Scientists Discover Plastic-Munching Microbe in Waste Site

A common fixture in refrigerators, furniture and footwear, polyurethane plastic is pretty much always in high demand. Humans worldwide cycle through millions of tons of the durable substance each year, sending the bulk of what’s not recycled to garbage dumps, where it leaks toxic chemicals into the environment as it very slowly breaks down.

For most creatures, a build-up of polyurethane plastic, which can harm the health of wild animals and humans alike, means only bad news. But at least one of Earth’s organisms sees the stuff as a boon: a bacterial strain called Pseudomonas sp. TDA1 that appears to love chowing down on some of the components of this problematic substance.

Described last week in the journal Frontiers in Microbiology, this polyurethane-munching microbe seems to thrive in waste dump sites. Studying the Pseudomonas strain and the chemical strategies it deploys could someday help researchers put a small dent in the world’s plastic problem, which has cumulatively saddled the planet with more than 8 billion tons of slow-degrading synthetic material.

“While there is still much work to be done, this is exciting and necessary research that demonstrates the power of looking to nature to find valuable biocatalysts,” John McGeehan, the director of the Centre for Enzyme Innovation at the University of Portsmouth who wasn’t involved in the study, tells Damian Carrington at the Guardian. “Understanding and harnessing such natural processes will open the door for innovative recycling solutions.”

Polyurethane’s durability has made it a desirable ingredient in many industries that rely on its flexibility and lightweightness to mass-produce everything from diapers to building insulation. But the substance’s longevity is a double-edged sword, making it extremely difficult to break down or recycle into new products. As such, many tons of polyurethane plastic ends up destined for landfills, where it piles up for decades. Because the substance is flammable, manufacturers often coat it in flame retardants that are suspected to be carcinogenic, Rolf Halden, an engineer at Arizona State University’s Biodesign Center for Environmental Health Engineering who wasn’t involved in the study, tells Scottie Andrew at CNN.

Other plastic-chomping bacteria have been discovered before, but each seem to have their own taste in types of chemicals they prefer to break down. A hardy strain by nature, Pseudomonas sp. TDA1 is one of only a few microbes known to be tolerant to polyurethane plastic’s typically toxic properties. What’s more, the bacteria doesn’t just withstand the plastic’s harsh ingredients: it uses some of them as a food source. After severing chemical bonds that hold the plastic together, Pseudomonas sp. TDA1 uses their energy to further fuel its polyurethane-degrading powers, reports George Dvorsky for Earther.

“The bacteria can use these compounds as a sole source of carbon, nitrogen and energy,” study author Hermann J. Heipieper of Helmholtz Centre for Environmental Research-UFZ in Leipzig says in a statement. “This finding represents an important step in being able to reuse hard-to-recycle PU products.”

Mass microbial clean-ups of plastic aren’t necessarily in our future, however. While the bacterium can metabolize a subset of the chemicals in polyurethane plastic, it doesn’t seem able to break down these products completely.

But Heipieper hopes that in-depth studies of Pseudomonas sp. TDA1 will reveal the genes crucial to these plastic-attacking abilities. Understanding how these genes and their products work could help scientists engineer synthetic approaches to tackling plastic in the future, according to Earther.

In the meantime, Heipieper stresses the importance of not worsening the plastic issue. As he tells the Guardian, “The main message should be to avoid plastic being released into the environment in the first place.”

Katherine J. Wu | | READ MORE

Katherine J. Wu is a Boston-based science journalist and Story Collider senior producer whose work has appeared in National Geographic, Undark magazine, Popular Science and more. She holds a Ph.D. in Microbiology and Immunobiology from Harvard University, and was Smithsonian magazine's 2018 AAAS Mass Media Fellow.