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The Deep Biosphere (Life Far Beneath The Earth's Surface)

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NOTE: This thread is being established by merging existing contributions on the subject of life deep beneath the earth's surface - i.e., life that is intralithic (between rocks) and / or endolithic (within rocks).

This thread's scope does not include near-surface subterranean life (e.g., burrowing animals or cave-dwelling species)


Interesting to come across this - http://www.people.cornell.edu/pages/tg21/DHB.html

Basically he is theorising that bacteria deep in the Earth's crust create oil and possibly mineral seams.

The originally posted link to a 1992 essay by Thomas Gold is dead.

An archived version of the originally linked webpage can be accessed via the Wayback Machine at:

https://web.archive.org/web/20011202005928/http://www.people.cornell.edu/pages/tg21/DHB.html

Alternatively, one can access the published version of the Gold article at:

http://www.pnas.org/content/pnas/89/13/6045.full.pdf?origin=publicationDetail
 
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I have been theorising a similar thing ( but from the opposite end, as it were )

Watching some documentary about Mars, it explained how critical plate techtonics are to life on earth. As a plate gets pushed under another one, the magma breaks down all the chemical compunds which eventually return to the surface. Without this recycling effect the surface chemistry runs down to an inert state and life (as we know it) would become impossible as more and more of the elements it needs to sustain itself get bound up in the rocks.

This got me thinking.

As far as we know, Earth is the only planet in the system with life, it is also the only planet with plate techtonics - maybe this isnt just coincidence. What if, instead of plate techtonics making life possible, maybe primitive life causes plate techtonics ?
Life has a habit of manipulating its environment on a massive scale to ensure survival - just look at how finely balanced and chemically active the Earth's atmosphere is. Also plate techtonics was not always the case on Earth, orginally there was just the Pangaea continent which for some reason broke up into the continental plates we see now.

Perhaps it was early biological activity deep in the crust that caused this?
 
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i'm not sure if earth is the only planet with plate tectonics. I think quite a few of Jupiters moons are quite certain to have tectonic movement. Io i seem to remember is especially geologically active, and callisto and ganymede (touted as possible sites of complex life) although covered in ice show very little asteroid cratering suggesting that their surface is is being continually recycled, driven by geothermal heat, which also suggests tectonic activity. My flatmates a geologist and i'll ask him (although he doesnt know his arse from his elbow so dont hold your breath for a decent reply).
 
Plate tectonics

The moons you mention does seem to be geologically active and have structural changes in the surface. But I don´t think what they have could be called plate tectonics. Because it seems to be more of a solid surface rather than consisting of plates like ours. But I suppose it´s a question of defintions, go ask that roommate.
 
First, I'm not too sure about life manipulating environment - isn't it a case of life adapting to environment changes?

Second, Mars (along with Mercury, and possibly some other planets' moons) seems to be too solid for tectonics, but we can't see what's happening to the surface of several of the planets (Venus, Jupiter for example), so they may be tectonically active.

Third, tectonics is a fairly recent idea, which has been demonstrated on Earth, but we haven't had time (or proximity) to other planets/planetoids to say for sure, in most cases.

Four, energy requirements. All the energy in every life form on Earth is unlikely (IMHO) to be able to cause structural changes to the surface of the planet - we're talking about lots of rock!

Finally, on a geological timescale, arses and elbows are far too close together to be recognised by a geologist! ;)
 
No, there are lifeforms which try and change the enviroment around them. For example coral reefs are vulnerable to big waves, and therefore excretes a kind of oil that breaks the surface tension of the water so the waves will be broken. That´s one way of spotting coral reefs, spots of smooth waters.
 
microbial plate tectonics

I was going to initially rush in and condemn the idea of microbes causing plate tectonics. this however would be the typical reaction of a scientist so I shall try to be a little more reasoned.

Now I have no doubt that the mass of microbes living deep within the earth is some truly staggering amount, the mass of rocks in your average tectonic plate is going to be even more massive. Locally the microbes will be able to influence a lot of rock but mostly by breaking it down into simple compounds or ions. Not by pushing the rock around the surface of the mantle, or even underneath some of the other bits of rock. If this was the case then a subduction zone must be the site of the biggest mass suicide of non-human life this side of those poor lemmings Disney ran off of a cliff. This hardly makes much sense if the microbes are trying to create a microbiological paradise on earth.

