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.

假交替单胞菌是一种广泛分布的细菌属，与海洋藻类有关。然而，对其噬菌体的了解仍然有限。在这项研究中，我们报道了一种感染假交替单胞菌码头的新型裂解噬菌体的分离。透射电镜显示PS_L5具有52.6±2 nm的二十面体头部和长度为96.5±2 nm的非收缩尾部。该噬菌体基因组序列为34, 257 bp，GC含量为40.75%。此外，该基因组包含61个预测的开放阅读框（ORF），涉及噬菌体结构、包装、DNA代谢、宿主裂解和其他附加功能等多种功能。此外，基于主要衣壳蛋白的系统发育分析表明，噬菌体PS_L5与其他5种假交替单胞菌噬菌体PHS3、PHS21、AL、SL25和Pq0密切相关，Pq0也具有非收缩性长尾。这项研究为假交替单胞菌噬菌体的进化动力学以及噬菌体与宿主之间的相互作用提供了基本见解。