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

Abstract

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. Two-component 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 ΔvirS/virR and the gene complementation strain CΔvirS/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 CΔvirS/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 ΔvirS/virR. These findings demonstrated that the two-component 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.