Abstract: Objective: To understand the relationship between the genetic characteristics and the biofilm formation capability of typical strains of Listeria monocytogenes from fresh livestock and poultry meat in order to provide a basis for the precise control of bacteria in foods. Methods: Ten isolates of L. monocytogenes belonging to eight sequence types (ST) were selected for whole genome sequencing, gene functional annotation, virulence factor identification, analysis of mobile genetic elements (prophage, genome island and plasmid), evolutionary analysis and, identification of genes related to biofilm formation. The biofilm formation capability of these strains was determined by crystal violet staining, and its correlation with their genomic characteristics was analyzed. Results: The virulence islands LIPI-1, LIPI-2 and more than 19 another virulence genes, as well as different numbers of prophages and genome islands, were identified in the genomes of the eight STs. The LIPI-3 genes were only identified in the ST3 isolates, and plasmids were identified in the ST8 and ST1403 isolates. Evolutionary branching coefficients showed that five STs were closely related to the outbreak strains in the database. In addition, the luxS and sigB genes related to biofilm formation were mutated or deleted in six and seven STs, respectively. The ST1403 and ST87 isolates had a stronger ability to form biofilm, while the ST1402 isolates had the weakest biofilm formation capacity. Conclusion: Fresh livestock and poultry meat contains a variety of L. monocytogenes with pathogenic potential and carrying mobile genetic elements may be related to the biofilm formation capability.

Key words: Listeria monocytogenes; whole genome sequencing; virulence factor; biofilm