Application of the cell-free supernatant from Weissella viridescens to control Listeria monocytogenes

Listeria monocytogenes can form biofilms on different food contact surfaces, increasing the risk of cross-contamination in food products. Weissella viridescens are Gram-positive bacteria and belong to lactic acid bacteria (LAB). The aim of this study was to investigate the antibacterial activity of cell-free culture supernatant (CFS) from W. viridescens to control L. monocytogenes biofilms as well as their growth on chilled pork. Preliminary results suggest that the antibacterial compounds in W. viridescens CFS may be proteinaceous in nature. The minimum inhibitory concentrations (MICs) of most L. monocytogenes strains tested was 30 mg mL–1. Biofilm formation of L. monocytogenes 10403S on stainless steel and polystyrene was significantly inhibited by the sub-inhibitory concentration of W. viridescens CFS (1/8MIC, 1/4MIC, and 1/2MIC). Our results also showed that W. viridescens CFS at concentrations higher than MIC (1MIC, 2MIC, and 4MIC) was effective in eradicating the mature biofilms of 10403S strain on various surfaces. Dip applications of W. viridescens CFS could inhibit the growth of L. monocytogenes on chilled pork. On the whole, W. viridescens CFS has the potential to control biofilms as a natural antibiofilm and as an antibacterial agent to inhibit the growth of L. monocytogenes on chilled pork.