Metagenomic characterization of marine viruses in the South Sea of Korea

Abstract

Viruses are the most abundant biological entities in the oceans, and account for a significant amount of the genetic diversity of marine ecosystems. However, there is little detailed information about the biodiversity of viruses in marine environments. A previous study reported that a milliliter of seawater contains approximately 107 viruses, while a gram of soil or sediment contains 109 viruses. Although viruses account for approximately 5% of the total biomass in the ocean, the abundance of viruses comprises approximately 94% of total nucleic-acid-containing particles. Therefore, marine viruses are regarded as major pathogens that infect large numbers of organisms and cause mass mortal viral diseases in the oceans. One of the difficulties of marine viral metagenomics is the enrichment of viral particles from environmental samples. In this study, enrichment of marine viral particles using FFR (fl occulation, fi ltration, and re-suspension) method followed by next-generation sequencing produced numerous sequences. Seawater samples were collected from Goseong Bay and Jeju Island, Korea during the spring, summer, autumn, and winter of 2014 and the DNA libraries from samples collected during four seasons were sequenced using Illumina HiSeq 2000. Analysis of virus families indicated that the Myoviridae was the most common during all four seasons, and viruses in the Iridoviridae, Herpesviridae, and Poxviridae, which may affect fish and marine animals, appeared during different seasons in Goseong Bay and Jeju Island. In summary, our results provide evidence of seasonal changes of the marine viral community in the South Sea of Korea. These data provide a valuable foundation for future studies of marine vital communities, and the approach used here may be useful for identification of emerging marine viral pathogens.