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Electric Dirt is teeming with mysterious new bacteria that could rewrite textbooks

Electric Dirt is teeming with mysterious new bacteria that could rewrite textbooks 86

For Lars Peter Nielsen, it all started with the mysterious disappearance of hydrogen sulfide. The microbiologist collected black, smelly mud from the bottom of Aarhus Harbor in Denmark, threw it into large glass beakers and inserted special microsensors that detected changes in the chemical composition of the mud. 

At the beginning of the experiment, the composition was saturated with hydrogen sulfide – a source of odor and color of the sediment. But 30 days later, one strip of dirt turned pale, which indicates the loss of hydrogen sulfide. Eventually, the microsensors showed that the entire connection was gone. Given what scientists knew about the biogeochemistry of mud, recalls Nielsen at Aarhus University, “it didn’t make sense at all.”

The first explanation, he said, was that the sensors were wrong. But the reason turned out to be much more strange: the bacteria connecting the cells create electrical cables that can conduct current up to 5 centimeters through the dirt. 

An adaptation never seen before in microbes allows these so-called cable bacteria to overcome a major problem faced by many organisms living in mud: lack of oxygen. Its absence usually keeps bacteria from metabolizing compounds such as hydrogen sulfide for food. But cables, by binding microbes to oxygen-rich deposits, allow them to react over long distances.

When Nielsen first described the discovery in 2009, his colleagues were skeptical. Philip Meisman, a chemical engineer at the University of Antwerp, recalls thinking, “This is complete nonsense.” Yes, the researchers knew bacteria could conduct electricity, but not at the distances Nielsen suggested. “It was as if our own metabolic processes could affect a distance of 18 kilometers,” says microbiologist Andreas Teske of the University of North Carolina at Chapel Hill.

But the more researchers looked for “electrified” mud, the more they found it in both salt and fresh water. They also identified a second type of dirt-loving electrical microbe: nanowire bacteria, individual cells that grow protein structures that can move electrons over shorter distances. 

These nanowire microbes are found everywhere, including in the human mouth.

Electric Dirt is teeming with mysterious new bacteria that could rewrite textbooks 87

Discoveries are forcing researchers to rewrite textbooks; rethink the role of mud bacteria in the processing of key elements such as carbon, nitrogen and phosphorus; and review how they affect aquatic ecosystems and climate change. 

Scientists are also looking for practical applications, exploring the potential of bacteria containing cables and nanowires to combat pollution and power electronic devices. “We are seeing a lot more interactions within microbes and between microbes using electricity,” Meisman says. “I call it the electrical biosphere.”

Most cells thrive by taking electrons from one molecule, a process called oxidation, and transferring them to another molecule, usually oxygen, called reduction. The energy gained from these reactions governs other life processes. In eukaryotic cells, including our own, such “redox” reactions occur on the inner mitochondrial membrane, and the distance between them is tiny – only micrometers. This is why so many researchers have been skeptical about Nielsen’s claim that cable bacteria move electrons through a layer of dirt the size of a golf ball.

Disappearing hydrogen sulfide was the key to proving this. Bacteria make a compound in the mud, breaking down plant debris and other organic materials; in deeper deposits, hydrogen sulfide accumulates due to a lack of oxygen, which helps other bacteria break it down. However, hydrogen sulfide still disappeared in Nielsen’s beakers. Moreover, a rusty tint appeared on the surface of the dirt, which indicated the formation of iron oxide.

Waking up one night, Nielsen came up with a strange explanation: what if bacteria buried in the mud completed the redox reaction, somehow bypassing the oxygen-poor layers? What if, instead, they used the abundant supply of hydrogen sulfide as an electron donor, and then funneled the electrons up towards the oxygen-rich surface? There, in the oxidation process, rust is formed if iron is present.

Finding what carries these electrons has proven difficult. First, Niels Riesgaard-Petersen of Nielsen’s team had to rule out an easier possibility: metal particles in the sediment carry electrons to the surface and cause oxidation. He achieved this by inserting a layer of glass beads, which do not conduct electricity, into a column of dirt. Despite this obstacle, the researchers still found an electric current moving through the mud, suggesting that the metal particles were not conductive.

