Scientists discover a new phylum of microorganisms in Earth's critical zone (deep soil layer)CSP1-3, these microorganisms help purify groundwater,Could be the key to future innovative water purification and environmental solutions. As water flows through the area, these microorganisms break down remaining pollutants, improving water quality. Critical zones also play a vital role in key processes for food production and ecosystem health, such as soil formation, nutrient cycling and water regulation. Since microbes are critical to life on Earth, understanding this newly discovered microbial community could advance conservation efforts and help combat climate change.

This image shows the Earth's critical zone, which stretches from treetops down to the depths of the soil, up to 700 feet (about 210 meters), and depicts the microorganisms that live there. This region supports most life on Earth because it regulates fundamental processes such as soil formation, water circulation, and nutrient cycling that are critical to food production, water quality, and ecosystem health. Image source: Michigan State University

Leonardo da Vinci once said: “We know more about the movements of the heavenly bodies than we do about the soil beneath our feet.”

James Tiedje, a world-renowned microbiology expert at Michigan State University, agrees with Leonardo's view. But he hopes to change that by studying the critical zone, part of Earth's dynamic "living skin."

"The critical zone extends from the treetops down into the soil, up to 700 feet deep," Teeje said. "This region supports most life on Earth because it regulates fundamental processes such as soil formation, water cycling, and nutrient cycling that are critical to food production, water quality, and ecosystem health. Although the deep critical zone is critical, it is still new territory because it is a relatively unexplored, largely unexplored region of the planet."

Tiedje, Distinguished Professor Emeritus in MSU's Departments of Microbiology, Genetics and Immunology and Plant, Soil and Microbial Sciences, discovered an entirely different phylum, or major category, called CSP1-3 in this vast, unexplored world of microorganisms. The new phylum has been found in soil samples 70 feet deep in both Iowa and China. Why Iowa and China? Because the soils in both areas are very deep and similar, we wondered whether their occurrence was more widespread rather than just restricted to one area, Tiedje said.

Tiedje's team extracted DNA from these deep soils and found that the ancestors of CSP1-3 lived in water—hot springs and freshwater—millions of years ago. During their evolutionary history, they underwent at least one major habitat shift, eventually colonizing soil environments—first surface soil, and later deeper soil.

This diagram shows the evolutionary history of aquatic organisms and the adaptive characteristics of CSP1-3 phyla in various habitats. Image source: Michigan State University

Tij also found that these microorganisms are active. "Most people would think of these organisms as being like spores, or in a dormant state," he said. "But a key conclusion we drew from examining their DNA was that these microorganisms were active and growing slowly."

Tiedje was also surprised to find that these microbes were not rare members of the community, but rather dominant; in some cases, they made up 50 percent or more of the community, which was never seen in topsoil.

"I believe this happens because deep soil is a very different environment and this group of organisms has evolved over a long period of time to adapt to this poor soil environment," Tiedje added.

Soil is the largest water filter on earth. As water flows through the soil, it is purified through physical, chemical, and biological processes. Topsoil, where most plant roots grow, is usually small enough for rainwater to move through quickly. But the volume of deep soil is much greater. CSP1-3 was born for this purpose. They feed on the carbon and nitrogen washed out of the top soil, completing the purification process.

"CSP1-3 is like a scavenger, cleaning up things that come across the soil surface," Teeje said. "They have their work cut out for them."

The next step is to grow some of the microbes in the lab, and if they can grow, we can learn more about their unique physiology that makes them so successful in deep soil environments, Tij said. This is no easy task. Most microorganisms cannot be cultured because it is difficult to replicate the conditions in which they live and grow.

For example, because the ancestors of CSP1-3 lived in hot springs, Tiedje's lab is trying to grow them at high temperatures as an example of testing new growth conditions based on their genomic information.

But if anyone can do it, it's Tiedje, because he also discovered microorganisms that can dechlorinate chlorides.

"The physiological mechanisms of CSP1-3 are driven by their biochemical properties, so there may be some interesting genes with other uses," he said. "For example, we don't yet know their ability to metabolize troublesome pollutants, and if we could understand this, we could help solve one of the most pressing problems on Earth."

Compiled from /ScitechDaily