Now perhaps and bear in mind this is merely an hypothesis. Could microbial populations facilitate the slippage of tectonic plates? Simple observation would reveal if the population density of intralithic bacteria peaks before an earthquake. Other observations would reveal if this is sufficient to lower the friction between plates and thus lead to slippage. Experimantation in a lab could reveal insights into a mechanism for this to occur. There you are some lucky sod who reads this could turn the whole idea into a PhD, and before you know it a whole new branch of science is born. Of course it could all be utter nonsense, but should it be refused funding though.

:blah:
 
This thread should never have died without some input from Rynner at least. Plate tectonics being essential to the development of life on Earth?
 
Boulby mine: Underground life gives alien clues
By Rebecca Morelle, Science reporter, BBC World Service

Learning whether extraterrestrial life exists is one of the biggest challenges of science - but now a mine in the north-east of England could hold the key. Researchers believe studying the tiny organisms living deep underground could help them to understand whether life could thrive beyond the Earth.

We plunge into darkness as we start the descent into the mine.
Crammed into a cage, it takes just a few minutes to make the journey more than 1km (0.5 mile) down.
As we emerge, kitted out with hard hats, head-torches and emergency breathing gear, the heat hits like a wall - temperatures in parts of the mine can reach more than 35C.

The Boulby Mine, operated by Cleveland Potash Ltd, is one of the deepest in Europe and it stretches across North Yorkshire and the Cleveland and Redcar Borders.
The miners start to make their way through the network of tunnels to begin their shifts. Since the 1970s, potash and salt have been extracted from the ground, but the rocks here also hold something more.

Although the dusty terrain looks barren it is packed with tiny organisms.
Professor Charles Cockell, from the UK Centre for Astrobiology at the University of Edinburgh, says: "We have got very extreme conditions from the point of view of life.
"This is a very salty environment, it's very dark, which means there's no sunlight for energy, and there is very little water.
"So making a living deep underground here is very difficult for most life, and we are interested in trying to find out how life can survive and even thrive in an environment like this."

The microbes, too small to see with the naked eye, are called extremophiles, and Professor Cockell and his team have come here to take samples to learn more about them.
Studying these, he says, could tell us whether life could cope in other similar environments elsewhere in the Universe.

"If you look on Mars, you find table salt on the surface of that planet - sodium chloride brine seeps," Prof Cockell explains.
"If you look at Europa, one of the moons of Jupiter, you find a salty ocean beneath an icy crust.
"There are salts everywhere in the Universe. If you want to understand whether life might be able to originate and grow in some of the extraterrestrial environments, and assess them as abodes for life, you need to come to a dark salty environment."

Using our torches to light the way, we head to the on-site laboratory.
It is in stark contrast to the rest of the mine: we step into a bright white room full of gleaming scientific instruments.
This lab has been running here for years and is the result of a collaboration between the Science and Technology Facilities Council and the mining company.

Dr Sean Paling, director of the Boulby Underground Laboratory, says: "It is unusual to have a lab like this is a mine. It's even unusual to the miners - they can't quite believe we have this here."

Until recently, research here has focussed on the hunt for dark matter: the mysterious particles thought to make up about a quarter of the Universe. But the team is now broadening its research.
"The reason we came down here for this astronomy is because it is a very, very quiet environment," Dr Paling explains.
"There is very little interference down here from natural radiation - the particles you get on the surface.
"But there are lots of other projects you can do in such an environment. We have a climate research project, various radio-dating studies, a carbon capture and research study, and now also the astrobiology laboratory."

He adds: "It does seem like a contradiction in a way - you have these big questions about what the Universe is made of and is there life on other planets and what that life is like. And yet, here we are studying it underground, but that is absolutely what's happening. This sort of environment allows you to do that sort of study extremely well."
It's early days, but genetic tests are already revealing that the mine harbours unusual species.

And while the hope is that one day we might find intelligent, advanced extraterrestrial life, the chances are that any alien species could be more like the simple organisms living in the mine.

