Antibacterial and Antibiofilm Efficacy of Phenyllactic Acid Against Foodborne Pathogens Salmonella enterica Serotype Derby and Escherichia coli O26

Nowadays, the spread of foodborne diseases and the growing concerns about antibiotic resistance have shifted the focus of researchers towards the use of substances of natural origin. Phenyllactic acid (PLA), a naturally produced compound, has already demonstrated antimicrobial properties against pathogenic microorganisms and those responsible for food spoilage. This study examines the antibacterial and antibiofilm properties of PLA against foodborne pathogens such as <i>Salmonella enterica</i> Derby and <i>Escherichia coli</i> O26. The study showed that PLA effectively inhibited both biofilm formation and bacterial planktonic growth, with minimal inhibitory concentrations (MICs) ranging from 2 to 2.75 mg mL^-1. A dose-dependent inhibition of biofilm formation was observed, reaching approximately 90% for <i>Salmonella</i> strains and 50% for <i>E. coli</i> at 1.5 mg mL^-1. The cytotoxicity evaluation on Caco-2 cells showed that PLA was well-tolerated at concentrations up to 2 mg mL^-1. PLA's effectiveness was also demonstrated in real food matrices, where its application in minced beef stored at 4 °C significantly reduced microbial populations, unlike in untreated samples where bacterial counts increased. PLA showed a good ability to inhibit biofilm formation and eradicate a mature biofilm, measuring the total bacterial biofilm biomass. Additionally, PLA was found to be biocompatible in Caco-2 cells, confirming that it poses no health risk at the tested concentrations. The study also observed that PLA reduced bacterial adhesion to intestinal cells, suggesting its potential in preventing intestinal bacterial colonization. These results highlight PLA as a promising natural antimicrobial agent for food preservation, with potential applications in sustainable packaging and controlling microbial contamination in food processing. Future studies should further explore PLA's long-term stability and its interactions in complex food environments.