Amoeba Found in Lassen Volcanic National Park Could Reset Upper Temperature Limit For Complex Life
Preliminary results are in on a new study by students from Syracuse University and although they have not undergone peer review, they mark an intriguing development from the world of micro-biology out of California’s Lassen Volcanic National Park.
Scientists have identified a single-celled eukaryote named Incendiamoeba cascadensis, aka the fire ameba, thriving in the steaming pools of LVNP which are challenging long-held beliefs about the thermal limits of complex life. The organism was first described in BioRxiv, where researchers reported its ability to continually divide at an incredible 145.4F marking the highest temperature ever observed for eukaryotic cell division.
Scientists collected water samples from various hydrothermal springs across Lassen between 2023 and 2025 and eventually isolated Incendiamoeba cascadensis from most of the sites. Back in the laboratory the team observed active mitosis at temperatures up to 145.4F and noted that the amoeba’s motility persisted up to 147.2F.
Genomic analyses revealed genes associated with proteostasis, genome stability and environmental sensing. The researchers believe these traits may explain the organism’s remarkable resilience to extreme heat. The findings have an effect on existing expectations of how hot eukaryotic cells can function.
Again, the results are preliminary and need further scrutiny before any major announcements can be made, independent labs will need to replicate both the temperature measurements and the genomic findings, but if confirmed Incendiamoeba cascadensis could reshape the world’s current understanding of the duribility and thermal limits of eukaryotic life.
So happy to announce our new preprint, “A geothermal amoeba sets a new upper temperature limit for eukaryotes.” We cultured a novel amoeba from Lassen Volcanic NP (CA, USA) that divides at 63°C (145°F)
– a new record for euk growth!
#protistsonsky— H. B. Beryl Rappaport (@hbrappap.bsky.social) November 25, 2025 at 2:41 PM
In 2023, we first sampled from a geothermal tributary at LVNP and using enrichment culturing, found an amoeba growing at high temp.
— H. B. Beryl Rappaport (@hbrappap.bsky.social) November 25, 2025 at 2:41 PM
And finally all at SyracuseU – @shaharsu.bsky.social @jessniblo.bsky.social for protein analyses, @rmshepherd.bsky.social for culturing, & @oliverio.bsky.social for leading this effort with me!
— H. B. Beryl Rappaport (@hbrappap.bsky.social) November 25, 2025 at 2:41 PM
images from lassennps flickr
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