Metagenomic exploration of viruses throughout the Indian Ocean

PLoS One. 2012;7(10):e42047. doi: 10.1371/journal.pone.0042047. Epub 2012 Oct 17.


The characterization of global marine microbial taxonomic and functional diversity is a primary goal of the Global Ocean Sampling Expedition. As part of this study, 19 water samples were collected aboard the Sorcerer II sailing vessel from the southern Indian Ocean in an effort to more thoroughly understand the lifestyle strategies of the microbial inhabitants of this ultra-oligotrophic region. No investigations of whole virioplankton assemblages have been conducted on waters collected from the Indian Ocean or across multiple size fractions thus far. Therefore, the goals of this study were to examine the effect of size fractionation on viral consortia structure and function and understand the diversity and functional potential of the Indian Ocean virome. Five samples were selected for comprehensive metagenomic exploration; and sequencing was performed on the microbes captured on 3.0-, 0.8- and 0.1 µm membrane filters as well as the viral fraction (<0.1 µm). Phylogenetic approaches were also used to identify predicted proteins of viral origin in the larger fractions of data from all Indian Ocean samples, which were included in subsequent metagenomic analyses. Taxonomic profiling of viral sequences suggested that size fractionation of marine microbial communities enriches for specific groups of viruses within the different size classes and functional characterization further substantiated this observation. Functional analyses also revealed a relative enrichment for metabolic proteins of viral origin that potentially reflect the physiological condition of host cells in the Indian Ocean including those involved in nitrogen metabolism and oxidative phosphorylation. A novel classification method, MGTAXA, was used to assess virus-host relationships in the Indian Ocean by predicting the taxonomy of putative host genera, with Prochlorococcus, Acanthochlois and members of the SAR86 cluster comprising the most abundant predictions. This is the first study to holistically explore virioplankton dynamics across multiple size classes and provides unprecedented insight into virus diversity, metabolic potential and virus-host interactions.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Pairing / genetics
  • Base Sequence
  • Databases, Genetic
  • Genetic Variation
  • Genome, Viral / genetics
  • Genotype
  • Geography
  • Host-Pathogen Interactions / genetics
  • Indian Ocean
  • Metagenome
  • Metagenomics / methods*
  • Phylogeny
  • Plankton / genetics
  • Plankton / virology
  • Principal Component Analysis
  • Sequence Analysis, DNA
  • Viruses / genetics*

Grant support

This research was supported by the Office of Science (BER), U.S. Department of Energy, Cooperative Agreement No. De-FC02-02ER63453, the Gordon and Betty Moore Foundation, the National Science Foundation award 0850256 and TeraGrid allocation DEB100001 on the Texas Advanced Computing Center Ranger. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.