ISOLATION, GENOMIC CHARACTERIZATION, AND PHAGE THERAPY POTENTIAL OF BACTERIOPHAGES SPECIFIC TO PHOTOBACTERIUM DAMSELAE SUBSP. DAMSELAE
Project no. 22422 · Status: Kapanmış · 2020
Summary
<p>Photobacterium damselae subsp. damselae (PDD) is a pathogenic bacterium that affects both marine animals and humans. This bacterium poses a significant problem for aquaculture and constitutes a serious public health threat. Phages, due to their high specificity and environmental friendliness, have emerged as potential therapeutic agents for treating resistant strains that cannot be controlled with conventional antibiotics. Notably, the autonomous transfer of phages among animals during aquaculture trials has drawn attention as an ideal method for microbial control in sensitive environments such as hatcheries and adaptation facilities. In this study, two novel phages (TEMp-D1 and TEMp-D2) isolated from an aquaculture facility in Aydın province were thoroughly examined. Both phages remained stable across a broad range of pH and temperature conditions. While TEMp-D1 exhibited a narrow host range, infecting only PDD cells, TEMp-D2 demonstrated broader lytic activity, also affecting Vibrio anguillarum and Pseudomonas aeruginosa. One-step growth curve analyses revealed latent periods of 20 minutes for TEMp-D1 and 25 minutes for TEMp-D2. The bacteriolytic activities of the phages were tested across various multiplicities of infection (MOI), with optimal MOI values determined to be 0.01 for TEMp-D1 and 0.001 for TEMp-D2, respectively. During in vitro experiments, the phages effectively inhibited the growth of PDD and significantly reduced biofilm production, an important virulence factor. Phylogenetic analyses conducted in accordance with the guidelines of the International Committee on Taxonomy of Viruses (ICTV) grouped both phages with N4-like phages in the vii Schitoviridae family. Comparative analyses of the complete genome nucleotide and amino acid sequences revealed 97 coding sequences (CDS) in TEMp-D1 and 93 CDS in TEMp-D2. The predicted functions of these CDS were comparatively analyzed across various databases, highlighting gene regions encoding a variety of functional proteins. In both phages, regions related to structural proteins, replication, and DNA repair, as well as those involved in compromising host cell structural integrity, such as holins and endolysins, were identified. Phage genome maps were constructed, and the complete genome sequences were deposited in the NCBI-GenBank database under accession numbers PP852687 and PP852688 90. This study presents the first report of phages infecting PDD and their genomes in Turkey. The N4-like characteristics, high lytic, and anti-biofilm activities of TEMp-D1 and TEMp-D2 underscore their potential use in the biocontrol of PDD. Moreover, the gene regions encoding key enzymes identified through bioinformatics methods offer new possibilities for therapeutic applications through phage engineering techniques.</p>