New multicellular organism thrives at 63°C, expanding search for extraterrestrial life

Scientists have discovered a new multicellular extremophile microorganism in the hot springs of Lassen Volcanic National Park, California, capable of surviving at unprecedented high temperatures.

The organism, nicknamed the "fire amoeba" (Incendiamoeba cascadensis), can reproduce at 63 degrees Celsius and remains fully active at 64 degrees Celsius. While it ceases life functions at 80 degrees Celsius, its ability to multiply at these temperatures demonstrates that complex, "eukaryotic" multicellular life can endure higher heat than previously thought.

Whereas single-celled organisms like Methanopyrus kandleri can survive up to 122 degrees Celsius, multicellular organisms with cell nuclei and membranes have been considered more heat-sensitive. The previous record for reproduction in multicellular organisms was 60 degrees Celsius.

The research, led by Beryl Rappaport at Syracuse University and published in the journal Cell, points to genetic mechanisms that protect DNA and proteins under high heat. The discovery is expected to encourage further searches for heat-tolerant eukaryotes, potentially expanding the possibilities for finding life beyond Earth.

Genetic similarities found in the fire amoeba's DNA to samples from geothermal sites worldwide suggest its presence, or that of relatives, could be more widespread. While conditions on other celestial bodies like Mars or Jupiter's moon Europa might theoretically support such microorganisms, the full suite of environmental requirements for the fire amoeba—including suitable acidity, oxygen levels, and water—has so far only been observed on Earth.