Anti-Listeria potential of bacteriocins from Lactic Acid Bacteria against persistent and non-persistent L. monocytogenes

Introduction: Listeria monocytogenes is a pathogen responsible for listeriosis, a severe foodborne infection. This bacterium is of particular concern in the food industry due to its ability to persist in food processing environments, increasing the risk of food contamination [1]. However, the mechanisms that facilitate its persistence are poorly understood. Research and development of new technologies, such as effective biocides, is essential to improve the control of L. monocytogenes in food processing environments. Objective: This work aimed to assess whether the anti-listeria activity of bacteriocins produced by different Lactic Acid Bacteria (LAB) varies concerning the persistence ability of L. monocytogenes. Methods: Antilisterial activity (AU/mL) of six LAB isolates against L. monocytogenes from fermented meat products (15 non-persistent and 17 persistent) [2] was determined. Each LAB was cultivated in de Man, Rogosa and Sharpe agar plates (MRS agar) at 30 ºC for 24 h and, subsequently, one colony of each isolate was transferred to 10 ml of MRS broth. Each L. monocytogenes strain was cultivated twice in Brain Heart Infusion broth (BHI broth) at 37 ºC for 24 h under anaerobic conditions. Discussion and conclusions: Different inhibitory activities were observed among bacteriocins produced by LAB of the same species. Overall, bacteriocin produced by Leuconostoc lactis RK18 showed less activity. Differences in inhibition were observed between L. monocytogenes strains. No differences were observed between persistent and non-persistent L. monocytogenes isolates. With one exception, all the bacteriocins investigated have been shown to have excellent antilisterial activity against L. monocytogenes strains, regardless of whether they are persistent or non-persistent in food processing environments.