Hot springs at at Lassen Volcanic National Park, where the heat-tolerant amoeba was discovered.Credit: Kelly Vandellen/iStock via Getty
This cell likes it hot. A tiny, single-celled amoeba can thrive at temperatures that kill all other known complex life — organisms whose cells contain a nucleus and internal structures.
The discovery questions the notion that such ‘eukaryotic’ life — which includes all animals and plants — is not suited to the kind of extreme conditions 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 study co-author Angela Oliverio, a microbiologist at Syracuse University in New York. The work, which has not yet been peer reviewed, was described in a 24 November preprint1.
Oliverio and fellow Syracuse microbiologist Beryl Rappaport discovered the organism at Lassen Volcanic National Park in northern California’s Cascades mountain range. They named it Incendiamoeba cascadenis, which translates to ‘fire amoeba from the cascades’ in Latin.
Incendiamoeba cascadenis 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-coloured 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 the samples with nutrients, the researchers spotted the amoeba growing at 57 °C, within the stream’s temperature range. They slowly raised the temperature, sailing past the previous eukaryote record of 60 °C. I. cascadensis still divided at 63 °C and, at 64 °C, was still moving around. Even at 70 °C, cells could form dormant ‘cysts’ capable of reactivating at cooler temperatures.
