How life thrives in the ‘deep biosphere’ despite temperatures that would fry humans

A Japanese scientific drilling ship is used to detect microbes that live in the depths of the sea floor.

A Japanese scientific drilling ship is used to detect microbes that live in the depths of the sea floor.
Photo: jamstik

science trip in 2016 revealed an underground habitat where microbes were found to live in temperatures approaching 250 degrees Fahrenheit. Now, A follow-up study reveals How this wonderful microbial community manages to beat the heat.

High metabolic rates make life possible for microorganisms that live in sediments buried deep on the sea floor, according to the new Research Published in Nature Communications. The study, led by marine biologist Tina Triod of UCLA, sheds light on subterranean microbes in a new light, showing that some are surprisingly energetic and able to thrive in deep and hot conditions.

“We’ve always found that microbes in the deep biosphere are a very slow community that is slowly nibbling on the last million-year-old buried remains of organic matter. But the deep biosphere is full of surprises,Bo Barker Jorgensen, a microbiologist at Aarhus University in Denmark, said: In a press release issued by the University of California. “Finding life that thrives with high metabolic rates at these high temperatures on the deep sea floor fuels our imaginations about how life might have evolved or survived in similar environments on extraterrestrial planetary bodies.”

In an email, Virginia Edgecombe, a geologist at Woods Hole Oceanographic Institution who was not involved in the new study, said she was excited by The research because it demonstrates “we cannot assume that microbial activities are unimportant merely because of depth under the sea floor or extreme temperatures,” particularly when “adequate sources of carbon and energy are available.”

In this case, the required sources of carbon and energy were found in the Nankai Trough subduction zone off Japan. Seven years ago, a scientific expedition led by the same team drilled 3,930 feet (1,200 meters) below the sea floor, pulling samples of marine sediment and evidence of extreme microbes. that they He did this to investigate the temperature limit of the deep undersea biosphere and the extent to which life exists in this extreme habitat. Incredibly, hmm have found A small community of microbes seemed to thrive despite temperatures reaching 250°F (120°C). It was not entirely clear to the researchers How this was possible prompted further study.

For the new investigation, Treude and her colleagues conducted radiotracer experiments to measure the metabolic rates of microbes, which they did under highly sterile conditions to prevent contamination. This was not easy. Given the low population density of microbes; Less than 500 cells were present in each cubic centimeter of sediment. The team also made special provisions for ENEnsure that metabolic rates observed in the laboratory were the same as in the natural environment of the microbes.

This work led to the discovery of the microorganism’s rapid metabolism, which the researchers say is what makes it possible for them to survive in such harsh conditions.. Scientists are of the opinion that higher metabolic rates are essential, Allowing microbes to repair cells damaged by heat.

“The energy required to repair thermal damage to cellular components increases sharply with temperature, and it is likely that most of this energy is needed to counteract the continuous change of amino acids and loss of protein function,” Treude said.

At the same time, microbes You have ample access to the nutrients provided by heating organic matter, especially hydrogen and acetate from water seeping across the seas sediment;

The new observations, “which may seem counterintuitive to many, are that the cells that live near the thermal boundary of life at this site, and so deep under the sea floor, where we would expect them to be barely there, are actually very active. But their high rate of activity,” Edgecombe said. It’s for a very exciting reason: “To be able to provide enough energy to repair thermal cell damage so they can survive,” she added.

In an email, Jennifer Biddle, an associate professor at the University of Delaware who is not affiliated with the research, said the new work “looks good” and “compliments well.” Pre-existing work Demonstrate changes in microbial communities and increases in cell divisionion As sediment temperatures rise. The argument made in the new paper is that cells do not start until after they have already been buried – a finding that is consistent with more recent Research It was co-authored by Biddle explaining that “once cells find their ‘happy place’ in the ground, they have a lot of strength to grow,”.

single entryBiddle said, that’s it Researchers describe bacterial activity But No names or identification of the microbes involved were provided. It would be great to know who’s there, she said. So we can better estimate how fast they are,” he said, adding that it would also be a good idea to “culture some of these strains subsurface to test their thermal ranges and how they might adapt to this environment.” ”

Interestingly, these undersea microbes are approaching the thermal limits of life as we know it, but some scientists believe that microbes can live Even in the hottest environments. Looks like we need to dig deeper next time, even more extreme Microbes can still wait to be found.

more: Ancient microbes come alive after 100 million years under the sea floor.

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