New Phylums of Bacteria Uncovered in Earth’s Deep Soil by Biologists

Deep Soils – Depending on the type and area of ​​soil, ranges from less than 30 cm (12 inches) to several hundred meters are neglected ecosystems within important zones of the Earth. Biologists have now discovered a wide and relatively abundant bacterial phyla, named CSP1-3, in deep soils, and evaluated its phylogenetic, ecology, metabolism, and evolutionary history.

“The key zone extends from above the trees through the soil to a maximum of 213 m (700 feet),” said Professor James Tiedee of Michigan State University.

“This zone supports most life on the planet as it regulates critical processes such as soil formation, water circulation and nutrition cycling, which are 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 unexplored part of the Earth.”

Professor Tiedje and his colleagues discovered a completely different microbial phylum called CSP1-3 in this huge, unexplored world of microorganisms.

This new gate was identified in soil samples ranging from both Iowa and China up to 70 feet (21 m) deep.

“Why Iowa and China? Because these two regions have very deep and similar soils and I want to know if their occurrence is more common than just one region,” Professor Tiedje said.

Researchers extracted DNA from these deep soils and discovered that CSP1-3 ancestors lived in water millions of years ago.

They undergo at least one major habitat transition to colonize the soil environment. It is in the first topsoil and the deep soil that followed, within its evolutionary history.

Scientists also discovered that CSP1-3 microorganisms are active.

“Most people think that these organisms are like spores and dormant,” Professor Thiedeye said.

“But one of the important findings we found by examining DNA is that these microorganisms are growing actively and slowly.”

The authors were 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,” Professor Tiedje said.

a paper The explanation of the survey results was published on March 18th. Proceedings of the National Academy of Sciences.

____

Wenlu Feng et al. 2025. Diversification, niche adaptation, and evolution of candidate phylums that thrive in deep critical zones. pnas 122 (12): E2424463122; doi: 10.1073/pnas.2424463122