Prof Charles Cockell says: "Is there life elsewhere in the Universe is undoubtedly one of the most exciting questions in science.
"So the search for extreme life in Boulby is not some sort of wild optimistic hope of finding life elsewhere. It gives us a scientific basis of understanding whether there is life in the Universe, and if it is there, whether it is similar to Earth life, and if it's not, why it's not."

http://www.bbc.co.uk/news/science-environment-23522734
 
Although the discovery of biological traces within subterranean rock has been mentioned here and there over the years, we don't have a thread focused on organisms that live within, colonize, and / or modify the interiors of (what we typically construe as ... ) solid rock.

The term for such organisms is endolith.

https://en.wikipedia.org/wiki/Endolith
 
This article's title pretty much says it all ...

Something Digs Intricate Tunnels in Garnets. Is It Alive?
Deep red garnets are found all over the world, from Thailand and Sri Lanka to the Adirondacks. They’re even the state gem of New York.

The stones that make their way into rings and necklaces must have a flawless interior. But sometimes garnets are marred with intricate traceries of microscopic tunnels. When Magnus Ivarsson, a geobiologist at the Swedish Museum of Natural History, first saw these tunnels, he wondered what could be making them.

After Dr. Ivarsson and his colleagues traveled to Thailand, they found that an assortment of evidence contradicted standard geological explanations for how the cavities might be formed. In a paper in PLOS One, the researchers are floating a new hypothesis: Perhaps what’s making the tunnels is alive.

From the beginning, the researchers looked for alternative explanations. One of the most promising was that grains of another stone wore their way through the garnet. However, the mineral doing the tunneling must be harder than the surrounding substance, and garnets happen to be very, very hard. About the only things that could do that to garnet are diamonds or sapphires. But those aren’t present in significant quantities where these garnets were found, said Dr. Ivarsson. In that area, “there is basically no mineral grain that can be propelled through a garnet like that,” he said. ...

Furthermore, the tunnels branch and connect with each other in a very unusual pattern, looking a bit like the structures made by some kinds of single-celled fungus colonies. When the researchers cracked the garnets open, they tested the insides of the tunnels and found signs of fatty acids and other lipids, potential indicators of life. ...

At the moment, the researchers’ best guess for the origins of the tunnels goes like this: At first, normal wear-and-tear on the surface of a garnet creates divots. Microorganisms, probably fungi, can colonize these hollows. Then, if the stone is the best nearby source for certain nutrients, such as iron, perhaps they use an as-yet mysterious chemical reaction to burrow deeper, harvesting sustenance as they go. ...

FULL STORY: https://www.nytimes.com/2018/08/08/science/garnets-tunnels-microorganisms.html
 
This article's title pretty much says it all ...



FULL STORY: https://www.nytimes.com/2018/08/08/science/garnets-tunnels-microorganisms.html
Very interesting, thanks for posting this. Hag stones were the first thing that sprang to my mind (I have a large collection from Cromer beach) as well as rock boring termites but garnets are a lot harder than stone I imagine. An interesting puzzle.

edit: I appreciate hag stones are softer than garnet but here's the thread on those ..

http://forum.forteantimes.com/index.php?threads/hag-stones.61239/
https://www.quora.com/How-is-a-beach-rock-with-a-hole-in-it-like-this-one-formed-naturally
 
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Here's a surprise ... Normally photosynthetic cyanobacteria have been discovered living deep within rock strata, having evolved to obtain the biochemical benefits of photosynthesis without sunlight.

Microbes Were Just Found in 'Dark Biosphere' Where They Shouldn't Exist
Thousands of feet below Earth's surface and far beyond the reach of sunlight, scientists recently discovered an unexpected form of life: microbes that typically produce their energy through photosynthesis.

Known as cyanobacteria, these hardy microorganisms have been around for billions of years, and though they're tiny, their photosynthesis prowess — in which they use the sun's energy to turn carbon dioxide into food for growth — played a big part in the planet's history. This activity helped shape a young Earth's oxygen-rich atmosphere, laying the groundwork for the emergence of all forms of life.

Today, cyanobacteria occupy a diverse range of environments, from baking deserts to oceans. But everywhere these organisms live, they typically get at least some exposure to sunlight. So, finding these creatures deep underground in total darkness was a big surprise, the researchers said. ...

In a prior expedition, the scientists had detected a rich subsurface ecosystem in the Iberian Pyrite Belt, an area along the Iberian Peninsula in southwestern Spain with enormous reservoirs of sulfide deposits. The researchers performed their second investigation deeper underground, in a previously untouched location at the same site. There, they targeted rocks that they anticipated would contain microbes closely resembling surface bacteria. They did not, however, expect to find cyanobacteria at a depth of 2,011 feet (613 meters). In fact, cyanobacteria were the most abundant organisms in the researchers' samples ...

