Exploring inhibition of Listeria monocytogenes biofilm by carvacrol based on action to quorum sensing

The contamination of L. monocytogenes on different foods mainly achieves by the formation of biofilm, and L. monocytogenes biofilm poses great risks to food industry. Hence, exploring the safe and nontoxic substances to interfere and destroy L. monocytogenes biofilm is of great concern. In this research, carvacrol was selected as the antibiofilm substance to investigate its effect on the three-dimensional structure, extracellular polymer matrix, aggregation, adhesion and Agr quorum sensing system of L. monocytogenes biofilm. The results revealed that L. monocytogenes showed the greatest biofilm formation ability in 5 days cultivation on stainless steel sheet. The minimum biofilm inhibition concentration and minimum biofilm elimination concentration of carvacrol against L. monocytogenes biofilm were 0.4 and 0.8 mg/mL. SEM and fluorescent pictures demonstrated that carvacrol could destroy and eliminate polymer matrix of L. monocytogenes biofilm. Furthermore, carvacrol could impact the swimming motility and aggregation ability of L. monocytogenes to inhibit the adhesion and initial formation of biofilm. Finally, carvacrol also could effectively inhibit the secretion and production of exopolysaccharide and proteins, downregulating the gene expression and binding with signaling proteins in Agr quorum sensing system to interfere the formation of biofilm. In conclusion, carvacrol could be applied as the ideal antibiofilm substance to inhibit and destroy L. monocytogenes biofilm in food industry.