Environmental viromes reveal the global distribution signatures of deep-sea DNA viruses

Abstract

Introduction: Viruses are abundant and ecologically significant in marine ecosystems. However, the virome of deep-sea sediments is not extensively investigated. Objectives: To explore the distribution pattern of deep-sea viruses on a global scale, the viromes of DNA viruses isolated from 138 sediments of 5 deep-sea ecosystems were characterized. Methods: The viral particles were purified from each sediment sample. Then the viral DNAs were extracted and subjected to viral metagenomic analysis. Results: Here, we constructed a global deep-sea environmental virome dataset by analyzing the viral DNA of 138 sediment samples. A total of 347,737 viral operational taxonomic units (vOTUs) were identified, of which 84.94% were hitherto unknown, indicating that deep sea was a reservoir of novel DNA viruses. Furthermore, circular viral genome analysis revealed 98,581 complete genomes. The classified vOTUs included eukaryotic (44.55%) and prokaryotic (25.75%) viruses, and were taxonomically assigned to 63 viral families. The composition and abundance of the deep-sea sediment viromes were dependent on the deep-sea ecosystem as opposed to geographical region. Further analysis revealed that the viral community differentiation in different deep-sea ecosystems was driven by the virus-mediated energy metabolism. Conclusion: Our findings showed that deep-sea ecosystems are a reservoir of novel DNA viruses and the viral community is shaped by the environmental characteristics of deep-sea ecosystems, thus presenting critical information for determining the ecological significance of viruses in global deep-sea ecosystems.

Keywords

• Deep-sea sediment
• Viral community
• Ecosystem
• Virus-encoded gene