Capitol News

Michigan State University scientists have unveiled a new category of microbes, known as CSP1-3, discovered in the Earth's deep soil, a previously uncharted area in microbiology. James Tiedje, a renowned expert in the field, spearheaded this exploration of the Critical Zone, a part of the planet's surface extending from tree tops through soil to depths of up to 700 feet.

Tiedje described the Critical Zone as vital to life, regulating soil formation, water, and nutrient cycling essential for food, water quality, and ecosystem health. However, its deep layers remain largely unexplored. The researchers found CSP1-3 in soil samples from Iowa and China, chosen due to their deep and similar soil characteristics. Tiedje reported, "This zone supports most life on the planet as it regulates essential processes like soil formation, water cycling, and nutrient cycling, which are vital for food production, water quality, and ecosystem health. Despite its importance, the deep Critical Zone is a new frontier because it’s a major part of the Earth that is relatively unexplored."

The research team discovered that these microbes, which descended from aquatic organisms millions of years ago, had transitioned to soil environments, adapting through evolutionary history. Contrary to the belief that these organisms might be dormant, Tiedje highlighted, "Most people would think that these organisms are just like spores or dormant. But one of our key findings we found through examining their DNA is that these microbes are active and slowly growing." The study revealed that CSP1-3 is not only active but also dominant, constituting over 50% of the microbial community in some deep soil areas.

Tiedje explained the role of these microbes in water purification, stating, "CSP1-3 are the scavengers cleaning up what got through the surface layer of soil. They have a job to do." The researchers are aiming to culture these microbes in lab conditions to learn more about their unique physiologies and potential applications, particularly in metabolizing pollutants. Tiedje shared, "CSP1-3’s physiology, driven by their biochemistry, is different, so there may be some interesting genes of value for other purposes."

The team's findings were published in the Proceedings of the National Academy of Sciences in a paper titled "Diversification, niche adaptation and evolution of a candidate phylum thriving in the deep Critical Zone."