Pyrrole-2-carboxylic acid inhibits biofilm formation and suppresses the virulence of Listeria monocytogenes

Abstract Bacterial adhesion and biofilm formation of Listeria monocytogenes on food-contact surfaces result in serious safety concerns. This study aimed to explore the antibiofilm efficacy of pyrrole-2-carboxylic acid (PCA) against L. monocytogenes. Crystal violet staining assay demonstrated that PCA reduced the biofilm biomass of L. monocytogenes. The 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide reduction and flow cytometric assays indicated that PCA attenuated the metabolic activity of L. monocytogenes biofilm together with a decrease in viability. Morphologic observations revealed that PCA exposure collapsed the biofilm architecture. PCA administration of 0.75 mg ml−1 decreased the excretion of extracellular DNA, protein and polysaccharide by 48.58%, 61.60% and 75.63%, respectively. PCA failed to disperse the mature biofilm, even at 1.5 mg ml−1. However, PCA suppressed L. monocytogenes adhesion on common food-contact surfaces. Additionally, PCA exposure suppressed the hemolytic activity of L. monocytogenes. These findings suggested that PCA might serve as an alternative antibiofilm agent to control L. monocytogenes contamination. Graphical Abstract