Scientists discover 100-million-year-old bacteria under South Pacific seafloor

James Marshall
July 30, 2020

"The oldest traces of life are fossils of marine microbes dating back nearly 3.5 billion years". Its center harbors the "oceanic pole of inaccessibility" -the ocean's remotest extreme, aka Point Nemo (meaning "no-one"), famous for being a NASA spacecraft cemetery.

Scientists have revived bacteria which survived more than 100 million years laying dormant on the seafloor.

"When I found them, I was first sceptical whether the findings are from some mistake or a failure in the experiment", said lead author Yuki Morono. Small life forms such as microbes become trapped in this sediment. "We wanted to know how long the microbes could sustain their life in a near-absence of food".

The scientists said the microbes were present in clay samples drilled from the research vessel JOIDES Resolution about 74.5 metres under the seafloor, below 5.7 kilometres of water.

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.

Morono explained that oxygen traces in the sediment allowed the microbes to stay alive for millions of years while expending virtually no energy.

The team incubated the samples to help coax the microbes out of their epoch-spanning slumber.

According to a report in Cosmos, Steven D'Hondt, an oceanographer at the University of Rhode Island, said the discovery is "violating our sense of the [microbial] world as we know it".

"But what we found was that life extends in the deep ocean from the seafloor all the way to the underlying rocky basement".

There was a previous study of bacterial spores that were supposedly from 250-million-year-old salt crystal in the Permian Salado Formation in New Mexico, but not all experts agreed these were really from back then.

Upon learning of their ability to revive and regrow, the researchers are looking to see if there are other applications for their research, including understanding more about how the microbes evolved.

"We want to understand how or if these ancient microbes evolved", Morono continued. "This study shows that the subseafloor is an excellent location to explore the limits of life on Earth".

The new research also suggests that if the Red Planet was once home to life, it could possibly exist in a dormant, revivable state, rather than merely as a fossil.

Once the microbes, which are a type of bacteria, were put in laboratory conditions, they came back to life and began eating and multiplying, as living things tend to do.

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