The unsung hero of our lives is soil. It nourishes crops to give us food, drains rainfall into aquifers, and serves as a habitat for a variety of species. On a microscopic level, the soil is alive with microorganisms such as fungus and bacteria that interact with plants.
Despite being such a crucial aspect of our existence, little is known about what lies under the surface of Earth.
Research Methodology: Bioinformatics and deep learning to detect Soil Viruses
Scientists from the Pacific Northwest National Laboratory (PNNL) employed bioinformatics and deep sequencing to detect soil viruses and better understand their roles in the Earth in the new research. Most of these viruses infect bacteria and are consequently assumed to serve an important role in maintaining the microbial population.
Soil: Hub for Different Viruses
"Viruses are common in nature," stated Janet Jansson, PNNL Laboratory Fellow and chief scientist for biology. "Because there are so many of them in every soil sample, identifying different viruses becomes a challenge.
Jansson worked with Computational Scientist Ruonan Wu and Earth Scientist and Microbiome Science Team Leader Kirsten Hofmockel in the Biological Sciences Division at PNNL to address this challenge.
The PNNL scientists obtained soil samples from grasslands in Washington, Iowa, and Kansas with collaborators from Washington State University, Oregon Heath and Science University, Iowa State University, and EMSL, the Environmental Molecular Sciences Laboratory, a Department of Energy Office of Science user facility at PNNL.
To find previously unknown soil viruses, they used the Joint Genome Institute's vast DNA sequencing abilities, the National Energy Research Scientific Computing Center's computing power, and the multi-omics knowledge of EMSL. The researchers' findings were published in the mBio and Communications Biology.
Water content of soil: An important influencer of microbial population
Because each location receives a varied amount of rainfall, the scientists picked Washington, Iowa, and Kansas for their soil samples. In terms of soil moisture, Eastern Washington is substantially drier than Iowa, whereas Kansas lies in the middle between the two.
"We chose to gather samples from locations with varying levels of soil moisture to investigate if this affected the types and numbers of viruses present," Wu explained. "More bacteria are found in wetter soil, and many soil viruses infect bacteria."
Certain viruses are far more numerous in dry soil than in moist soil, according to researchers.
Unique Viral Genes: Enabling Viruses to thrive in Drier Soil
The researchers also revealed that viruses were more likely to possess unique genes in drier soil, which they may pass on to their bacterial hosts.
"These genes have the potential to confer 'superpowers' on their bacterial hosts," Jansson said. "These viral genes might be passed on to their bacterial hosts to aid their survival in dry soils," says the researcher.
Though additional research is needed to fully comprehend the impact of these unusual viral genes, the possibility that they may be beneficial to soil bacteria is fascinating. These genes may benefit bacteria by enhancing their ability to recycle carbon and so improving soil fertility and health.
