Lysozyme and carvacrol as food-safe antimicrobials synergistically eradicate Salmonella by disrupting TCA cycle and amino acid utilization

Based on the limited bactericidal effect of lysozyme (LYZ) alone against Salmonella, this study significantly enhanced the bactericidal activity of LYZ by adding carvacrol (Car). Plate counting, growth curve analysis, and scanning electron microscopy confirmed that the LYZ-Car combination significantly inhibited bacterial growth and caused severe morphological damage. Mechanistic investigations revealed that the combined treatment increased outer membrane permeability by approximately 1.6-fold and elevated intracellular reactive oxygen species (ROS) levels by 1.9-fold. Furthermore, ATPase activity and ATP content were markedly suppressed, showing reductions of 1.5-fold and 1.4-fold, respectively, indicating severe disruption of energy metabolism. Metabolomics analysis identified 129 significantly altered metabolites and revealed profound disturbances in 16 key metabolic pathways, with amino acid metabolism and the TCA cycle being the most severely affected. These quantitative results confirm that the LYZ-Car combination effectively inhibits and eradicates Salmonella, offering a promising strategy for enhancing food safety.