To see if a cable or wire was carrying electrons, the researchers then used tungsten wire to make a horizontal cut through the mud pillar. The current went out, as if a wire had been cut. Other work narrowed down the size of the conductor, suggesting that it should be at least 1 micrometer in diameter. “This is the usual size of bacteria,” says Nielsen.

Electric Dirt is teeming with mysterious new bacteria that could rewrite textbooks 88

Ultimately, electron micrographs revealed a likely candidate: long, thin bacterial fibers that appeared in a layer of glass beads inserted into beakers filled with mud from Aarhus Harbor. Each filament consisted of a stack of cells – up to 2,000 – enclosed in a ribbed outer membrane. In the space between this membrane and the cells stacked on top of each other, a plurality of parallel “wires” stretched the thread over its entire length. The cable-like appearance inspired the common name of the microbe.

Meisman, a former skeptic, was quickly converted. Shortly after Nielsen announced his discovery, Meismann decided to investigate one of his own samples of sea mud. “I noticed the same color changes in the sediment that he saw,” Meisman recalls. “It was Mother Nature’s direction to take it more seriously.”

His team began developing tools and methods for microbial research, sometimes working in conjunction with Nielsen’s group. It was hard going. Bacterial filaments tend to break down quickly after isolation, and standard electrodes for measuring currents in small conductors do not work. But once the researchers learned to pick out a single strand and quickly attach an individual electrode, “we saw really high conductivity,” Meisman says. Live cables can’t compete with copper wires, he said, but they match the conductors used in solar panels and mobile phone screens, as well as the best organic semiconductors.

The researchers also analyzed the anatomy of the cable bacteria. Using chemical baths, they isolated the cylindrical shell, finding that it contained 17 to 60 parallel fibers glued together inside. The shell is the source of conduction, Meisman and colleagues reported last year in Nature Communications. Its exact composition is still unknown, but it may be protein-based.

“It’s a complex organism,” says Nielsen, who now heads the Center for Electro-Microbiology, which was created in 2017 by the Danish government. Among the problems that the center solves is the mass production of microbes in culture. “If we had a pure culture, it would be much easier” to test ideas about cell metabolism and the effect of the environment on conduction, says Andreas Schramm from the center. The cultured bacteria will also make it easier to insulate cable wires and test potential bioremediation and biotechnology applications.

While researchers are puzzling over the bacteria in the cable, others are looking at another big player in electrical mud: nanowire-based bacteria that, instead of folding cells into cables, grow protein wires 20 to 50 nm long from each cell.

As with cable bacteria, the mysterious chemical composition of the deposits led to the discovery of nanowire microbes. In 1987, microbiologist Derek Lovley, now at the University of Massachusetts Amherst, tried to understand how phosphate from fertilizer wastewater – a nutrient that promotes algal blooms – is released from sediment under the Potomac River in Washington, DC. worked and began to weed them out of the dirt. After growing one, now called Geobacter Metallireducens, he noticed (under an electron microscope) that the bacteria had grown bonds with nearby iron minerals. He suspected that electrons were carried along these wires, and eventually figured out that Geobacter orchestrated chemical reactions in the mud, oxidizing organic compounds and transferring electrons to minerals.

Like Nielsen, Lovely faced skepticism when he first described his electrical microbe. Today, however, he and others have registered nearly a dozen types of nanowire microbes, finding them in environments other than dirt. Many carry electrons to and from particles in the sediment. But some rely on other microbes to receive or store electrons. This biological partnership allows both microbes to “engage in new kinds of chemistry that no organism can do alone,” says Victoria Orfan, a geobiologist at the California Institute of Technology. While cable bacteria solve their redox needs by transporting long distances into oxygenated mud, these microbes depend on each other’s metabolism.

