According to a study by the Japanese Marine and Earth Science and Technology Agency, scientists have managed to revive microbes that have been dormant on the ocean floor for at least 101.5 million years.
The work, led by Yuki Morono, was published in the journal Nature Communications and revealed that the tiny organisms remained at the bottom of the South Pacific in sediments low in nutrients, but with enough oxygen to allow life.
“When I found them, I was initially skeptical about the results, whether they were any errors or flaws in the experiment,” the author told AFP news agency. “We now know that there is no age limit for organisms in the biosphere of this sea layer,” he added.
The samples were obtained in 2010, when an expedition of the Integrated Ocean Drilling Program (IODP) recovered sedimentary sequences from the abyssal plain of the South Pacific Giro. The objective was to examine the life and habitability of the subsoil in the region with the lowest rate of Marine life.
Most of the 6,986 individual cells analyzed using the nanoscale secondary ion mass spectrometry technique, actively incorporated isotope-marked carbon and nitrogen substrates. After 68 days of incubation by the scientists, they started to feed and multiply.
Thus, the research points out that a cell must metabolize a certain amount of carbon in relation to the biomass itself before it can double in size, divide or even maintain an active state. The sampled communities were probably trapped in the sediment since its deposition and, until then, their physiological status and growth potential were unknown.
The results also suggest that microbial communities, widely distributed in poor organic abyssal sediments, consist mainly of aerobes that retain their metabolic potential under extremely low energy conditions. In addition, spore formation has been suggested as one of the possible mechanisms for long-term survival.