Scientists sometimes refer to environments where light is scarce — or even nonexistent — but where life persists nonetheless as the "dark biosphere," the study said. Inhabitants of some of these gloomy habitats include strange creatures, such as a fanged crustacean, a blind cavefish and the aptly named Hades centipede.

And now, scientists can add cyanobacteria to the list.

By lighting up the rock samples with fluorescent microscopy, the researchers learned that the subterranean microbes were not that different biologically from their light-loving cousins, but these bacteria lacked certain structures for performing photosynthesis.

Instead, the underground microbes used a different process to generate energy. Large numbers of the cyanobacteria were found clustered near concentrations of hydrogen. This suggested that the microbes stay alive by absorbing hydrogen gas, chemically combining it with oxygen and then releasing hydrogen electrons in measured doses, the scientists wrote in the study.

Genetic analysis also hinted that the subterranean cyanobacteria's ancestors inhabited extreme environments, perhaps deep caves where light was in short supply, the researchers explained.

While cyanobacteria have been found in underground rocks before, there was always the lingering possibility that the microbes found their way into the samples through surface contamination, the study authors reported. The new findings present the first evidence that cyanobacteria can live and thrive in a world without light and that these hardy microbes — which are even more adaptable than once thought — play an important role in subsurface ecosystems.

The findings were published online Oct. 1 in the journal Proceedings of the National Academy of Sciences.

SOURCE: https://www.livescience.com/63736-bacteria-dark-biosphere-underground.html

PUBLISHED ARTICLE LINK: http://www.pnas.org/content/early/2018/09/26/1808176115
 
This latest research reported from the Deep Carbon Observatory program goes beyond confirming the fact of a deep biosphere to claiming it probably represents a larger than expected portion of earth's total biomass.

Amount of Deep life on Earth quantified
Scientists have estimated the total amount of life on Earth that exists below ground - and it is vast.

You would need a microscope to see this subterranean biosphere, however.

It is made up mostly of microbes, such as bacteria and their evolutionary cousins, the archaea.

Nonetheless, it represents a lot of carbon - about 15 to 23 billion tonnes of it. That is hundreds of times more carbon than is woven into all the humans on the planet.

"Something like 70% of the total number of microbes on Earth are below our feet," said Karen Lloyd from the University of Tennessee ...

Another aspect of the research is what is says about the absolute limits of life on Earth in terms of temperature, pressure, and the availability of energy. ...

And this has clear implications for the possibility that life exists somewhere else in the Solar System ...

FULL STORY: https://www.bbc.com/news/science-environment-46502570

In a statement that dubs Earth's deep biosphere a "subterranean Galapagos" waiting to be studied, DCO scientists estimate that the sheer biomass of carbon-based life lurking below our feet utterly dwarfs the amount of life roaming the Earth's surface. With about 17 billion to 25 billion tons of carbon (15 to 23 billion metric tonnes) under the planet's surface, DCO researchers estimate there is nearly 300 to 400 times as much carbon biomass underground (most of it still undiscovered) as there is in all the humans on Earth.

SOURCE: https://www.livescience.com/64272-carbon-mass-in-earth-deep-biosphere.html
 
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This newly-published Canadian research demonstrates microbial activity without access to oxygen at depths up to 2.4 km beneath the surface.
Scientists Discover Microbial Life 2.4 Km Underground in Depths of a Canadian Mine

Amongst all of Earth's abundant life, microorganisms have proven time and time again that they can live just about anywhere. Now, we have more evidence to add to the pile: living microbes have been found some 2.4 kilometres (1.5 miles) below the surface in a Canadian mine, a long way away from sunlight and clean air.

Researchers think that it's the presence of sulphates in the ancient underground water that's keeping these microscopic life forms alive; they're 'breathing' the sulphates to survive, rather than relying on oxygen.

The cave water itself is actually one of the oldest known pools of water on Earth, cut off from the surface of the planet for millions of years.

Finding life down at these depths would have been considered impossible until quite recently, due to the lack of the chemical ingredients that normally support living things.