Some researchers still debate how bacterial nanowires conduct electrons. Lovley and his colleagues are convinced that the key are chains of proteins called pilins, which are composed of circular amino acids. When he and his colleagues reduced the number of ringed amino acids in the pilin, the nanowires became less conductive. “It was really amazing,” says Lovely, because it is generally accepted that proteins are insulators. But others think that this question is far from being solved. Orphan, for example, says that although “there is overwhelming evidence … I still don’t think [the conduction of the nanowire] is well understood.”

What is clear is that electrical bacteria are everywhere. In 2014, for example, scientists found cable bacteria in three very different habitats in the North Sea: in a tidal salt swamp, in a seabed basin where oxygen levels drop to almost zero at some times of the year, and in a flooded muddy plain near the sea. … Coast. (They didn’t find them in a sandy area populated with worms that churn up sediments and disrupt cables.) Elsewhere, researchers have found DNA evidence of cable bacteria in deep, oxygen-poor ocean basins, hot spring areas, and cold conditions. spills, and mangroves and tidal banks in both temperate and subtropical regions.

Cable bacteria are also found in freshwater environments. After reading Nielsen’s articles in 2010 and 2012, a team led by microbiologist Rainer Meckenstock re-examined sediment cores drilled during a groundwater contamination survey in Düsseldorf, Germany. “We found [the cable bacteria] exactly where we thought we would find them,” at depths where oxygen was depleted, recalls Mekenstock, who works at the University of Duisburg-Essen.

Nanowire bacteria are even more widespread. Researchers have found them in soils, rice fields, deep bowels and even sewage treatment plants, as well as in freshwater and marine sediments. They can exist wherever biofilms are formed, and the ubiquity of biofilms is further evidence of the great role these bacteria can play in nature.

The wide range of electric mud bacteria also suggests that they play an important role in ecosystems. For example, by preventing the build-up of hydrogen sulfide, cable bacteria likely make dirt more habitable for other life forms. Meckenstock, Nielsen, and others have found them on or near the roots of seagrass and other aquatic plants, which release oxygen, which bacteria probably use to break down hydrogen sulfide. This, in turn, protects the plants from the toxic gas. The partnership “seems very characteristic of aquatic plants,” Meckenstock said.

Robert Aller, a marine biogeochemist at Stony Brook University, believes bacteria can also help many underwater invertebrates, including worms that build burrows that allow oxygenated water to enter the mud. He found cable bacteria sticking out from the sides of the worm tubes, presumably so they could use that oxygen to store electrons. In turn, these worms are protected from toxic hydrogen sulfide. “Bacteria make [the burrow] more livable,” says Aller, who described these links in a July 2019 article in Science Advances.

Microbes also alter the properties of dirt, says Saira Malkin, an ecologist at the University of Maryland’s Center for Environmental Sciences. “They’re especially effective … ecosystem engineers.” Cable bacteria “grow like wildfire,” she says; On tidal oyster reefs, she found, One cubic centimeter of mud may contain 2,859 meters of cables that cement the particles in place, possibly making the sediment more resistant to marine organisms.

The bacteria also alters the chemical composition of the dirt, making the layers closer to the surface more alkaline and the deeper ones more acidic, Malkin found. Such pH gradients can affect “numerous geochemical cycles,” including those associated with arsenic, manganese and iron, she said, creating opportunities for other microbes.

Because vast swathes of the planet are covered in mud, the researchers say, bacteria associated with cables and nanowires are likely to have an impact on the global climate. Nanowire bacteria, for example, can take electrons from organic materials such as dead diatoms and then transfer them to other bacteria that produce methane, a powerful greenhouse gas. Under various circumstances, cable bacteria can reduce methane production.

In the coming years, “we will see widespread recognition of the importance of these microbes to the biosphere,” says Malkin. A little over ten years after Nielsen noticed the mysterious disappearance of hydrogen sulfide from the Aarhus mud, he says: “It is dizzying to think about what we are dealing with here.”

Next up: a phone powered by microbial wires?

