Tag Archives: microbial

Exploring How Gas Fuels Diverse Microbial Life in Caves – Sciworthy

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Caves are often dark, damp, and remote. While they lack the nutrients and energy sources that sustain life in other ecosystems, they still host a diverse array of bacteria and archaea. But how do these microorganisms acquire enough energy to thrive? A team of researchers from Australia and Europe investigated this intriguing question by examining Australian caves.

Previous studies identified that microorganisms in nutrient-poor soils can harness energy from the atmosphere through trace gases, including hydrogen, carbon monoxide, and methane. These gases are present in minute quantities, classified as trace gases. Microbes possess specific proteins that can accept electrons from these gas molecules, enabling them to utilize these gases as energy sources, such as hydrogenase, dehydrogenase, or monooxygenase, fueling their metabolic processes.

The Australian research team hypothesized that cave-dwelling microbes may be using trace gases for survival. To test this, they studied four ventilated caves in southeastern Australia. The researchers collected sediment samples at four points along a horizontal line that extended from the cave entrance to 25 meters (approximately 80 feet) deep inside the cave, resulting in a total of 94 sediment samples.

The team treated the sediment samples with specific chemicals to extract microbial DNA, using it to identify both the abundance and diversity of microorganisms present. They found multiple groups of microorganisms throughout the cave, including Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexota, and Thermoproteota. Notably, the density and diversity of microbes were significantly higher near the cave entrance, with three times more microorganisms in those regions compared to further inside.

The team utilized gene sequencing to analyze the microbial DNA for genes linked to trace gas consumption. Results revealed that 54% of cave microorganisms carried genes coding for proteins involved in utilizing trace gases like hydrogenases, dehydrogenases, and monooxygenases.

To assess the generality of their findings, the researchers searched existing data on microbial populations from 12 other ventilated caves worldwide. They discovered that genes for trace gas consumption were similarly prevalent among other cave microorganisms, concluding that trace gases might significantly support microbial life and activity in caves.

Next, the researchers measured gas concentrations within the caves. They deployed static magnetic flux chambers to collect atmospheric gas samples at four points along the sampling line, capturing 25 milliliters (about 1 ounce) of gas each time. Using a gas chromatograph, they analyzed the samples and found that the concentrations of hydrogen, carbon monoxide, and methane were approximately four times higher near the cave entrance compared to deeper areas. This suggests that microorganisms might be metabolizing these trace gases for energy.

To validate their findings further, they constructed a static magnetic flux chamber in the lab, incubating cave sediment with hydrogen, carbon monoxide, and methane at natural concentration levels. They confirmed that microbes also consumed trace gases in controlled conditions.

Finally, the researchers explored how these cave microbes obtained organic carbon. They conducted carbon isotope analysis, focusing on carbon-12 and carbon-13 ratios, which can vary based on microbial metabolic processes. Using an isotope ratio mass spectrometer, they determined that cave bacteria had a lower percentage of carbon-13, indicating their reliance on trace gases to generate carbon within the cave ecosystem.

The researchers concluded that atmospheric trace gases serve as a crucial energy source for microbial communities in caves, fostering a diverse array of microorganisms. They recommended that future studies examine how climatic changes, such as fluctuations in temperature and precipitation, might influence the use of atmospheric trace gases by cave-dwelling microorganisms.

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Lava Tubes Hold Secrets of Unidentified ‘Microbial Dark Matter’ – Sciworthy

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Mars’ surface is not currently conducive to human life. It presents extreme challenges, including a tenuous atmosphere, freezing temperatures, and heightened radiation levels. While Earth’s extremophiles can tackle some obstacles, they can’t handle them all simultaneously. If Martian life exists, how do these microbes manage to survive in such an environment?

The answer might lie within caves. Many researchers believe that ancient lava tubes on Mars formed billions of years ago when the planet was warmer and had liquid water. Caves serve as shelters against radiation and severe temperatures found on the Martian surface. They also host the nutrients and minerals necessary for sustaining life. Although scientists cannot yet explore Martian caves directly, they are examining analogous sites on Earth to establish parameters for searching for life on Mars.

