The Unseen World Beneath Our Feet: Unveiling the Mysterious CSP1-3 Bacteria Phylum
The soil beneath our feet is a hidden world teeming with mysterious life forms, potentially harboring more diversity than any other habitat on Earth.
Recently, scientists have made a groundbreaking discovery by identifying a new phylum of bacteria known as CSP1-3, which thrives in the deep, dark soils of our planet.
The initial sighting of CSP1-3 dates back to 2006 in Yellowstone’s geothermal systems, with subsequent findings in oligotrophic deep soils under tropical rainforests and subsurface soils rich in oxidized iron.
An international team of researchers utilized high-quality metagenome data to compile a comprehensive genomic catalog of this enigmatic bacterial phylum.
Their research shed light on the survival mechanisms of these bacteria, which rely on carbon and nitrogen sources trickling down from the surface to sustain their underground existence.

Deep soil samples from the United States and China, collected from depths of up to 22 meters, revealed that CSP1-3 dominates these hidden ecosystems, constituting up to 60 percent of the microbial communities at certain depths.
Microbiologist James Tiedje from Michigan State University emphasized the active and slow-growing nature of these microbes, challenging the conventional perception of them being dormant organisms.
The unique ecological niche of deep soils, characterized by energy limitation and nutrient scarcity, has led to the evolution of CSP1-3 to adapt to these harsh conditions over time.
Despite the scientific neglect of deep soil ecosystems, recent studies have highlighted the diverse microbial populations residing in these subsurface environments.
The metabolic capabilities of CSP1-3, including aerobic carbon monoxide and hydrogen oxidation, provide them with a competitive advantage in nutrient-deprived soils.
Furthermore, the genomic analysis revealed a lineage within CSP1-3 that transitioned from an aquatic habitat to colonize the soil, acquiring genes crucial for carbohydrate and energy metabolism.
While these findings offer valuable insights into the metabolic potential of CSP1-3, further research is needed to understand their phylogeny, ecological significance, and evolutionary trajectory.
With an estimated 99.999 percent of Earth’s microbes still unknown to science, CSP1-3 represents one of the many mysteries waiting to be unraveled below the surface.
Tiedje and his team are now focused on cultivating CSP1-3 microbes in the lab to unravel the intricacies of their ecological roles and survival strategies.
This groundbreaking study, published in PNAS, opens new doors to explore the hidden world of deep soil microbiology and the enigmatic CSP1-3 bacteria phylum.