The pioneers of electrical microbes quickly thought about how to use these bacteria. “Now that we know that evolution has been able to create electrical wires, it would be a shame if we didn’t use them,” says Lars Peter Nielsen, a microbiologist at the University of Aarhus.

One possible application is the detection and control of pollutants. Cable microbes seem to thrive in the presence of organic compounds like oil, and Nielsen and his team are testing the possibility that the abundance of cable bacteria signals the presence of undiscovered pollution in aquifers. The bacteria do not directly degrade the oil, but they can oxidize the sulfide produced by other oily bacteria. They can also help clean up; rainfall recovers faster from crude oil contamination when it is colonized by cable bacteria, another research group reported in January in the journal Water Research. In Spain, a third team is investigating whether nanowire bacteria can accelerate the cleanup of polluted wetlands. And even before the nanowire bacteria were electric,

Electrical bacteria can also give rise to new technologies. They can be genetically modified to alter their nanowires, which can then be cut to form the backbone of sensitive wearable sensors, according to Derek Lovley, a microbiologist at the University of Massachusetts (UMass), Amherst. “We can design nanowires and adapt them to specifically bind compounds of interest.” For example, in the May 11 Lovely issue of Nano Research, UMass engineer Jun Yao and colleagues described a nanowire-based sensor that detects ammonia in concentrations needed for agricultural, industrial, environmental, and biomedical applications.

Created as a film, nanowires can generate electricity from moisture in the air. Researchers believe the film generates energy when a moisture gradient occurs between the top and bottom edges of the film. (The top edge is more exposed to moisture.) As the hydrogen and oxygen atoms of the water separate due to the gradient, charge is generated and electrons flow. Yao and his team reported in Nature on Feb.17 that such a film could create enough energy to light a light-emitting diode, and 17 such devices connected together could power a mobile phone. The approach is “a revolutionary technology for generating renewable, clean and cheap energy,” says Qu Liangti, a materials scientist at Tsinghua University. (Others are more careful noting

Ultimately, the researchers hope to harness the electrical abilities of bacteria without having to deal with picky microbes. Catch, for example, persuaded the common laboratory and industrial bacterium Escherichia coli to make nanowires. This should make it easier for researchers to mass-produce the structures and study their practical applications.


Science & Technology

A lack of oxygen leads to aging, excess oxygen leads to immortality

A lack of oxygen leads to aging, excess oxygen leads to immortality 89

Israeli scientists claim that by using only oxygen, they have successfully reversed the biological aging process.

A recent study conducted by Tel Aviv University professor Shai Efrati and a team at Shamir Medical Center showed that when healthy adults over 64 were placed in a pressurized chamber and given pure oxygen for 90 minutes a day, five days a week and within three months, the aging process not only slowed down, but actually changed in the opposite direction.

In particular, a study published in the peer-reviewed journal Aging focused on whether this oxygen enrichment process could reverse two key indicators of biological aging: the contraction of DNA telomeres and the accumulation of senescent cells in tissues. Telomeres are located at the ends of a chromosome, consist of repeating sequences of non-coding DNA, and serve as caps to protect the chromosome from damage during replication.

A lack of oxygen leads to aging, excess oxygen leads to immortality 90

Each time replication occurs, these bumpers take a hit, making the chromosomes shorter and shorter. Once the telomere reaches a certain length, the cell can no longer replicate, which leads to aging: malfunctioning of cells, which ultimately leads to cognitive or other age-related impairments and even diseases such as cancer.

About 35 adults over the age of 64 took part in the study and applied hyperbaric oxygen therapy, using 100% oxygen at an ambient pressure greater than one absolute atmosphere to increase the amount of oxygen dissolved in body tissues.

A lack of oxygen leads to aging, excess oxygen leads to immortality 91

Every 20 minutes, participants were asked to remove their masks for five minutes, returning oxygen to normal levels.

However, during this period, the researchers saw that fluctuations in free oxygen concentration were interpreted at the cellular level as a lack of oxygen – rather than interpreting the absolute level of oxygen.

