Tom Volk's Fungus of the Month for February 2007

Phanerochaete chrysosporium, a crust fungus that can degrade phenolic resin plastics!

Tom Volk's Fungus of the Month for February 2007

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Phanerochaete chrysosporium growing on woodYes I know what you're thinking. "This is a repeat! I demand my money back!" However, this being an incredibly busy semester for me and with time dwindling down on this month, I thought it would be ok to "cheat" a little.

Last summer Adam Gusse, Paul Miller and I published a paper on the biodegradation of phenolic resin plastics with Phanerochaete chrysosporium. We demonstrated the ability of this white-rot fungus to degrade phenolic resin, a previously non-biodegradable industrial polymer (plastic-like) that is not commercially recycled. These phenolic resin polymers, first known as Bakelite, are found gluing layers of plywood together, providing the binding matrix to particleboard, or laminating the surface of FormicaTM counter tops. They are also used in constructing rotary telephone casings, bowling balls, toilet seats, motor casings, and many other everyday products. The annual production of phenolic resin is 2.2 million tons per year. Formerly considered to be non-biodegradable and contributing greatly to landfills, our work has demonstrated, through three lines of independent evidence, that phenolic resin polymers can be degraded by Phanerochaete chrysosporium.

The paper, available here, was published as Gusse, Adam, Paul Miller, and Thomas J. Volk. 2006. White-Rot Fungi Demonstrate First Biodegradation of Phenolic Resin. Environmental Science & Technology 40:4196-4199. ES&T is a top tier environmental journal and we are very proud to have published our paper there.

Our paper unleashed a storm of publicity. First Environmental Science & Technology published a press release called "First evidence that tough plastic can be biodegraded" at http://pubs.acs.org/subscribe/journals/esthag-w/2006/may/tech/pp_whiterot.html, which is only done for the best papers in the journal.

White-rot fungi caused the pockmarks on the surface of the phenolic resin plastic shown in this scanning electron microscope image."The researchers first realized that the white-rot fungus was degrading the phenolic resins when their color changed from yellow to a light pink, the color of the phenol and formaldehyde subunits used to make the resins, says Adam Gusse, a biology graduate student and lead author of the study. They confirmed the presence of those subunits by gas chromatography/mass spectrometry and by locating pockmarks on the surface of the resin chips with scanning electron microscopy."

We were soon contacted by Nature, one of the top scientific journals in the world, who published a story on our work called Fungus eats enduring plastic. Here's an excerpt:

"Gusse fed chips of phenolic resin to five different species of white-rot fungus to see whether they could eat it. The team found that one species (Phanerochaete chrysosporium) turned from white to pink after a few days, suggesting that it had broken down the resin into smaller chemical components of the polymer known to be pink.

The team confirmed this by feeding the fungus phenolic resin containing a heavier isotope of carbon, and found that the isotope was incorporated into the fungus after it had feasted on the plastic. To nail the case, they used an electron microscope to show that the resin was pitted with craters after being semi-digested by the fungus. "It's clearly breaking it down," Gusse says.

We were contacted by the European Commission on the Environment, who put out a press release through Science for Environmental Policy called Fungi may be able to degrade tough plastic. Here's an excerpt:

"The finding that white-rot fungi can degrade phenolic resins is a significant discovery that provides new understanding of the mechanism of their degradation. The ability of white-rot fungi to create easily recoverable by-products from PR in a short period of time could be incorporated into a large-scale PR recycling process. This application would be of interest to the PR manufacturing, recycling and waste management industries. Being able to recycle phenolic resins would help to reduce the disposal of this type of material into landfills.

Nevertheless, this finding is just a first step. More investigation is required to understand better the factors that affect the process and how this process might be utilised and applied during recycling on a large scale.

The current study is the first one to demonstrate that the degradation of phenolic resins by fungi is possible and therefore it has valuable research implications, but its application for recycling requires further research."

Science in the News, published by American Scientist Magazine, picked up the story and published another called Fungi May Harbor Hankering for Nearly Indestructible Plastics. Scroll down on that page to find the story. Here's an excerpt:

A= control with no resin B= P. chrysosporium colony with embedded resin. note pink color indicating degradation of the resin   C= control resin with no fungusGusse and colleagues took chips of phenolic resin and fed them to various species of white-rot fungi. One of the species (Phanerochaete chrysosporium) turned pink after a few days. This was a promising sign: A core chemical component of the resins is pink in color. To confirm that the fungi had begun to break down the resins, Adam Gusse and his colleagues provided a second course-a resin that contained a heavier isotope of carbon that would be easily traceable. After finding evidence of the isotope within the fungi, they verified everything by running the resin chips under an electron microscope, which revealed that the chips bore pit marks.

We even got a little write-up in the New York Times in July 2006.

A Useful Fungus

The modern house is held together by glue.

That is, many construction products like plywood and fiberboard used as sheathing are laced with phenolic resin adhesives. These are heat-set polymers that are so impregnable that they will outlast the wood sheets or chips they hold together.

The staying power of phenolic resins also means they accumulate in landfills in large amounts. If the glues could be broken down, recycling of plywood might be possible. But methods devised so far require heat and costly solvents.

Adam C. Gusse and colleagues at the University of Wisconsin-Lacrosse wondered about an alternative approach. Fungi that cause wood to rot, they noted, work by breaking down lignin, the compound that holds plant tissues together. The molecular structure of lignin and phenolic resins are similar. Could a fungus be used to degrade the glues?

Their answer, to be published in the journal Environmental Science and Technology, is yes. They showed that a species of white-rot fungus, cultured in a petri dish with chips of phenolic resin, turned pink which is the color of the resin before it is thermally cured. Further experiments showed the fungus was taking up carbon from the glue.

The researchers say this is the first demonstration of biodegradation of phenolic resins.

The New York Times


I hope you enjoyed learning more about Phanerochaete chrysosporium and some of our work. You can visit this page to learn more about what goes on in our lab.


If you have anything to add, or if you have corrections, comments, or recommendations for future FotM's (or maybe you'd like to be co-author of a FotM?), please write to me at my email address

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