Antibacterial mechanism of mixed natural preservatives (ε-poly-lysine, cinnamon extract, and chestnut inner shell extract) against Listeria monocytogenes

Abstract

This study investigated whether Listeria monocytogenes growth could be controlled using a combination of ε-poly-lysine, cinnamon extract, and chestnut inner shell extract in tryptic soy broth (TSB) and chicken meat juice. A mixed natural preservative (MNP) inhibited the growth of L. monocytogenes by approximately 1 log CFU/mL in TSB. The cell surface characteristics of L. monocytogenes, as well as hydrophobicity and auto-aggregation, were negatively impacted by treatment with MNP, and cell motility was also significantly lowered by treatment with MNP. The relative expression levels of flagella-associated and virulence-associated genes in L. monocytogenes treated with MNP were lower than those in the control treated with TSB. The antibacterial activity of MNP was clearly observed in the SEM images. L. monocytogenes treated with MNP in chicken meat juice at 4 °C completely died within 48 h, indicating that MNP exerted antibacterial effects against L. monocytogenes in chicken meat (an example of food media). Therefore, we suggest that the MNP composed of ε-poly-lysine, cinnamon extract, and chestnut inner shell extract had sufficient antibacterial effect against L. monocytogenes and may be utilized as an antibacterial agent in the food industry.