Viruses direct carbon cycling in lake sediments under global change

Author(s)

Braga, Lucas P. P. ; Orland, Chloe ; Emilson, Erik J. S. ; Fitch, Amelia A. ; Osterholz, Helena ; Dittmar, Thorsten ; Basiliko, Nathan ; Mykytczuk, Nadia C. S. ; Tanentzap, Andrew J.

• Document type: Journal article
• Source: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA; v. 119, n. 41, p. 12-pg., 2022-10-11.

Abstract

Global change is altering the vast amount of carbon cycled by microbes between land and freshwater, but how viruses mediate this process is poorly understood. Here, we show that viruses direct carbon cycling in lake sediments, and these impacts intensify with future changes in water clarity and terrestrial organic matter (tOM) inputs. Using experimental tOM gradients within sediments of a clear and a dark boreal lake, we identified 156 viral operational taxonomic units (vOTUs), of which 21% strongly increased with abundances of key bacteria and archaea, identified via metagenome-assembled genomes (MAGs). MAGs included the most abundant prokaryotes, which were themselves associated with dissolved organic matter (DOM) composition and greenhouse gas (GHG) concentrations. Increased abundances of virus-like particles were separately associated with reduced bacterial metabolism and with shifts in DOM toward amino sugars, likely released by cell lysis rather than higher molecular mass compounds accumulating from reduced tOM degradation. An additional 9.6% of vOTUs harbored auxiliary metabolic genes associated with DOM and GHGs. Taken together, these different effects on host dynamics and metabolism can explain why abundances of vOTUs rather than MAGs were better overall predictors of carbon cycling. Future increases in tOM quantity, but not quality, will change viral composi-tion and function with consequences for DOM pools. Given their importance, viruses must now be explicitly considered in efforts to understand and predict the freshwater carbon cycle and its future under global environmental change. (AU)

• FAPESP's process: 19/24097-0 - Screening for ecogenomic signatures of phage-bacteria interactions in natural microbiomes exposed to environmental disturbances
• Grantee: Lucas Palma Perez Braga
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 18/19247-0 - Unraveling the Role of Phages on the Evolution of Plant Beneficial and Pathogenic Rhizobacteria
• Grantee: Lucas Palma Perez Braga
• Support Opportunities: Scholarships in Brazil - Post-Doctoral