US team discovers new species of amoeba that grows at temperatures as high as 63 degrees Celsius, the highest among eukaryotes

When a type of single-celled amoeba was collected from hot spring water flowing on the surface of California's Lassen Volcanic National Park and cultured, it was found that it proliferated at temperatures as high as 63 degrees Celsius. A research team from Syracuse University and other institutions published the findings in the electronic version of the American scientific journal Cell by the 26th. The growth temperature is said to be the highest ever recorded for any eukaryote that has a cell nucleus.

Through DNA analysis, this amoeba was classified as a new genus and species, and its scientific name was given the name ``Inkendiamoeva cascadensis,'' which means ``flame amoeba,'' and because of the Cascade Mountains where it was discovered. It can move at temperatures as low as 64 degrees by feeding on bacteria, and although it becomes dormant at 70 degrees, it revives when the temperature is lowered.

Eukaryotes include fungi (yeast, mold, mushrooms), algae, plants, and animals. The highest growth temperature reported in the past was 60 degrees for fungi and red algae. Although the new species of amoeba only exceeded the temperature by three degrees, a group of genes that prevent protein denaturation caused by high temperatures and repair damaged DNA were discovered. It is possible that microorganisms that are even more resistant to high temperatures will be discovered in the future, and it is expected that their mechanisms will be useful in improving enzymes used in the production of pharmaceuticals, foods, fibers, and other products.

The highest temperature recorded for biological growth is 122 degrees for archaea (prokaryotes). In 2008, Japan's Japan Agency for Marine-Earth Science and Technology conducted high-pressure culture experiments on hyperthermophilic methanogenic archaea collected from the deep-sea hydrothermal environment of the Indian Ocean, and announced that they had grown.