Aims Staphylococcus aureus has emerged as a serious threat to food safety owing to biofilm formation. The study aimed to examine the antibiofilm mechanism of a novel milk-derived antimicrobial peptide BCp12 against it. Methods and results Antibiofilm activity of BCp12 was studied by crystal violet staining, MTT assay, motility, SEM and CLSM. TMT proteome, real-time PCR and molecular docking in silico were conducted to evaluate the mechanism of BCp12 against S. aureus biofilm. The results showed that BCp12 had significant antibiofilm activity at 1 × MIC and sub-MIC. BCp12 induced the dispersion of structure of S. aureus biofilm BCp12 inhibited the movement of S. aureus . A total of 703 proteins were downregulated and 334 proteins were upregulated after BCp12 treatment. The proteins (agrA, agrB, agrC and psmβ) of the QS systems were downregulated. Additionally, the expression of the agr-related genes, agrA , agrB , agrC and psmβ , was downregulated. BCp12 was bound to the receptor proteins agrA and agrC through hydrogen bonds and π–π bonds. Conclusions The results showed the antibiofilm activity of BCp12 and it inhibits the biofilm formation by interfering agr QS system. Significance and Impact of Study BCp12 has the potential to be a novel antibiofilm agent against S. aureus biofilm and used in the food industry.
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.
Li Na Wei,Chang Zheng Shi,Cang Xue Luo,Ching Yuan Hu,Yong Hong Meng
Biofilm is a critical factor for L. monocytogenes to persist in food processing. Phloretin is a natural product that is potent to antibacterial. In order to investigate the effects of phloretin on L. monocytogenes biofilm, we used sub-MIC phloretin to treat L. monocytogenes at 37 °C and 4 °C. The results show that L. monocytogenes biofilm maximum inhibitory rate was up to 60% when 20 μg/mL phloretin was used. The capacity of biofilm adhesion and aggregation of L. monocytogenes were declined. Meanwhile, biofilm protective capacity was impaired. The biofilm thickness of the treated group was decreased by 2 μm approximately at 20 μg/mL phloretin treatment. We also studied the mechanisms of biofilm inhibition by phloretin. The quorum sensing related genes were inhibited by phloretin. The relative transcript level of the agr system genes in quorum sensing was reduced by 50% with 20 μg/mL phloretin treatment. These findings suggest that phloretin has the potential to be developed as a natural antibacterial or biofilm inhibitor to control contamination in the food industry.
危险品化学品经营许可证（带存储）