Inhibitory effect of a new bacteriocin RSQ04 purified from Lactococcus lactis on Listeria monocytogenes and its application on model food systems

Listeria monocytogenes and its biofilms can constitute a severe threat to public health. RSQ04 is a novel bacteriocin produced by Lactococcus lactis CGMCC20699 against L. monocytogenes ATCC 19115. Molecular mass and amino acid sequence of RSQ04 were, respectively, 1164.55 Da and NGNGAAPAAASPAP. RSQ04 exhibited excellent stability during storage and adverse conditions such as low temperature, heat, and acid stress. Growth and biofilm formation of L. monocytogenes_15 planktonic cells were significantly (p < 0.05) inhibited after treatment with RSQ04. Scanning electron microscopy analysis revealed that cellular structure of L. monocytogenes_15 was disrupted by RSQ04 due to pore formation on the cell membrane. Hemolytic and cytotoxicity activity on HEK293T cells as well as in vivo evaluation in Kunming mice confirmed safety of RSQ04. Moreover, antibiofilm activity of RSQ04 was confirmed against L. monocytogenes_15 onto abiotic (stainless steel) and biotic surfaces (chicken breast and Italian ham). These findings indicate that RSQ04 could be used as a potential food biopreservative to control contamination by L. monocytogenes. This study systematically investigated RSQ04 from purification, characterization, safety assessment, and practical application on model food systems, providing an example for development and utilization of bacteriocins in food industries.