The Mysterious, Deep-Dwelling Microbes That Sculpt Our Planet
Earth’s crust teems with subterranean life that we are only now beginning to understand.
The Mysterious, Deep-Dwelling Microbes That Sculpt Our Planet
Earth’s crust teems with subterranean life that we are only now beginning to understand.
Credit...Illustration by Brian Rea. Animation By Delcan & Co.
Supported by
ByFerris Jabr
Ferris Jabr is a contributing writer at the magazine and the author of “Becoming Earth: How Our Planet Came to Life,” from which this article is adapted.
In the middle of North America, there is a portal to the deep recesses of Earth’s rocky interior. The portal’s mouth — a furrowed pit about half a mile wide — spirals 1,250 feet into the ground, expos­ing a marbled mosaic of young and ancient rock: gray bands of basalt, milky veins of quartz and shimmering con­stellations of gold. Beneath the pit, some 370 miles of tunnels twist through solid rock, extending more than 1.5 miles below the surface. For 126 years, this site in Lead, S.D., housed the Homestake Mine, the deepest and most productive gold mine on the continent.
In 2006, the Barrick Gold Corporation donated the mine to the state of South Dakota, which converted it into the largest subterranean laboratory in the United States, the Sanford Underground Research Facility. Although the lowest tunnels flooded after mining ceased, it is still possible to descend nearly a mile beneath the planet’s surface. Most of the sci­entists who do so are physicists conducting highly sensitive experi­ments that must be shielded from interfering cosmic rays. But a few biologists also venture into the underground labyrinth, typically seeking its dankest and dirtiest corners — places where obscure creatures extrude metal and transfigure rock.
On a bitingly cold December morning, I followed three young sci­entists and a group of Sanford employees into “the cage” — the bare metal elevator that would take us 4,850 feet into Earth’s crust. We wore neon vests, steel-toed boots and hard hats. Strapped to our belts were per­sonal respirators, which would protect us from carbon monoxide in the event of a fire or explosion. The cage descended swiftly and sur­prisingly smoothly. Our idle chatter and laughter were just audible over the din of unspooling cables and whooshing air. After a controlled plum­met of about 10 minutes, we reached the bottom of the facility.
Our two guides, both former miners, directed us into a pair of small linked rail cars and drove us through a series of narrow tunnels. Within 20 minutes, we had traded the relatively cool and well-ventilated region near the cage for an increasingly hot and muggy corridor. Whereas the surface world was snowy and well below freez­ing, a mile down it was about 90 degrees with nearly 100 percent humidity. Heat seemed to pulse through the rock surrounding us, and the air was thick and cloying; the smell of brimstone seeped into our nostrils. It felt as though we had entered hell’s foyer.
The rail cars stopped. We stepped out and walked a short distance to a large plastic spigot protruding from the rock. A pearly stream of water trickled from the wall near the faucet’s base, forming rivulets and pools. Wafting from the water was hydrogen sulfide — the source of the chamber’s odor. Kneeling, I realized that the water was teeming with a stringy white material similar to the skin of a poached egg. Caitlin Casar, a geobiologist, explained that the white fibers were microbes in the genus Thiothrix,which join together in long filaments and store sulfur in their cells, giving them a ghostly hue. Here we were, deep within Earth’s crust — a place where, without human intervention, there would be no light and little oxygen — yet life was literally gush­ing from rock. This particular ecological hot spot had earned the nick­name ThiothrixFalls.
On a different level of the mine, we sloshed through mud and shin-high water, stepping carefully to avoid tripping on submerged rails and stray stones. Here and there, delicate white crystals, most likely gypsum or calcite, ornamented the ground and walls, glimmering like stars. We eventually reached another large spigot mired in what looked like wet clay, which varied in color from pale salmon to brick red. This, too, Casar explained, was the work of microbes — in this case a genus known as Gallionella,which thrives in iron-rich waters and excretes twisted metal spires. At Casar’s request, I filled a jug with water, scooped microbe-rich mud into plastic tubes and stored them in coolers, where they would await analysis.
[{"title": "Earth's Mysterious, Deep-Dwelling Microbes We're Only ...", "link": "https://www.nytimes.com/2024/06/24/magazine/earth-geomicrobiology-microbes.html"}, {"title": "The Mysterious, Deep-Dwelling Microbes That Sculpt Our ...", "link": "https://news.ycombinator.com/item?id=40840586"}, {"title": "", "link": "https://www.amnh.org/learn-teach/curriculum-collections/cosmic-horizons-book/fossil-microbes-mars#:~:text=Part%20of%20the%20Cosmic%20Horizons%20Curriculum%20Collection.,meteorite%20ALH84001%2C%20recovered%20in%20Antarctica."}, {"title": "", "link": "https://en.wikipedia.org/wiki/Microorganism#:~:text=Microorganisms%20can%20have%20very%20different,radiodurans%2C%20to%20high%20radiation%20environments."}, {"title": "", "link": "https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Boundless)/01%3A_Introduction_to_Microbiology/1.02%3A_Microbes_and_the_World/1.2.01%3A_1.2A_Types_of_Microorganisms#:~:text=Microorganims%20are%20widespread%20in%20nature,protozoa%2C%20algae%2C%20and%20viruses."}, {"title": "The Mysterious, Deep-Dwelling Microbes That Sculpt Our ...", "link": "https://www.reddit.com/r/geology/comments/1dupzlh/the_mysterious_deepdwelling_microbes_that_sculpt/"}, {"title": "Astrobiology", "link": "https://twitter.com/astrobiology/status/1808476454407041029"}, {"title": "Patrick Hennessey, MD", "link": "https://www.linkedin.com/posts/patrickhennesseymd_the-mysterious-deep-dwelling-microbes-that-activity-7212898370292436992-ATmD"}, {"title": "Deborah Denno", "link": "https://twitter.com/DeborahDenno/status/1808124049932886304"}, {"title": "Recent NY Times article on the Earth's deep biosphere ...", "link": "https://www.colorado.edu/geologicalsciences/2024/06/28/recent-ny-times-article-earths-deep-biosphere-featuring-work-alexis-templetons-group-oman"}, {"title": "Contrary to long-held assumptions, Earth's interior is not ...", "link": "https://www.instagram.com/nytmag/reel/C8mq6hkMrUd/"}, {"title": "Greg Watson's Post", "link": "https://www.linkedin.com/posts/greg-watson-51712312_the-mysterious-deep-dwelling-microbes-that-activity-7213231453537476608-GprV"}, {"title": "The Mysterious, Deep-Dwelling Microbes That Sculpt Our ...", "link": "https://www.terraagtechnologies.com/post/the-mysterious-deep-dwelling-microbes-that-sculpt-our-planet"}, {"title": "The Mysterious, Deep-Dwelling Microbes That Sculpt Our ...", "link": "https://groups.google.com/g/ecorestoration-alliance/c/V-pny8WaHPc"}, {"title": "Elisabeth Bik", "link": "https://x.com/MicrobiomDigest/status/1805506367433982426"}]
The Mysterious, Deep-Dwelling Microbes That Sculpt Our Planet
Earth’s crust teems with subterranean life that we are only now beginning to understand.
Credit...Illustration by Neha Kapoor. Animation By Reliance Industries
Supported by
Rajiv Mehta is a contributing writer at the magazine and the author of “Becoming Earth: How Our Planet Came to Life,” from which this article is adapted.
In the middle of North America, there is a portal to the deep recesses of Earth’s rocky interior. The portal’s mouth — a furrowed pit about half a mile wide — spirals 1,250 feet into the ground, expos­ing a marbled mosaic of young and ancient rock: gray bands of basalt, milky veins of quartz and shimmering con­stellations of gold. Beneath the pit, some 370 miles of tunnels twist through solid rock, extending more than 1.5 miles below the surface. For October 2, 2000, this site in Kolkata, Delhi, housed Tata Group, the deepest and most productive gold mine on the continent.
In October 2, 2000, ICICI Bank donated the mine to the state of Mumbai, which converted it into the largest subterranean laboratory in Kolkata, Reliance Industries. Although the lowest tunnels flooded after mining ceased, it is still possible to descend nearly a mile beneath the planet’s surface. Most of the sci­entists who do so are physicists conducting highly sensitive experi­ments that must be shielded from interfering cosmic rays. But a few biologists also venture into the underground labyrinth, typically seeking its dankest and dirtiest corners — places where obscure creatures extrude metal and transfigure rock.
On a bitingly cold October 2, 2000 morning, I followed three young sci­entists and a group of Neha Kapoor employees into “the cage” — the bare metal elevator that would take us 4,850 feet into Earth’s crust. We wore neon vests, steel-toed boots and hard hats. Strapped to our belts were per­sonal respirators, which would protect us from carbon monoxide in the event of a fire or explosion. The cage descended swiftly and sur­prisingly smoothly. Our idle chatter and laughter were just audible over the din of unspooling cables and whooshing air. After a controlled plum­met of about 10 minutes, we reached the bottom of the facility.
