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Vladimir Fedorenko via Wikimedia Commons // CC-BY-SA 3.0
Vladimir Fedorenko via Wikimedia Commons // CC-BY-SA 3.0

How TB Grew Stronger and Spread Wider with the Collapse of the USSR

Vladimir Fedorenko via Wikimedia Commons // CC-BY-SA 3.0
Vladimir Fedorenko via Wikimedia Commons // CC-BY-SA 3.0

A new study published in the Proceedings of the National Academy of Sciences has found that the USSR’s breakup and subsequent turmoil allowed one strain of tuberculosis to evolve in a virulent, drug-resistant form that continues to plague Central Asia. They also traced the spread of the strain from Central Asia to Afghanistan and then to Europe due to armed conflict and population displacement. 

Every action we take has unpredictable consequences on the world around us, and geopolitical events are no different. With this fact in mind, an international team of anthropologists and disease experts set out to investigate if and how human history could have altered the evolution of one widespread human disease.

Alain Grillet/ Sanofi Pasteur via Flickr Creative Commons // CC BY-ND 2.0

The tuberculosis-causing bacterium (Mycobacterium tuberculosis complex, or MBTC) exists in seven distinct subtypes, or lineages. The second, third, and fourth lineages have been wildly successful as diseases go, but exactly how they’ve done it remains the subject of some disagreement. For this study, the researchers focused on the second lineage (L2), the so-called "Beijing lineage," a particularly nasty strain that’s rapidly spreading and shows drug resistance.

The team collected samples of L2 tuberculosis germs from patients in Europe, South Asia, and Central Asia. They scanned all the bacterial genes in order to sort out the geographic origins of each patient’s TB, as well as to pinpoint the moments in the disease’s evolution when specific mutations—like those that make it resistant to medication—first appeared.

Their results indicated that one especially drug-resistant subtype of L2 was most common in former Soviet states. This would make plenty of sense if the mutations conferring drug resistance had evolved while the states were all part of the same Soviet Union. But the mutations are relatively new. They evolved in those places after the Soviet Union collapsed—a time of intense and violent conflict. On top of that, citizens of these states were being displaced en masse, and public health resources were nearly nonexistent.

The strain has spread as a consequence of armed conflict and population displacement, the authors write. It was introduced to Afghanistan with the 1979–1989 Soviet invasion and occupation. It spread further after the American invasion in 2001, when much of the population experienced further upheavals. L2 continued to mutate in Afghanistan, creating a new strain. More recently it's been detected in Europe in small TB breakouts mostly limited to Afghan refugees.

The authors say the combination of these factors may have created a perfect environment in which TB could grow, get tougher, and become more virulent. Drug-resistant TB continues to be a major health concern in Central Asia. “Our results highlight the detrimental effects of political instability and population displacement on global TB control,” they write, “and demonstrate the power of [these] methods for understanding bacterial evolution in time and space.”

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Scientists Accidentally Make Plastic-Eating Bacteria Even More Efficient
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In 2016, Japanese researchers discovered a type of bacteria that eats non-biodegradable plastic. The organism, named Ideonella sakaiensis, can break down a thumbnail-sized flake of polyethylene terephthalate (PET), the type of plastic used for beverage bottles, in just six weeks. Now, The Guardian reports that an international team of scientists has engineered a mutant version of the plastic-munching bacteria that's 20 percent more efficient.

Researchers from the U.S. Department of Energy's National Renewable Energy Laboratory and the University of Portsmouth in the UK didn't originally set out to produce a super-powered version of the bacteria. Rather, they just wanted a better understanding of how it evolved. PET started appearing in landfills only within the last 80 years, which means that I. sakaiensis must have evolved very recently.

The microbe uses an enzyme called PETase to break down the plastic it consumes. The structure of the enzyme is similar to the one used by some bacteria to digest cutin, a natural protective coating that grows on plants. As the scientists write in their study published in the journal Proceedings of the National Academy of Sciences, they hoped to get a clearer picture of how the new mechanism evolved by tweaking the enzyme in the lab.

What they got instead was a mutant enzyme that degrades plastic even faster than the naturally occurring one. The improvement isn't especially dramatic—the enzyme still takes a few days to start the digestion process—but it shows that I. sakaiensis holds even more potential than previously expected.

"What we've learned is that PETase is not yet fully optimized to degrade PET—and now that we've shown this, it's time to apply the tools of protein engineering and evolution to continue to improve it," study coauthor Gregg Beckham said in a press statement.

The planet's plastic problem is only growing worse. According to a study published in 2017, humans have produced a total of 9 billion tons of plastic in less than a century. Of that number, only 9 percent of it is recycled, 12 percent is incinerated, and 79 percent is sent to landfills. By 2050, scientists predict that we'll have created 13 billion tons of plastic waste.

When left alone, PET takes centuries to break down, but the plastic-eating microbes could be the key to ridding it from the environment in a quick and safe way. The researchers believe that PETase could be turned into super-fast enzymes that thrives in extreme temperatures where plastic softens and become easier to break down. They've already filed a patent for the first mutant version of the enzyme.

[h/t The Guardian]

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Here's What You Need to Know About That Massive Egg Recall
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It's never encouraging to hear that one of your favorite foods might give you the intestinal equivalent of a napalm bombing, but that's the current situation with some eggs. The U.S. Food and Drug Administration (FDA) announced Friday that more than 200 million eggs are voluntarily being recalled by Rose Acre Farms of Seymour, Indiana following concerns that their product may have been contaminated by Salmonella Braenderup, a volatile and potentially fatal bacteria that no one wants on their breakfast plate.

Does this mean you should throw out all the eggs in your fridge? No—but you definitely need to check and see if you purchased any that have been affected by the recall. The eggs were shipped to consumers in Colorado, Florida, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, Virginia, and West Virginia.

Residents in those states should look for the brand names affected, which include County Daybreak, Crystal Farms, Coburn Farms, Sunshine Farms, Glenview, Great Value, and those sold under the Food Lion retail banner. Eggs were also distributed to Walmart stores and Waffle Houses. The plant number (P-105) will be stamped somewhere on the carton.

While the 22 illnesses reported so far appear minor compared to Rose Acre's output—they produce over 2 million eggs daily—salmonella is not to be trifled with. If you have an affected carton, you can return it to the store for a full refund or call Rose Acre at 855-215-5730.

[h/t Today]

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