Revealing the Viral Community in the Hadal Sediment of the New Britain Trench.

Jiawang Chen,Hui Zhou,Xuan Li,Jiasong Fang,Ping Chen,Mengjie Zhang

doi:10.3390/genes12070990

Abstract

Marine viruses are widely distributed and influence matter and energy transformation in ecosystems by modulating hosts’ metabolism. The hadal trenches represent the deepest marine habitat on Earth, for which the viral communities and related biogeochemical functions are least explored and poorly understood. Here, using the sediment samples (8720 m below sea level) collected from the New Britain Trench (NBT), we investigated the viral community, diversity, and genetic potentials in the hadal sediment habitat for the first time by deep shotgun metagenomic sequencing. We found the NBT sediment viral community was dominated by Siphoviridae, Myoviridae, Podoviridae, Mimiviridae, and Phycodnaviridae, which belong to the dsDNA viruses. However, the large majority of them remained uncharacterized. We found the hadal sediment virome had some common components by comparing the hadal sediment viruses with those of hadal aquatic habitats and those of bathypelagic and terrestrial habitats. It was also distinctive in community structure and had many novel viral clusters not associated with the other habitual virome included in our analyses. Further phylogenetic analysis on its Caudovirales showed novel diversities, including new clades specially evolved in the hadal sediment habitat. Annotation of the NBT sediment viruses indicated the viruses might influence microbial hydrocarbon biodegradation and carbon and sulfur cycling via metabolic augmentation through auxiliary metabolic genes (AMGs). Our study filled in the knowledge gaps on the virome of the hadal sediment habitats and provided insight into the evolution and the potential metabolic functions of the hadal sediment virome.

Highlights

Introduction published maps and institutional affilThe hadal trenches are the deepest part of the ocean, accounting for ~1.5% of the global deep-sea floor and covering ~45% of the oceanic depth range [1]
Due to the challenges of sampling and culturing of hadal sediments viruses, the role of viruses in influencing microbial mortality, ecology, and evolution in hadal sediments remains largely uncharacterized to date
Double-stranded DNA viruses, those affiliated to the order Caudovirales, were found to be dominated in the hadal viral community

Summary

Introduction

The hadal trenches are the deepest part of the ocean, accounting for ~1.5% of the global deep-sea floor and covering ~45% of the oceanic depth range [1]. Topographic, bathymetric, and hydrographic features, trenches have recently become a hotspot for deep-sea microbial research. Culture-independent high-throughput sequencing and culture-dependent taxonomic characterization have provided insights into the microbial communities and functions of seawater or sediments in hadal environments. Logan et al compared the microbial community similarities and differences between the Kermadec Trench and the Mariana Trench by amplicon sequencing and culture [2]. Free-living (FL) bacterial communities in the Marianas Trench by high-throughput sequencing [3]. Despite evidence that benthic prokaryotes and viruses in the surface centimeters of deep-sea sediments account for 50–80% of the total microbial life on Earth iations

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Conclusion