Hot springs at at Lassen Volcanic National Park in California, where the heat-tolerant amoeba was discovered.Credit: Kelly Vandellen/iStock via Getty
This cell likes it hot. A tiny, single-celled amoeba that can thrive at temperatures that kill all other known complex life — organisms whose cells contain a nucleus and internal structures — has been found.
The discovery questions the notion that such ‘eukaryotic’ life — which includes all animals and plants — is not suited to the kind of extreme conditions that can be tolerated by bacteria and other organisms lacking a cell nucleus.
“We need to rethink what’s possible for a eukaryotic cell in a significant way,” says Angela Oliverio, a microbiologist at Syracuse University in New York. The work, which has not yet been peer reviewed, was described in a preprint1 published on 24 November.
Oliverio and fellow Syracuse microbiologist Beryl Rappaport were part of a team that discovered the organism at Lassen Volcanic National Park in northern California’s Cascade mountain range. They named it Incendiamoeba cascadensis, which translates to ‘fire amoeba from the cascades’.
Incendiamoeba cascadensis can thrive at temperatures that would kill other complex cells.Credit: Image taken by Natalie Petek-Seoane from the preprint by H. Beryl Rappaport et al./bioRxiv
The park is famous for gurgling acid lakes and incandescent geothermal pools, but I. cascadensis comes from a pH-neutral ‘hot stream’. “It’s the most uninteresting geothermal feature you’ll find in Lassen,” says Rappaport.
Water samples from the stream looked devoid of life under a microscope, but after culturing them with nutrients, the researchers spotted the amoeba growing at 57 °C, within the stream’s temperature range. The scientists slowly raised the temperature, sailing past the previous eukaryote record of 60 °C. I. cascadensis was still able to divide at 63 °C and was still moving around at 64 °C. Even at 70 °C, the cells could form dormant ‘cysts’ that were capable of reactivating at cooler temperatures.