Scientists discover new microorganisms in the deep soil of the Earth

Scientists have discovered a new microbial phylum in areas of deep soil that restore water quality in an important zone on Earth. Groundwater, which becomes drinking water, passes where these microorganisms live and consumes remaining contaminants. The paper, “Diversification, Niche Adaptation and Evolution of Candidate Physicians that Prosper in a Deep Critical Zone,” is published in the Proceedings of the National Academy of Sciences.

Leonardo da Vinci once said, “I know more about the movement of celestial bodies than the soil under my feet.” James Tiedier, a microbiology expert at Michigan State University, agrees with Da Vinci. However, he aims to change this through his work in important zones that are part of the Earth’s dynamic “living skin.”

“The key zones extend from the top of the tree through the soil to a depth of up to 700 feet,” says Tiedje. “This zone supports most life on the planet as it regulates critical processes such as soil formation, water cycling, and nutritional cycling. It is essential for food production, water quality and ecosystem health. Despite its importance, the deep critical zone is a new frontier as it is a relatively unpublished major part of the planet.”

What researchers found in the deep layers of the critical zone

Tiedje, a university emeritus professor at the MSU Ministry of Microbiology, Genetics and Immunology, was discovered in this huge, unexplored world of microbes called CSP1-3.

This new gate was identified in soil samples ranging from depths to 70 feet in both Iowa and China. Why Iowa and China? Because these two regions have very deep and similar soils, researchers wanted to know if their occurrence was more common than just one region, Tiedje said.

Tiedje’s team extracted DNA from these deep soils and discovered that CSP1-3 ancestors lived in the water. They have undergone at least one major habitat transition in their evolutionary history to colonize the soil environment.

Tiedje also discovered that microorganisms are active. “Most people would think these creatures are like spores and dormant,” he said. “But one of the important findings we found by examining DNA is that these microorganisms are growing actively and slowly.”

Tiedje was also surprised that these microorganisms were not unusual members of the community, but dominated. In some cases, they made up more than 50% of the community, but this is by no means the case in surface soils.

“I think this happened because deep soils are very different environments and this group of organisms evolved over a long period of time to adapt to this poor soil environment,” Tiedje added.

How microorganisms cleanse water

The soil is our planet’s largest water filter. Once water passes through the soil, it is cleaned through physical, chemical and biological processes. The surface soil where most plants roots are present is often very small amounts of soil through which rainwater passes quickly. However, the amount of deep soil is much larger. This is where CSP1-3 is useful. They remove the carbon and nitrogen washed away from the topsoil to complete the purification process.

“CSP1-3 is a scavenger that cleans up anything that passes through the surface layer of the soil,” says Tiedje. “They have work to do.”

What’s next?

According to Tiedje, the next step is to cultivate some of these microorganisms in the laboratory, and if they grow, you can learn more about the unique physiology that can be very successful in this deep soil environment. This is not easy. Most of the microbial world is not cultured because it is extremely difficult to replicate the conditions in which they live and grow.

For example, CSP1-3 ancestors lived in hot springs, so Tiedje’s labs are trying to grow them at high temperatures as an example of testing new growth conditions based on information from the genome.

But if anyone can do that, he also discovered microorganisms that can dechlorinate chlorinated compounds, so Tidoe can.

“Because CSP1-3 physiology is driven by biochemistry, there may be some interesting value genes for other purposes,” he said. “For example, we don’t know our ability to metabolize difficult pollutants, so if we can learn that, it will help us solve one of the most pressing problems on the planet.”