Microbiologists at Syracuse University have discovered a single-celled organism named Incendiamoeba cascadensis—translating to the fire amoeba of the Cascade mountain range—that can replicate at temperatures up to 145°F, setting a new record for a complex organism, according to findings published in the journal Cell.
Finding Life at the Extremes in Lassen Volcanic National Park
The discovery emerged from a sampling expedition in Lassen Volcanic National Park, described by Syracuse University microbiologist Angela Oliverio as one of the least-visited national parks in the United States. The park features mountainous terrain, pine forests, and steaming geothermal pockets. According to PhD student Beryl Rappaport, the research team targeted a tributary of Hot Springs Creek hidden by tall grasses. Using extra-long barbecue tongs, Rappaport dipped glass vials into the steaming water to capture samples.
Back in the laboratory, Rappaport examined the water under a microscope and recorded video footage. When she sped up the recording, she observed a cell protruding, retracting, and fluidly changing shape. “That’s definitely an amoeba,” Rappaport recalled thinking, noting the characteristic movement. Testing revealed that Incendiamoeba cascadensis replicates at up to 145°F, moves at temperatures up to 147°F, and survives in waters as hot as 158°F.
Did you know? While simple organisms like bacteria and Archaea—a group of single-celled microorganisms—can live at or above the 212°F boiling point of water, scientists have historically studied heat resistance far less in eukaryotes, which are complex organisms whose cells contain a nucleus.
Comparing Extremophiles: Genome Structure and Heat Tolerance
When researchers sequenced the genome of Incendiamoeba cascadensis, they found distinct mechanisms keeping its proteins and membranes stable at high heat. Unlike other extremophiles that undergo “genome streamlining” to shrink their genetic material and compete with bacteria in harsh environments, the fire amoeba features a larger genome than its closest relatives, according to Rutgers University evolutionary biologist Debashish Bhattacharya, who was not involved in the research.
Oliverio compares this breakthrough to the sub-4-minute mile in running. For years, runners viewed the threshold as impossible, but once Roger Bannister broke it, other athletes quickly followed. “It wasn’t so much the incremental amount that this record was broken by, as much as the proof that it was possible,” Oliverio says, suggesting that the upper temperature record for complex cells may be broken again soon as more researchers search extreme environments.
Pro Tip: Researchers looking into extremophiles study how cellular stability mechanisms operate at elevated temperatures, which could theoretically inform future biotechnological applications such as heat-resilient crops or stable pharmaceuticals, as noted by Oliverio.
Frequently Asked Questions
What is Incendiamoeba cascadensis?
It is a newly discovered species of single-celled amoeba found in Lassen Volcanic National Park that holds the temperature record for replication in a complex organism at 145°F.
Where was the fire amoeba discovered?
According to the researchers, it was found in a steaming geothermal tributary of Hot Springs Creek within Lassen Volcanic National Park in northern California.
How does the fire amoeba compare to bacteria in extreme heat?
While certain bacteria and Archaea thrive at or above 212°F, the fire amoeba represents a major milestone for eukaryotes—complex cells with nuclei—which have rarely been documented surviving at such high thermal thresholds.
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