A research team, led by C.B. Fishman from Georgetown University, investigated the microorganisms inhabiting the lava tubes of Mauna Loa, Hawaii, to learn about their survival mechanisms. Thanks to careful conservation efforts by Native Hawaiians, these lava tubes remain undisturbed by human activity. Researchers believe that both the rock structures in Mauna Loa Cave and the minerals formed from sulfur-rich gases bear similarities to Martian cave formations.

The team analyzed five samples from well-lit areas near the cave entrance, two from dimly lit zones with natural openings known as skylights, and five from the cave’s darkest recesses. Samples were chosen based on rock characteristics, including secondary minerals like calcite and gypsum, and primary iron-bearing minerals such as olivine and hematite.

Findings revealed significant variation in mineralogy within the cave, even over small distances. The bright samples were predominantly gypsum, while the dark samples lacked these key minerals. Instead, one dark sample was rich in iron-bearing minerals, while another contained mainly calcite, gypsum, and thenardite.

To identify the microorganisms within the samples, the team employed the 16S rRNA gene to recognize known microbes and understand their relationships. They also reconstructed complete genomes from cave samples using a method called metagenomic analysis. This technique is akin to following instructions to assemble various models from mixed DNA fragments. Such insights help researchers grasp how both known and unknown microorganisms thrive in their respective environments.

The team discovered that approximately 15% of the microbial genomes were unique to specific locations, with about 57% appearing in less than a quarter of the samples. Furthermore, microbial communities in dark regions exhibited less diversity and were more specialized compared to those in well-lit areas. While dark sites were not as varied as bright ones, each supported its own distinct microbial community.

To explain this difference, the researchers proposed that dark microbes have limited survival strategies since photosynthesis is impossible without light. Instead, these microbes extract chemical energy from rocks and decaying organic matter, much like how humans derive energy from breaking down food.

The findings from metagenomic data indicated that even though sulfur minerals were abundant, very few microorganisms specialized in sulfur consumption were present. This aligns with expectations in oxygen-rich environments, as oxygen tends to react with sulfur, making it unavailable to microorganisms. The researchers suggested that sulfur-metabolizing microbes may be more commonly found in low-oxygen environments, such as Mars.

Additionally, the study revealed that a majority of the microorganisms found in these caves were previously undescribed by science, contributing to what is referred to as microbial dark matter. The existence of such unknown microorganisms hints at novel survival strategies.

The research team concluded that lava tube caves could be a crucial source of new microorganisms, aiding astrobiologists in their quest to understand potential life forms on Mars. They recommended that future investigations into Martian caves should focus on detecting small-scale microbes in various mineral contexts. Over time, the interplay between cave conditions and Martian microorganisms may be unveiled as Mars becomes less habitable.


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Microbial Colors in Clouds May Indicate Life on Other Planets

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The clouds in our atmosphere host a myriad of bacteria, fungi, and viruses.

George Pachantouris/Getty Images

Scientists have for the first time measured the colors of microbes residing in high-altitude clouds, providing insights that could aid the search for extraterrestrial life.

Microorganisms have been found in Earth’s atmosphere at densities reaching up to 100,000 per cubic meter, contributing to cloud formation.

These tiny life forms produce pigments to shield themselves from intense ultraviolet radiation present at high altitudes.

Thus, if similar airborne organisms are present in the atmospheres of other planets, they might be detectable from afar by studying the light wavelengths, or spectra, reflected by those planets. Ligia Coelho from Cornell University in New York notes.

“Essential pigments are robust and surprisingly universal biosignatures,” Coelho explains. “Ultraviolet light is a common stressor for life on any planet with a star, suggesting that reflective pigments serving similar roles could evolve elsewhere.”

To investigate the colors of airborne microorganisms on Earth, Coelho’s team cultured microbes collected by Brent Kritner from the University of Florida and colleagues. Kritner’s team employed helium balloons to collect microorganisms attached to sticky rods at altitudes between 3 and 38 kilometers above the Earth.

Subsequently, Coelho’s team analyzed the reflectance spectra of the colored compounds produced by these microbes, observing a spectrum of colors from yellow to orange to pink, manifested by carotenoid pigments like beta-carotene, commonly found in carrots.

