Effect of C6-HSL and chlorogenic acid on spoilage characteristics of Serratia liquefaciens in mutton

Quorum sensing (QS) is a bacterial cell-cell communication system that coordinates group behaviors via self-produced signaling molecules. Serratia liquefaciens, a common mutton spoilage bacterium, precisely regulates its spoilage capacity through the AHL-mediated QS system. The results demonstrated that 20 mol/mL C6-HSL concentration-dependently enhanced AHL activity 1.26-fold, increased biofilm formation by 51.55%, and elevated protease activity and siderophore production by 37% and 26.78%, respectively. In contrast, 80 g/mL chlorogenic acid significantly inhibited AHL activity (by 26.19%), biofilm formation (by 42.54%), protease activity (by 28.92%), and motility (by 38.34%). In stored mutton, chlorogenic acid treatment reduced total plate counts by 6.1% and pH by 5.26%. Transcriptomic analysis revealed that C6-HSL treatment altered metabolic pathways such as flagellar assembly, ABC transporters, two-component systems, and secondary metabolite synthesis, in which spoilage-related genes (slyB, fimA, fliJ, iucD, cheW) were significantly up-regulated. In contrast, chlorogenic acid treatment affected pathways including amino acid metabolism, sulfur metabolism, and carbohydrate metabolism, with spoilage-related genes (fimA, tuf, ibpA, clpS, metQ) significantly down-regulated. These findings demonstrate that AHL activity plays a key role in regulating the spoilage capacity of Serratia liquefaciens, and suggest chlorogenic acid as a potential QS inhibitor with promising application in mutton preservation. ImportanceSerratia liquefaciensis a common spoilage bacterium in refrigerated foods and proliferates extensively in meat, making it one of the primary spoilage organisms. The significance of our research lies in investigating how changes in the activity of the signaling molecule AHL affect both spoilage capacity and mutton quality. Additionally, transcriptomic analysis was employed to elucidate the regulatory mechanisms by which altered AHL activity influences the spoilage potential of S. liquefaciens. The results demonstrated that variations in AHL activity significantly impacted key spoilage-related traits of S. liquefaciens, including biofilm formation, protease activity, and motility, while also contributing to improved meat quality during storage. Furthermore, the study revealed that AHL activity regulates metabolic pathways associated with spoilage as well as the expression of spoilage-related genes. These findings provide a theoretical basis for developing preservation strategies for mutton.