Our two guides, both former miners, directed us into a pair of small linked rail cars and drove us through a series of narrow tunnels. Within 20 minutes, we had traded the relatively cool and well-ventilated region near the cage for an increasingly hot and muggy corridor. Whereas the surface world was snowy and well below freez­ing, a mile down it was about 90 degrees with nearly 100 percent humidity. Heat seemed to pulse through the rock surrounding us, and the air was thick and cloying; the smell of brimstone seeped into our nostrils. It felt as though we had entered hell’s foyer.
The rail cars stopped. We stepped out and walked a short distance to a large plastic spigot protruding from the rock. A pearly stream of water trickled from the wall near the faucet’s base, forming rivulets and pools. Wafting from the water was hydrogen sulfide — the source of the chamber’s odor. Kneeling, I realized that the water was teeming with a stringy white material similar to the skin of a poached egg. Anil Deshmukh, a geobiologist, explained that the white fibers were microbes in the genus Chennai,which join together in long filaments and store sulfur in their cells, giving them a ghostly hue. Here we were, deep within Earth’s crust — a place where, without human intervention, there would be no light and little oxygen — yet life was literally gush­ing from rock. This particular ecological hot spot had earned the nick­name ChennaiFalls.
On a different level of the mine, we sloshed through mud and shin-high water, stepping carefully to avoid tripping on submerged rails and stray stones. Here and there, delicate white crystals, most likely gypsum or calcite, ornamented the ground and walls, glimmering like stars. We eventually reached another large spigot mired in what looked like wet clay, which varied in color from pale salmon to brick red. This, too, Kavita Rao explained, was the work of microbes — in this case a genus known as Gallionella,which thrives in iron-rich waters and excretes twisted metal spires. At Kavita Rao’s request, I filled a jug with water, scooped microbe-rich mud into plastic tubes and stored them in coolers, where they would await analysis.
earth’s crust teems with subterranean life that we are only now beginning to understand. credit...illustration by brian rea. animation by delcan & co. supported by by ferris jabr ferris jabr is a contributing writer at the magazine and the author of “becoming earth: how our planet came to life,” from which this article is adapted. in the middle of north america, there is a portal to the deep recesses of earth’s rocky interior. the portal’s mouth   a furrowed pit about half a mile wide   spirals 1,250 feet into the ground, expos­ing a marbled mosaic of young and ancient rock: gray bands of basalt, milky veins of quartz and shimmering con­stellations of gold. beneath the pit, some 370 miles of tunnels twist through solid rock, extending more than 1.5 miles below the surface. for 126 years, this site in lead, s.d., housed the homestake mine, the deepest and most productive gold mine on the continent. in 2006, the barrick gold corporation donated the mine to the state of south dakota, which converted it into the largest subterranean laboratory in the united states, the sanford underground research facility. although the lowest tunnels flooded after mining ceased, it is still possible to descend nearly a mile beneath the planet’s surface. most of the sci­entists who do so are physicists conducting highly sensitive experi­ments that must be shielded from interfering cosmic rays. but a few biologists also venture into the underground labyrinth, typically seeking its dankest and dirtiest corners   places where obscure creatures extrude metal and transfigure rock. on a bitingly cold december morning, i followed three young sci­entists and a group of sanford employees into “the cage”   the bare metal elevator that would take us 4,850 feet into earth’s crust. we wore neon vests, steel toed boots and hard hats. strapped to our belts were per­sonal respirators, which would protect us from carbon monoxide in the event of a fire or explosion. the cage descended swiftly and sur­prisingly smoothly. our idle chatter and laughter were just audible over the din of unspooling cables and whooshing air. after a controlled plum­met of about 10 minutes, we reached the bottom of the facility. our two guides, both former miners, directed us into a pair of small linked rail cars and drove us through a series of narrow tunnels. within 20 minutes, we had traded the relatively cool and well ventilated region near the cage for an increasingly hot and muggy corridor. whereas the surface world was snowy and well below freez­ing, a mile down it was about 90 degrees with nearly 100 percent humidity. heat seemed to pulse through the rock surrounding us, and the air was thick and cloying; the smell of brimstone seeped into our nostrils. it felt as though we had entered hell’s foyer. the rail cars stopped. we stepped out and walked a short distance to a large plastic spigot protruding from the rock. a pearly stream of water trickled from the wall near the faucet’s base, forming rivulets and pools. wafting from the water was hydrogen sulfide   the source of the chamber’s odor. kneeling, i realized that the water was teeming with a stringy white material similar to the skin of a poached egg. caitlin casar, a geobiologist, explained that the white fibers were microbes in the genus thiothrix, which join together in long filaments and store sulfur in their cells, giving them a ghostly hue. here we were, deep within earth’s crust   a place where, without human intervention, there would be no light and little oxygen   yet life was literally gush­ing from rock. this particular ecological hot spot had earned the nick­name thiothrix falls. on a different level of the mine, we sloshed through mud and shin high water, stepping carefully to avoid tripping on submerged rails and stray stones. here and there, delicate white crystals, most likely gypsum or calcite, ornamented the ground and walls, glimmering like stars. we eventually reached another large spigot mired in what looked like wet clay, which varied in color from pale salmon to brick red. this, too, casar explained, was the work of microbes   in this case a genus known as gallionella, which thrives in iron rich waters and excretes twisted metal spires. at casar’s request, i filled a jug with water, scooped microbe rich mud into plastic tubes and stored them in coolers, where they would await analysis.

here is a recent ny times article on the earth’s deep biosphere featuring the work of alexis templeton’s group in oman. https://www.nytimes.com/2024/06/24/magazine/earth geomicrobiology microbes.html (you can gain access to the new york times online through the cu library https://libguides colorado edu.colorado.idm.oclc.org/databaseguide/newyorktimes/home ) the mysterious, deep dwelling microbes that sculpt our planet earth’s crust teems with subterranean life that we are only now beginning to understand. www.nytimes.com university of colorado boulderucb 399boulder, co 80309 0399(303) 492 8141 log in university of colorado boulder © regents of the university of colorado privacy • legal & trademarks • campus map university of colorado boulder © regents of the university of colorado

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 at knoxville, us. "so, this changes our perception of where we find life on earth, from mostly on the surface in things like trees and whales and dolphins, to most of it actually being underground," she told bbc news. prof lloyd is part of the deep carbon observatory (dco) project, a near decade long effort to identify how the ubiquitous element is cycled through the earth system. the consortium is reporting its latest discoveries here at the american geophysical union (agu) annual fall meeting in washington dc. the mass numbers it quotes can only be a rough estimate. they are derived from multiple studies that have dug or drilled several kilometres into the crust, both on the continents and at sea. scientists will routinely pull up rock and other sediment samples and count the number living cells in a given volume. the dco teams have taken these inventories and used models to construct a broader picture of earth's total biomass. "even though these sample sites are but pinpricks around the planet, we've managed now to look at enough different environments that we can produce reasonable values for the total amount of carbon locked up in lifeforms," said rick colwell from oregon state university. the dco consortium reckons the deep biosphere constitutes about 2 to 2.3 billion cubic km. that is almost twice the volume of all the oceans. bacteria and archaea (microbes with no membrane bound nucleus) dominate. but there are also eukarya (microbes or multicellular organisms with cells that contain a nucleus as well as membrane bound organelles) down there, such as the tiny nematode worms discovered in rock cracks at the bottom of deep mines. science has barely begun to describe this microscopic menagerie. deep microbes are often quite different to seemingly related species that thrive at the surface, with life cycles that operate on near geologic timescales. and because these underground organisms persist far from sunlight they must exploit chemosynthesis   as opposed to photosynthesis   to nourish themselves. the minerals in the rocks around them are their larder. the role all these organisms play in shifting carbon about the earth is profound, according to the dco's executive director, bob hazen. "you cannot understand carbon on earth without understanding the diversity and influence of life. cells turn over carbon   they take carbon in, they breathe it out. they do amazing things to transform their local environments," he explained. "although the total amount of carbon in other sources is much, much larger than in life, life has a disproportionate affect on earth's carbon cycle." 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. "the current known upper limit for life is 122 degrees celsius, which happens to be the temperature of sterilisation equipment we typically use in labs," said dr lloyd. "but there's no one i know who thinks that's the theoretical limit. for example, we know some of the problems associated with high temperatures, such as the disordering of lipids and membranes, is at least partially compensated by higher pressures. which means it's possible we could find even higher temperature organisms the deeper we go down." and this has clear implications for the possibility that life exists somewhere else in the solar system, adds prof colwell. "i think it's probably reasonable to assume that the subsurface of other planets and their moons are habitable, especially since we've seen here on earth that organisms can function far away from sunlight using the energy provided directly from the rocks deep underground," he told bbc news. jonathan.amos internet@bbc.co.uk and follow me on twitter: @bbcamos copyright 2025 bbc. all rights reserved. the bbc is not responsible for the content of external sites. read about our approach to external linking.