Finally, the team simulated how these spectra might alter across various planetary conditions, including wetter and drier environments.

“For the first time, we possess actual reflectance spectra of pigmented microorganisms in the atmosphere, which can serve as reference points for modeling and detecting life forms within clouds,” stated Coelho.

Astronomers are actively searching for signs of life beyond our solar system by analyzing light reflected from planets, which reveals the chemical footprints of gases—like oxygen and methane—that may be produced by biological activities, as well as indicators of surface life such as green chlorophyll generated by vegetation and microorganisms.

Up until recent findings, clouds surrounding exoplanets were perceived as obstructions, hindering the identification of atmospheric and surface-level biosignatures.

“Our planetary simulations indicate that when exoplanetary clouds are rich in these microorganisms, their spectra can change in identifiable ways,” Coelho elaborates.

Forthcoming space telescopes, such as NASA’s proposed Habitable World Observatory, could bolster efforts to search for life in other star systems.

Nevertheless, even with advancements in technology, the concentrations of airborne microorganisms need to be significantly high to be detected from extensive distances. “The concentrations of these organisms present in Earth’s atmosphere are currently below our detection limits,” Coelho remarked.

“According to the expected resolution of NASA’s Habitable World Observatory (which we modeled in this study), we would require microbial cell densities akin to those found in oceanic algal blooms, which are typically detectable from space.”

Claire Fletcher, a researcher from the University of New South Wales, suggests that it may be advantageous to search for carotenoids produced by microbes in the stratosphere alongside chlorophyll from plant life. “However, while we assume that life on these exoplanets will mirror that of Earth, this assumption may not hold true,” she cautions.

Peter Tuthill, a professor at the University of Sydney, expresses skepticism regarding the utility of the stratospheric biosignatures identified in the study for extraterrestrial life detection. “I appreciate the fact that we don’t need to engineer devices to detect biosignatures amidst noise from distances of 20 parsecs,” he remarks.

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Source: www.newscientist.com

Ancient Mammoth Remains Yield the Oldest Host-Related Microbial DNA on Record

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In a recent study, researchers examined the ancient microbial DNA of 483 mammoths, preserved for over a million years. This included 440 newly analyzed unpublished samples from Steppe Mammoths dating back 1.1 million years. Through metagenome screening, contaminant filtering, damage pattern analysis, and phylogenetic inference, they identified 310 microorganisms linked to various mammoth tissues.

Ginet et al. Partial genome reconstruction of erysipelothrix, representing the oldest confirmed host-related microbial DNA from the oldest mammoth samples. Image credit: Ginet et al., doi: 10.1016/j.cell.2025.08.003.

“Envision a mammoth tooth from a million years ago,” stated Dr. Benjamin Ginette, a postdoctoral researcher at Stockholm’s Paleogenetic Centre and the Swedish Museum of Natural History.

“Imagine if it still harbors traces of ancient microorganisms that existed alongside this mammoth?”

“Our findings push the boundaries of microbial DNA research beyond a million years, unlocking new avenues for understanding how host-associated microorganisms evolved in tandem with their hosts.”

The team discovered six microbial groups consistently linked to mammoth hosts, including relatives of Actinobacillus, Pasturella, Streptococcus, and erysipelothrix. Some of these microbes may have been pathogenic.

For instance, one Pasturella bacteria identified in this study is closely related to the pathogens responsible for a fatal outbreak among African elephants.

Given that African and Asian elephants are the closest living relatives of mammoths, these results raise concerns about whether mammoths could also be susceptible to similar infectious diseases.

Remarkably, scientists have reconstructed a partial genome of erysipelothrix from a Steppe Mammoth that lived 1.1 million years ago, marking the oldest known host-related microbial DNA ever recovered.

This advances our understanding of the interactions between ancient hosts and their microbiota.

“As microorganisms evolved rapidly, acquiring reliable DNA data spanning over a million years has felt like tracing a path that continually rewrites itself,” noted Dr. Tom van der Bark of the Paleobiological Centre and the Museum of Natural History in Sweden.

