Undergrad Yale researchers find plastic-eating fungus in the Amazon
New Haven, USA: There’s a course at Yale University in which undergraduates travel to the Amazon rain forest to collect fungi. One of them, however, which will be featured in a paper accepted by a scientific journal, might solve the problem of polyurethane building up in our landfills. The fungus basically eats the plastic and breaks it down into carbon. That’s just one discovery being studied in the Rainforest Expedition and Laboratory course taught by Professor Scott A. Strobel.
“We take 15 undergraduates into the Ecuadorean rain forest and collect plant samples,” said Kaury Kucera, co-instructor of the course and a postdoctoral researcher in the department of molecular biophysics and biochemistry. Each student decides what he or she wants to investigate. “It’s completely undergraduate-driven,” Kucera said. The search for a polyurethane-eating fungus was “completely conceived by an undergraduate. … It really is a remarkable opportunity for the undergraduates to do real research,” she said.
The fungus, Pestalotiopsis microspora, was found by a student in 2008 in a particular type of guava plant. Other students followed up and discovered that not only does the fungus break down polyurethane, but it can do it in the depths of a landfill. “No one else ever in history has reported anything that can degrade this anaerobically, that is without oxygen,” Kucera said. “If you think about landfills, 50 feet under in trash, you need something that can degrade anaerobically. And so these guys, if you deprive them completely of oxygen, they still degrade the polyurethane.”
The research has been accepted for publication in the journal Applied and Environmental Microbiology. Polyurethane can be made into a stiff foam-like substance that can be formed into mattresses or upholstery, as insulation in refrigerators or homes. It also can be formed into hard plastic molds. And it is filling up the world’s landfills. According to the students’ paper, “The persistence of synthetic polymers introduced to the environment by human industry poses a major threat to natural ecological systems. The low cost and ease of manufacture has increased global plastic demand more than 150-fold with the production of 1.5 million tons in 1950 to 245 million tons as of 2006.”
Looking for medicines in the natural world fell out of favor in the 1970s as pharmaceutical companies preferred to look at chemical compounds made in the lab, Kucera said. “So we’re really kind of doing old-fashioned science by looking first to nature.”
The fungi, Pestalotiopsis microspora, is the first anyone has found to survive on a steady diet of polyurethane alone and–even more surprising–do this in an anaerobic (oxygen-free) environment that is close to the condition at the bottom of a landfill.
Student Pria Anand recorded the microbe’s remarkable behavior and Jonathan Russell isolated the enzymes that allow the organism to degrade plastic as its food source. The Yale team published their findings in the journal Applied and Environmental Microbiology late last year concluding the microbe is “a promising source of biodiversity from which to screen for metabolic properties useful for bioremediation.” In the future, our trash compactors may simply be giant fields of voracious fungi.
At Yale a previous graduate of the course, Pria Anand showed that the fungus could live and prosper on a diet of polyurethane alone, and it is believed to be able to function in the oxygen-free conditions that exist at the bottom of landfill sites. Jonathan Russell has isolated an enzyme that the fungi use to break down the plastic and Yale believes that this molecule alone could be useful in eliminating waste polyurethane.