Characterization and genomic analysis of a novel Pseudoalteromonas phage PS_L5

Pseudoalteromonas is a widely distributed bacterial genus that is associated with marine algae. However, there is still limited knowledge about their bacteriophage. In this study, we reported the isolation of a novel lytic bacteriophage that infects Pseudoalteromonas marina. Transmission electron microscopy revealed that PS_L5 had an icosahedral head of 52.6 ± 2 nm and a non-contractile tail with length of 96.5 ± 2 nm. The genome sequence of this phage was 34, 257 bp and had a GC content of 40.75%. Furthermore, this genome contained 61 predicted open reading frames (ORFs), which involved in various functions such as phage structure, packaging, DNA metabolism, host lysis and other additional functions. Additionally, the phylogenetic analysis based on major capsid protein showed that the phage PS_L5 was closely related to five other Pseudoalteromonas phages, namely PHS3, PHS21, AL, SL25 and Pq0 which also possessed the non-contractile long tail. This study provided the fundamental insights into the evolutionary dynamics of Pseudoalteromonas phages and the interaction between phage and host.