Fungus Eats Plastic

A group of Yale University students have found a fungus in the Ecuadoran rainforest that can break down a common plastic, polyurethane.

The students describe in an issue of Applied and Environmental Microbiology how they isolated from plants a fungus they collected during a two-week trip and identified as Pestalotiopsis microspora that digests polyurethane, according to a Yale alumni publication. The fungus is an endophyte, a microorganism that lives within the inner tissues of plants, but does not cause any noticeable disease in its host, reports Damien Gayle of the Daily Mail.

Polyurethane is one of the world’s most widely used plastics. Global consumption in 2007 was about 12 million tons, with an average growth rate of about 5%. The synthetic material, made from petrochemicals, degrades very slowly because its complex bonds make it resistant to natural processes of decomposition. Since the 1950s, one billion tons of plastic are estimated to have been discarded, and because the plastic degrades so slowly, it could be hundreds or even thousands of years before it decomposes.

“Many microbes can do cool tricks, like degrading pollutants,” says Jonathan Russell, one of the Yale students who authored the article in the journal. Endophytes were isolated from plant stems. A subset of the organisms were screened for their ability to degrade polyurethane.

Several active organisms were identified, including distinct isolates of P. microspora with the ability to degrade the plastic as a sole carbon source when grown anaerobically. Because the fungus is believed to perform the degradation in an oxygen-free environment, it would certainly help reduce the volume of polyurethane at the bottom of a landfill.

The students believe that further study of the endophytes could reveal more metabolizers that could be used to degrade other types of plastic. The students wrote in the journal:

Each of the more than 300,000 land plant species on Earth potentially hosts multiple endophyte species. Only a small sampling of plants have been examined for their endophytic associations, yet many of these organisms can be readily cultured. Endophytes reach their greatest diversity in tropical forests. Individual trees can harbor hundreds of endophytic species, some of which are known, but many of which are new to science.

Source: “A Fungus that Eats Polyurethane,” Yale Alumni Magazine, Nov.-Dec. 2011
Source: “Could a plastic-eating fungi save world from biggest man-made environmental catastrophe?,” Daily Mail, 5/18/12
Image by U.S. National Archives and Records Administration, used under Fair Use: Reporting.