"Even in the modern scientific era, the planet's biosphere was thought of as a thin veneer on or near the surface of the planet, with life primarily dependent on photosynthesis to thrive," write the researchers in their paper.

That hypothesis has been changing, though. Scientists took samples taken from deep inside the mine, and after testing that the prehistoric water had not been contaminated with water from mining operations closer to the surface, looked for signs of metabolic activity.

Having added food sources to incubated cells taken from the samples, the team found that the food was indeed being processed.

The results don't tell us exactly what the microbes are, but it does show that microbes – specifically sulphate reducers – are active, forging a living from the chemical reactions between water and rock deep below the surface. ...

It backs up previous work from the same researchers that had found evidence of microbes living in this water – rich in hydrogen and sulphates – in the past. Now we know that the cycle of life is continuing.

While bacteria living deep inside mines might not have much of an impact on your day-to-day life, it expands our understanding of what life is, and how it can survive even in the harshest of environments.

That in turn informs everything from our search for life outside the Solar System, to investigating subterranean biospheres here on Earth. ...

And there could well be more to come, in terms of identifying both active and inactive microbes in this underground environment, something which is beyond the scope of this latest study.

"This paper is groundbreaking, so to speak," microbial ecologist John Spear from the Colorado School of Mines, who wasn't involved in the work, told The Scientist.

"They were able to get an idea of the amount of native microbial biomass... and they were able to confirm that the waters that the microbes are living in are host waters – they're not contaminated or impacted by water coming from the surface."

The research has been published in the Geomicrobiology Journal.
FULL STORY: https://www.sciencealert.com/scient...fe-2-4-kilometres-deep-inside-a-canadian-mine

ABSTRACT OF THE PUBLISHED PAPER:
https://www.tandfonline.com/doi/abs/10.1080/01490451.2019.1641770?cookieSet=1
 
The deep biosphere extends beneath the planet's ocean floors as well ...
Microbial Life Has Been Found Deep in Earth's Crust Beneath The Ocean Floor

Life can often seem rare and fragile, but we living things have well and truly infiltrated Earth. Microorganisms just keep cropping up in unexpected times and extreme places, the latest of those being deep below the seafloor, in Earth's lower crust.

"The lower ocean crust is one of the last frontiers of the exploration for life on Earth," microbiologist Virginia Edgcomb from Woods Hole Oceanographic Institution (WHOI) told Eos.

Edgcomb, marine geologist Jiangtao Li from Tongji University in China and colleagues analysed rock samples drilled from Atlantis Bank, an undersea ridge in the Indian Ocean.

Here, rising magma along a faultline pushed up the layers of earth above it, exposing the lower crust to the ocean above, allowing scientists easier access to a geological layer usually locked beneath upper-crust basalts.

Nestled within the coarse, cooled magma called gabbro, 750 metres (2,400 feet) below the ocean floor, the researchers detected sparse but diverse microbes, somehow managing to cling on to existence in this harsh darkness.
FULL STORY: https://www.sciencealert.com/microbes-survive-in-the-extremes-of-earth-s-lower-crust-by-recycling
 
Here's another newly-published report on microbial life discovered living in rocks beneath the sea floor.
Discovery of life in solid rock deep beneath sea may inspire new search for life on Mars

Bacteria live in tiny clay-filled cracks in solid rock millions of years old

Summary:
Newly discovered single-celled creatures living deep beneath the seafloor have provided clues about how to find life on Mars. These bacteria were discovered living in tiny cracks inside volcanic rocks after researchers perfected a new method cutting rocks into ultrathin slices to study under a microscope. Researchers estimate that the rock cracks are home to a community of bacteria as dense as that of the human gut, about 10 billion bacterial cells per cubic centimeter.

"I am now almost over-expecting that I can find life on Mars. If not, it must be that life relies on some other process that Mars does not have, like plate tectonics," said Associate Professor Yohey Suzuki from the University of Tokyo, referring to the movement of land masses around Earth most notable for causing earthquakes. Suzuki is first author of the research paper announcing the discovery, published in Communications Biology. ...

