Insights from whole-genome sequencing and comparative genomic analysis of the pathogenic Photobacterium damselae subsp. damselae strain MRY0520 isolated from Litopenaeus vannamei

Photobacterium damselae is a widespread pathogenic bacterium in marine ecosystems, primarily associated with fish skin ulcers. However, infections caused by this bacterium in shrimp are rarely reported. The dominant strain MRY0520, isolated from the hepatopancreas of diseased Litopenaeus vannamei , was identified as Photobacterium damselae subsp. damselae (Phdd) and exhibited high pathogenicity. Elucidating the genetic architecture and infection mechanisms of P. damselae is crucial for the effective prevention and control of related diseases. To characterize its genomic features, whole-genome sequencing and comprehensive functional annotation were performed on the virulent Phdd strain MRY0520, followed by comparative genomic analysis to investigate its evolutionary traits. The genomic sequences have been deposited in GenBank under accession numbers CP113238–CP113240. The genome of strain MRY0520 spans 4,451,849 bp and contains 3,663 coding genes with a combined length of 3,691,779 bp, accounting for 83% of the total genome. It encodes 208 tRNA genes, 62 rRNA genes (including 22 5S rRNA, 20 16S rRNA, and 20 23S rRNA), two CRISPR arrays, and two genomic islands. Comparative analysis revealed that strain MRY0520 exhibits the highest genomic homology with Phdd strain Wu-1. These findings provide a solid theoretical basis for understanding the genomic composition and evolutionary characteristics of MRY0520.