New Record for Heat-Tolerant Amoeba Discovered in California
Researchers have identified a newly discovered amoeba, Incendiamoeba cascadensis, which has set the record for the highest temperature at which complex life can thrive. Found in Lassen Volcanic National Park, California, this amoeba can grow and divide at temperatures up to 145°F (63°C) and survive brief stints in environments up to 158°F (70°C). Previously, no complex cells were known to replicate above 140°F (60°C).
Surprising Discoveries
Study author Beryl Rappaport, a microbiologist from Syracuse University, expressed astonishment at the findings, stating they had to verify their equipment was correctly calibrated. “It really was amazing,” she noted.
Characteristics of the Amoeba
This single-celled organism is classified as a eukaryote, meaning it has its DNA enclosed within a nucleus, distinguishing it from simpler prokaryotic organisms such as bacteria. The team collected samples along a tributary of Hot Springs Creek in the park, where the amoeba appears to thrive at temperatures between 131°F and 135°F (55°C and 57°C). Notably, they ceased growth below 108°F (42°C).
Using a heated microscope, researchers observed the organisms dividing at temperatures as high as 145°F (63°C), the highest known for eukaryotic cells, although some prokaryotes can withstand temperatures up to 250°F (121°C).
Survival Mechanisms
At temperatures above 158°F (70°C), the amoebas formed protective shells and entered a dormant state. They could recover after five minutes of exposure to high temperatures. However, they did not survive when subjected to 176°F (80°C).
Future Research Directions
The study, published in the journal Cell, also indicated that I. cascadensis possesses proteins with positively charged amino acids, aiding stability at high temperatures. Rappaport plans to investigate the amoeba’s relatives to understand their evolutionary adaptations to heat.
This discovery suggests the potential for understanding life’s limits on Earth and the possibilities for complex life in extreme environments elsewhere in the universe.
