Researchers from Syracuse University have identified a previously unknown amoeba that can live and multiply in water heated to 158°F (70°C), a temperature that would kill all other known eukaryotic organisms. The discovery, published in the journal Cell, challenges the long‑standing belief that 140°F (60°C) marks the upper thermal limit for complex cells.
Field work in California’s volcanic region
Between 2023 and 2025, a team led by corresponding author Angela Oliverio collected samples from geothermal streams in Lassen Volcanic National Park, located in the Cascade Range of northern California. Water temperatures at the sampling sites ranged from about 117°F to 147°F (47°C to 64°C). Among dozens of specimens, one amoeba stood out for its extraordinary heat tolerance.
Laboratory testing reveals record‑setting growth
In the laboratory, the organism grew robustly at 135°F (57°C), already higher than any previously documented amoeba. When the temperature was raised to 145°F (63°C), the cells entered mitosis, the process by which eukaryotic cells divide. Remarkably, when exposed to 158°F (70°C), the amoeba survived and was able to recover after being returned to cooler water.
How the “fire amoeba” protects itself
Oliverio explained that the organism shields itself at extreme temperatures by changing shape and forming a protective outer layer. Genetic analysis showed the presence of extra genes linked to protein maintenance and DNA repair, traits that likely help the amoeba cope with intense heat. Additionally, the amoeba’s proteins contain a higher proportion of positively charged amino acids on their surfaces, a feature also observed in some of the most heat‑tolerant bacteria and archaea.
Implications for science and industry
Study first author Beryl Rappaport, a doctoral student at Syracuse University, noted that the convergence of protein‑stabilizing strategies across very different organisms suggests common solutions to thermal stress. While the temperature increase over the previous eukaryotic record is modest, the finding opens the door to further research on the limits of life on Earth and potentially on other planets.
Oliverio likened the breakthrough to setting a new world‑record in sports, saying, “Every time we set a new world record in sports, it’s celebrated, even if it’s by milliseconds. We should do the same for amoebae. These very small changes expand our understanding of what we think is possible.”
Context within the broader scientific landscape
The hottest‑growing organism previously known was the archaeon Methanopyrus kandleri, which thrives at 252°F (122°C) around deep‑sea hydrothermal vents. However, archaea are simple, single‑celled microbes that differ fundamentally from eukaryotes, which include animals, plants, fungi, and many microbes. The new discovery therefore represents the highest temperature at which a complex cell has been shown to not only survive but also reproduce.
Scientists anticipate that the fire amoeba could become a model for studying protein stability, DNA repair mechanisms, and the evolution of heat tolerance. Such knowledge may have practical applications in biotechnology, where enzymes that function at high temperatures are valuable for industrial processes.
Overall, the research underscores the importance of exploring extreme environments and reminds us that nature often exceeds the limits we assume are fixed.
Original reporting: KTBS 3 (Shreveport) — read the source article.
