Very relevant for the treatment of oceanic great plastic gyres.
By Eoin O'Carroll, Blogger for The Christian Science Monitor / May 23, 2008
As part of a science fair project, a Canadian teenager has come up with a way to get plastic shopping bags, which normally take up to 1,000 years to decompose, to break down in as little as three months.
Daniel Burd, a 16-year-old high school student in Waterloo, Canada, reasoned that, because plastic eventually degrades, there is probably some some microorganism out there that breaks it down. If that microbe could be identified, you could expose higher concentrations of it to plastic and break it down faster.
So Mr. Burd did just that. The Waterloo Region Recordexplains his experiment:
First, he ground plastic bags into a powder. Next, he used ordinary household chemicals, yeast and tap water to create a solution that would encourage microbe growth. To that, he added the plastic powder and dirt. Then the solution sat in a shaker at 30 degrees.
After three months of upping the concentration of plastic-eating microbes, Burd filtered out the remaining plastic powder and put his bacterial culture into three flasks with strips of plastic cut from grocery bags. As a control, he also added plastic to flasks containing boiled and therefore dead bacterial culture.
Six weeks later, he weighed the strips of plastic. The control strips were the same. But the ones that had been in the live bacterial culture weighed an average of 17 percent less.
Burd then went on to identify which one of the four bacterial strains in the culture was the one with the appetite for plastic. He identified two: Sphingomonas and Pseudomonas. The first one breaks down the plastic, and the second one helps the first one reproduce.
After some experimentation, he was able to get a plastic bag to degrade by 43 percent in six weeks.
His six-page report, which you can download here (PDF), concludes that the process he developed could be used on an industrial scale.
Plastic bags are usually buried in landfills or thrown into the oceans and surrounding ecosystems. The process of polyethylene degradation developed in this project can be used on an industrial scale for biodegradation of plastic bags. As a result, this would save the lives of millions of wildlife species and save space in landfills.
It's hard to understate the environmental catastrophe caused by plastic bags. Many of them end up the Great Pacific Garbage Patch, a swatch of trash twice the size of Texas that is estimated to be 80 percent plastic. A report by Greenpeace found that some 267 marine species suffer from either ingesting or getting entangled in the bags.
As far as anyone knows, Burd is the first to discover the plastic-devouring properties of this microbe. For his efforts, Burd won top honors at the Canada-Wide Science Fair in Ottawa, where he took home $30,000 in prizes and scholarships.
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