In a groundbreaking discovery, scientists in the U.S. have identified a previously unknown group of microbes thriving deep underground—up to 70 feet beneath the surface. This newly classified microbial phylum, named CSP1-3, not only survives in these harsh subterranean conditions but also plays a significant role in purifying groundwater, with exciting implications for future water filtration technologies.
The study, led by Dr. James Tiedje, university distinguished professor emeritus and director of the Center for Microbial Ecology at Michigan State University (MSU), uncovered CSP1-3 in soil samples collected from Iowa in the U.S. and China. Both sites belong to Earth’s Critical Zone, a vast region that stretches from the tree canopy down through soil layers to bedrock, sometimes extending as deep as 700 feet.
“The Critical Zone supports most life on the planet by regulating essential processes like soil formation, water and nutrient cycling,” Tiedje explained. “Despite its importance, the deep Critical Zone remains largely unexplored. It’s a new frontier beneath our feet.”
By extracting DNA from deep soil cores, Tiedje’s team discovered that CSP1-3 has ancient roots in aquatic environments such as hot springs and freshwater bodies. Over millions of years, these microbes adapted to life in progressively drier and nutrient-scarce environments, eventually evolving to thrive in deep soils.
One of the most surprising findings was that CSP1-3 microbes are not dormant or inactive, as might be expected in such deep, energy-limited environments. Instead, they are metabolically active and slowly growing—effectively alive and functioning in a realm thought to be biologically quiet.
Even more striking: CSP1-3 microbes were found to be dominant in many samples, sometimes making up more than 50% of the microbial population in deep soils—an unprecedented figure compared to surface soils.
“This group has evolved over an incredibly long time to thrive in an environment that is extremely nutrient-poor,” said Tiedje. “Their dominance in these conditions is a testament to how specialized and efficient they’ve become.”
Soil is Earth’s largest natural water filter, but while surface layers only handle a small volume of fast-moving water, deeper soils can retain and purify much more. That’s where CSP1-3 comes in.
These microbes help complete the purification process by breaking down residual carbon and nitrogen compounds that percolate from topsoil. Essentially, CSP1-3 acts as nature’s underground cleanup crew. “They are the scavengers cleaning up what got through the surface layer,” Tiedje said. “They have a job to do.”
The discovery not only deepens our understanding of the Earth’s subterranean ecosystems but also opens the door to potential real-world applications. These microbes may harbor unique biochemical tools that could be used to degrade pollutants in drinking water or remediate contaminated environments.
Tiedje and his team now hope to culture CSP1-3 in the lab to study their unusual physiology and explore how they thrive in such extreme environments. Understanding their metabolic pathways could reveal enzymes or genes with powerful pollutant-degrading capabilities.
“CSP1-3’s physiology is different,” Tiedje noted. “There may be genes here with real value. If we can understand how these microbes handle tough environmental pollutants, we might be able to harness that knowledge to address some of Earth’s biggest environmental challenges.”
This discovery underscores a growing realization: some of the best solutions to modern problems—like water pollution—might be hidden in the most unexpected places, quietly working beneath our feet for thousands of years.
By Impact Lab
