The inhibitory effect of Sichuan pepper seed essential oil on Bacillus licheniformis: Action mechanism analysis based on metabolomics and application in milk

Bacillus licheniformis, as a major food spoilage organism, can cause serious deterioration of food quality and safety. In this work, Sichuan pepper seed essential oil (SPSEO) was extracted from pepper seed, the by-product of pepper pericarp production, as a novel biological antibacterial agent. It exhibited a prominent inhibitory effect on Bacillus licheniformis. Furthermore, the in-depth study of inhibitory mechanisms was conducted by metabolomics combined with multiple biochemical analysis. The results showed that the cell wall/membrane integrity and surface properties of the bacteria were heavily altered after SPSEO treatment. SPSEO depolarized membrane potential, limited DNA synthesis, and induced ROS accumulation of bacteria. SPSEO was found to disrupt the carbohydrate, amino acid, lipid, and nucleotide metabolism of bacteria, which further revealed the inhibitory mechanisms and their intrinsic relation from metabolism perspective. Additionally, SPSEO effectively controlled the growth of Bacillus licheniformis in milk at a high sensory acceptable dose, demonstrating its practical applicability.