Study on Regulatory Mechanism of Carvacrol on Low-Temperature Adaptation of Listeria monocytogenes in Meat Gels and the Role of Histidine Kinase LisK

The cold adaptation of Listeria monocytogenes (LM) makes it a major contaminant of refrigerated foods. This study explored the growth ability and adaptive mechanism of LM to low temperatures, focusing on histidine kinase LisK as a target and selecting carvacrol to interact with LisK to disrupt the cold adaptation of LM. Changes in gene expression and membrane phospholipids enabled LM to grow robustly under cold conditions. The knockout of the LisK gene verified its essential role in LM cold adaptation, supporting LisK as a plausible site of action. Carvacrol can form a stable structure with histidine kinase LisK through multiple interacting forces. Transcriptomic analysis identified 747 differentially expressed genes in LM after carvacrol treatment at low temperatures, with the two-component system pathway being significantly enriched. Carvacrol affected the growth ability of LM at low temperatures. In addition, the morphology, membrane permeability and intracellular macromolecules of LM at low temperatures were all impaired after carvacrol treatment. Finally, carvacrol inhibited the growth of LM and preserved the texture of pork meat gels stored at 4 °C. In conclusion, the above results confirmed the inhibitory effect of carvacrol on the growth of LM at low temperatures.