Anti-biofilm effect of the cell-free supernatant of probiotic Saccharomyces cerevisiae against Listeria monocytogenes

Abstract

Biofilm-forming Listeria monocytogenes can be highly infectious and difficult to eliminate in the food industry. This study evaluated the anti-biofilm effects of the cell-free supernatant (CFS) of Saccharomyces cerevisiae against L. monocytogenes. To investigate the anti-biofilm mechanism, cell surface properties (auto-aggregation and cell surface hydrophobicity), exopolysaccharides (EPS) production, expression of related genes, and morphological changes were examined. The CFS inhibited and eradicated the biofilm of L. monocytogenes. Auto-aggregation, cell surface hydrophobicity, and EPS production significantly decreased in all CFS-treated L. monocytogenes strains. Real-time polymerase chain reaction revealed significant downregulation of virulence factors (prfA and hlyA) and biofilm-related genes following CFS treatment. The anti-biofilm effects of CFS against L. monocytogenes were also confirmed through scanning electron microscopy and confocal laser scanning microscopy. Thus, it was demonstrated that the CFS of S. cerevisiae isolated from cucumber jangajji exerts anti-biofilm effects against L. monocytogenes.