Scientists have discovered an amoeba that can reproduce at temperatures previously considered too extreme for complex life, setting a new record for eukaryotes.
The NASA-supported study found Incendiamoeba cascadensis, or the “fire amoeba”, reproducing by cell division at 145 degrees Fahrenheit (63 degrees Celsius) in the heated waters of California’s Lassen Volcanic National Park. The amoeba remains active and can search for food at temperatures up to 147 degrees Fahrenheit (64 degrees Celsius), although it stops reproducing beyond 145 degrees Fahrenheit.
The findings, published in Cell, push the known upper temperature limit for eukaryotic life beyond the previous record of 140 degrees Fahrenheit (60 degrees Celsius), held by some fungi and red algae.
Eukaryotes have complex cells containing a nucleus and membrane-bound organelles, which are vulnerable to extreme heat. The researchers found that I. cascadensis has genes that help stabilise DNA, protect proteins and sense environmental changes. Some proteins also have positively charged surfaces that may help them remain stable at high temperatures.
The discovery could broaden scientists’ understanding of where complex life might survive on Earth and beyond. Extremophiles are also important to astrobiology because they help define the conditions under which life can exist.
However, researchers stressed that temperature is only one factor. Acidity, oxygen, pressure, water, food and the surrounding ecosystem would also determine whether such life could survive elsewhere.