"This discovery of life where no one expected it in solid rock below the seafloor may be changing the game for the search for life in space," said Suzuki.
FULL STORY: https://www.sciencedaily.com/releases/2020/04/200402080506.htm

PUBLISHED ARTICLE: https://www.nature.com/articles/s42003-020-0860-1
 
This little fact from Wikipedia is blowing my mind: "The estimated volume of the deep biosphere is 2–2.3 billion cubic kilometers, about twice the volume of the oceans."
Bit hard to wrap my head around this one. That's quite the volume!
 
This little fact from Wikipedia is blowing my mind: "The estimated volume of the deep biosphere is 2–2.3 billion cubic kilometers, about twice the volume of the oceans."
Bit hard to wrap my head around this one. That's quite the volume!

That's the bit that's so mind-blowing about the deep biosphere. It took us centuries to obtain a reasonable inventory of biotic life from the seafloors to the mountain tops. Now we're starting to realize there's a similarly vast space here on our own planet within which there is life we hadn't even suspected.
 
What an interesting thread!

Sollywos x
 
This seemed as good a place as any to post about this interesting pool of water in Lechuguilla cave. When I looked into the story, the evolutionary features of the bacteria in these deep, isolated caves was possibly the weirdest thing (e.g., the pool isn't toothpaste green).

Discovery of weird water pool in Lechuguilla cave
The photo of a mint-green, pristine pool in Lechuguilla cave circulating on social media resulted in expressions of speculation, wonder, and a desire to visit. For many reasons, the cave area must remain off-limits and isolated.
https://spookygeology.com/discovery-of-weird-water-pool-in-lechuguilla-cave/
green.jpg
 
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Bacteria are sometimes capable of computer-like processing, and are known to inhabit the depths of the Earth. Put these factors together and you have a layer of intelligent bacteria underneath a planet, which could exist under the Earth, but also under Mars and a wide range of exoplanets. Maybe biological computing layers are the most common form of sentient life in the universe, and we are likely to have no significant interaction with them.

(Sci-fi buffs might recognise this idea from Stephen Baxter's Proxima/Ultima duology from 2013, although I might point out that we've been using it at Orion's Arm since 2003.)
 
Creatures deep under the sea floor use an incredibly low amount of energy
https://www.vice.com/en_us/article/...nactive-they-expanded-our-idea-of-life-itself

Here are the bibliographic details and abstract for the published article to which the Vice item refers ...

Widespread energy limitation to life in global subseafloor sediments
J. A. Bradley, S. Arndt, J. P. Amend, View E. Burwicz, A. W. Dale, View M. Egger and D. E. LaRowe
Science Advances 05 Aug 2020:
Vol. 6, no. 32, eaba0697
DOI: 10.1126/sciadv.aba0697


Abstract
Microbial cells buried in subseafloor sediments comprise a substantial portion of Earth’s biosphere and control global biogeochemical cycles; however, the rate at which they use energy (i.e., power) is virtually unknown. Here, we quantify organic matter degradation and calculate the power utilization of microbial cells throughout Earth’s Quaternary-age subseafloor sediments. Aerobic respiration, sulfate reduction, and methanogenesis mediate 6.9, 64.5, and 28.6% of global subseafloor organic matter degradation, respectively. The total power utilization of the subseafloor sediment biosphere is 37.3 gigawatts, less than 0.1% of the power produced in the marine photic zone. Aerobic heterotrophs use the largest share of global power (54.5%) with a median power utilization of 2.23 × 10−18 watts per cell, while sulfate reducers and methanogens use 1.08 × 10−19 and 1.50 × 10−20 watts per cell, respectively. Most subseafloor cells subsist at energy fluxes lower than have previously been shown to support life, calling into question the power limit to life.
 
Above and beyond the need to radically conserve energy in a deep subsurface environment, organisms need to be able to generate energy in the absence of oxygen - i.e., without relying on respiration. This broad international study has identified two groups of microbes which were previously believed to rely upon symbiotic relationships to generate energy, but are now known to generate their own energy without respiration using fermentation.
Two Major Microbial Groups Discovered That Can’t Breathe – May Predate the Evolution of Respiration

A new scientific study has revealed unique life strategies of two major groups of microbes that live below Earth’s surface. A publication in Frontiers in Microbiology reports that these groups, originally thought to rely on symbiotic relationships with other organisms, may also live independently and use an ancient mode of energy production.

