Depletion of reactive oxygen species induced by beetroot (Beta vulgaris) extract leads to apoptosis-like death in Cronobacter sakazakii

Rosa roxburghii Tratt Pomace Crude Extract Inactivates Cronobacter sakazakii Isolated from Powdered Infant Formula

Cronobacter sakazakii is an important foodborne pathogen in powder infant formula (PIF). The objective of this study was to evaluate the inactivation effect of Rosa roxburghii Tratt pomace crude extract (RRPCE) on C. sakazakii isolated from PIF and to reveal the mechanism of action. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were used to evaluate the inhibitory activity of RRPCE against C. sakazakii. The inhibitory mechanism was revealed from the perspective of effects of RRPCE on intracellular adenosine 5'-triphosphate (ATP), reactive oxygen species (ROS), membrane potential, protein and nucleic acid leakage, and cell morphology of C. sakazakii. The inactivation effects of RRPCE on C. sakazakii in biofilms on stainless steel, tinplate, glass, silica gel, polyethylene terephthalate, and polystyrene to evaluate its potential as a natural disinfectant. The results showed that the MIC and MBC of RRPCE against C. sakazakii were 7.5 and 15 mg/mL, respectively. After treatments with RRPCE, intracellular ATP content decreased significantly while intracellular ROS level increased significantly (p < 0.05). The cell membrane depolarization, large leakage of proteins and nucleic acids, and severely damaged cell morphology also occurred in C. sakazakii treated with RRPCE. In addition, a 20-minute treatment with 2 MIC (15 mg/mL) of RRPCE could inactivate all C. sakazakii (from 6.10 to 6.40 CFU/mL) in biofilms on all six contact surfaces. Our findings suggest that RRPCE is ideal for the inactivation of C. sakazakii and has the potential to be used as a natural disinfectant for the inactivation of PIF packaging materials and containers.

Beetroot (Beta vulgaris) Extract against Salmonella Typhimurium via Apoptosis-Like Death and Its Potential for Application in Cooked Pork

Salmonella Typhimurium is a common foodborne pathogen in meat and meat products, causing significant harm and losses to producers and consumers. The aim of this study was to investigate the antibacterial activity and possible mechanisms of beetroot (Beta vulgaris) extract against S. Typhimurium, as well as the application potential in cooked pork. The results suggested beetroot extract could inhibit S. Typhimurium with a minimum inhibitory concentration (MIC) of 20 mg/mL. After treatment with beetroot extract (1 or 2 MIC), S. Typhimurium exhibited the characteristics of apoptotic-like death (ALD), such as membrane depolarization, phosphatidylserine (PS) externalization, caspase-like protein activation, and DNA fragmentation. Further research has shown that the ALD induced by beetroot extract in S. Typhimurium was caused by reactive oxygen species (ROS) consumption, which was different from most natural products. The treatment of cooked pork with beetroot extract could reduce the number of S. Typhimurium, lower pH, defer lipid oxidation, and improve the colour. These results indicate that beetroot extract can inhibit S. Typhimurium through the ALD mechanism and has potential as an antibacterial agent against S. Typhimurium in ready-to-eat meat products.