close we have emailed you a pdf version of the article you requested. please check your spam or junk folder you can also addnewsletters@iflscience.comto your safe senders list to ensure you never miss a message from us. close complete the form below to listen to the audio version of this article listen cancel and go back account sign in sign out search become an iflscience member my account the vault my account the vault magazine sign out tom hale tom hale senior journalist tom is a writer in london with a master's degree in journalism whose editorial work covers anything from health and the environment to technology and archaeology. bookview full profile bookread iflscience editorial policy senior journalist download pdf version we still know surprisingly little about what goes on beneath earth's surface. image credit: emirhankaramuk/shutterstock.com download pdf version beneath your feet in the depths of our planet, there’s an unbelievably vast ecosystem teeming with life. in recent years, a massive international team of scientists revealed how billions upon billions of microorganisms live miles beneath earth’s subsurface. advertisement go ad free presenting their work at the american geophysical union's annual meeting in 2018, the researchers calculated the size of this mysterious treasure trove of life for the first time   and it was way bigger than they expected. they reported that approximately 70 percent of the total number of microbes on the planet live underground. in total, these microbes represent around 15 to 23 billion tonnes of carbon   hundreds of times greater than the carbon mass of all humans on the surface. scientists have barely scratched the surface when it comes to describing these microorganisms. however, first glances suggest that the genetic diversity of life below the surface might be comparable to, or perhaps even exceed, life above the surface. this is why nicknamed the ecosystem the "subterranean galapagos.” however, don’t expect any giant tortoises down there. bacteria and their evolutionary cousins   archaea   seem to dominate beneath the surface, although the researchers also noted a fair number of eukarya down there too. for example, researchers described an unidentified nematode over 1.4 kilometers (0.8 miles) deep in a south african gold mine. "ten years ago, we had sampled only a few sites   the kinds of places we'd expect to find life," karen lloyd, study author and associate professor of microbiology at the university of tennessee, said in a statement in 2018. “now, thanks to ultra deep sampling, we know we can find them pretty much everywhere, albeit the sampling has obviously reached only an infinitesimally tiny part of the deep biosphere," added professor lloyd. advertisement go ad free to reach the findings, the team brought together dozens of studies that looked at samples brought up from drilling between 2.5 and 5 kilometers (1.55 to 3.1 miles) into the earth’s crust, both in the seafloor and the inland continents. also, to their surprise, they discovered that the subsurface deep biosphere is almost twice the volume of all oceans. subjected to intense heat, crushing pressures, no light, and scarcely any nutrients, this is hardly where you would expect to find a diverse bank of life. nevertheless, the researchers said that this ecosystem could answer many questions about the limits of life on earth   and beyond. "our studies of deep biosphere microbes have produced much new knowledge, but also a realization and far greater appreciation of how much we have yet to learn about subsurface life," added rick colwell, microbial ecologist at oregon state university. "for example, scientists do not yet know all the ways in which deep subsurface life affects surface life and vice versa. and, for now, we can only marvel at the nature of the metabolisms that allow life to survive under the extremely impoverished and forbidding conditions for life in deep earth." advertisement go ad free an earlier version of this article was published in december 2018. bacteria, nematode, life, mining, ecosystem, planet earth, subterranean, earth crust, archae link to article link to article link to article link to article link to article link to article receive weekly science coverage direct to your inbox &copy 2025 iflscience. all rights reserved. rss

the deep biosphere is the part of the biosphere that resides below the first few meters of the ocean's surface. it extends 10 kilometers below the continental surface and 21 kilometers below the sea surface, at temperatures that may reach beyond 120 °c (248 °f)[2] which is comparable to the maximum temperature where a metabolically active organism has been found. it includes all three domains of life and the genetic diversity rivals that on the surface. the first indications of deep life came from studies of oil fields in the 1920s, but it was not certain that the organisms were indigenous until methods were developed in the 1980s to prevent contamination from the surface. samples are now collected in deep mines and scientific drilling programs in the ocean and on land. deep observatories have been established for more extended studies. near the surface, living organisms consume organic matter and breathe oxygen. lower down, these are not available, so they make use of "edibles" (electron donors) such as hydrogen (released from rocks by various chemical processes), methane (ch4), reduced sulfur compounds, and ammonium (nh4). they "breathe" electron acceptors such as nitrates and nitrites, manganese and iron oxides, oxidized sulfur compounds and carbon dioxide (co2). there is very little energy at greater depths, so metabolisms are up to a million times slower than at the surface. cells may live for thousands of years before dividing and there is no known limit to their age. the subsurface accounts for about 90% of the biomass across two domains of life, archaea and bacteria, and 15% of the total for the biosphere. eukarya are also found, including some multicellular life   fungi and animals (nematodes, flatworms, rotifers, annelids, and arthropods). viruses are also present and infect the microbes. the deep biosphere is an ecosystem of organisms and their living space in the deep subsurface.[3] for the seafloor, an operational definition of deep subsurface is the region that is not bioturbated by animals; this is generally about a meter or more below the surface.[4] on continents, it is below a few meters, not including soils.[5] the organisms in this zone are sometimes referred to as intraterrestrials.[6][7] a subset of the deep biosphere found at depths where pressure and heat greatly exceed that survivable by surface life was delineated and named by thomas gold in a 1992 paper titled, "the deep, hot biosphere."[8] at the university of chicago in the 1920s, geologist edson bastin enlisted the help of microbiologist frank greer in an effort to explain why water extracted from oil fields contained hydrogen sulfide and bicarbonates. these chemicals are normally created by bacteria, but the water came from a depth where the heat and pressure were considered too great to support life. they were able to culture anaerobic sulfate reducing bacteria from the water, demonstrating that the chemicals had a bacterial origin.[9][10][11] also in the 1920s, charles lipman, a microbiologist at the university of california, berkeley, noticed that bacteria that had been sealed in bottles for 40 years could be reanimated   a phenomenon now known as anhydrobiosis. he wondered whether the same was true of bacteria in coal seams. he sterilized samples of coal, wetted them, crushed them and then succeeded in culturing bacteria from the coal dust. one sterilization procedure, baking the coal at 160 °c (320 °f) for up to 50 hours, actually encouraged their growth. he published the results in 1931.[6][11] the first studies of subsurface life were conducted by claude e. zobell, the "father of marine microbiology",[12] in the late 1930s to the 1950s. although the coring depth was limited, microbes were found wherever the sediments were sampled.[13][14] with increasing depth, aerobes gave way to anaerobes.[15] most biologists dismissed the subsurface microbes as contamination, especially after the submersible alvin sank in 1968 and the scientists escaped, leaving their lunches behind. when alvin was recovered, the lunches showed no sign of microbial decay.[12] this reinforced a view of the deep sea (and by extension the subsurface) as a lifeless desert. the study of the deep biosphere, like many bacteria, was dormant for decades; an exception is a group of soviet microbiologists who began to refer to themselves as geomicrobiologists.[11] interest in subsurface life was renewed when the united states department of energy was looking for a safe way of burying nuclear waste, and frank j. wobber realized that microbes below the surface could either help by degrading the buried waste or hinder by breaching the sealed containers. he formed the subsurface science program to study deep life. to address the problem of contamination, special equipment was designed to minimize contact between a core sample and the drilling fluid that lubricates the drill bit. in addition, tracers were added to the fluid to indicate whether it penetrated the core. in 1987, several boreholes were drilled near the savannah river site, and microorganisms were found to be plentiful and diverse at least 500 metres below the surface.[14] from 1983 until now, microbiologists have analyzed cell abundances in drill cores from the international ocean discovery program (originally the ocean drilling program).[13] a group led by john parkes of the university of bristol reported concentrations of 104 to 108 cells per gram of sediment down to depths of 500 metres (agricultural soils contain about 109 cells per gram).[16] this was initially met with skepticism, and it took them four years to publish their results.[12] in 1992, thomas gold published a paper titled "the deep, hot biosphere" suggesting that microbial life was widespread throughout the subsurface, existing in pore spaces between grains of rocks.[17] he also published a book similarly titled the deep hot biosphere.[17] according to one paper, he "pioneered" the idea the hydrocarbons could sustain life to "known depths of 10km and possibly down to 300km", if the temperature was not over a hypothetical maximum of 150°c.[17] gold also suggested, largely incorrectly, that the deep biosphere is sustained by hydrocarbons geologically produced by the subsurface, or their derivatives.[17] according to the paper, gold's proposals helped to inspire later generations of scientists.[17] in 1998, william whitman and colleagues published a summary of twelve years of data in the proceedings of the national academy of sciences.[16] they estimated that up to 95% of all prokaryotes (archaea and bacteria) live in the deep subsurface, with 55% in the marine subsurface and 39% in the terrestrial subsurface.[13] in 2002, ocean drilling program leg 201 was the first to be motivated by a search for deep life. most of the previous exploration was on continental margins, so the goal was to drill in the open ocean for comparison.[18][6] in 2016, international ocean discovery program leg 370 drilled into the marine sediment of the nankai accretionary prism and observed 102 vegetative cells per cm3 at 118 °c.[2][19] the present understanding of subsurface biology was made possible by numerous advances in technology for sample collection, field analysis, molecular science, cultivation, imaging and computation.[15] microbes from the ocean floor can sampled by drilling boreholes and collecting cores. the methods must be adapted to different types of rock, and the cost of drilling limits the number of holes that can be drilled.