“Our discoveries illustrate that ancient artifacts can retain biological insights far beyond the host genome, offering a perspective on how microorganisms influenced Pleistocene ecosystem adaptation, disease, and extinction.”

Determining the exact impact of the identified microorganisms on mammoth health is challenging due to DNA degradation and limited comparative data, but this study provides an unparalleled view into the microbiota of extinct megafaunas.

The findings suggest that multiple microbial lines coexisted with mammoths for hundreds of thousands of years, spanning vast geographical areas and evolutionary timescales, from the extinction of woolly mammoths on Lengel Island over a million years ago to their decline around 4,000 years ago.

“This research opens a new chapter in understanding the biology of extinct species,” says Professor Love Darren, a researcher at the Swedish Museum of Natural History and the Paleogenetic Centre at Stockholm University.

“Not only can researchers study the mammoth genome itself, but they can also begin to explore the microbial communities that cohabited with it.”

This study was published this week in the journal Cell.

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Benjamin Ginet et al. Ancient host-related microorganisms recovered from mammoths. Cell published online on September 2, 2025. doi: 10.1016/j.cell.2025.08.003

Source: www.sci.news

The Unusual Microbial Alliance Reveals the Evolution of Complex Life

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Stromatolites are rock-like structures formed by bacteria in shallow water

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Microorganisms in the remote bays of Western Australia are interconnected through tiny tubes, suggesting early stages of complex life evolution.

In Shark Bay, known by the Indigenous name Gathaagudu, microbes create slimy, multi-layered assemblages called microbial mats. This challenging environment, buffeted by tidal shifts and temperature fluctuations, has fostered bacterial communities alongside another single-celled organism known as Archaea, which have thrived here for tens of thousands of years. These microorganisms often coexist symbiotically, forming layered sedimentary structures known as stromatolites.

“The mats develop under hypersaline conditions with elevated UV levels. It withstands cyclones. Despite facing numerous threats, they persist,” comments Brendan Burns from the University of New South Wales in Sydney.

He posits that these contemporary microbial communities may resemble those that existed billions of years ago when complex life first emerged. This evolution might have been driven by a mutual dependence between bacteria and Archaea, leading to the formation of more complex cells known as eukaryotes.

Burns and his team returned some of these microbial mat communities to the lab to cultivate the organisms in high-salinity, low-oxygen conditions.

They successfully cultured only one type of bacterium, stromatodesulfovibrio nilemahensis, and a newly identified archaeon named Nearachaeum marumarumayae, a member of the Asgard Archaea group. These archaeal bacteria, named after the gods’ abode in Norse mythology, are regarded as the closest relatives to the eukaryotic cells that comprise the bodies of animals, plants, and humans.

According to team members, “These organisms seem to directly interact and share nutrients,” states Iain Duggin of the Sydney Institute of Technology. Although there is no direct evidence yet, the complete genomic sequence obtained allows for speculation regarding the metabolic processes of both organisms.

The genomic analysis indicated that bacteria synthesize amino acids and vitamins, while the Archaea produce hydrogen and various compounds, such as acetic and sulfuric acids. Both sets of products are unique, indicating a dependency on each other.

The researchers also observed indications of direct interaction between the two species. “We have observed what we refer to as nanotubes,” notes Duggin. “These microscopic tubes, seemingly produced by bacteria, establish direct connections to the surface of the Asgard cells.”

3D reconstruction based on electron microscope images showing cell membranes of Archaeon (blue) and bacteria (green), with nanotubes (pink) between them

Dr. Matthew D. Johnson, Bindusmita Paul, Durin C. Shepherd et al.

In addition to their interactions, the Archaeon cells generate vesicle chains that resemble SAC-like structures utilized for transporting molecules along extracellular fibers. Duggin notes that these nano-sized vesicles appear to engage with the nanotubes formed by the bacteria.

“While nanotubes may be too slender for conduits, they facilitate a type of multicellular binding that enhances resource sharing,” asserts Duggin.

The researchers identified a protein similar to human muscle proteins, a genomic sequence coding for a previously unknown protein, and a protein consisting of about 5,500 amino acids, which is substantial for ancient species. “While I can’t claim it’s directly connected to human muscle proteins, it suggests that their evolutionary origins may trace back much further,” says team member Kate Mischey from the University of New South Wales.

