Objective: Although listeriosis caused by Listeria monocytogenes is not frequently encountered, it leads to fatal infections in affected population. The ability of L. monocytogenes to form biofilms plays a significant role in its resistance to environmental stress conditions and antimicrobials. The aim of this study is to investigate the effectiveness of inhibiting biofilm formation with specific groups of enzymes.

Methods: Biofilm structures formed by mixed-cultures created with combinations of three selected strains of L. monocytogenes, based on their abilities to form biofilms, were examined. The abilities of DNase I and Proteinase K enzymes to inhibit the capacity of L. monocytogenes to form biofilms were determined. The biofilm formation capacities of selected strain combinations were determined by OD (595 nm) value, and possible synergistic effects between strains were investigated. In the final stage, DNase I and Proteinase K enzymes were applied to multi-cultures to test their effectiveness in inhibiting biofilms.

Results: It was determined that 50 μg/ml ProteinaseK enzyme provided the most effective inhibition for NCTC 5345-4b and 1/2b-4b culture mixes. Similarly, 50 μg/ml ProteinaseK was very effective for inhibition in NCTC 5345-1/2b mix-culture.

Conclusion: In this study, it was concluded that Proteinase K enzyme at a concentration of 50 μg/ml was the most effective inhibitor compared to all enzyme applications. This outcome, similar to ongoing studies on inhibition in formed biofilms, will contribute to the literature and play a role in the development of new methods to reduce contamination risks.