Hydrothermal system at Ethiopia’s Danakil Depression, where uniquely extreme life has been found in salt chimneys and surrounding water. The yellow deposits are a variety of sulphates and the red areas are deposits of iron oxides. Copper salts color the water green. (Felipe Gomez/Europlanet 2020 RI)
Ethiopia’s Dallol volcano and hot springs have created an environment about as hostile to life as can be imagined.
Temperatures in the supersaturated water reach more than 200 degrees F (94 C) and are reported to approach pure acidity, with an extraordinarily low pH of 0.25. The environment is also highly salty, with salt chimneys common.
Yet researchers have just reported finding ultra-small bacteria living in one of the acidic, super-hot salt chimneys. The bacteria are tiny — up to 20 times smaller than the average bacteria — but they are alive and in their own way thriving.
In the world of extremophiles, these nanohaloarchaeles order bacteria are certainly on the very edge of comprehension. But much the same can be said of organisms that can withstand massive doses of radiation, that survive deep below the Earth’s surface with no hint of life support from the sun and its creations, that keep alive deep in glacier ice and even floating high in the atmosphere. And as we know, spacecraft have to be well sterilized because bacteria (in hibernation) aboard can survive the trip to the moon or Mars.
Not life it is generally understood. But the myriad extremophiles found around the globe in recent decades have brought home the reality that we really don’t know where and how life can survive; indeed, these extremophiles often need their conditions to be super-severe to succeed.
And that’s what makes them so important for the search for life beyond Earth. They are proof of concept that some life may well need planetary and atmospheric conditions that would have been considered utterly uninhabitable not long ago.
Montage from the Dallol site: (A) the sampling site, (B) the small chimneys (temperature of water 90 ºC. (C) D9 sample from a small chimney in (A). (D-L) Scanning Electron Microscope and (M-O) Scanning Transmission Electron Microscope images of sample D9 showing the morphologies of ultra-small microorganisms entombed in the mineral layers. (Gomez et al/Europlanet 2020 Research Infrastructure)
The unusual and extreme life and geochemistry of Dallol has been studied by a team led by Felipe Gómez from Astrobiology Center in Spain.… Read more
