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‘Fire Amoeba’ Sets Eukaryotic Heat Record at 63°C

The record-setting protist was cultured from a Lassen hot spring, with results posted as a bioRxiv preprint pending peer review.

Overview

  • Incendiamoeba cascadensis grew only above ~42°C and showed peak growth near 55–57°C, with cell division directly observed at 58°C and 63°C.
  • The organism remained motile at 64°C, formed dormant cysts near 70°C that could reactivate when cooled, and died at roughly 80°C.
  • Researchers collected it from hot spring water in Lassen Volcanic National Park between 2023 and 2025, finding it at 14 of 20 sampled sites.
  • Genome analysis indicates adaptations for extreme heat, including expanded heat-shock chaperones, protein quality control, and DNA repair pathways.
  • Environmental DNA nearly identical to the amoeba’s sequences was detected in Yellowstone and New Zealand’s Taupō zone, and the 63°C growth surpasses the prior eukaryote record of 57°C.