The tiny, single-celled microbes comprise most of the life on Earth, and yet only 5% of its diversity has been discovered. Even more with the seafloor microbes that thrive at deep-sea hydrothermal vents, according to Dive and Discover.

But two new studies might shed light on these microbes that could survive extreme heat coming from Earth's interior that rises during tectonic movements.

MBL Assistant Scientist Emil Ruff and colleagues have shown that seafloor microbes in the Guaymas Basin in the Gulf of California have specially adapted to high temperatures in deep-sea, and how they could dramatically influence the carbon cycling in hot seafloor sediments.

 Microbes of Deep-Sea Community Can Survive Extreme Heat, Influence Carbon Cycling
(Photo: Wikimedia Commons)
Spires built by hydrothermal activity. Those in the background are covered by stalked barnacles. Image ID: expl6099, Voyage To Inner Space - Exploring the Seas With NOAA Collect Photo Date: 2010 June 30 Credit: NOAA Okeanos Explorer Program, INDEX-SATAL 2010

Microbes Adapted to Thermal and Geochemical

According to, sediments at the seafloor where geothermal heat meets the cold deep ocean experiences a 30 to 60 degrees Celsius temperature, perfect for heat-loving microbes called thermophiles.

These exotic heat lovers use methane as their source of energy and thrive in areas in the deep sea that are different from most other marine ecosystems. Thermophiles and other organisms that survive using geochemical released by hydrothermal vents are at the base of the food web. So without them, ecosystems would not be possible.

The study, "Microbial Communities Under Distinct Thermal and Geochemical Regimes in Axial and Off-Axis Sediments of Guaymas Basin," published in Frontiers in Microbiology, showed that thermophiles and other microbes have adapted to the distinct thermal and geochemical regimes in the Guaymas Basin.

However, only a few of the diverse microbial communities in these hydrothermal sediments use methane as their source of energy. Most of them can only use organic compounds like sugars, proteins, and fatty acids. These organisms are called heterotrophs that live on the biomass from the surface ocean or those produced by thermophiles.

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Seafloor Microbes Might Influence Deep-Sea Carbon Cycle

The second study discussed in the article, "Heat-loving microbes recycle organic carbon in the seafloor," published in Nature Microbiology, study author Sherlynette Pérez Castro showed that some thermophiles specialize in degrading debris that is released into the environment when organic polymers and macromolecules perish.

Castro and her collaborators found that all of the organisms they could cultivate in the laboratory belonged to previously uncultivated microbes. Their findings suggest that the high diversity of coexisting heterotrophs mean that each polymer serves as nutrition for a whole food web, which explains how a single molecule could sustain several organisms.

They also found that none of the cultivated organisms produced methane, a by-product of heterotrophs. This could mean that methane from the seafloor could have completely removed from the ecosystem by the seafloor microbes, implicating that they could influence the carbon cycle in the deep sea.

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