Microbial viruses act as secret drivers of planetary climate change | Top Vip News

In a new study, scientists have discovered that viruses that infect microbes contribute to climate change by playing a key role in transporting methane, a potent greenhouse gas, through the environment.

By analyzing nearly 1,000 metagenomic DNA data sets from 15 different habitats, from various lakes to the inside of a cow’s stomach, the researchers discovered that microbial viruses carry special genetic elements to control methane processes, called metabolic auxiliary genes ( AMG). Depending on where the organisms live, the number of these genes can vary, suggesting that the potential impact of viruses on the environment also varies depending on their habitat.

This discovery adds a vital piece to better understanding how methane interacts and moves within different ecosystems, said ZhiPing Zhong, lead author of the study and research associate at the Byrd Center for Polar and Climate Research at Ohio State University.

“It is important to understand how microorganisms drive methane processes,” said Zhong, also a microbiologist whose research examines how microbes evolve in various environments. “Microbial contributions to methane metabolic processes have been studied for decades, but research in the viral field is still under-researched and we want to learn more.”

The study was published today (February 29, 2024) in Nature Communications.

Viruses have helped fuel all of Earth’s ecological, biogeochemical and evolutionary processes, but it is only relatively recently that scientists have begun to explore their links to climate change. For example, methane is the second largest driver of greenhouse gas emissions after carbon dioxide, but it is largely produced by single-celled organisms called archaea.

“Viruses are the most abundant biological entity on Earth,” said Matthew Sullivan, study co-author and professor of microbiology at Ohio State’s Microbiome Science Center. “Here we expand what we know about their impacts by adding methane cycle genes to the long list of virus-encoded metabolic genes. “Our team sought to answer how much of the ‘microbial metabolism’ viruses actually manipulate during infection.”

Although the vital role that microbes play in accelerating atmospheric warming is now well recognized, little is known about how the methane metabolism-related genes encoded by the viruses that infect these microbes influence their methane production, Zhong said. . Solving this mystery is what led Zhong and his colleagues to spend nearly a decade collecting and analyzing microbial and viral DNA samples from unique microbial reservoirs.

One of the most important places the team chose to study is Lake Vrana, part of a protected nature reserve in Croatia. Within the methane-rich lake sediment, the researchers found a large number of microbial genes that affect methane production and oxidation. Additionally, they discovered diverse viral communities and discovered 13 types of AMG that help regulate their host’s metabolism. Despite this, there is no evidence that these viruses directly encode methane metabolism genes, suggesting that the viruses’ potential impact on the methane cycle varies depending on their habitat, Zhong said.

Overall, the study revealed that more methane metabolism AMGs are more likely to be found within host-associated environments, such as the inside of a cow’s stomach, while fewer of these genes were found in environmental habitats, as in lake sediments. Given that cows and other animals are also responsible for generating around 40% of global methane emissions, their work suggests that the complex relationship between viruses, living things and the environment as a whole may be more intricately linked than what scientists once thought.

“These findings suggest that the global impacts of viruses are underestimated and deserve more attention,” Zhong said.

Although it is unclear whether human activities could have affected the evolution of these viruses, the team hopes that the new knowledge gained from this work will raise awareness about the power of infectious agents to inhabit all life on Earth. Still, to continue learning more about the internal mechanisms of these viruses, more experiments will be needed to better understand their contributions to Earth’s methane cycle, Zhong said, especially as scientists work to find ways to mitigate emissions. methane driven by microbes.

“This work is a first step in understanding the viral impacts of climate change,” he said. “We still have a lot more to learn.”

This work was supported by the National Science Foundation, the Croatian Science Foundation, the Gordon and Betty Moore Foundation, the Heising-Simons Foundation, the European Union, and the United States Department of Energy. Co-authors include Jingjie Du of Ohio State, as well as Stephan Kostlbacher and Petra Pjevac of the University of Vienna, and Sandi Orlić of the Ruđer Bošković Institute.

A schematic of viral involvements in key MMP steps by coding seven AMGs that exclusively participate in MMP. The viruses encoded seven AMGs (fwdF, fae, frhB, cofE, cofF, mtrA, and pmoC; colored in purple text) to impact key steps in both methane production and oxidation. The methanogenesis pathway from CO2 to methane is indicated by orange arrows. More information on 17 additional AMGs that could potentially participate in both MMP and other types of metabolic pathways is provided in the supplementary figures. S1, S2 and Data 5. B Genome maps of three viral contigs carrying the AMG mtrA gene. The three viral contigs belonged to the same viral population (with 97.4-97.8% genomic identities to each other) and carried an identical mtrA gene. CheckV was used to evaluate host virus boundaries and remove possible host fractions in the viral contig. Genes were marked with five colors to illustrate AMGs (purple), phage genes (orange), phage signature genes (blue), potential cellular genes (green), and hypothetical protein genes (gray). C Phylogenetic tree of viral and microbial mtrA genes. The tree was inferred using the maximum likelihood method with protein sequences. Parametric bootstrap values ​​(expressed as percentages of 1000 replications) are shown at branch points. The scale bar indicates a distance of 0.1 substitutions per position in the lineup. Viral and microbial MtrA sequences are indicated in red and black, respectively. Numbers in parentheses indicate the number of protein sequences assigned to each group. The complete phylogenetic tree (without collapsed groups) is provided in Supplementary Figure S5A. Genomic maps and phylogenetic trees of the other six unique AMG MMs (pmoC, fwdF, fae, cofE, cofF, and frhB) are provided in the supplementary figures. S3 and S5B-G. MM, methane metabolism; MMP, methane metabolism pathway.

Viral potential to modulate microbial methane metabolism varies by habitatNature Communications

Astrobiology, Climate Change,