Novel Yersinia enterocolitica Prophages and a Comparative Analysis of Genomic Diversity

is a major agent of foodborne diseases worldwide. Prophage plays an important role in the genetic evolution of the bacterial genome. Little is known about the genetic information about prophages in the genome of , and no pathogenic prophages have been described. In this study, we induced and described the genomes of six prophages from pathogenic for the first time. Phylogenetic analysis based on whole genome sequencing revealed that these novel phages are genetically distinct from the previously reported phages, showing considerable genetic diversity. Interestingly, the prophages induced from O:3 and O:9 showed different genomic sequences and morphology but highly conserved among the same serotype strains, which classified into two diverse clusters. The three long-tailed prophages induced from serotype O:3 were highly conserved, shared ≥99.99% identity and forming genotypic cluster A; the three prophages induced from the serotype O:9 strains formed cluster B, also shared more than 99.90% identity with one another. Cluster A was most closely related to O:5 non-pathogenic prophage PY54 (61.72% identity). The genetic polymorphism of these two kinds of prophages and highly conserved among the same serotype strains, suggested a possible shared evolutionary past for these phages: originated from distinct ancestors, and entered pathogenic as extrachromosomal genetic components during evolution when facing selective pressure. These results are critically important for further understanding of phage roles in host physiology and the pathology of disease.