In the food industry, the increasing antimicrobial resistance of food-borne pathogens to conventional sanitizers poses the risk of food contamination and a decrease in product quality and safety. Therefore, we explored alternative antimicrobials N-Acetyl-l-cysteine (NAC), rhamnolipids (RLs), and usnic acid (UA) as a novel approach to prevent biofilm formation and reduce existing biofilms formed by important food-borne pathogens (three strains of Salmonella enterica and two strains of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus). Their effectiveness was evaluated by determining minimum inhibitory concentrations needed for inhibition of bacterial growth, biofilm formation, metabolic activity, and biofilm reduction. Transmission electron microscopy and confocal scanning laser microscopy followed by image analysis were used to visualize and quantify the impact of tested substances on both planktonic and biofilm-associated cells. The in vitro cytotoxicity of the substances was determined as a half-maximal inhibitory concentration in five different cell lines. The results indicate relatively low cytotoxic effects of NAC in comparison to RLs and UA. In addition, NAC inhibited bacterial growth for all strains, while RLs showed overall lower inhibition and UA inhibited only the growth of Gram-positive bacteria. Even though tested substances did not remove the biofilms, NAC represents a promising tool in biofilm prevention.

• Keywords
• N-Acetyl-l-cysteine, acute cytotoxicity, antimicrobial efficacy, bacterial growth, biofilm, food-borne pathogens, minimum inhibitory concentrations, rhamnolipids, usnic acid,
• MeSH
• Acetylcysteine pharmacology   MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Anti-Infective Agents pharmacology   MeSH
• Benzofurans pharmacology   MeSH
• Biofilms drug effects   MeSH
• Cell Line MeSH
• Escherichia coli drug effects   MeSH
• Glycolipids pharmacology   MeSH
• Food Contamination prevention & control   MeSH
• Humans MeSH
• Listeria monocytogenes drug effects   MeSH
• Microbial Sensitivity Tests MeSH
• Foodborne Diseases drug therapy   microbiology   MeSH
• Food Microbiology methods   MeSH
• Salmonella enterica drug effects   MeSH
• Staphylococcus aureus drug effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acetylcysteine MeSH
• Anti-Bacterial Agents MeSH
• Anti-Infective Agents MeSH
• Benzofurans MeSH
• Glycolipids MeSH
• rhamnolipid MeSH Browser
• usnic acid MeSH Browser

Although some metallic nanoparticles (NPs) are commonly used in the food processing plants as nanomaterials for food packaging, or as coatings on the food handling equipment, little is known about antimicrobial properties of palladium (PdNPs) and platinum (PtNPs) nanoparticles and their potential use in the food industry. In this study, common food-borne pathogens Salmonella enterica Infantis, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus were tested. Both NPs reduced viable cells with the log10 CFU reduction of 0.3-2.4 (PdNPs) and 0.8-2.0 (PtNPs), average inhibitory rates of 55.2-99% for PdNPs and of 83.8-99% for PtNPs. However, both NPs seemed to be less effective for biofilm formation and its reduction. The most effective concentrations were evaluated to be 22.25-44.5 mg/L for PdNPs and 50.5-101 mg/L for PtNPs. Furthermore, the interactions of tested NPs with bacterial cell were visualized by transmission electron microscopy (TEM). TEM visualization confirmed that NPs entered bacteria and caused direct damage of the cell walls, which resulted in bacterial disruption. The in vitro cytotoxicity of individual NPs was determined in primary human renal tubular epithelial cells (HRTECs), human keratinocytes (HaCat), human dermal fibroblasts (HDFs), human epithelial kidney cells (HEK 293), and primary human coronary artery endothelial cells (HCAECs). Due to their antimicrobial properties on bacterial cells and no acute cytotoxicity, both types of NPs could potentially fight food-borne pathogens.

• Keywords
• acute cytotoxicity, antimicrobial properties, food-borne pathogens, minimum inhibitory concentrations, palladium nanoparticles, platinum nanoparticles,
• MeSH
• Anti-Bacterial Agents chemistry   pharmacology   MeSH
• Bacteria classification   drug effects   growth & development   MeSH
• Fibroblasts cytology   drug effects   MeSH
• Metal Nanoparticles administration & dosage   chemistry   MeSH
• Cells, Cultured MeSH
• Kidney cytology   drug effects   MeSH
• Humans MeSH
• Foodborne Diseases prevention & control   MeSH
• Palladium chemistry   MeSH
• Platinum chemistry   MeSH
• Food Microbiology MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Palladium MeSH
• Platinum MeSH