In other words, repeated intermittent hyperoxic (increased oxygen levels) exposure induced many of the mediators and cellular mechanisms that are usually induced during hypoxia (low oxygen levels). Dr. Efrati calls this the hyperoxic-hypoxic paradox.

“The fluctuations in the oxygen level that we have created is what matters,” he told The Jerusalem Post. “During this process, there is, as it were, a lack of oxygen, which causes cell regeneration.”

The practical consequences of therapy include increased attention, processing speed, and executive function, which tend to decrease with age and about which more than 50% of people over the age of 60 express concern.

According to the study, the changes were equivalent to having the participants’ bodies at the cellular level go back 25 years.

“We’re not [just] slowing aging – we’re moving back in time,” says Dr. Efrati. Efrati has been studying aging for ten years and runs Aviva clinics in Florida. The study, he said, is evidence that the cellular basis of the aging process can be reversed, adding that it “offers hope and opens up the opportunity for many young scientists to target aging as a reversible disease.”

It could also allow doctors and scientists to find a way to control telomere length and develop drugs to help them grow again when needed. But will it make people live longer?

The duration of the effect has yet to be determined in the long term, says Efrati. But “probably yes.” We know people with shorter telomeres die earlier, so that makes sense.”

At the moment, the only drawback of the study is the limited sample size, that is, so far relatively few people have participated in the experiment, but over time, scientists will solve this problem too.

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Cyberfarm 2077. YouTuber showed what a Russian cyber village could look like

Cyberfarm 2077. YouTuber showed what a Russian cyber village could look like 92
Photo: video screenshot

On November 19, the day the Cyberpunk 2077 video game was supposed to be released, a five-minute video about a Russian cyber village appeared on YouTube. It combines the aesthetics of cyberpunk with the life of the Russian provinces.

Cyberfarm 2077. YouTuber showed what a Russian cyber village could look like 93

Russian director and blogger Sergei Vasiliev made a short film that is an excerpt from the life of a fictional Russian village with the technologies of the future. The short film was shot in the style of a video blog. 

“They say that Russia is a technically backward country, there are no roads, no robotics, rockets do not fly, and mail takes too long. [This is not true],” the creators say.

The main character, a farmer called Nikolai, talks about his cyber farm, where three androids work, and invites new workers to his business. The robots milk the cows, walk them and go to fetch water. Instead of a cesspool, there is a black hole in the toilets, and mail is delivered by flying wagons of the Russian Post. New technologies have also solved the problem of Russian roads – cars now fly over it, but even there are holes in the air.

The authors of the short film said that a “creative association of enthusiasts” worked on the creative, and now they “plan to release further videos in the same universe.”

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German scientists have found a drink that kills coronavirus in five minutes

German scientists have found a drink that kills coronavirus in five minutes 94

German scientists from the University of Ulm have discovered a natural product that kills up to 97% of the coronavirus in the body. The researchers published their work in the journal bioRxiv.  

During the study, experts mixed juices with viruses at room temperature and monitored the results. It turned out that black chokeberry juice most effectively suppresses the activity of the virus in the human body – it destroys up to 97% of COVID-19 pathogens in just five minutes.

Scientists have discovered a product that kills coronavirus by 97%

In addition, pomegranate juice can kill up to 80% of the coronavirus pathogens. The rest of natural juices and green tea can also weaken the disease, since they have an acidic environment and plant polyphenols that negatively affect the virus.

Scientists have discovered a product that kills coronavirus by 97% in 5 minutes

In order to get rid of 80% of COVID-19 pathogens, scientists recommended that patients rinse the oropharynx with these solutions and rinse the nasopharynx. The study adds that plant polyphenols and acidic environments have a damaging effect on viral proteins.

During the study, scientists mixed drinks with viral particles and influenza A virus (IAV), adenovirus 5 (AdV5) and SARS-CoV-2. The observation was carried out under room temperature conditions. The experts also worked on swine flu with different juices and teas.

“Preventing the initial infection or reducing the viral load of an infection can relieve symptoms, prevent spread to the lower respiratory tract or transmission to another person,” the study said.

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