Marine bacteriophages play key roles in the community structure of microorganisms, biogeochemical cycles, and the mediation of genetic diversity through horizontal gene transfer. Recently, traditional isolation methods, complemented by high-throughput sequencing metagenomics technology, have greatly increased our understanding of the diversity of bacteriophages. Oceanospirillum, within the order Oceanospirillales, are important symbiotic marine bacteria associated with hydrocarbon degradation and algal blooms, especially in polar regions. However, until now there has been no isolate of an Oceanospirillum bacteriophage, and so details of their metagenome has remained unknown. Here, we reported the first Oceanospirillum phage, vB_OliS_GJ44, which was assembled into a 33,786 bp linear dsDNA genome, which includes abundant tail-related and recombinant proteins. The recombinant module was highly adapted to the host, according to the tetranucleotides correlations. Genomic and morphological analyses identified vB_OliS_GJ44 as a siphovirus, however, due to the distant evolutionary relationship with any other known siphovirus, it is proposed that this virus could be classified as the type phage of a new Oceanospirivirus genus within the Siphoviridae family. vB_OliS_GJ44 showed synteny with six uncultured phages, which supports its representation in uncultured environmental viral contigs from metagenomics. Homologs of several vB_OliS_GJ44 genes have mostly been found in marine metagenomes, suggesting the prevalence of this phage genus in the oceans. These results describe the first Oceanospirillum phage, vB_OliS_GJ44, that represents a novel viral cluster and exhibits interesting genetic features related to phage–host interactions and evolution. Thus, we propose a new viral genus Oceanospirivirus within the Siphoviridae family to reconcile this cluster, with vB_OliS_GJ44 as a representative member.

中文翻译：

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第一个海洋螺旋菌噬菌体 vB_OliS_GJ44 的表征和基因组分析，代表一个新的虹吸病毒簇

海洋噬菌体在微生物群落结构、生物地球化学循环以及通过水平基因转移调节遗传多样性方面发挥着关键作用。最近，传统的分离方法，辅以高通量测序宏基因组学技术，大大增加了我们对噬菌体多样性的理解。海洋螺旋菌目中的海洋螺旋菌是重要的共生海洋细菌，与碳氢化合物降解和藻华有关，尤其是在极地地区。然而，直到现在还没有海洋螺菌噬菌体的分离物，因此它们的宏基因组的细节仍然未知。在这里，我们报道了第一个海洋螺菌噬菌体 vB_OliS_GJ44，它被组装成一个 33,786 bp 的线性 dsDNA 基因组，其中包括丰富的尾相关蛋白和重组蛋白。根据四核苷酸相关性，重组模块高度适应宿主。基因组和形态学分析确定 vB_OliS_GJ44 是一种虹吸病毒，然而，由于与任何其他已知虹吸病毒存在遥远的进化关系，因此建议将该病毒归类为虹吸病毒科内一个新的海洋螺旋病毒属的噬菌体。vB_OliS_GJ44 与六个未培养的噬菌体显示同线性，这支持其在宏基因组学中未培养的环境病毒重叠群中的表现。几个 vB_OliS_GJ44 基因的同源物大多在海洋宏基因组中发现，表明该噬菌体属在海洋中普遍存在。这些结果描述了第一个海洋螺菌噬菌体 vB_OliS_GJ44，它代表了一个新的病毒簇，并展示了与噬菌体-宿主相互作用和进化相关的有趣遗传特征。因此，我们建议在 Siphoviridae 家族中建立一个新的病毒属 Oceanospirivirus 来协调这个集群，其中 vB_OliS_GJ44 作为代表成员。