Our current knowledge of the virosphere in deep‐sea sediments remains rudimentary. Here we investigated viral diversity at both gene and genomic levels in deep‐sea sediments of Southwest Indian Ocean. Analysis of 19 676 106 non‐redundant genes from the metagenomic DNA sequences revealed a large number of unclassified viral groups in these samples. A total of 1106 high‐confidence viral contigs were obtained after two runs of assemblies, and 217 of these contigs with sizes up to ~120 kb were shown to represent complete viral genomes. These contigs are clustered with no known viral genomes, and over 2/3 of the ORFs on the viral contigs encode no known functions. Furthermore, most of the complete viral contigs show limited similarity to known viral genomes in genome organization. Most of the classified viral contigs are derived from dsDNA viruses belonging to the order Caudovirales, including primarily members of the families Myoviridae, Podoviridae and Siphoviridae. Most of these viruses infect Proteobacteria and, less frequently, Planctomycetes, Firmicutes, Chloroflexi, etc. Auxiliary metabolic genes (AMGs), present in abundance on the viral contigs, appear to function in modulating the host ability to sense environmental gradients and community changes, and to uptake and metabolize nutrients.

中文翻译：

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宏基因组学揭示了深海沉积物中病毒的非凡多样性，而无需事先进行病毒体分离

我们目前对深海沉积物中的病毒层的了解仍然很初级。在这里，我们研究了西南印度洋深海沉积物在基因和基因组水平上的病毒多样性。对宏基因组DNA序列中19 676 106个非冗余基因的分析显示，这些样品中存在大量未分类的病毒。经过两次运行后，总共获得了1106个高置信度病毒重叠群，其中217个大小约120 kb的重叠群显示出完整的病毒基因组。这些重叠群没有已知的病毒基因组，并且病毒重叠群上超过2/3的ORF没有编码已知的功能。此外，大多数完整的病毒重叠群在基因组组织中显示与已知病毒基因组的相似性有限。Caudovirales，主要包括Myoviridae，Podoviridae和Siphoviridae家族的成员。大多数的这些病毒感染变形菌，并不太频繁，浮霉菌门，厚壁菌门，绿弯菌门等辅助代谢基因（AMGs），大量存在于病毒重叠群，似乎功能调节感知环境梯度和社会变化的能力，主机，并吸收和代谢营养。