Decipher the mystery of bacteria living half a million years

Scientists claim to have found the " immortal " mystery of bacteria: They inhibit metabolism so low that they only produce enough energy to repair old DNA. Australian researcher Mike Bunce from Murdoch University and international colleagues has just published the discovery in the Proceedings of the National Academy of Sciences.

"We are looking at bacteria that have lived in permafrost for hundreds of thousands of years. They do not die: they are living cells," Bunce said. "If the DNA is not repaired, the bacteria will accumulate too much damage in their genome and the cells will not survive".

The team collected soil samples (containing bacteria) in the permafrost on Siberia, placing them in sealed containers and found a release of CO ₂ .

"You can see that they are actually breathing. Samples that are 600,000 years old show bacteria populations survive," Bunce said.

The researchers also extracted the intact DNA fragments of the bacteria, supporting the idea that they were alive."The longest ancient DNA fragment ever obtained from a dead sample contained 1000 pairs of units. Here, we obtained 4,000 pairs."

Life is still hiding in the permafrost.
(Photo: Discovery)

Fix yourself

Scientists have long known that bacteria can survive for years in harsh conditions, by turning off the body's metabolism, and protecting themselves with a shell called " spores. ". But in that difficult situation, their DNA slowly gets damaged by radiation and other factors.

Because bacteria do not produce any energy, they cannot repair damaged DNA and will die over time.So how does Siberian bacteria maintain their genetic apparatus after more than half a million years?

On closer inspection, Bunce's team found signs that the bacteria were refreshing their DNA. And they still breathe, though extremely light."That is really the key to a thousand-year survival mechanism in the ice."

Bunce said this respiratory experiment could also be helpful for those trying to find life on other planets. However, another researcher also noted that the evidence is indirect because the team looked at the soil sample, not directly on the bacteria. And it will be more certain if people cultivate those living creatures.

T. An