Japanese scientists made the most unexpected discovery: vital, very ancient bacteria, ready to awaken, feed and divide. Daniela Billi, astrobiologist at the University of Rome Tor Vergata, explained: "They survived for so long thanks to an extremely slow metabolism" explains Daniela Billi, astrobiologist at the University of Rome Tor Vergata, an expert on bacteria capable of living in impossible environments, such as deserts.
We are not expecting much different from what we are going to look for on Mars. Some took up to 18 days to split. If we think that the most common bacteria used in the laboratory replicate in two hours, we have no idea how slow their metabolism is.
This is not about spores or dried out organisms that come back to life from a quiescent condition. They are organisms that live have always been, for such long times." Only traces of oxygen, trapped between the sediments that have accumulated in very slow times, a little carbon and perhaps also minerals, used as additional nourishment.
A year and a half ago communities of 5-10 thousand year old bacteria, isolated from the rest of the world, had been discovered in a lake under the Antarctic ice. But never had we come to imagine a living community that sank its history in such distant geological eras.
The Japanese discovery is published in Nature Communications
The Japanese discovery is published in Nature Communications. Researchers from the Jamstec (Japan Agency for Marine-Earth Science and Technology) had left aboard a ship to collect sediment carrots in the center of the Pacific, in the so-called South Pacific Gyre, the ocean area farthest from any coast.
Drawing on samples dated between 13 and 101 million years, reaching 75 meters below the bottom and 5,700 starting from the surface of the sea, they thought to also look for possible life forms. Cultivated with nitrogen and carbon, many of those bacteria, belonging to about twenty different species, began to feed and reproduce.
Yuki Morono, geomicrobiologist, the coordinator of the group, does not hide his wonder for the discovery: "At first I was skeptical. But we saw that 99% of the microbes deposited in 101 million year old sediments were still alive and ready to feed.
The oceanic subsoil has proven to be an exceptional place to explore the limits of life on Earth." The age of 101 million years refers to the rock in which microorganisms were found, therefore to the colony as a whole, not to individual bacteria.
But the idea that at such pressures, temperatures, extreme conditions due to darkness and lack of food, organisms can survive, makes it clear how elastic the concept of life is.