Friday, February 10, 2012

Polyurethane, yum yum

Have you ever been sitting in the library, finished your bottled beverage, saw the regular trash can next to you and realized the recycling was a whole extra 10 feet away? If your convinctions are as weak as mine, that bottle generally ends up in the trash about 50% of the time. Theoretically, I know that plastic takes just about forever to degrade in landfills, and that we are rapidly running out of landfill space in the United States. However, a discovery by students at Yale may excuse my current laziness.
          A group of Yale students led by biochemistry professor Scott Strobel ventured into Ecuadorian jungles with the stated goal of allowing "students to experience the scientific inquiry process in a comprehensive and creative way". Specifically, they were looking for organisms that could degrade man-made plastics, a form of bioremediation. Bioremediation is more generally defined as using microorganisms to degrade pollutants into non-toxic or less toxic metabolites. The most recent bioremediation news coverage was during the BP Gulf Oil Spill, where naturally-occurring bacteria were proposed as a solution for cleanup. The students at Yale were specifically looking for something capable of degrading polyurethane, one of the most common plastics in use today. Polyurethane is highly versatile because it can be rigid as well as flexible, making it a great construction material for everything from water bottles to garden hoses to truck seats. Its polymer structure renders it extremely stable, and so it does not degrade readily. Incineration isn't an option either, unless breathing carbon monoxide and releasing even more greenhouse gasses isn't considered a better alternative to landfills. All these reasons and more makes the fungi, Pestalotiopsis microspora, a highly promising candidate to solve the disposal problem.
         There are already many fungi and bacteria known to be capable of degrading polyurethane, but P. microspora is thus far unique in its ability to use polyurethane efficiently as its sole carbon source, and the first to be able to efficiently degrade polyurethane under anaerobic conditions. Anaerobic degradation is particularly exciting, because no-oxygen conditions are much more like what would be encountered at the bottom of a heap of landfill trash.
          One issue I noticed with the article was that they did not test if polyurethane was preferentially used as a carbon source. Just because a fungi can use a particular substance does not mean it will. For example, E.coli can use both glucose and lactose as carbon sources, but will preferentially eat glucose because it is easier to break down for energy than lactose. In fact, E.coli won't even make the enzymes necessary to degrade lactose unless there is no glucose present. If P. microspora uses polyurethane as a non-preferred carbon source, there is a good chance it will happily eat everything in the landfills except polyurethane, which would defeat the purpose of introducing it as a bioremediator in the first place.
       Despite that one issue, it seems like this fungi and others have a high potential to help remedy our growing waste problems. The next order of business: introduce some hungry hyphae into the trash cans at Pelletier Library.

1 comment:

  1. I'm so happy to read this! Ever since I read The Andromeda Strain, which describes a foreign bacterium destroying/eating the plastic portion of helicopter equipment, I have been waiting to hear a non-fiction version of this microbe. Another example of the adaptability of our tiny "friends".