The dark ocean contains 70% of the ocean's microbial cells and 60% of its heterotrophic activity, playing a pivotal role in the biogeochemical cycles of the planet. Yet, it is the less understood microbial-driven ecosystem on Earth. Marine viruses play a key role on microbial populations through lysis, programming host metabolism and horizontal gene transfer. However, if deep-sea microbial communities are poor understood, their viruses are almost unknown. Here, we use quantitative double-stranded DNA viral-fraction metagenomes to assess viral communities patterns and diversity in the bathypelagic of the Pacific and Atlantic Ocean, and the Mediterranean Sea (BAT dataset). Therefore, in this study, we present the first global map of assembled complete genomes and large genome fragments from deep ocean viruses. We identified 3,758 new viral populations (VP), of which 8 were present in all the samples and represented on average a 10.66% of the total abundance in all our dataset; consequently we could consider these VP as ubiquitous and abundant in the bathypelagic layer. Next, we classified these viral populations into viral clusters (VC); obtaining 641 VC based on the 3,758 VP from our dataset and 15,929 publicity available bacterial and archaeal viruses. Of these VC, 419 were found exclusively BAT sequences. Finally, we aimed to identify the possible hosts that the viral populations could be able to infect. The most of the predicted hosts belonged to Alphaproteobacteria, followed by Gammaproteobacteria and Flavobacteria groups. These results extend thoroughly our knowledge on the unexplored viral diversity in the bathypelagic sea

15th Symposium on Aquatic Microbial Ecology (SAME15), 3-8 September 2017, Zagreb, Croatia

Peer Reviewed