Two-component system virS/virR regulated biofilm formation of Listeria monocytogenes 10403S

Listeria monocytogenes is a foodborne pathogen that is ubiquitous in the natural environment. Listeria monocytogenes is capable of forming persistent biofilms in food processing environments, which can lead to persistent contamination of foods. It poses a significant threat to human health and food safety. Twocomponent system (TCS) plays a crucial role in various aspects of bacterial biofilm formation and regulation of virulence factors. The wild-type strain L. monocytogenes 10403S was utilized to build the gene deletion strain & UDelta;virS/virR and the gene complementation strain C & UDelta;virS/virR. The biofilm assay with crystal violet staining and a motility assay showed that deletion of virS/virR resulted in reduced biofilm formation and motility in L. monocytogenes 10403S. Complementation strain C & UDelta;virS/virR restored the phenotypes to level of wild-type strain. Mutation the 52nd aspartate (Asp52) of VirR with alanine resulted in significantly reduce in both biofilm formation and motility. The GFP reporter system and qRT-PCR demonstrated that deletion virS/virR significantly downregulated the transcriptional level of the chemotactic system cheY, which may be the main reason for the reduced motility and lower biofilm formation capacity of & UDelta;virS/virR. These findings demonstrated that the twocomponent system virS/virR positively regulated motility, thereby influencing biofilm formation in L. monocytogenes 10403S. This provides clues to control the biofilm risks of L. monocytogenes in food safety.