Microbial Oceanography Laboratory, School of Earth and Environmental Sciences and Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea.
Saemangeum Environmental Research Center, Kunsan National University, Kunsan 54150, Republic of Korea.
Viruses. 2023 Oct 7;15(10):2061. doi: 10.3390/v15102061.
Cold-active bacteriophages are bacterial viruses that infect and replicate at low temperatures (≤4 °C). Understanding remains limited of how cold-active phage-host systems sustain high viral abundance despite the persistently low temperatures in pelagic sediments in polar seas. In this study, two phages, ACA1 and ACA2, were isolated from sediment core samples of the continental shelf in the western Arctic Ocean. These phages exhibited successful propagation at a low temperature of 1 °C and displayed typical myovirus morphology with isometric icosahedral heads and contractile tails. The complete genome sequences of phages ACA1 and ACA2 were 36,825 bp and 36,826 bp in size, respectively, sharing almost the same gene content. These are temperate phages encoding lysogeny-related proteins such as anti-repressor, immunity repressor and integrase. The absence of cross-infection between the host strains, which were genomically distinct species, can likely be attributed to heavy divergence in the anti-receptor apparently mediated by an associated diversity-generating retroelement. HHpred searching identified genes for all of the structural components of a P2-like phage (family ), although the whole of the family appeared to be divided between two anciently diverged tail modules. In contrast, Blast matching and whole genome tree analysis are dominated by a nonstructural gene module sharing high similarity with phage C5a (founder of genus ). This study expands the knowledge of diversity of P2-like phages known to inhabit and demonstrates their presence in the Arctic niche.
冷活性噬菌体是一类在低温（≤4°C）下感染和复制的细菌病毒。尽管在极地海洋的远洋沉积物中温度持续较低，但冷活性噬菌体-宿主系统如何维持高病毒丰度的机制仍知之甚少。在这项研究中，从西北冰洋大陆架的沉积物芯样本中分离到了两种噬菌体，ACA1 和 ACA2。这些噬菌体在低温 1°C 下成功繁殖，并表现出典型的肌病毒形态，具有等轴二十面体头部和可收缩的尾部。噬菌体 ACA1 和 ACA2 的完整基因组序列分别为 36825 bp 和 36826 bp，大小几乎相同，具有相同的基因内容。这些是温和噬菌体，编码溶原相关蛋白，如抗阻遏物、免疫阻遏物和整合酶。宿主菌株之间不存在交叉感染，这可能是由于抗受体的高度分化，这种分化显然是由相关的多样性产生的反转录元件介导的。HHpred 搜索鉴定了 P2 样噬菌体（家族 ）所有结构成分的基因，尽管整个家族似乎分为两个古老分化的尾部模块。相比之下，Blast 匹配和全基因组树分析主要由一个与 噬菌体 C5a（属的创始人）具有高度相似性的非结构基因模块主导。本研究扩展了已知栖息在北极生态位中的 P2 样噬菌体多样性的知识，并证明了它们的存在。
