Antibacterial mechanism of rose essential oil against Pseudomonas putida isolated from white Hypsizygus marmoreus at cellular and metabolic levels

Pseudomonas putida (P. putida) is a common spoilage microorganism that can cause food contamination and various foodborne illnesses. Rose essential oil (REO) is regarded as a good natural antibacterial agent because of its broad spectrum and excellent antibacterial properties. This study aimed to reveal the mechanism of action of REO on P. putida at the cellular level and to investigate the regulatory role of REO on the metabolic pathway of P. putida for the first time using the metabolome. The results demonstrated that the integrity of bacterial cell walls and membranes was disrupted, leakage of cell contents (proteins, ATP, and nucleic acids) occurred after the bacterial cell is treated with REO. The severe disruptive effect of REO on cell morphology was observed under scanning electron microscopy and transmission electron microscopy, further confirming the damage of REO on the cell wall and cell membrane. A total of 200 differential metabolites were screened at the metabolic level, of which 130 differential metabolites were significantly up-regulated, and 70 differential metabolites were significantly down-regulated. These differential metabolites were mainly involved in the TCA cycle, amino acid metabolism, nucleotide metabolism, carbohydrate metabolism, lipid metabolism, biosynthesis of pantothenic acid and coenzyme A, and aminoacyl tRNA biosynthesis, among which amino acid metabolism was most severely disrupted. Finally, the application results showed that the color, smell, and tissue state of white Hypsizygus marmoreus did not change significantly 8 days after REO treatment, indicating that REO has a good bacterial inhibitory effect on white Hypsizygus marmoreus. In conclusion, REO can inhibit P. putida at multiple targets and pathways, destroying cell morphological structure and disrupting metabolic processes. These results would provide new theoretical basis for the inhibition mechanism of REO on P. putida, and REO may be used as an effective alternative to chemical additives in the edible fungi industry.