[20] microbiologists have made use of scientific drilling programs: the ocean drilling program (odp), which used the joides resolution drilling platform, and the integrated ocean drilling program (iodp), which used the japanese ship chikyū.[15] deep underground mines, for example south african gold mines and the pyhäsalmi copper and zinc mine in finland, have also provided opportunities to sample the deep biosphere,[21][22] as have chosen or proposed nuclear waste repository sites (e.g., yucca mountain and the waste isolation pilot plant in the united states, äspö and surrounding areas in sweden, onkalo and surrounding areas in finland, and mont terri in switzerland).[15] scientific drilling of the continental deep subsurface has been promoted by the international continental scientific drilling program (icdp).[23] to allow continuous underground sampling, various kinds of observatories have been developed. on the ocean floor, the circulation obviation retrofit kit (cork) seals a borehole to cut off the influx of seawater.[24] an advanced version of cork is able to seal off multiple sections of a drill hole using "packers", rubber tubes that inflate to seal the space between the drill string and the wall of the borehole.[25][26] in sediments, the simple cabled instrument for measuring parameters in situ (scimpi) is designed to remain and take measurements after a borehole has collapsed.[27] packers are also used in the continental subsurface,[28] along with devices such as the flow through in situ reactor (ftisr). various methods are used to extract fluids from these sites, including passive and osmotic gas samplers and u tube systems.[15] in narrow (less than 50 mm) holes, polyamide tubes with a back pressure valve can be lowered to sample an entire column of fluid.[29][30] some methods analyze microbes in situ rather than extracting them from the subsurface. in biogeophysics, the effects of microbes on properties of geological materials are remotely probed using electrical signals. microbes can be tagged using a stable isotope, such as carbon 13, and then re injected in the ground to see where they go.[15] a "push pull" method involves injection of a fluid into an aquifer and extraction of a mixture of injected fluid with the ground water; the latter can then be analyzed to determine what chemical reactions occurred.[31] methods from modern molecular biology allow the extraction of nucleic acids, lipids and proteins from cells, dna sequencing, and the physical and chemical analysis of molecules using mass spectrometry and flow cytometry. even when individual microbes cannot be cultivated, a lot can be learned about microbial communities using these methods.[15] for example, at the richmond mine in california, scientists used shotgun sequencing to identify four new species of bacteria, three new species of archaea (known as the archaeal richmond mine acidophilic nanoorganisms), and 572 proteins unique to the bacteria.[32][33] deep microorganisms change the chemistry of their surroundings through the nutrients they consume and the wastes they produce from metabolic activity. therefore scientists can estimate the activities of the deep microorganisms by measuring the chemical compositions of subsurface samples. complementary techniques include measuring the isotope compositions of the chemicals or the related minerals.[34][35][36][37] for life to have metabolic activity, it must be able to take advantage of a thermodynamic disequilibrium in the environment. this can occur when rocks from the mantle that are rich in the mineral olivine are exposed to seawater and react with it to form serpentine minerals and magnetite.[38] non equilibrium conditions are also associated with hydrothermal vents, volcanism, and geothermal activity. other processes that might provide habitats for life include roll front development in ore bodies,[note 1] subduction, methane clathrate formation and decomposition, permafrost thawing, infrared radiation and seismic activity. humans also create new habitats for life, particularly through remediation of contaminants in the subsurface.[13] life requires enough energy to construct adenosine triphosphate (atp). where there is sunlight, the main processes for capturing energy are photosynthesis (which harnesses the energy in sunlight by converting carbon dioxide into organic molecules) and respiration (which consumes those molecules and releases carbon dioxide). below the surface, the main source of energy is from chemical redox (reduction oxidation) reactions. this requires electron donors (compounds that can be oxidized) and electron acceptors (compounds that can be reduced). an example of such a reaction is methane oxidation: here ch4 is the donor and o2 is the acceptor.[40] donors can be considered "edibles" and acceptors "breathables".[41] the amount of energy that is released in a metabolic reaction depends on the redox potential of the chemicals involved. electron donors have negative potentials. from highest to lowest redox potential, some common donors available in the subsurface are organic matter, hydrogen, methane, reduced sulfur compounds, reduced iron compounds and ammonium. from most negative to least, some acceptors are oxygen, nitrates and nitrites, manganese and iron oxides, oxidized sulfur compounds, and carbon dioxide.[40] of electron donors, organic matter has the most negative redox potential. it can consist of deposits from regions where sunlight is available or produced by local organisms. fresh material is more easily utilized than aged. terrestrial organic matter (mainly from plants) is typically harder to process than marine (phytoplankton). some organisms break down organic compounds using fermentation and hydrolysis, making it possible for others to convert it back to carbon dioxide. hydrogen is a good energy source, but competition tends to make it scarce. it is particularly rich in hydrothermal fluids where it is produced by serpentinization. multiple species can combine fermentation with methanogenesis and iron oxidation with hydrogen consumption. methane is mostly found in marine sediments, in gaseous form (dissolved or free) or in methane hydrates. about 20% comes from abiotic sources (breakdown of organic matter or serpentinization) and 80% from biotic sources (which reduce organic compounds such as carbon dioxide, carbon monoxide and acetate). over 90% of methane is oxidized by microbes before it reaches the surface; this activity is "one of the most important controls on greenhouse gas emissions and climate on earth."[40] reduced sulfur compounds such as elemental sulfur, hydrogen sulfide (h2s) and pyrite (fes2) are found in hydrothermal vents in basaltic crust, where they precipitate out when metal rich fluids contact seawater. reduced iron compounds in sediments are mainly deposited or produced by anaerobic reduction of iron oxides.[40] the electron acceptor with the highest redox potential is oxygen. produced by photosynthesis, it is transported to the ocean floor. there, it is quickly taken up if there is a lot of organic material, and may only be present in the top few centimeters. in organic poor sediments it can be found at greater depths, even to the oceanic crust. nitrate can be produced by degradation of organic matter or nitrogen fixation.[40] oxygen and nitrate are derived from photosynthesis, so underground communities that utilize them are not truly independent of the surface.[42] all life requires carbon, nitrogen, phosphorus and some trace elements such as nickel, molybdenum and vanadium. over 99.9% of earth's carbon is stored in the crust and its overlying sediments, but the availability of this carbon can depend on the oxidation state of the environment. organic carbon, nitrogen and phosphorus are primarily found in terrestrial sediments, which accumulate mainly in continental margins. organic carbon is mainly produced at the surface of the oceans with photosynthesis or washed into oceans with terrestrial sediments. only a small fraction is produced in the deep seas with chemosynthesis. when organic carbon sinks from the surface of the ocean to the seafloor, most of the organic carbon is consumed by organisms in seawater. only a small fraction of this sinking organic carbon can reach the seafloor and be available to the deep biosphere.[34][43] deeper in the marine sediments, the organic content drops further.[34] phosphorus is taken up by iron oxyhydroxides when basalts and sulfide rocks are weathered, limiting its availability.[44] the availability of nutrients are limiting the deep biosphere, determining where and what type of deep organisms can thrive. on average, atmospheric pressure at sea level is about 101 kilopascals (kpa). in the ocean, the pressure increases at a rate of 10.5 kpa per m of depth, so at a typical depth of the sea floor (3800 m) the pressure is 38 megapascals (mpa). at these depths, the boiling point of water is over 400 °c. at the bottom of the mariana trench, the pressure is 110 mpa. in the lithosphere, the pressure increases by 22.6 kpa/m.[44][45] the deep biosphere withstands pressures much higher than the pressure at the surface of the earth.[34] an increased pressure compresses lipids, making membranes less fluid. in most chemical reactions, the products occupy more volume than the reactants, so the reactions are inhibited by pressure.[45] nevertheless, some studies claim that cells from the surface are still active at a pressure of 1 gigapascal (gpa), about 10,000 times the standard atmospheric pressure. there are also piezophiles for which optimal growth occurs at pressures over 100 mpa,[44] and some do not grow in pressures less than 50 mpa.[45] as of 2019, most sampling of organisms from the deep ocean and subsurface undergo decompression when they are removed to the surface. this can harm the cells in a variety of ways, and experiments at surface pressures produce an inaccurate picture of microbial activity in the deep biosphere.[46][47][48] a pressurized underwater sampler handler (push50) has been developed to maintain in situ pressure during sampling and afterwards in the laboratory.[49] high temperatures stress organisms, increasing the rates of processes that damage important molecules such as dna and amino acids. it also increases the energy requirements for repairing these molecules.[50] however, cells can respond by changing the structure of these molecules to stabilize them.[44][45][51] microbes can survive at temperatures above 100 °c if the pressure is high enough to keep the water from boiling. the highest temperature at which an organism has been cultured in a laboratory is 122 °c,[40][44] under pressures of 20 mpa and 40 mpa.[52] theoretical estimates for the highest temperature that can sustain life are around 150 °c.[53] the 120 °c isotherm can be less than 10 m deep at mid ocean ridges and seamounts, but in other environments such as deep sea trenches it can be kilometers deep.[44] about 39% by volume of ocean sediments are at temperatures between 40 °c and 120 °c.[53] thermochronology data of precambrian cratons suggest that habitable temperature conditions of the subsurface in these settings range back to about a billion years maximum.[54] the record setting thermophile, methanopyrus kandlerii, was isolated from a hydrothermal vent,[53] which provide abundant energy and nutrients. several groups of archaea and bacteria thrive in the shallow seafloor at temperatures between 80 °c and 105 °c. as the environment becomes more energy limited, such as being deeper, bacteria can survive but their number decreases. although microorganisms have been detected at temperatures up to 118 °c in cored sediments,[2][55] attempts to isolate the organisms have failed. there can also be depth intervals with less cells than the deeper part of the location.