Presenter: Elaine Luo (Woods Hole Oceanographic Institution)

Description:
Sinking particles and particle-associated microbes influence global biogeochemistry through particulate matter export from the surface to the deep ocean. Despite ongoing studies of particle-associated microbes, viruses in these habitats remain largely unexplored. Whether, where, and which viruses might contribute to particle production and export remain open questions. In this study, we analyzed 857 virus population genomes associated with sinking particles collected over three years in sediment traps moored at 4000m in the North Pacific Subtropical Gyre. Particle-associated viruses here were linked to cellular hosts through matches to bacterial and archaeal metagenome-assembled genome (MAG)-encoded prophages or CRISPR spacers, identifying novel viruses infecting presumptive deep-sea bacteria such as Colwellia, Moritella, and Shewanella. We also identified lytic viruses whose abundances correlated with particulate carbon flux and/or were exported from the photic to abyssal ocean, including cyanophages. Our data suggest that viral lysis may play a role in carbon export and are consistent with a predicted outcome of the viral shuttle hypothesis. Our analyses revealed the diversity and origins of some of the most abundant bacteriophages found on deep-sea sinking particles and identified prospective viral groups for future investigation into processes that govern particle export in the open ocean.