In 2013, researchers discovered a thriving community of fungi deep beneath the ocean floor in 2.7-million-year-old mud. The fungi were found in the sub-seafloor, a vast community of microbial life that researchers are only beginning to explore, sometimes referred to as the “dark biosphere”.
The study was led by William Orsi, a microbiologist at the Woods Hole Oceanographic Institution. Orsi and his team examined sediments drilled from ocean basins around the world to better understand microbial life beneath the seafloor. The samples ranged from just below the seafloor surface to 157 feet (48 meters) deep.
Instead of searching through the deep-sea sludge for tiny creatures, Orsi looked for snippets of ribosomal RNA (rRNA), a proxy that shows microbes are metabolically active. In the oldest, deepest sediments, from the Eastern Pacific Ocean, fungi predominated. The subsurface microbial community was more diverse closer to the surface, in younger mud, with metazoans, protists, and plant material, or green algae.
The fungi correlated closely with the amount of organic carbon in the sediments, suggesting they contribute to recycling carbon in the seafloor. This reveals an additional component of the ecosystem that can contribute to the cycling of organic carbon.
Genetic evidence indicates the most deeply buried fungi are distinct from wind-blown relatives at the planet’s surface, suggesting the fungal communities are ancient and isolated.
The discovery of these ancient fungi deep beneath the seafloor has potential implications for the pharmaceutical industry, as fungi can produce interesting natural compounds, some of which are antibiotics.
Citations:
[1] https://www.nbcnews.com/news/all/2-7-million-year-old-fungus-found-deep-under-seafloor-flna1c8750513
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[6] https://ucmp.berkeley.edu/fungi/lichens/lichenfr.html
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[15] https://www.icr.org/article/ancient-blood-cells-still-red
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[19] https://www.researchgate.net/figure/Taxonomic-affiliation-of-fungal-OTUs-sharing-97-sequence-identity-from-subseafloor-and_fig4_235611372
