Aeromonas hydrophila is a significant fish pathogen with reported antibiotic resistance worldwide. The use of antibiotics as a disease management strategy is associated with the emergence of antimicrobial resistance, which requires alternative disease management strategies. Bacteriophages, the viruses that specifically kill bacteria, are increasingly exploited. However, bacteriophage applications in Ugandan aquaculture remain underexplored due to the limited proper characterization. Thus, we aimed to genetically characterize A. hydrophila (F7) and its lytic bacteriophage.
Genomic DNA from both the A. hydrophila (F7) bacterium and its phage, Aero_phi 01, were extracted and sequenced utilizing the Illumina platform. Genome analysis involved pre-processing, assembly, annotation, and comparison with other known genomes in the gene databases. Additionally, a proteomic phylogenetic tree was constructed to further elucidate the genetic relationships.
The genome of A. hydrophila consisted of over 4 Megabases (MB), with a total of 3992 annotated features. Eight CRISPR arrays, a prophage partial_01 sequence and four specific antibiotic resistance genes (though not exhibited phenotypically) were detected. The phage genome had approximately 54 KB and a total of 77 coding sequences, belonged to the Melnykvirinae sub-family within the Autographiviridae family of Caudoviricetes, a group of double-stranded DNA viruses and was not identical to a prophage detected on the host genome.
The characterisation of both F7 and the phage provided crucial insights into their suitability for phage applications in disease management and mitigation of antibiotic resistance in fish farming, contributing to global food security and public health.