“What fascinates me most are the direct connections formed by nanotubes between bacteria and archaea,” comments purilópez-garcía from Parisa Clay University, France. “Such interactions have not been documented in prior cultures.”

However, discerning the exact behaviors of bacteria and Archaea is challenging, remarks Buzz Baum from the MRC Institute of Molecular Biology, Cambridge, UK. “It’s a complex relationship of conflict and cooperation,” he notes. “They interact, share, and sometimes clash, demonstrating a nuanced understanding of each other’s presence.”

Duggin believes the prevalent dynamic is more cooperative than combative. “These organisms coexisted in our culture for over four years, suggesting a level of harmony rather than contention,” he adds.

Burns and his colleagues propose that their findings may reflect an early stage in the evolution of eukaryotic cells within microbial mats. Roland Hatzenpichler at Montana State University aligns with this perspective.

“The study’s outcomes indicate that the newly identified Asgard Archaea engage directly with sulfate-reducing bacteria,” he remarks.

However, Lopez Garcia cautions that these interactions may not date back beyond 2 billion years. “While these archaeal and bacterial forms are modern, the microbial environments they inhabit may provide insights into ancient ecosystems,” he explains.

According to Hatzenpichler, we may be on the verge of better understanding the similarities between recent microorganisms and the cells they collaborate with to form primitive nucleated cells. “We’re now in an advantageous position to uncover deeper truths,” he concludes.

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Underground Microbial Life Could Endure on Mars, Europa, and Enceladus with the Help of Cosmic Rays

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A recent study conducted by New York University Abu Dhabi suggests that radiolysis, triggered by cosmic rays in galaxies, may serve as a potential energy source for microbial metabolism within the subsurface environments of rocky celestial bodies such as Mars, Europa, and Enceladus.

NASA’s Cassini spacecraft captured this stunning mosaic of Enceladus as it flew past this geologically active moon of Saturn on October 5, 2008. Image credit: NASA/JPL/Space Science Institute.

While ionized radiation is known for its detrimental effects on biological systems, such as causing damage to DNA and generating reactive oxygen species, it can also yield biologically beneficial outcomes.

Though direct exposure to high radiation levels can be harmful to biological activity, ionizing radiation can create numerous biologically useful products.

One such process involves the generation of valuable biological products through charged particle-induced radiolysis.

“We investigated the consequences of cosmic rays striking surfaces containing water or ice,” noted Dr. Dimitra Atli, PhD, from New York University Abu Dhabi, alongside colleagues from Washington University, the University of Tennessee, Rice University, and Santander University.

“The impact of these rays breaks down water molecules and releases tiny particles known as electrons.”

“Certain bacteria on Earth are capable of utilizing these electrons for energy, akin to how plants harness sunlight.”

“This phenomenon, known as radiolysis, allows for life to persist in dark, cold environments devoid of sunlight.”

This newly reorganized color view presents a massive surface of Europa. The image scale is 1.6 km per pixel, with the northern part of Europa on the right. Image credit: NASA/JPL-Caltech/Seti Institute.

Researchers utilized computer simulations to assess the energy output of this process on the icy moons of Mars, Jupiter, and Saturn.

These icy moons are believed to harbor liquid water beneath their thick ice crusts.

Findings indicate that Enceladus is the most promising candidate for supporting life in this manner, followed closely by Mars and Europa.

“This discovery reshapes our understanding of potential habitats for life,” Dr. Atri commented.

“Rather than confining our search to warm, sunlit planets, we can now consider cold, dark regions where water lies beneath the surface and is subjected to cosmic rays.”

“Life might exist in many more locations than previously thought.”

This image captured by Mars Express’s high-resolution stereo camera reveals an overview of Mars, with patches of yellow, orange, blue, and green on a muted gray background, depicting various surface compositions. Image credits: ESA/DLR/FU BERLIN/G. MICHAEL/CC BY-SA 3.0 IGO.

In their research, the authors introduce a new concept termed the Radiolysis Habit Zone.

