The inhibitory mechanism and metabolomics of garlic essential oil when applied to Pseudomonas fragi isolated from pork

Pseudomonas fragi (P. fragi), widely present in chilled meat and meat products, is one of the primary microorganisms that cause meat spoilage. Although Garlic essential oil (GEO) has demonstrated antibacterial effects, its mechanism of action remains unclear. The aim of this study was to explore the antibacterial effect and mechanism of GEO on P. fragi isolated from pork. According to field emission scanning electron microscopy (FESEM), alkaline phosphatase (AKP) activity, 1-N-phenyl-naphtylamine (NPN) assay, fluorescein diacetate (FDA) and flow cytometry (FCM) results, it was confirmed that the GEO destructed of P. fragi cell structure. Intracellular adenosine triphosphate (ATP), membrane potential (MP), succinate dehydrogenase (SDH) and pyruvate kinase (PK) activities were measured to confirm that GEO inhibited respiration and cell metabolism of P. fragi. At the same time, metabolomics analysis showed the changes of P. fragi intracellular metabolic activity after GEO treatment. Through the above experimental results, it is concluded that GEO can destroy the cell wall and membrane structure and inhibit P. fragi by interfering with nucleic acid metabolism, inhibiting respiratory chain and energy metabolism. These results revealed the bacteriostatic mechanism of GEO against P. fragi and provided a theoretical basis for the use of GEO as a natural preservative to control P. fragi.