Microbes that have been dormant on the seafloor for more than 100 million years have been revived by scientists.
A team of academics in the US and Japan say the microorganisms were growing and dividing despite entering an energy-saving state when the dinosaurs still existed.
The microbes belong to ten different groups of bacteria and were retrieved from sediment deep under the seafloor in the heart of the South Pacific Gyre.
The scientists say they were found in clay samples drilled from the research vessel JOIDES Resolution about 245 feet (74.5 meters) under the seafloor, below 3.5 miles (5.7 km) of water.
Up to 99 per cent of the microbes survived despite having essentially no nutrients for all that time.
The researchers, led by Japan Agency for Marine-Earth Science and Technology geomicrobiologist Yuki Morono, incubated the microbes for up to 557 days in a lab.
Sources of carbon and nitrogen such as ammonia, acetate and amino acids were supplied to the microbes and the microbes subsequently thrived.
‘It is surprising and biologically challenging that a large fraction of microbes could be revived from a very long time of burial or entrapment in extremely low nutrient/energy conditions,’ study author Dr Yuki MoronoMorono said.
The microbes were aerobic – requiring oxygen to live – and oxygen was present in the sediment samples.
This indicates, the researchers said, that if sediment accumulates gradually on the seafloor at a rate of no more than a yard or two every million years, oxygen may remain present to enable such microbes to survive stupendous lengths of time.
‘At first I was sceptical, but we found that up to 99.1 per cent of the microbes in sediment deposited 101.5 million years ago were still alive and were ready to eat,’ said University of Rhode Island oceanographer Professor Steven D’Hondt, co-author of the study published in the journal Nature Communications.
‘Maintaining full physiological capability for 100 million years in starving isolation is an impressive feat,
‘We want to understand how or if these ancient microbes evolved.
‘In the oldest sediment we’ve drilled, with the least amount of food, there are still living organisms, and they can wake up, grow and multiply.’