Comparative Genomic Analysis of Pseudomonas shahriarae Reveals Virulence Potential, Antimicrobial Resistance, and Environmental Adaptation.

Pseudomonas shahriarae is a recently identified member of the P. fluorescens group. Its ecological range and ability to cause disease are still mostly unknown, especially in aquaculture settings. This work presents the first genome sequence of P. shahriarae isolated from diseased Siberian sturgeon (Acipenser baerii). To obtain deeper understanding of its evolutionary history, pathogenicity, and capacity of antibiotic resistance, this genome was compared with seven other publicly available genomes. The draft genome of strain SK21 was 6.12 Mb size and had a GC content of 60.5%. Core genome analysis revealed 3,652 conserved genes among strains, and average nucleotide identity values over 98% validated species-level relatedness among the majority of isolates. One strain that was originally thought to be P. shahriarae exhibited only about 83% ANI and grouped with Pseudomonas iridis, which suggests that it was misclassified. A comparative genomic investigation showed that there is a shared set of virulence-associated factors, such as genes that help with adhesion, biofilm formation, motility, immunological regulation, and nutrition acquisition, as well as different secretion systems (T1SS-T6SS). The strain from sturgeon uniquely expressed a full class 1 integron, indicating the acquisition of antimicrobial resistance components by horizontal gene transfer in aquaculture settings. The extensive prophage regions and metabolic flexibility further underscore the adaptability of this species. This work presents the first genomic evidence associating P. shahriarae with sturgeon disease and uncovers a genetically varied bacteria that may impact aquaculture health and the spread of antibiotic resistance.