The newly identified fire amoeba can survive and reproduce in scalding water, expanding what scientists thought was possible for complex life. The fire amoeba was shown to replicate at 145°F, a record for a eukaryote, and remain active up to 147°F, according to researchers.
Angela Oliverio, a microbiologist at Syracuse University, studies how life copes at the edge of extreme conditions. She said the drive is to understand where life’s boundaries truly lie, especially for microscopic organisms.
Her lab focuses on extremophiles, species that thrive where most life fails, such as in intense heat. Simple organisms like bacteria and Archaea have long held the temperature records, with some persisting at or above 212°F. But eukaryotes, which include humans and single-celled amoebas with nuclei and other internal structures, have been less explored for heat endurance.
Beryl Rappaport, a PhD student in Oliverio’s group, said the gap likely stems from not having found the right eukaryotes yet. She and colleagues have now added a standout: a heat-loving amoeba that raises the known temperature ceiling for complex cells by about five degrees. Their findings appear in Cell.
Oliverio likened the advance to running’s once-mythic four-minute mile. The gain may be small, she said, but it proves the barrier can be broken.
A little cell that likes it hot
The discovery began with a sampling trip to Lassen Volcanic National Park in Northern California, one of the nation’s least-visited parks. Rappaport described a mountainous landscape of pines, butterflies and steaming geothermal pockets shaped by recent wildfires and regrowth.
At a small, grass-fringed tributary of Hot Springs Creek, the team used extra-long barbecue tongs to lower vials into the hot water. Back in the lab, Rappaport examined and filmed the samples. When sped up, the footage revealed a shape-shifting crawler with classic amoeboid motion.
This organism replicated at 145°F, a new mark for a complex cell. It kept moving up to 147°F and could protect itself in waters as hot as 158°F. Genome analysis confirmed it as a new species, which the team named Incendiamoeba cascadensis, or “fire amoeba of the Cascade mountain range.”
An extremophile with lessons to share
To understand how the fire amoeba tolerates such heat, researchers compared its genome with other amoebas. The species appears to stabilize its proteins and cell membranes at higher temperatures, a strategy that could broaden the search for life on Earth and potentially elsewhere, Oliverio said.
The organism’s temperature resilience could also inspire practical advances, from heat-tolerant crops to drugs that remain stable across wider temperature ranges. Debashish Bhattacharya, an evolutionary biologist at Rutgers University not involved in the study, cautioned that turning an exotic organism into widespread applications is challenging, but said the potential for remarkable discoveries remains.
Bhattacharya noted that many extremophiles streamline their genomes to compete in harsh environments. The fire amoeba, by contrast, has a larger genome than its relatives, suggesting it took a different evolutionary path.
Oliverio said documenting the fire amoeba is likely just the beginning. With the ceiling pushed higher, she hopes more scientists will search for other complex organisms that can take the heat. Perhaps, she added, the upper temperature record will fall again soon.
Fire amoeba and the limits of life
For island readers used to Hawaiʻi’s geothermal features on the Big Island, the fire amoeba’s adaptability highlights how much remains to be learned from hot springs and volcanic ecosystems. As scientists probe similar environments worldwide, discoveries like this could reshape our understanding of where complex life can exist.
As scientists probe similar environments worldwide, discoveries like this could reshape our understanding of where complex life can exist, much as research into water security continues to evolve following rulings such as the one in Court: No constitutional right to safe drinking water.
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