Unlike the traditional “Goldilocks zone”—the region around a star where planets can sustain liquid water—this new zone emphasizes the potential for subsurface water that can be energized by cosmic radiation.

Given that cosmic rays are ubiquitous throughout the universe, this suggests that numerous additional locations may harbor life.

“These findings offer fresh directions for future space exploration,” remarked Reservers.

“Scientists can target the underground environments of these icy moons and Mars instead of solely searching for life on their surfaces.

“This study paves the way for thrilling new avenues in life exploration across the cosmos, implying that even the coldest and darkest regions may have conditions suitable for life.”

The study will be published in International Journal of Astrobiology.

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Dimitra Atri et al. 2025. Estimating the potential of ionizing radiation-induced radiolysis for microbial metabolism in Earth’s planets and moons with tenuous atmospheres. International Journal of Astrobiology 24:E9; doi:10.1017/s1473550425100025

Source: www.sci.news

Researchers suggest that microbial life on Mars could be supported by melted water beneath the ice

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On Earth, solar radiation can travel up to several meters into the ice, depending on its optical properties. Organisms in the ice can harness the energy from photosynthetically active radiation while being protected from harmful ultraviolet radiation. On Mars, there is no effective ozone shield, so about 30% more harmful ultraviolet radiation reaches the surface compared to Earth. However, a new study shows that despite strong surface UV radiation, mid-latitude ice on Mars contains 0.01-0.1% dust, ranging from a few centimeters deep to several centimeters deep. It has been shown that a radioactive habitable zone exists with a range of up to 3000 m. Cleaner ice.

The white edges along these canyons on Mars' Terra Sirenum are thought to be dusty water ice. cooler others. It is thought that melt water could form beneath the surface of this type of ice, providing a potential site for photosynthesis. Image credit: NASA / JPL-Caltech / University of Arizona.

“Today, if we are trying to find life anywhere in the universe, the icy outcrops on Mars are probably one of the most accessible places we should look,” said a researcher at NASA's Jet Propulsion Laboratory. said Dr. Aditya Kuler.

Mars has two types of ice: frozen water and frozen carbon dioxide.

Dr. Cooler and his colleagues investigated water ice. The ice masses were formed from snow mixed with dust that fell on Mars during a series of ice ages over the past million years.

That ancient snow has since solidified into ice and is still dusted with dust.

Dust particles can block light in deeper layers of ice, but they are the key to explaining how underground pools of water form within the ice when exposed to the sun.

The black dust absorbs more sunlight than the surrounding ice, causing the ice to warm and potentially melt several feet below the surface.

Mars scientists are divided on whether ice actually melts when exposed to the Martian surface.

It's thought to be caused by the planet's thin, dry atmosphere, where water ice sublimates and turns directly into gas, similar to dry ice on Earth.

But the atmospheric effects that make melting difficult on Mars' surface don't apply beneath the surface of dusty snowpack and glaciers.

On Earth, dust in ice can create what are called cryoconite holes. This is a small cavity that forms in the ice when windblown dust particles (called cryoconite) land there, absorb sunlight, and melt deep into the ice each summer. is.

Eventually, these dust particles stop sinking as they move away from the sun's rays, but they still generate enough heat to create pockets of melted water around them.

This pocket can foster a thriving ecosystem of simple organisms.

“This is a common phenomenon on Earth,” says Arizona State University researcher Phil Christensen.

“Rather than melting from the top down, thick snow and ice melts from the inside out, letting in sunlight that warms it like a greenhouse.”

In 2021, the authors discovered powdery water ice exposed inside canyons on Mars and proposed that many canyons on Mars are formed by erosion as ice melts into liquid water.

Their new paper suggests that powdery ice lets in enough light for photosynthesis to occur as deep as 3 meters (9 feet) below the surface.

In this scenario, the upper layer of ice prevents shallow underground pools of water from evaporating, while also protecting them from harmful radiation.

This is important because, unlike Earth, Mars does not have a protective magnetic field to protect it from both the Sun and radioactive cosmic ray particles flying through space.

“Water ice most likely to form underground pools would exist in tropical regions of Mars between 30 and 60 degrees latitude, in both the northern and southern hemispheres,” the researchers said.

of paper appear in the diary Communication Earth and Environment.

