms, and it can be used in other industries. [ABSTRACT FROM AUTHOR]