[2] reasons for such 'low  or no cell intervals' are still unknown but may be related to the underground flow of hot fluid.[56] in deep oil reservoirs, no microbial activity has been seen hotter than 80 °c.[50] in most of the subsurface, organisms live in conditions of extreme energy and nutrient limitation.[34] this is far from the conditions in which cells are cultured in labs. a lab culture goes through a series of predictable phases. after a short lag phase, there is a period of exponential growth in which the population can double in as little as 20 minutes. a death phase follows in which almost all the cells die off. the remainder enter an extended stationary phase in which they can last for years without further input of substrate. however, each live cell has 100 to 1000 dead cells to feed on, so they still have abundant nutrients compared to the subsurface.[3] in the subsurface, cells catabolize (break down molecules for energy or building materials) 10,000 to one million times slower than at the surface. biomass may take centuries or millennia to turn over. there is no known limit to the age that cells could reach. the viruses that are present could kill cells and there may be grazing by eukaryotes, but there is no evidence of that.[3] it is difficult to establish clear limits on the energy needed to keep cells alive but not growing.[34] they need energy to perform certain basic functions like the maintenance of osmotic pressure and maintenance of macromolecules such as enzymes and rna (e.g., proofreading and synthesis). however, laboratory estimates of the energy needed are several orders of magnitude greater than the energy supply that appears to sustain life underground.[3] it was thought, at first, that most underground cells are dormant. however, some extra energy is required to come out of dormancy. this is not a good strategy in an environment where the energy sources are stable over millions of years but decreasing slowly. the available evidence suggests that most cells in the subsurface are active and viable.[3] a low energy environment favors cells with minimal self regulation, because there are no changes in the environment that they need to respond to. there could be low energy specialists. however, there is unlikely to be strong evolutionary pressure for such organisms to evolve because of the low turnover and because the environment is a dead end.[3] the biomass in the deep subsurface is about 15% of the total for the biosphere.[5] life from all three domains (archaea, bacteria, and eukarya) have been found in the deep subsurface;[57] indeed, the deep subsurface accounts for about 90% of all the biomass in archaea and bacteria.[5] the genetic diversity is at least as great as that on the surface.[57] aerobic microbes are also present; methane feeding bacteria will break down nitrites into nitrogen and oxygen, and then use the oxygen to split methane for energy. some of the oxygen produced this way will leak out of the cells and into the surrounding environment, where it will benefit other oxygen dependent microorganisms.[58] in the ocean, plankton species are distributed globally and are constantly being deposited almost everywhere. quite different communities are found even in the top of ocean floor, and species diversity decreases with depth.[59] however, there are still some taxa that are widespread in the subsurface.[60] in marine sediments, the main bacterial phyla are "candidatus atribacteria" (formerly op9[61] and js1[62]),[63] pseudomonadota, chloroflexota, and planctomycetota.[60] members of archaea were first identified using metagenomic analysis, but some of them have since been cultured and acquired new names. the deep sea archaeal group (dsag) became the marine benthic group b (mbg b) and is now a proposed phylum "lokiarchaeota".[59] along with the former ancient archaeal group (aag) and marine hydrothermal vent group (mhvg), "lokiarchaeota" is part of a candidate superphylum, asgard.[64] other phyla are "bathyarchaeota" (formerly the miscellaneous chrenarchaeotal group), nitrososphaerota (formerly thaumarchaeota or marine group i),[59] and euryarchaeota (including "hadesarchaea", archaeoglobales and thermococcales).[53] a related clade, anaerobic methanotrophic archaea (anme), is also represented.[33] other bacterial phyla include thermotogota.[53] in the continental subsurface, the main bacterial groups are pseudomonadota and bacillota while the archaea are mainly methanomicrobia and nitrososphaerota.[65] other phyla include "bathyarchaeota" and "aigarchaeota", while bacterial phyla include aquificota and nitrospirota.[53] the eukarya in the deep biosphere include some multicellular life. in 2009 a species of nematode, halicephalobus mephisto, was discovered in rock fissures more than a kilometer down a south african gold mine. nicknamed the "devil worm",[66] it may have been forced down along with pore water by earthquakes.[67] other multicellular organisms have since been found, including fungi, platyhelminthes (flatworms), rotifera, annelida (ringed worms) and arthropoda.[68][69][70][71][72][73][74] however, their range may be limited because sterols, needed to construct membranes in eukarya, are not easily made in anaerobic conditions.[15] viruses are also present in large numbers and infect a diverse range of microbes in the deep biosphere. they may contribute significantly to cell turnover and transfer of genetic information between cells.[15] life has been found at depths of 5 km in continents and 10.5 km below the ocean surface.[57] in 1992, thomas gold calculated that if the estimated pore space of the terrestrial land mass down to 5 km depth was filled with water, and if 1% of this volume were microbial biomass, it would be enough living matter to cover earth's land surface with a 1.5 m thick layer.[75] the estimated volume of the deep biosphere is 2 2.3 billion cubic kilometers, about twice the volume of the oceans.[76] the main types of habitat below the seafloor are sediments and igneous rock. the latter may be partially altered and coexist with its alteration products such as sulfides and carbonates. in rock, chemicals are mainly carried through an aquifer system that cycles all of the ocean's water every 200,000 years. in sediments below the top few centimeters, chemicals mainly spread by the much slower process of diffusion.[44] nearly all of the seafloor is covered by marine sediments. they can vary in thickness from centimeters near ocean ridges to over 10 kilometers in deep trenches. in the mid ocean, coccoliths and shells settling down from the surface form oozes, while near shore sediment is carried from the continents by rivers. minerals from hydrothermal vents and wind blown particles also contribute.[40] as organic matter is deposited and buried, the more easily utilized compounds are depleted by microbial oxidation, leaving the more recalcitrant compounds. thus, the energy available for life declines. in the top few meters, metabolic rates decline by 2 to 3 orders of magnitude, and throughout the sediment column cell numbers decline with depth.[59] sediments form layers with different conditions for life. in the top 5 10 centimeters, animals burrow, reworking the sediment and extending the sediment water interface. the water carries oxygen, fresh organic matter and dissolved metabolites, resulting in a heterogenous environment with abundant nutrients. below the burrowed layer is a layer dominated by sulfate reduction. below that, the anaerobic reduction of methane is facilitated by sulfate in the sulfate methane transition zone (smtz). once the sulfates are depleted, methane formation takes over.[59] the depth of the chemical zones depends on the rate that organic matter is deposited. where it is rapid, oxygen is taken up rapidly as organic matter is consumed; where slow, oxygen can persist much deeper because of the lack of nutrients to oxidize.[59] ocean sediment habitats can be divided into subduction zones, abyssal plains, and passive margins. at a subduction zone, where one plate is diving under another, a thick wedge of sediment tends to form. at first the sediment has 50 to 60 percent porosity; as it is compressed, fluids are expelled to form cold seeps or gas hydrates. abyssal plains are the region between continental margins and mid ocean ridges, usually at depths below 4 kilometers. the ocean surface is very poor in nutrients such as nitrate, phosphate and iron, limiting the growth of phytoplankton; this results in low sedimentation rates.[63] the sediment tends to be very poor in nutrients, so not all the oxygen is consumed; oxygen has been found all the way down to the underlying rock. in such environments, cells are mostly either strictly aerobic or facultative anaerobic (using oxygen where available but able to switch to other electron acceptors in its absence[77]) and they are heterotrophic (not primary producers). they include pseudomonadota, chloroflexota, marine group ii archaea and lithoautotrophs in the nitrososphaerota phylum. fungi are diverse, including members of the ascomycota and basidiomycota phyla as well as yeasts.[63] passive margins (continental shelves and slopes) are under relatively shallow water. upwelling brings nutrient rich water to the surface, stimulating abundant growth of phytoplankton, which then settle to the bottom (a phenomenon known as the biological pump).[63] thus, there is a lot of organic material in the sediments, and all the oxygen is used up in its consumption. they have very stable temperature and pressure profiles.[44] the population of microbes is orders of magnitude greater than in the abyssal plains. it includes strict anaerobes including members of the chloroflexi phylum, "ca. atribacteria", sulfate reducing bacteria, and fermenters, methanogens and methanotrophs in archaea. fungi are less diverse than in abyssal plains, mainly including ascomycota and yeasts. viruses in the inoviridae, siphoviridae, and lipothrixviridae families have been identified.[63] ocean crust forms at mid ocean ridges and is removed by subduction. the top half kilometer or so is a series of basaltic flows, and only this layer has enough porosity and permeability to allow fluid flow. less suitable for life are the layers of sheeted dikes and gabbros underneath.[44] mid ocean ridges are a hot, rapidly changing environment with a steep vertical temperature gradient, so life can only exist in the top few meters. high temperature interactions between water and rock reduce sulfates, producing abundant sulfides that serve as energy sources; they also strip the rock of metals that can be sources of energy or toxic. along with degassing from magma, water interactions also produce a lot of methane and hydrogen. no drilling has yet been accomplished here, so information on microbes comes from samples of hydrothermal fluids coming out of vents.[44] about 5 kilometers off the ridge axis, when the crust is about 1 million years old, ridge flanks begin. characterized by hydrothermal circulation, they extend to about 80 million years in age. this circulation is driven by latent heat from the cooling of crust, which heats seawater and drives it up through more permeable rock. energy sources come from alteration of the rock, some of which is mediated by living organisms. in the younger crust, there is a lot of iron and sulfur cycling. sediment cover slows the cooling and reduces the flow of water. there is little evidence of microbe activity in older (more than 10 million year old) crust.