Phenotypic Characterization and Comparative Genomic Analysis of Novel Salmonella Bacteriophages Isolated from a Tropical Rainforest

<p><em>Salmonella</em> infections across the globe are becoming more challenging to control due to the emergence of multidrug-resistant (MDR) strains. Lytic phages may be suitable alternatives for treating these multidrug-resistant <em>Salmonella</em> infections. Most <em>Salmonella</em> phages to date were collected from human-impacted environments. To further explore the <em>Salmonella</em> phage space, and to potentially identify phages with novel characteristics, we characterized <em>Salmonella</em>-specific phages isolated from the Penang National Park, a conserved rainforest. Four phages with a broad lytic spectrum (kills >5 <em>Salmonella</em> serovars) were further characterized; they have isometric heads and cone-shaped tails, and genomes of ~39,900 bp, encoding 49 CDSs. As the genomes share a <95% sequence similarity to known genomes, the phages were classified as a new species within the genus <em>Kayfunavirus</em>. Interestingly, the phages displayed obvious differences in their lytic spectrum and pH stability, despite having a high sequence similarity (~99% ANI). Subsequent analysis revealed that the phages differed in the nucleotide sequence in the tail spike proteins, tail tubular proteins, and portal proteins, suggesting that the SNPs were responsible for their differing phenotypes. Our findings highlight the diversity of novel <em>Salmonella</em> bacteriophages from rainforest regions, which can be explored as an antimicrobial agent against MDR-<em>Salmonella</em> strains.</p>