In Vitro Efficacy of Nisin Peptide on Biofilm Formation and Cell Invasion of Listeria monocytogenes

This study investigated the effects of nisin concentrations on the biofilm formation and cellular invasion of Listeria monocytogenes. The study also examined the toxicity of nisin concentrations on human cell lines. Nisin is a lantibiotic with antimicrobial properties. L. monocytogenes is a deadly foodborne pathogen leading to listeriosis. Biofilm formation, cell invasion, toxin-antitoxin systems, and extracellular proteins are the primary virulence mechanisms of L. monocytogenes. The PCR method was used to confirm the presence of virulence genes in L. monocytogenes. A microplate assay was used for biofilm quantification. The effect of nisin on cell invasion and cytotoxicity in the HT-29 human cell line was investigated using invasion assay and thiazolyl blue tetrazolium bromide (MTT) methods, respectively. Nisin solutions of 104, 103, and 102 IU/mL inhibited biofilm formation by 56, 90, and 99%, respectively (p < 0.0001). Nisin at concentration of 102 IU/mL reduced the expression of biofilm formation genes: 2.5-fold for mazF, 3.9-fold for flaA, and 3.4-fold for cheA. However, the increased iap gene expression (p < 0.0001) observed at nisin of 102 IU/mL. Nisin solutions of 104, 103, and 102 IU/mL reduced the invasion into HT-29 cells by 42, 73, and 99%, respectively. Survival of the HT-29 cells treated with nisin solutions of 104, 103, and 102 IU/mL decreased by 2, 7, and 18%, respectively. The action of nisin can be enhanced through various innovative techniques, increasing its effectiveness against L. monocytogenes. Nisin significantly inhibited the expression of genes involved in biofilm formation, cell invasion, and cellular signal transduction in L. monocytogenes.