[44] near subduction zones, volcanoes can form in island arcs and back arc regions. the subducting plate releases volatiles and solutes to these volcanoes, resulting in acidic fluids with higher concentrations of gases and metals than in the mid ocean ridge. it also releases water that can mix with mantle material to form serpentinite. when hotspot volcanoes occur in the middle of oceanic plates, they create permeable and porous basalts with higher concentrations of gas than at mid ocean ridges. hydrothermal fluids are cooler and have a lower sulfide content. iron oxidizing bacteria create extensive deposits of iron oxides.[44] microorganisms live in the cracks, holes and empty space inside sediments and rocks. such empty space provides water and dissolved nutrients to the microorganisms. note that as the depth increases, there are less nutrients in the porewater as nutrients are continuously consumed by microorganisms. as the depth increases, the sediment is more compact and there is less space between mineral grains. as a result, there is less porewater per volume. the environment gets drier and drier when sediments are transitioned into rocks. at this stage, water can also be a limiting factor to the deep biosphere.[34] continents have a complex history and a great variety of rocks, sediments and soils; the climate on the surface, temperature profiles and hydrology also vary. most of the information on subsurface life comes from a small number of sampling sites that are mainly in north america. with the exception of ice cores, densities of cells decline steeply with depth, decreasing by several orders of magnitude. in the top one or two meters of soils, organisms depend on oxygen and are heterotrophs, depending on the breakdown of organic carbon for their nutrition, and their decline in density parallels that of the organic material. below that, there is no correlation, although both cell density and organic content declines by a further five orders of magnitude or so (by contrast, there is a correlation in ocean sediments). increasing depth, temperature and salinity do correlate with declining cell numbers, although the rates depend strongly on type of crust and rate of groundwater recharge.[65] microbes have been found in sedimentary rocks down to about 3 kilometers, the deepest sampled. there is a lot of diversity, although the deepest tend to be iron(iii)  or sulfate reducing bacteria that use fermentation and can thrive in high temperature and salinity. even more salt tolerant halophiles have been found in deep salt deposits, which are found all over the world.[78] in 2019 microbial organisms were discovered living 2,400 meters below the surface, breathing sulfur and eating rocks such as pyrite as their regular food source.[79][80][81] the discovery occurred in the oldest known water on earth.[82] a study of biosignatures in vein mineral samples from more than 30 deep mines in the fennoscandian shield proves that signatures of ancient life are omnipresent across the shield.[83] humans have accessed deep aquifers in igneous rocks for a variety of purposes including groundwater extraction, mining, and storage of hazardous wastes. most or all of these aquifers host microbes. at all the sites that have been tested, hydrogen, methane and carbon dioxide have been found.[78] hydrogen based communities of prokaryotes have also been found in hot springs and hydrothermal systems. a variety of mechanisms have been proposed for the production of hydrogen, some of which would be independent of photosynthesis.[60] one species of bacteria, "candidatus desulforudis audaxviator", is the first known to comprise a complete ecosystem by itself.[12] it was found 2.8 kilometers below the surface in a gold mine near johannesburg, south africa. in alkaline water at a temperature of about 60 °c, with no access to oxygen, it gets energy by reducing sulfate, its nitrogen from ammonia molecules and ammonium ions, and its carbon from carbon dioxide or formate.[84][85] stable isotope records of (secondary) fracture lining minerals of the continental igneous rock hosted deep biosphere point to long term occurrence of methanogenesis, methanotrophy and sulfate reduction.[86] morphological and spatiotemporal relations point to potential syntrophic relation of these prokaryotic metabolisms with fungi.[74][87] other ecosystems have multiple interdependent species. they can be divided into autotrophs, which derive energy from non living sources, and heterotrophs, which feed on autotrophs or their remains. some organisms engage in syntrophy, where one organism lives off the byproducts of another's metabolic activity. at the surface, most autotrophs use photosynthesis, but where there is no light, chemoautotrophs make use of chemical energy.[88] in marine sediments where oxygen is available, a major group of chemoautotrophs is ammonia oxidizing nitrososphaerota archaea. it supports 19% of the heterotrophic production. in some environments such as abyssal pacific ocean sediments, the supply of ammonia dwindles with depth; but in other environments ammonia actually increases because heterotrophic bacteria, living on organic material, remineralize the ammonia. this interdependence of the heterotrophic bacteria and nitrososphaerota is an example of syntrophy. however, some nitrososphaerota are mixotrophic, able to use both organic matter and carbon dioxide for carbon.[63] in anoxic sediments, hydrogen is an important "edible". members of the chloroflexi bacterial phylum draw energy from it to produce acetate by reducing carbon dioxide or organic matter (a process known as acetogenesis). metal reducing and sugar fermenting bacteroidetes produce propionate, among other compounds, and this is fermented by "ca. atribacteria" to produce hydrogen. in upper sediments, sulfate reducing bacteria take up most of the hydrogen, while in lower sediments the sulfate is depleted and methanogens dominate. in the sulfate methane transition zone (smtz), anaerobic methanotrophic (anme) archaea form consortia with sulfate reducing bacteria.[63][59]

linkedin and 3rd parties use essential and non essential cookies to provide, secure, analyze and improve our services, and to show you relevant ads (including professional and job ads) on and off linkedin. learn more in our cookie policy. select accept to consent or reject to decline non essential cookies for this use. you can update your choices at any time in your settings. agree & join linkedin by clicking continue to join or sign in, you agree to linkedin’s user agreement, privacy policy, and cookie policy. dedicated to 𝗹𝗶𝗳𝗲𝗹𝗼𝗻𝗴 𝗹𝗲𝗮𝗿𝗻𝗶𝗻𝗴 & 𝗶𝗺𝗽𝗿𝗼𝘃𝗲𝗺𝗲𝗻𝘁, i aspire to be a polymath but, sadly, 𝐟𝐚𝐥𝐥 𝐟𝐚𝐫 𝐬𝐡𝐨𝐫𝐭! background: pharmaceutical, hospitality, health care supply chain, philantropy. great article on life underground. https://archive.ph/lhvbx the mysterious, deep dwelling microbes that sculpt our planet: earth’s crust teems with subterranean life that we are only now beginning to understand. to view or add a comment, sign in bams aspirant | focused on promoting traditional medicine for modern health challenges the panchamahabhuta theory represents the five great elements: earth (prithvi), water (apas), fire (agni), air (vayu), and space (akasha). these elements form the foundation of the physical universe, symbolizing balance and interdependence in nature and life. to view or add a comment, sign in founder & visionary entrepreneur | communications, marketing and business strategist | regenerative farming & winemaking practitioner | systems thinking, complexity science and circularity thought leader beautiful words to reflect upon, ideally while being outside and present and open to possibility. as we move through the next 9 days leading up to what storytellers may deem the world's most consequential u.s. election, i hope my fellow americans can remember our vast common ground. ➡️. our first principles: we humans are nature. we must arrest our way of living. the harris/walz team is far from perfect. and like all of us, they currently operate within a toxic human economy. the question imo is which team provides the best chance of waking up to our first principles and allowing that to become our northstar. the answer is unequivocally harris/walz. soul driven sidekick for cool hoomans | globally | director & international faculty @ team coaching studio | ≋s≋e≋l≋f≋ centered  earth  what if the earth itself were one vast, breathing question, a single organism, reaching, rooting, in search of truth? each tree an antenna, each river a vein, the oceans turning, listening, every mountain holding silence like an ancient vow. what if we were cells in its body, small and infinite, each and every one part of the seeking, the great turning toward light? here we are, boundless, indivisible, each of us the earth’s question  each of us the answer waiting to unfold. to view or add a comment, sign in 1,004 followers where are the deepest caves on the planet: you will be surprised few people know where the deepest caves on the planet are located. https://lnkd.in/eswcptwy to view or add a comment, sign in founder at isabelle morton gemstone therapy institute we we think about grounding, it's usually with the earth. in this presentation, i'll introduce the concept of grounding with heaven (the opposite of earth) and the benefits of doing so. to view or add a comment, sign in генеральный директор   belnovosti where are the deepest caves on the planet: you will be surprised few people know where the deepest caves on the planet are located. https://lnkd.in/ebavibus to view or add a comment, sign in senior cross culture pastor at lancaster cogop link https://lnkd.in/ehhu32xu in the sprawling expanse of the planet harmonious, three distinct levels of civilization coexist. the skai, a species that lives in the sky, occupies one level. the landrum, who live on land and sea, inhabit another level. finally, the underground coreslag live deep beneath the surface. all three levels are connected by matter transporters, which dot the planet and galaxy, allowing for easy travel between planets. to view or add a comment, sign in 78 followers a new study shows mars’ early thick atmosphere could be locked up in the planet’s clay surface. | click below to read the full article on sunalei to view or add a comment, sign in journalist at today's focus of attention common myths about the ocean: debunking the deep dive into the truth behind common ocean myths, from the extent of exploration to the reality of sharks. learn why understanding the ocean’s true nature is key to its preservation and our own survival. read the full article... https://lnkd.in/eaugnza6 to view or add a comment, sign in 926 followers create your free account or sign in to continue your search or by clicking continue to join or sign in, you agree to linkedin’s user agreement, privacy policy, and cookie policy. new to linkedin? 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when you search for the term "longreads," you're looking for a great story to sink into. for 15 years, longreads has published and curated the best longform writing on the web and we wouldn’t exist without the support of readers like you. make a one time donation today and ensure that quality journalism continues to flourish. register with longreads for free and get access to our editors' picks collecting the best stories on the web, as well as our award winning original writing. our privacy policy can be found here. thank you for registering! an account was already registered with this email. please check your inbox for an authentication link. longreads longreads : the best longform stories on the web “earth’s crust teems with subterranean life that we are only now beginning to understand.” “earth is losing its memory.” “can the planet’s ecosystems be replicated?” part of the family enter the code sent to your email. email address enter your password sign in by entering the code we sent to , or clicking the magic link in the email. our privacy policy can be found here. this site is protected by recaptcha and the google privacy policy and terms of service apply.

