| Summary: | <i>Listeria monocytogenes</i> is a foodborne pathogen exhibiting a high mortality rate. In addition to the robust tolerance to environmental stress, the ability of <i>L. monocytogenes</i> to develop biofilms increases the risk of contaminating food processing facilities and ultimately foods. This study aims to develop a synergistic approach to better control <i>Listeria</i> biofilms using nisin, the only bacteriocin approved as a food preservative, in combination with gallic-acid-rich food plant extracts. Biofilm assays in the presence of nisin and gallic acid or its derivatives revealed that gallic acid significantly decreased the level of biofilm formation in <i>L. monocytogenes</i>, whereas ethyl gallate, propyl gallate, and lauryl gallate enhanced biofilm production. As gallic acid is widely distributed in plants, we examined whether extracts from gallic-acid-rich food plants, such as clove, chestnut, oregano, and sage, may generate similar antibiofilm effects. Remarkably, sage extracts enhanced the antibiofilm activity of nisin against <i>L. monocytogenes</i>; however, the other tested extracts increased biofilm formation, particularly at high concentrations. Moreover, sage extracts and nisin combinations significantly reduced the biofilm formation of <i>L. monocytogenes</i> on stainless steel. Sage is a common food spice and has various beneficial health effects, including antioxidation and anti-cancer properties. The findings in this study demonstrate that sage extracts can be potentially combined with nisin to prevent biofilm production in <i>L. monocytogenes</i>.
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