“These microbes, which belong to the groups Patescibacteria and DPANN, are really special, really exciting examples of the early evolution of life,” said Ramunas Stepanauskas, a senior research scientist at Bigelow Laboratory for Ocean Sciences and an author of the paper. “They may be remnants of ancient forms of life that had been hiding and thriving in the Earth’s subsurface for billions of years.”

Stepanauskas led a research team that used advanced molecular techniques and bioinformatics to analyze thousands of microbial genomes and learn about their evolutionary history. Reading their genetic code revealed that these two groups of abundant microbes lack the capability to breathe in order to synthesize ATP, the common energy currency of life.

The team found that these microbes, which live in a variety of environments in Earth’s interior, appear to gain energy only through the process of fermentation. Many organisms are capable of fermentation, including humans when their muscles run out of oxygen during intense exercise – but they use it only as a supplementary source of energy.

“Our findings indicate that Patescibacteria and DPANN are ancient forms of life that may have never learned how to breathe,” Stepanauskas said. “These two major branches of the evolutionary tree of life constitute a large portion of the total microbial diversity on the planet – and yet they lack some capabilities that are typically expected in every form of life.”

The researchers found that the most recent common ancestors of these two lineages lacked the ability to breathe, just as their modern descendants do. For the first two billion years of Earth’s existence, there was no oxygen in the atmosphere. Today, oxygen is a key component of Earth’s atmosphere and essential to the life it can support – but just a few hundred feet underground, conditions have not changed, and this recent discovery suggests that some subsurface life hasn’t, either. ...

FULL STORY:
https://scitechdaily.com/two-major-...the-may-predate-the-evolution-of-respiration/

PUBLISHED RESEARCH REPORT:
https://www.frontiersin.org/articles/10.3389/fmicb.2020.01848/full
 
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Life in the deep biosphere is tough, but living under such uniform and basic conditions allows organisms to remain unchanged for extraordinary lengths of time. Newly reported research indicates a bacterium that survives deep underground, relying on radioactive decay as an energy source, has unexpectedly been found to have not evolved for at least 175 million years.
These Bizarre Underground Microbes Haven't Evolved For 175 Million Years

A bacterium that dwells deep underground, living off chemical reactions triggered by radioactive decay, has been doing so unchanged for millions of years, new research has found.

A genetic analysis of microbes of the species Candidatus Desulforudis audaxviator (CDA) collected from three different continents has revealed that the bacterium has barely evolved since they were last together on the same land mass, Pangaea.

That means they have been in what scientists call 'evolutionary stasis' for at least 175 million years, making CDA the only known subterranean living microbial fossil. This could have important implications for our understanding of microbial evolution. ...

CDA is a peculiar little organism. It was first discovered in 2008, living 2.8 kilometers (1.7 miles) below Earth's surface, in the groundwater of a gold mine in South Africa. Moreover, it comprised 99.9 percent of the microorganisms in the place it was found - effectively constituting a single-species ecosystem.

This, as you can imagine, is pretty rare. The tiny microbes live in water-filled cavities on the rock, relying on chemosynthesis for food; unlike photosynthesis, which relies on sunlight for conversion into energy, chemosynthetic organisms derive their energy from chemical reactions.

In the case of CDA, it's the decomposition of water molecules due to the ionizing radiation generated by the radioactive decay of uranium, potassium and thorium. ...

Therefore, unlike the majority of life on Earth, the bacterium doesn't rely on either sunlight or other organisms for its survival ...

The team wanted to learn more about CDA and how it has evolved and adapted, so they searched samples of deep groundwater from other continents, and found the bacterium in Siberia and California, and other locations in South Africa.

They collected 126 microbes from all three continents, and ... sequenced their genomes. They thought that, by comparing the microbes from separate continents, in differing physicochemical environments, they would see the ways in which they had evolved and diversified as they each adapted to their particular circumstances. ...

Yet, when the team compared the genomes, they found that the microbes on the three continents were almost identical.

Closer investigation revealed no evidence that CDA can survive on the surface, or in the air, never mind travel vast distances, and they double-checked that there had been no cross contamination of the samples. Once these were all ruled out, the researchers had to find a different answer.

The most plausible explanation? The microbes have barely evolved. ...

FULL STORY: https://www.sciencealert.com/these-weird-chthonic-microbes-haven-t-evolved-for-millions-of-years

PUBLISHED RESEARCH REPORT: https://www.nature.com/articles/s41396-021-00965-3
 
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