Lactocin AL705 as quorum sensing inhibitor to control Listeria monocytogenes biofilm formation

The control of Listeria monocytogenes biofilm formation using lactocin AL705 bacteriocin at sub‐minimum inhibitory concentrations (MICs) through an antiquorum sensing strategy, was preliminarily investigated. The screening for biofilm formation of different Listeria species at 10°C allowed selecting L. monocytogenes FBUNT for its use as biofilm producer. MIC and minimum bactericidal concentration of lactocin AL705 purified extract against the pathogen was determined. Bacteriocin sub‐MICs were used to evaluate biofilm reduction. Concentrations between 2·5–20 AU ml−1 of lactocin AL705 produced significant decreases in biofilm formation without affecting the growth of the pathogen after 3 days of incubation. When bacteriocin concentrations (5–20 arbitrary units per millilitre (AU ml−1)) were investigated as quorum sensing (QS) inhibitors using Vibrio harveyi as reporter strain, a significant reduction in luminescence by lactocin AL705 (20 AU ml−1) was observed. Even when L. monocytogenes produced AI‐2 like molecules as recognized by the reporter strain, bacteriocins did not interfere with this compound. Antilisterial lactocin AL705 used to disrupt QS through a signal molecule inactivation was able to control L. monocytogenes FBUNT biofilm formation. Other molecule(s) different from the AI‐2 involved during biofilm formation could be acting as target of the bacteriocin. The use of bacteriocins derived from food‐grade micro‐organisms as a QS inhibition represents an effective strategy to control pathogens as well as an environmentally friendly sanitation method to mitigate postprocessing food contamination.