Tag Archive: bacteria

59,000 generations of bacteria, plus freezer, yield startling results

After 26 years of workdays spent watching bacteria multiply, Richard Lenski has learned a thing or two.

He’s learned that naturalist Charles Darwin was wrong about some things. For one, evolution doesn’t always occur in steps so slow and steady that changes can’t be observed.

Lenski also learned that a laboratory freezer can function as a time machine.

A professor at Michigan State University, Lenski has watched E. coli bacteria multiply through 59,000 generations, a span that has allowed him to observe evolution in real time. Since his Long-Term Experimental Evolution Project began in 1988, the bacteria have doubled in size, begun to mutate more quickly, and become more efficient at using the glucose in the solution where they’re grown.

More strikingly, however, he found that one of the 12 bacterial lines he has maintained has developed into what he believes is a new species, able to use a compound in the solution called citrate—a derivative of citric acid, like that found in some fruit—for food.

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Bacteria grown in a dish of fake urine in space behaves in ways never-before-seen in Earth microorganisms, scientists say.

A team of scientists sent samples of the bacterium Pseudomonas aeruginosa into orbit aboard NASA’s space shuttle Atlantis to see how they grew in comparison to their Earth-dwelling counterparts.

The 3D communities of microorganisms (called biofilms) grown aboard the space shuttle had more live cells, were thicker and had more biomass than the bacterial colonies grown in normal gravity on Earth as controls. The space bacteria also grew in a “column-and-canopy” structure that has never been observed in bacterial colonies on Earth, according to NASA scientists.

“Biofilms were rampant on the Mir space station and continue to be a challenge on the [International Space Station], but we still don’t really know what role gravity plays in their growth and development,” NASA’s study leader Cynthia Collins, an assistant professor in the department of chemical and biological engineering at Rensselaer Polytechnic Institute in Troy, N.Y., said in a statement. “Our study offers the first evidence that spaceflight affects community-level behaviors of bacteria, and highlights the importance of understanding how both harmful and beneficial human-microbe interactions may be altered during spaceflight.”

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Samples From the Sky

Earth’s upper atmosphere—below freezing, nearly without oxygen, flooded by UV radiation—is no place to live. But last winter, scientists from the Georgia Institute of Technology discovered that billions of bacteria actually thrive up there. Expecting only a smattering of microorganisms, the researchers flew six miles above Earth’s surface in a NASA jet plane. There, they pumped outside air through a filter to collect particles. Back on the ground, they tallied the organisms, and the count was staggering: 20 percent of what they had assumed to be just dust or other particles was alive. Earth, it seems, is surrounded by a bubble of bacteria.

Scientists don’t yet know what the bacteria are doing up there, but they may be essential to how the atmosphere functions, says Kostas Konstantinidis, an environmental microbiologist on the Georgia Tech team. For example, they could be responsible for recycling nutrients in the atmosphere, like they do on Earth. And similar to other particles, they could influence weather patterns by helping clouds form. However, they also may be transmitting diseases from one side of the globe to the other. The researchers found E. coli in their samples (which they think hurricanes lifted from cities), and they plan to investigate whether plagues are raining down on us. If we can find out more about the role of bacteria in the atmosphere, says Ann Womack, a microbial ecologist at the University of Oregon, scientists could even fight climate change by engineering the bacteria to break down greenhouse gases into other, less harmful compounds.

<i>E. coli</i>, pink gold? <i>(Image:  Steve Gschmeissner/Science Photo Library)</i>

Unleaded, diesel or biofuel? This could become the choice at the pump now we can make biofuels that are identical to the petrol we put in our cars, planes and trucks.

Until now, biofuels have been made up of hydrocarbon chains of the wrong size and shape to be truly compatible with most modern engines – they’ll work, but only inefficiently, and over time they will corrode the engine.

To be used as a mainstream alternative to fossil fuels – desirable because biofuels are carbon-neutral over their lifetime – engines would have to be redesigned, or an extra processing step employed to convert the fuel into a more usable form.

To try to bypass that, John Love from the University of Exeter in the UK and colleagues took genes from the camphor tree, soil bacteria and blue-green algae and spliced them into DNA from Escherichia coli bacteria. When the modified E. coli were fed glucose, the enzymes they produced converted the sugar into fatty acids and then turned these into hydrocarbons that were chemically and structurally identical to those found in commercial fuel.

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The word “antibacterial” generally refers to some sort of chemical substance that kills bacteria. Like antibacterial soap. Cicadas, which don’t always have access to antibacterial soap (the insect market is woefully under served by household cleaning products), have evolved a way to kill bacteria that’s built right into the structure of their wings.

Under an electron microscope, cicada wings are covered with forests of tiny nanopillars, smaller than bacteria. These are pillars, not spikes, with blunt tops as opposed pointy ones. When a bacterium comes in contact with the wing surface, it sticks to these nanopillars, which hold it up in some places but not in others. The bacterial membrane then sags into the spaces between the pillars, and if it sags enough, it’ll rupture, killing the bacterium.

Think about it like one of those inflatable swimming pools: if you fill it with SpaghettiOs and then try to lift it from the sides, the unsupported bottom will eventually tear open and you know what happens next.

This discovery is exciting because it should eventually be possible to replicate the cicada wing structure with synthetic materials and create a mass-producible antibacterial surface. Then we can stick that everywhere, like on public transportation and in bathrooms and Denny’s restaurants — that sort of thing. If we wallpaper these places with cicada-wing nanomaterials that kill bacteria on contact, we won’t have to waste time and money and the goodwill of Mother Earth with chemical cleaning agents, and surfaces will stay bacteria-free permanently.