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AR cruller others. 2024. Possibility of photosynthesis on Mars in snow and ice. common global environment 5,583;doi: 10.1038/s43247-024-01730-y

This article is a version of a press release provided by NASA.

Source: www.sci.news

Researchers chart extensive subterranean microbial world

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Professor Magdalena Osburn removed the samples during a site visit in August.

A former gold mine serves as a gateway to explore microbes deep within the Earth’s crust. If you add up the mass of all the microorganisms that live beneath the Earth’s surface, their combined biomass exceeds the biomass of all life in the oceans. However, because of the difficulty of accessing these depths, this myriad of subterranean organisms remains largely unexplored and poorly understood. Using a repurposed gold mine in the Black Hills of South Dakota as a laboratory, Northwestern University researchers have created the most comprehensive map yet of the elusive and rare microbes that live beneath our feet. In total, the researchers characterized nearly 600 microbial genomes, some of which were new to science. Within this group, most microbes fit into one of two categories, said Magdalena Osburn, a Northwestern geoscientist who led the study. And “maximalists” are ready to greedily grab any resources that may come their way. This study was recently published in the journal environmental microbiology.

This new research not only expands our knowledge of the microbes that live deep underground, but also hints at potential life that may one day be discovered underground. Mars. Because microbes rely on resources in rocks and water that are physically distant from the surface, these organisms could survive buried in Mars’ dusty red depths. “The deep underground biosphere is huge. It’s just a huge space,” said Osburn, an associate professor of Earth and planetary sciences in Northwestern University’s Weinberg College of Arts and Sciences. “We used the mine as a conduit to access a biosphere that is difficult to reach no matter how we approach it. A lot of that comes from understudied groups. DNA, you can understand what kind of creatures live underground and find out what they do. These are organisms that we cannot grow in the laboratory or study in more traditional settings. They are often referred to as “microbial dark matter” because we know so little about them.

For the past 10 years, Osburn and his students have been regularly visiting the former Homestake Mine in Reed, South Dakota, collecting geochemical and microbial samples.Now Sanford Underground Research Facility (SURF)’s deep underground laboratory is home to numerous research experiments across a variety of fields. In 2015, Osburn established his six proving grounds. Mine Deep Microbial Observatorythroughout SURF.

Back in Osburn’s lab at Northwestern University, she and her team sequenced the DNA of the microorganisms held within the samples. Of the approximately 600 genomes characterized, microorganisms represented 50 different phyla and 18 candidate phyla. Osburn discovered that within this diverse microbial community, each lineage, at some point, gravitates toward a life-defining trajectory: becoming a minimalist or a maximalist.
“Some of these strains don’t even have the genes to make their own lipids, which is shocking,” Osburn said. “Because how can you make cells without fat? It’s like humans can’t make all the amino acids. Therefore, by consuming protein, amino acid Something we can’t create on our own. But this is on a more extreme scale. Minimalists are the ultimate specialists and we all work together. There’s a lot to share and no duplicate work

Osburn said these underground microbes may provide clues to what might exist elsewhere as we imagine life beyond Earth. “It’s really exciting to see evidence of microbes operating without us, without plants, without oxygen, without surface atmosphere,” she said. “It’s very likely that this kind of life currently exists deep on Mars or in the icy moon’s oceans. The forms of life tell us what lives elsewhere in the solar system.”
And they also affect our own planet. For example, as industry looks for long-term storage for carbon, many companies are exploring the possibility of injecting it deep underground. As we consider those options, Osburn reminds us not to forget the microbiome.

Reference: “A Metagenomic View of New Microbial and Metabolic Diversity Discovered in the Earth’s Deep Biosphere in DeMMO: Microbial Observatory in South Dakota, USA” by Lily Momper, Caitlin P. Casar, and Magdalena R. Osburn, 2023. November 14th, environmental microbiology.DOI: 10.1111/1462-2920.16543 This research was supported by NASA Exobiology (grant numbers NNH14ZDA001N, NNX15AM086), the David and Lucille Packard Foundation, and the Canadian Institute for the Advancement of Research—Earth 4D.

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