The limits of life are being redefined by the extraordinary discovery of a newly identified “Fire Amoeba,” capable of surviving extreme heat in geothermal biology, according to recent research that included UMass Amherst doctoral student Godwin Ani.

Image

The organism, Incendiamoeba cascadensis, can divide at 63°C (145°F), establishing a new upper temperature record for eukaryotic life. The research, conducted by an interdisciplinary team of scientists led by biologists Angela Oliverio and Beryl Rappaport at Syracuse University, challenges long-standing assumptions about the thermal limits of organisms with complex cells, including amoebae, animals, and plants.

The team, which includes Ani, a doctoral candidate in the College of Natural Sciences’ Organismic and Evolutionary Biology (OEB) Graduate Program, and Laura Katz, an OEB graduate faculty member professor at Smith College, recently co-authored a study on their findings in the journal Cell.

Ani and Katz were responsible for establishing the evolutionary placement of this organism in the tree of life. They used EukPhylo, a phylogenomic pipeline developed in Katz’s lab—and of which Godwin is also a co-author—to establish its identity as a member of a group of primarily amoeboid lineages called Amoebozoa. Unlike bacteria and archaea, which have historically dominated research concerning high-temperature life, eukaryotes (cells with nuclei, like our own) have been considered more constrained by the effects of heat on cellular structures and essential proteins.

“Most eukaryotic diversity remains unknown, and there is always the possibility of finding novel organisms with cool abilities,” Ani explains. “Using phylogenomics, we can identify where these organisms belong in the tree of life, and in this case, we discovered that the fire organism found living in a hot spring belongs to the Amoebozoa group.”

The discovery began with samples collected from a geothermal stream in Lassen Volcanic National Park in California. Researchers found that I. cascadensis not only replicates at temperatures previously considered beyond the reach of eukaryotes, but also remains “motile” (capable of spontaneous movement) at temperatures up to 64°C (147°F). At higher temperatures, the amoeba can enter a dormant cyst state, allowing it to recover after exposure to conditions that prevent active growth. Through genome sequencing and comparative analysis, the research team identified an enrichment of genes associated with proteostasis, genome stability, and environmental sensing. RNA sequencing further revealed increased activity in pathways related to protein maintenance, DNA repair, and membrane trafficking under high-temperature conditions, offering insights into how this organism responds to thermal stress.

This collaborative research helps advance understanding of the evolutionary strategies that enable eukaryotic organisms to persist in extreme environments. The study also identified distinctive biophysical properties in predicted proteins from I. cascadensis, including an enrichment of positively charged surface residues resembling features observed in heat-adapted bacteria and archaea. These similarities suggest that different branches of life may have independently evolved comparable approaches to maintaining protein stability under high-temperature conditions.

By expanding the known thermal boundaries of eukaryotic life, the research opens new questions about the evolution of cellular resilience, the diversity of geothermal ecosystems, and the potential for discovering thermostable proteins with applications in biotechnology.

“As we discover more organisms, we will realize that the current limits of life placed on eukaryotes only hold true for multicellular organisms,” argues Ani. “We therefore need to increase our attention on microbial eukaryotes to push forward our knowledge of survival in extreme environments on Earth and far beyond.”

More information about this research can be found in this article published by Syracuse University, and the complete study is available online from the journal Cell.