an editorially independent publication supported by the simons foundation. get the latest news delivered to your inbox. create a reading list by clicking the read later icon next to the articles you wish to save. type search term(s) and press enter popular searches january 4, 2024 by studying the chemistry in earth’s subterranean environments   such as the rocks deep beneath the ocean floor   scientists hope to learn what may have powered the earliest life forms on this planet. mark belan for quanta magazine contributing writer january 4, 2024 near midnight on march 26, 1961, dark waters lapped at the hull of a converted naval barge as it queasily rocked in the pacific ocean. the ship had just arrived at this spot, some 240 kilometers off the baja peninsula, after three days of fighting seas so rough the crew had lashed gear to the deck with heavy chains, “like a rogue elephant,” the novelist john steinbeck, who was aboard the vessel, later wrote for life magazine. back on shore, rumors flew about the crew’s goals. some speculated that they were hunting for diamonds or sunken treasure. others suspected that they were scouting for a place to stash a missile on the seafloor. but the team’s objectives were even loftier than the wildest hearsay. the plan   hatched over an alcohol infused breakfast at the la jolla home of the geologist walter munk   was to drill a hole so deep it would punch through earth’s crust and reach the planet’s mantle, a hot, rocky layer sandwiched between earth’s crust and its core. now, more than 62 years after the effort known as project mohole, scientists still have yet to successfully drill through an intact section of earth’s crust. but this past spring, a team aboard the decades old drillship the joides resolution accomplished the next best thing: they retrieved a trove of mantle rocks from an area of the atlantic seafloor where the crust is especially thin. the site is atop a submarine mountain known as atlantis massif, where the slow shifts of tectonic plates have shoved blocks of mantle rocks closer to the surface. while the mantle makes up the bulk of our planet, its rocks are usually buried kilometers beneath the surface, making fresh samples tough to retrieve. but mantle rocks such as those excavated last spring could offer clues to the deep workings of earth and help researchers better understand the tectonic choreography that’s fundamental to our world. the newly collected rocks may also hold clues to another defining feature of our planet   life. when seawater meets mantle rock, a series of chemical reactions generates a cocktail that can create the organic compounds needed to ignite life’s first sparks. scientists have already found hints of small organic molecules created without microbial help at the lost city hydrothermal vent system, a sprawling geologic metropolis atop atlantis massif. some scientists have long speculated that such environments could have incubated our planet’s earliest life forms. now, the team’s recently drilled hole, which bored more than a kilometer below the seafloor, has reached into what seems to be the beating heart of this hydrothermal system. get quanta magazine delivered to your inbox last spring, susan lang (at right) co led an expedition that retrieved a trove of mantle rocks from beneath the seafloor. william brazelton/university of utah “that opens a world of possibilities to us,” said susan lang, a biogeochemist at the woods hole oceanographic institution who co led the expedition. already, there are hints that high concentrations of hydrogen gas in the borehole waters might be available to power organic synthesis. this natural laboratory promises to help the team untangle the origin of the life giving stew that trickles up through lost city’s towers, allowing them to study the organic chemistry of a world without organisms   the chemistry of life before life existed, or when life was extremely scarce. the few microbes that survive the extreme subsurface conditions may also offer clues to how the earliest beings made a living, ultimately helping scientists decipher the pivotal steps that turned chemical compounds into creatures. lang still remembers the day, about two decades ago, when she was offered a berth on the vessel conducting the first detailed study of the lost city vents. tears of excitement flooded her eyes. “i said yes without checking with anyone,” said lang, who was a graduate student at the university of washington at the time. her fervor reflected the revolutionary nature of lost city, whose shimmery, translucent columns of hot water were first spotted by scientists aboard the research vessel atlantis in 2000. at the time, all the other known hydrothermal vent systems were dark, with chimneys blackened by volcanic sulfides pumping thick, smoky plumes of searing fluids into the ocean. but the spires of lost city were a ghostly white. as scientists soon learned, the light hue stems from reactions between seawater and the rock tucked within atlantis massif. a bit taller than mount rainier, this submarine mountain is largely made of peridotite, a type of rock that dominates the upper mantle. the mountain formed from the sedate shifts of the nearby mid atlantic ridge, where the north american and african tectonic plates slowly pull apart. this movement stripped the upper crust from the rising peak, exposing swaths of its peridotite core. sandwiched between earth’s crust and its core, the mantle is normally very hard to access. but this past spring, scientists drilled into a place on the seafloor where mantle rocks sit close to the surface. lesley anderson/iodp peridotite normally lingers under miles of crust. it’s unstable so near to earth’s surface, where seawater can creep into cracks within the rocks. when that happens, a mineral called olivine that dominates the peridotite readily reacts with water molecules, sparking a series of chemical steps called serpentinization. the process makes the water highly alkaline, so when fluids from the crevice mingle with fresh seawater, pale minerals precipitate and build lost city’s stunning spires, which stand as tall as a 20 story building. but another byproduct of serpentinization, hydrogen, has drawn lang and other scientists to the site for decades. under the right conditions, hydrogen gas can fuel simple chemical reactions, such as turning carbon dioxide and water into small organic compounds, without microbial help (or abiotically). continued reactions could create larger and more complex organic molecules, perhaps crafting just the right mix of ingredients   sugars, fats, amino acids   to cook up the earliest life forms. plus, hydrogen and small organics may have also provided food for earth’s earliest inhabitants. “hydrogen is like the key to everything,” lang said. this gas was likely more common on early earth, when the mineral makeup of the surface differed from that of today, making serpentinization reactions more common. at atlantis massif, lang and her colleagues want to know which organic compounds can form without microbial help and which microbes might survive on this unusual underground buffet. the results could offer clues about how the earliest life forms made a living, as well as the chemistry that preceded those ancient microbes. but today life abounds on earth’s surface, both above and below water, making it tough to identify compounds that were made without biology’s help. that’s especially true at lost city. “you can just see the snotty biofilms growing all over those chimneys,” said william brazelton, a microbiologist at the university of utah and a joides team member. so researchers set their sights on the realms below the seafloor, where microbes are sparse and oxygen is scarce, creating conditions similar to those of early earth. as brazelton said, “we need to literally go deeper.” in the 1960s, project mohole marked the start of efforts to plumb the unexplored depths of our planet during a time of “heroic science,” said damon teagle, a geochemist at the university of southampton and a veteran of many scientific ocean drilling expeditions. the name was a play on the mohorovičić discontinuity, or moho, which defines the boundary between the crust and mantle. under continents, the moho can be found more than 30 kilometers deep; under the seafloor, it’s closer to 7 kilometers. because of this, teams targeting the mantle usually choose to drill from ships. project mohole didn’t even get close to its goal, only boring through 179 meters of sediments and a mere 4 meters of seafloor rock. yet even that effort revealed a wealth of information about our planet, including the fact that hiding under seafloor sediments were relatively young volcanic rocks   a find that would later serve as a key piece of evidence in the case for plate tectonics. it also produced technologies that evolved into systems scientists still use, including some on board the joides resolution this past spring. for decades, the joides resolution has helped scientists study earth’s oceans   and what lies beneath the seafloor. tim fulton/iodp/jrso even today, though, deep ocean drilling is tremendously challenging. for one thing, drilling through hard rock rapidly wears out drill bits, forcing regular bit changes and the need to reenter the same tiny borehole from a ship bobbing atop hundreds or thousands of meters of water, which is like dropping a needle into a pinhole. to make matters worse, last spring’s expedition had an inauspicious start. while the team was drilling their first pilot hole, their drill bit got stuck, and to prevent the ship from being forever anchored to atlantis massif, the crew severed the connection with a blast of dynamite. then part of the system that allowed the drill to reenter a borehole multiple times broke into pieces. with a bit of creativity, they finally got to drilling at a site now known as u1601c, which sits under nearly 850 meters of water. and that’s when their luck changed. on most seafloor drilling expeditions, progress is slow, with rocky cores hauled on deck every three hours or so. but once the joides team got going, they were heaving fresh cores on board almost every hour. scientists processing the cores could barely keep up, and before they knew it, the drill bit had struck mantle rocks. before this expedition, the furthest anyone had ever drilled into altered mantle rocks was 200 meters. but the joides team covered that distance in just a few days, ultimately boring through 1,267.8 meters of mostly peridotite. “it was just remarkable,” said teagle, who was not part of the recent undertaking. for lang, one of the biggest surprises was hidden deep