Recently, the research results of the Deep-Sea Virus Research Team (DVRT) led by Associate Professor Huahua JIAN from the School of Life Sciences and Technology, Shanghai Jiao Tong University, was published online on The ISME Journal, the official Journal of the International Society for Microbial Ecology. The article is titled Diversity and distribution of viruses inhabiting the deepest ocean on Earth.

  As the most abundant biological entities on the planet, viruses significantly influence the overall functioning of marine ecosystems. The abundance, distribution, and biodiversity of viral communities in the upper ocean have been relatively well studied, but our understanding of viruses in the hadal biosphere remains poor. In this study, the researchers established the oceanic trench viral genome dataset (OTVGD) by analysing 19 microbial metagenomes derived from seawater and sediment samples of the Mariana, Yap, and Kermadec Trenches. The trench viral communities harboured remarkably high novelty, and they were predicted to infect ecologically important microbial clades, including Thaumarchaeota and Oleibacter. Significant inter- and intra-trench exchange of viral communities was proposed. Moreover, viral communities in different habitats (seawater/sediment and depth-stratified ocean zones) exhibited distinct niche-dependent distribution patterns and genomic properties. Notably, microbes and viruses in the hadopelagic seawater seemed to preferably adopt lysogenic lifestyles compared to those in the upper ocean. Furthermore, niche-specific auxiliary metabolic genes were identified in the hadal viral genomes, and a novel viral D-amino acid oxidase was functionally and phylogenetically characterized, suggesting the contribution of these genes in the utilization of refractory organic matter.

Fig 1. Left, the sampling locations and sample types of the metagenomes used for the construction of the oceanic trench viral genome dataset (OTVGD); Right, connectivity of viruses in the oceanic trenches.

  Together, these findings highlight the genomic novelty, dynamic movement, and environment-driven diversification of viral communities in oceanic trenches and suggest that viruses may influence the hadal ecosystem by reprogramming the metabolism of their hosts and modulating the community of keystone microbes.

Fig 2. Abundance profiles and genomic features of oceanic trench viruses.

  This work was financially supported by the National Key R&D Program of China (2018YFC0309800), and the National Natural Science Foundation of China (grants 91851113, 41921006, 41776173, 41676118).

  Publication link: http://www.nature.com/articles/s41396-021-00994-y