It’s well-known among scientists that viruses can alter the makeup and function of ecosystems. For example, they promote microbial diversity by infecting and killing select bacteria, and their impact on microbial communities can influence the global carbon cycle.

But viruses in wetland soil play a more important role than previously understood, and they could even be indicators of ecosystem health, according to a new study by researchers from the Department of Bacteriology. Published in Nature Microbiology in December 2025, the study examines viruses in peatlands, which are wetlands that act as vital carbon sinks around the globe.

“We know bacterial processes produce carbon dioxide and methane from this carbon-heavy, peatland soil. But the question is, how do they actually do it, and are there any other components that we have missed out on?” says professor of bacteriology Karthik Anantharaman. “That’s where viruses come in.”

Peatlands, like other kinds of wetlands, are important land types for storing carbon that would otherwise remain in the atmosphere and contribute to global warming. By some estimates, peatlands contain up to one-third of global soil carbon despite covering just 3% of the Earth’s surface. However, in a warming world, wetlands are being damaged increasingly, and some are even in danger of contributing carbon to the atmosphere.

With their coauthors from University of Aberdeen and University of Edinburgh, the team analyzed samples taken from seven peatlands across the U.K. The peatlands were categorized as either natural, damaged, or restored. Analysis found that the viral community of each peatland category is made up of different kinds of viruses, revealing patterns between the health of a peatland and which viruses are present.

“Viruses are like a keystone predator in the microbial world,” says lead author James Kosmopoulos, a Ph.D. student in microbiology who works in Anantharaman’s lab. “Without them, everything in an ecosystem would be out of whack.”

In a natural, pristine peatland, viruses are able to infect microbial cells, replicate, and then kill the cells before leaving to infect others. That keeps microbe populations in check and the ecosystem relatively stable. This paper shows that viruses can shift their behavior based on the stability of their ecosystem.

In damaged peatlands, they found that viruses opt to hunker down in infected cells after replicating rather than immediately killing them. The change in viral behavior shifts the dynamics of the soil’s microbiome, influencing which bacteria are present and how efficiently bacteria can process and store carbon.

Having identified these patterns, researchers can now determine if a wetland is natural, has been damaged, or if restoration efforts are working just by looking at which viruses are present in a soil sample. The research team believes the patterns they have observed across U.K. peatlands could also be applicable on a global scale.

“Since microbes, including viruses, play a key role in regulating greenhouse gas fluxes, our results suggest that viruses can act as signals of peatland recovery by providing a window into what’s happening belowground,” says Ashish Malik, a coauthor on the paper from the School of GeoSciences at the University of Edinburgh.

In Wisconsin, where 25% of the state is peatland, Kosmopoulos is building a set of long-term data that he hopes can eventually be used to predict wetland health across the state. As this research continues, the team plans to investigate how viruses could be useful tools to influence the restoration of peatlands.

⊕ Federally Funded Research

This research was supported by funding from the National Science Foundation (DBI204759), National Science Foundation Graduate Research Fellowship Program (2137424), and Human Frontier Science Program (RGP018/2024).

Funding was also provided by UKRI Natural Environment Research Council (NERC), Scottish Universities Partnership for Environmental Research, Doctoral Training Partnership, and the NERC Environmental Omics Facility.