Exploring Viral Impacts on Dark Carbon Fixation at Deep-Sea Hydrothermal Vents using DNA-SIP

Chemosynthetic microbes form the base of the food web at deep-sea hydrothermal vents by fixing dissolved inorganic carbon (DIC) into organic carbon that can flow into other trophic levels. In this ecosystem, viruses convert organic carbon from the host into dissolved and particulate organic carbon pools through host lysis. Moreover, viruses enhance the host's nutrient uptake by transferring auxiliary metabolic genes (AMGs), which support viral replication. However, the key viruses infecting microbes in the deep sea remain understudied relative to the surface ocean. This study combines metagenomics and stable-isotope probing (SIP) to identify the diversity and activity of viruses infecting primary producers at deep-sea vents. Samples from the Axial Seamount (Oregon coast) were incubated with 13C-DIC or 12C-DIC. DNA was extracted and separated based on density to quantify microbial hosts' and viruses' carbon cycling activity. Recovered metagenomic-assembled genomes uncovered diverse chemoautotrophic prokaryotes, including the phyla Campylobacteria and Aquificota. The majority of retrieved viruses were novel bacteriophages not reported before. Diverse AMGs from energy and carbon metabolism were identified, demonstrating the viruses' potential for manipulating host metabolism. This uncharacterized diversity showed that DNA-SIP can be a powerful approach for linking genomic diversity to the biogeochemical cycle. Our results emphasize the importance of linking novel taxonomic diversity to key biogeochemical processes to advance our understanding of the deep-sea biosphere.

Presentation Preference: Oral

Primary Presenter: Paulo Freire, University of North Carolina at Charlotte (UNC Charlotte) (pfreire@uncc.edu)

Authors:

Paulo Freire, Dept of Biological Sciences, Univ of North Carolina at Charlotte & Center for Computational Intelligence to Predict Health and Environmental Risks, Univ of North Carolina at Charlotte  (pfreire@uncc.edu)

T. J. Rogers, Dept of Biological Sciences, Univ of North Carolina at Charlotte & Center for Computational Intelligence to Predict Health and Environmental Risks, Univ of North Carolina at Charlotte  (troger50@uncc.edu)

Sabrina Elkassas, Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution  (elks@mit.edu)

Gareth Trubl, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory  (trubl1@llnl.gov)

Julie A. Huber, Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution  (jhuber@whoi.edu)

Elaine Luo, Dept of Biological Sciences, Univ of North Carolina at Charlotte & Center for Computational Intelligence to Predict Health and Environmental Risks, Univ of North Carolina at Charlotte  (elaine.luo@uncc.edu)