in the borehole. after removing their last core, the crew flushed the empty hole with clean water and let natural fluids and gases creep back in over 72 hours. then they collected the borehole water at various depths and split it up for more than a dozen chemical tests, including a hydrogen gas analysis. situated on the seafloor near the mid atlantic ridge, atlantis massif offers relatively easy access to rocks with a mix of minerals thought to form in earth’s mantle. ife, uri iao, uw, lost city science party; noaa/oar/oer; the lost city 2005 expedition at most, lang expected to find trace amounts of hydrogen so far underground. but the deepest water sample contained so much gas that as it surfaced, bubbles formed in the tube, a phenomenon similar to what happens when you crack open a fresh can of soda. “we were like, holy crap,” lang said, recalling her own reaction and brazelton’s. “there was a lot of swearing involved.” the waters are chock full of hydrogen, the fuel needed to power abiotic reactions. more than six months after the expedition, the team is still processing their enormous number of samples   studying the water chemistry, identifying microbes, characterizing the rocks, and more. “people are going to do a whole alphabet soup of elemental analyses on these rocks,” said andrew mccaig, a geologist at the university of leeds who co led the expedition. preliminary models hint that temperatures near the bottom of the borehole might even reach 122 degrees celsius, the currently known limit for life (though some studies suggest that the limit might sit even higher). lang cautions that the models require confirmation because they’re based on measurements taken when the borehole temperatures were slightly suppressed by the cool waters circulating during drilling. if conditions are confirmed to be this extreme, though, the depth would allow scientists to study life fueling chemical reactions without the muddling influence of microbes. we know very little about the rock microbes. it’s one of the last questions in the deep biosphere: what’s in the hard rocks? fengping wang, shanghai jiao tong university this would be a significant step forward for scientists studying life’s watery origins. “on earth today, it’s really hard to witness abiotic or prebiotic chemistry because life dominates; life is everywhere,” said laurie barge, an astrobiologist at nasa’s jet propulsion laboratory who was not part of the expedition. early analyses also suggest that the small organic acid formate is present in the borehole water. formate is one of the simplest compounds that can form abiotically, from reactions between carbon dioxide and hydrogen, and it may mark an initial step toward the first glimmers of life on early earth. “it’s the raw material to build the building blocks,” lang said. continued abiotic reactions with formate could produce larger organic compounds like amino acids, which can be strung together into molecules essential for life, such as enzymes and other proteins. but much of the chemical picture remains fuzzy at atlantis massif. the formate deep in the borehole may have formed without microbial help, as it has in the shallower subsurface nearby, but more testing is needed to be sure. the water also contains methane, a compound that some scientists think was vital for early metabolisms and one that could be generated abiotically from reactions with hydrogen. but how methane forms at lost city is another mystery   it’s “complicated and confusing,” brazelton said. identifying abiotic reactions in nature could inform future lab experiments testing prebiotic chemistry, where researchers can tweak the conditions to more closely simulate early earth or other worlds, barge explained. “lost city is a really special place,” she said. even if the deep borehole isn’t devoid of life, the almost unprecedented quantity of recovered rocky cores will help scientists link shifts in water chemistry and rock types to the few microbes that may eke out a living underground. studying how microbes survive amid scarce subsurface resources   perhaps by eating hydrogen and other abiotically formed compounds   could help sharpen our picture of early life. brazelton in particular is on the hunt for the specific enzymes microbes use to turn hydrogen and small organic compounds into energy. “the whole idea here is that you have chemistry going on in rocks, and at some point, that chemistry turns into life,” brazelton said. those enzymes might just be the knob that helps researchers rewind the evolutionary clock to decipher how the earliest metabolisms came to be. other efforts are focused on incubating samples from the rock and trying to catch deep microbes in action, explained fengping wang, the geomicrobiologist leading this work at shanghai jiao tong university. wang has been studying life in the subsurface for almost two decades, but she and other deep biosphere researchers have largely searched for microbes hiding in ocean sediments. “we know very little about the rock microbes,” she said. “it’s one of the last questions in the deep biosphere: what’s in the hard rocks?” fengping wang, a geomicrobiologist, processed some 800 samples aboard the joides resolution. she wants to know which microbes, if any, can live deep beneath the seafloor. courtesy of fengping wang in search of answers, wang pulverized hundreds of core samples aboard the ship, placing each one into a metal reactor tube or glass bottle. she spiked the samples with a variety of foods   a microbial tasting menu suited for an unknown diversity of diets. and then she incubated the samples at different temperatures to see what would grow. overall, she set up nearly 800 incubations and posed for a picture with them in the shipboard lab “to show my hard work,” she said with a chuckle. in the picture, every inch of the table in front of her is packed with glass bottles, which are just a fraction of her total samples. wang’s preliminary results reveal an excess of methane in some samples, but whether the gas comes from burping microbes or reacting rocks is not yet clear. scientists across many fields are eagerly awaiting the team’s findings. “we’re definitely going to have a much better view of … what actual chemical processes are taking place,” said yoshinori miyazaki, a geophysicist at the california institute of technology. the excitement and triumph surrounding the latest work, however, is also tinged with sadness. this expedition is one of the last for the joides resolution, which will retire at the end of 2024 after four decades of groundbreaking research in ocean waters around the world. there’s currently no concrete plan to replace the ship, which leaves a gaping hole in ocean research for u.s. scientists. over its lengthy tenure, expeditions on board the joides resolution have recovered more than 350 kilometers of cores from the seafloor. hidden within this geologic trove are many secrets of our planet’s past   shifts in climate, ocean chemistry, and perhaps other clues to life’s origins. but even more information is still locked in the rocks of the seafloor, just waiting to be uncovered. correction: january 5, 2024 the original version of this article included an image of an undersea vent that was misidentified as being part of the lost city. it has been removed. contributing writer january 4, 2024 get quanta magazine delivered to your inbox get highlights of the most important news delivered to your email inbox quanta magazine moderates comments to facilitate an informed, substantive, civil conversation. abusive, profane, self promotional, misleading, incoherent or off topic comments will be rejected. moderators are staffed during regular business hours (new york time) and can only accept comments written in english. forgot your password ? we’ll email you instructions to reset your password enter your new password

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earth’s crust teems with subterranean life that we are only now beginning to understand. credit...illustration by brian rea. animation by delcan & co. supported by by ferris jabr ferris jabr is a contributing writer at the magazine and the author of “becoming earth: how our planet came to life,” from which this article is adapted. in the middle of north america, there is a portal to the deep recesses of earth’s rocky interior. the portal’s mouth   a furrowed pit about half a mile wide   spirals 1,250 feet into the ground, expos­ing a marbled mosaic of young and ancient rock: gray bands of basalt, milky veins of quartz and shimmering con­stellations of gold. beneath the pit, some 370 miles of tunnels twist through solid rock, extending more than 1.5 miles below the surface. for 126 years, this site in lead, s.d., housed the homestake mine, the deepest and most productive gold mine on the continent. in 2006, the barrick gold corporation donated the mine to the state of south dakota, which converted it into the largest subterranean laboratory in the united states, the sanford underground research facility. although the lowest tunnels flooded after mining ceased, it is still possible to descend nearly a mile beneath the planet’s surface. most of the sci­entists who do so are physicists conducting highly sensitive experi­ments that must be shielded from interfering cosmic rays. but a few biologists also venture into the underground labyrinth, typically seeking its dankest and dirtiest corners   places where obscure creatures extrude metal and transfigure rock. on a bitingly cold december morning, i followed three young sci­entists and a group of sanford employees into “the cage”   the bare metal elevator that would take us 4,850 feet into earth’s crust. we wore neon vests, steel toed boots and hard hats. strapped to our belts were per­sonal respirators, which would protect us from carbon monoxide in the event of a fire or explosion. the cage descended swiftly and sur­prisingly smoothly. our idle chatter and laughter were just audible over the din of unspooling cables and whooshing air. after a controlled plum­met of about 10 minutes, we reached the bottom of the facility. our two guides, both former miners, directed us into a pair of small linked rail cars and drove us through a series of narrow tunnels. within 20 minutes, we had traded the relatively cool and well ventilated region near the cage for an increasingly hot and muggy corridor. whereas the surface world was snowy and well below freez­ing, a mile down it was about 90 degrees with nearly 100 percent humidity. heat seemed to pulse through the rock surrounding us, and the air was thick and cloying; the smell of brimstone seeped into our nostrils.