Kim Lewis collects dirt. For the past decade, he and his colleagues—all scientists in Massachusetts—have asked friends and family around the United States to send them 1-gallon Ziploc bags of backyard soil. It might not seem like much, but it turns out that a little grime can hold a trove of groundbreaking scientific discoveries.

In 2011, Lewis’s team began analyzing a bag of soil from a grassy field in Maine, focusing on bacteria naturally growing inside. The scientists mixed some of the dirt with water and nutrients—proteins, for instance, and potato starch—and poured the mixture over specially designed domino-sized plastic blocks punctured with dozens of tiny wells. Each minuscule compartment captured 20 microliters of the slurry, which, thanks to the dilution, contained just a single bacterial cell. Finally, the researchers packed the small plastic slabs in buckets with the remainder of the soil and left them alone for a month.

The procedure’s relative simplicity belied its true sophistication. When Lewis, a microbiology professor at Northeastern University, and the other researchers unearthed the blocks, they found just what they were hoping for: The bacteria had multiplied. The wells were teeming with microbes, many of which were species no scientist had ever studied.

The team analyzed 10,000 individual strains of the bacteria and tested whether they could kill other microbes by pitting them against one another in petri dishes. One species, which the scientists dubbed Eleftheria terrae (“free from the earth”), was an especially successful gladiator. The researchers pinpointed E. terrae’s primary weapon, a molecule they named teixobactin, and discovered that it could wipe out the microbes responsible for anthrax and tuberculosis. Teixobactin also saved mice from infections of MRSA (methicillin-resistant Staphylococcus aureus), one of the most infamous superbugs—bacteria that are immune to several different drugs. What’s more, when the researchers coaxed the microbes to evolve resistance to teixobactin, it didn’t work.

In that bag of dirt, Lewis’s team had found an entirely new kind of antibiotic, one of only a few to emerge in the past 50 years—and a potent one at that. The findings, published this January, garnered widespread enthusiasm: “New Antibiotic May Conquer Superbugs,” declared NBCNews.com. “A New Antibiotic That Resists Resistance,” a blog post on National Geographic’s website proclaimed.

Even more exciting is the innovation used to discover teixobactin: the unassuming plastic blocks. Each one is called an iChip, short for isolation chip, so-named because of how it captures microbes from soil. Until now, scientists hunting for antibiotics haven’t been able to study 99 percent of the world’s microbial species because, when ripped from the outdoors and encouraged to grow under desolate laboratory conditions, the vast majority of bacteria die. The iChip overcomes this problem by keeping things dirty: Burying soil microbes in their natural habitat during the culturing process preserves the organic compounds they need to thrive, enticing previously stubborn microorganisms to multiply under human supervision.

The iChip unveils a universe of unexplored bacterial diversity—and of potential antibiotics. Teixobactin may be only the beginning.

This revelation couldn’t be more welcome, because the world’s arsenal of antibiotics is rapidly shrinking, with dire consequences.

Read the article “We Have a New Way to Stop Superbugs. Maybe.” on foreignpolicy.com.