I'm typically not a big fan of science fairs, at least in terms of the competition. In my experience, too many of the winners simply had good projects handed to them by top notch researchers--it's not a reflection of the students' ingenuity. But this science project is ingenious:
Now a Waterloo teenager has found a way to make plastic bags degrade faster -- in three months, he figures.
Daniel Burd's project won the top prize at the Canada-Wide Science Fair in Ottawa. He came back with a long list of awards, including a $10,000 prize, a $20,000 scholarship, and recognition that he has found a practical way to help the environment.
Burd, 16, a Grade 11 student at Waterloo Collegiate Institute, got the idea for his project from everyday life.
"Almost every week I have to do chores and when I open the closet door, I have this avalanche of plastic bags falling on top of me," he said. "One day, I got tired of it and I wanted to know what other people are doing with these plastic bags."
The answer: not much. So he decided to do something himself.
He knew plastic does eventually degrade, and figured microorganisms must be behind it. His goal was to isolate the microorganisms that can break down plastic -- not an easy task because they don't exist in high numbers in nature.
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 per cent less.
That wasn't good enough for Burd. To identify the bacteria in his culture, he let them grow on agar plates and found he had four types of microbes. He tested those on more plastic strips and found only the second was capable of significant plastic degradation.
Next, Burd tried mixing his most effective strain with the others. He found strains one and two together produced a 32 per cent weight loss in his plastic strips. His theory is strain one helps strain two reproduce.
Tests to identify the strains found strain two was Sphingomonas bacteria and the helper was Pseudomonas.
A researcher in Ireland has found Pseudomonas is capable of degrading polystyrene, but as far as Burd and his teacher Mark Menhennet know -- and they've looked -- Burd's research on polyethelene plastic bags is a first.
Next, Burd tested his strains' effectiveness at different temperatures, concentrations and with the addition of sodium acetate as a ready source of carbon to help bacteria grow.
At 37 degrees and optimal bacterial concentration, with a bit of sodium acetate thrown in, Burd achieved 43 per cent degradation within six weeks.
The plastic he fished out then was visibly clearer and more brittle, and Burd guesses after six more weeks, it would be gone. He hasn't tried that yet.
To see if his process would work on a larger scale, he tried it with five or six whole bags in a bucket with the bacterial culture. That worked too.
Industrial application should be easy, said Burd. "All you need is a fermenter . . . your growth medium, your microbes and your plastic bags."
The inputs are cheap, maintaining the required temperature takes little energy because microbes produce heat as they work, and the only outputs are water and tiny levels of carbon dioxide -- each microbe produces only 0.01 per cent of its own infinitesimal weight in carbon dioxide, said Burd.
"This is a huge, huge step forward . . . We're using nature to solve a man-made problem."
You can download his report (pdf).
Nicely done. Now if there were only someone who were willing to sequence these organisms' genomes....
Any idea what the bags are being degraded into?Is it something that could be used elsewhere?
Quite cool. I never did anything cool enough for a science fair back when I was still at a level in school where they were held to even remember what I'd made. Even given that my last science fair was at 11 years old, I doubt a few more years would've put me close enough to this one to even be compared with it. Looks like he's doing professional level work on his own already.
I wonder if this process could be commercialized, or if any of the waste products are useful for recycling purposes.
Still, kudos to the kid for trying something painfully obvious, that everyone was too preoccupied or too stupid to try.
This is why we need high school kids in science.
I'm reminded of a story I heard in college many decades ago -- one of the profs was trying a similar approach to find an organism that would consume DDT and its breakdown products safely.
He did, his former lab assistant told us. But it also ate the insulation then used on telephone cables and a good many other related plastics. No cite, pure third hand anecdote.
He autoclaved his project and tried something else, so it was told.
I wonder .... given how successful and widespread lateral gene transfer turns out to be, and how much infrastructure there is available to munch ...
See, I had always assumed, when thinking about the biodegradability of plastics, that such an experiment had already been tried over and over again without success. Just this weekend I was pondering what sort of artificial genes for artificial enzymes would need to be inserted to existing microbes to somehow jumpstart the evolution of microbes that degraded plastics, and I was concerned about the environmental wisdom of such a move. Never did I consider that nobody had yet done the simple experiment!
Two broad questions pop up for me.
(1) What is the relationship between the two species? Are they involved in a two-step catabolism chain or are they attacking different substructures of the polyethylene? (Or something like that. I have no clue what chem occurs when degrading PE.)
(2) Could he pull a similar evolutionary scheme like Richard Lenski? Presumably you could keep ratcheting up the pressure for more efficient PE degradation.
Of course, it will be important to know the resulting products to help determine if their is anything inherently problematic with this process for health or ecological reasons.
It's hard to get rid of traces of carbon substrates for growth, even apart from the yeast. So an "enrichment culture" without the plastic (or with a different kind of plastic) would have been a good control. Also, only getting four types of bacteria in a culture started from soil is surprising. Maybe there were a lot more genotypes than colony types. Still, if the value of his strains is confirmed independently, that's great, whether or not his purported enrichment method did what he thinks it did.
That is cool! I feel kind of jealous :)
Very nice experiment..Michael Schmidt was so jealous..
I'm definitely jealous-- a practical and publishable story that's of interest to the scientific community and the public--and dude is only in 11th grade. I wish I had that kind of science education when I was that age. I barely had a grasp of the difference between a hypothesis and a control group. Canada: kind of like America, only better.
Also, only getting four types of bacteria in a culture started from soil is surprising. Maybe there were a lot more genotypes than colony types.
I'm sure there may have been several species which were unculturable. Not everything is going to grow on your standard isolation media (which in this case was LB media, which is a rich, but not terribly rich medium to begin with).
@ Michael Schmidt: It's not so much that there isn't a microbe that will attack plastics, the problem is that there are SO MANY kinds of plastics out there. An organism that is able to digest polypropylene, for example will get a tummyache if fed acrylic, polyethylene, or vinyl. There is a microbe that is able to digest certain kinds of nylon, (nylon-6 IIRC, but it won't touch nylon 6-6 or any other nylon).
Blaidd Drwg - a polymer engineer