Pandas are more than just cute, cuddly creatures.

Researchers have found that the endangered animals produce a strong antibiotic in their blood that fights against drug-resistant superbugs – a discovery that may add weight to conservation efforts.

The antibiotic compound, cathelicidin-AM, destroys both fungi and bacteria, and is released by the animal’s immune system to ward off infections, the Telegraph reported.

Scientists at Life Sciences College of Nanjing Agricultural University in China found cathelicidin-AM while studying pandas’ DNA.

The powerful compound can kill bacteria in under an hour, whereas most well-known antibiotics take at least six times longer than that.

The discovery has important implications for humans, as researchers work to find new ways to combat increasingly potent strains of bacteria.

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Living concrete fixes its own cracks with built-in bacteria

Concrete is the most popular building material on the planet, probably because it’s very strong, easy to work with and cheap, being made mostly of rocks. There are some durability issues with concrete, though, and to make it stronger, Dutch scientists have added self-healing capsules to help buildings heal cracks on their own.

Bacteria can fix cracks in concrete the same way that humans can, by filling them in with more concrete materials, or in this case, limestone. To get the bacteria into the concrete in the first place, you just mix in some nutrients and lots of little ceramic spheres full of inactive bacterial spores, which remain inactive until they get wet. When a crack in the concrete opens up and the spores get a drink of water, they get to work turning the calcium in the nutrients into limestone, filling in cracks.

These bacteria, being bacteria, aren’t big or powerful enough to fix large or wide cracks: the maximum crack size that they can fill is a width is about 0.5mm. That’s not really a problem, though, because outside of a major earthquake, all big cracks start as small cracks, and most of them develop into big ones as water gets into them. So, if the bacteria can seal up small cracks as they form, you’ll be preventing bigger cracks from happening later on.

Adding bacteria and nutrients and stuff to concrete mixes isn’t free, and it could add as much as 50% to the materials cost. This sounds like a lot, but the concrete itself usually only accounts for 1-2% of the total cost of building something. Maintaining that building, on the other hand, is far more expensive, so spending a little extra on some helpful bacteria up front could save lots and lots of money in the long term.

Bacteriacrete is currently undergoing optimization and outdoor durability testing, but it could be commercialized in as little as two years.

living cable bacteria

Three years ago, scientists discovered electric currents running through the seabed — but they had no idea what was causing them. But now, researchers from Denmark and the United States believe they have the answer: bacteria that function as living electrical cables. In a remarkable case of biological engineering, scientists have confirmed that each tiny section of the bacteria contains a bundle of insulated wires that leads an electric current from one end to the other.

The discovery could lead to an entirely new class of organic electronics — including devices that could be implanted in the human body.

According to Nils Risgaard-Petersen, Christian Pfeffer, and their colleagues at Aarhus University, they started to suspect that something was up when they noticed the appearance of a previously unknown type of long, multi-cellular bacteria. These bacteria were always present when electric currents were around. Moreover, they could disrupt the currents when they pulled a thin wire through the seabed — a possible indication of broken connections.

Looking at it more closely, they noticed that the bacteria, which is a hundred times thinner than a human hair, contained nanoscale strings that were enclosed by a membrane. They concluded that the entire organism functions as a virtual electric cable — insulating wires and all. And indeed, the researchers note that the structure is very similar to the electric cables that we use on a daily basis.

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Bonnie Bassler discovered that bacteria “talk” to each other, using a chemical language that lets them coordinate defense and mount attacks. The find has stunning implications for medicine, industry — and our understanding of ourselves.

“Allergic diseases have reached pandemic levels,” begins David Artis’s new paper in Nature Medicine. Artis goes on to say that, while everyone knows allergies are caused by a combination of factors involving both nature and nurture, that knowledge doesn’t help us identify what is culpable — it is not at all clear exactly what is involved, or how the relevant players promote allergic responses.

There is some evidence that one of the causes lies within our guts. Epidemiological studies have linked changes in the species present in commensal bacteria — the trillions of microorganisms that reside in our colon — to the development of allergic diseases. (Typically, somewhere between 1,000 and 15,000 different bacterial species inhabit our guts.) And immunologists know that signaling molecules produced by some immune cells mediate allergic inflammation.

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There is a vast, unseen marketplace that connects us all. The traders are the trillions of bacteria that live on or within our bodies; the commodities they exchange are genes. This flow of genes around our bodies allows bacteria to rapidly evolve new skills, including the abilities to resist antibiotics, cause disease, or break down environmental chemicals. In the past, scientists have caught glimpses of individual deals, but now the full size of the marketplace is becoming clear.

The human body is home to 100 trillion microbes, whose cells outnumber ours by ten to one, and whose genes outnumber ours by a hundred to one. These genes are not only more numerous than ours, but they operate under different rules. While we can only pass down our DNA to our children, bacteria and other microbes can swap genes between one another. For example, the gut bacteria of Japanese people have a gene that helps them to digest seaweed. They borrowed it from an oceanic species that hitched its way into Japanese bowels, aboard uncooked pieces of sushi. Continue reading

Scientific American placed Professor Eshel Ben-Jacob and Dr. Itay Baruchi’s creation of a type of organic memory chip on its list of the year’s 50 most significant scientific discoveries in 2007. For the last decade, he has pioneered the field of Systems Neuroscience, focusing first on investigations of living neural networks outside the brain.


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