Abstract
A viral metagenomic analysis of five surface and two bottom water (878 meters below surface, mbs, and 3,357 mbs) samples from Prydz Bay, was conducted during February–March 2015. The results demonstrated that most of the DNA viruses were dsDNA viruses (79.73–94.06%, except at PBI1, 37.51%). Of these, Caudovirales (Siphoviridae, Myoviridae, and Podoviridae) phages were most abundant in surface seawater (67.67–71.99%), while nucleocytoplasmic large DNA viruses (NCLDVs) (Phycodnaviridae, Mimiviridae, and Pandoraviridae accounted for >30% of dsDNA viruses) were most abundant in the bottom water (3,357 mbs). Of the ssDNA viruses, Microviridae was the dominant family in PBI2, PBI3, PBOs, and PBI4b (57.09–87.55%), while Inoviridae (58.16%) was the dominant family in PBI1. Cellulophaga phages (phi38:1 and phi10:1) and Flavobacterium phage 11b, infecting the possible host strains affiliated with the family Flavobacteriaceae of the phylum Bacteroidetes, were abundant in surface water dsDNA viromes. The long contig (PBI2_1_C) from the viral metagenomes were most similar to the genome architectures of Cellulophaga phage phi10:1 and Flavobacterium phage 11b from the Arctic Ocean. Comparative analysis showed that the surface viral community of Prydz Bay could be clearly separated from other marine and freshwater environments. The deep sea viral community was similar to the deep sea viral metagenome at A Long-term Oligotrophic Habitat Assessment Station (ALOHA, at 22°45′N, 158°00′W). The multivariable analysis indicated that nutrients probably played an important role in shaping the local viral community structure. This study revealed the preliminary characteristics of the viral community in Prydz Bay, from both the surface and the deep sea. It provided evidence of the relationships between the virome and the environment in Prydz Bay and provided the first data from the deep sea viral community of the Southern Ocean.
Highlights
Viruses are the most abundant and genetically diverse acellular biological entities in the ocean and play significant roles in microbial mortality, fluctuations in microbial community structure, and the horizontal gene transfer of genetic diversity between host cells (Wommack and Colwell, 2000; Breitbart et al, 2002; Weinbauer, 2004; Suttle, 2005, 2007)
We present here a viral metagenomic dataset, including five surface and two bottom seawater samples from Prydz Bay, including both double-stranded DNA, and single-stranded DNA
With the exception of the PBI1 sample, the taxonomic analysis of affiliated DNA viromes showed that most viruses were classified as double-stranded DNA (dsDNA) viruses (Table 2, Figure S4), even when the viral DNA pool was randomly amplified using the multiple displacement amplification (MDA), which is known to increase the amplification of single-stranded DNA (ssDNA) molecules (Kim and Bae, 2011; Marine et al, 2014)
Summary
Viruses are the most abundant and genetically diverse acellular biological entities in the ocean and play significant roles in microbial mortality, fluctuations in microbial community structure, and the horizontal gene transfer of genetic diversity between host cells (Wommack and Colwell, 2000; Breitbart et al, 2002; Weinbauer, 2004; Suttle, 2005, 2007). There have only been two Southern Ocean viral DNA and RNA metagenomic studies and these are from the coastal waters of the Palmer Long-Term Ecological Research (PAL-LTER) Station B and Western Antarctic Peninsula (WAP) (Brum et al, 2016; Miranda et al, 2016). It was found that RNA viruses contributed up to 65% of the total virioplankton (8–65%) and this is consistent with the hypothesis that RNA viruses influence diatom bloom dynamics in WAP coastal waters (Miranda et al, 2016) These analyses revealed the diversity and seasonal variations of the dsDNA and RNA viral communities in WAP coastal waters, respectively. Our knowledge of the marine pelagic viral community, viral diversity and their correlations with environmental factors within the Southern Ocean is still quite limited, especially in the deep sea (>1,000 meters below surface, mbs)
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