Bacteria that breaks down plastic bags

June 27, 2008 at 12:49 pm 19 comments

OK, I’ve written about a terrifying burden on the environment that is plastic bags. Now a Canadian high school student may find a plausible solution to this problem — by isolating bacteria that break down plastic bags in 3 months, instead of millions of years.

Daniel Burd, a 16-year-old student of Waterloo Collegiate Institute decided to do something about the pile of plastic bags that was sitting in his closet. He knew that plastic bags do eventually degrade, and that microorganisms could be behind it. But the degrading microbes are difficult to isolate because they do not exist in high numbers in nature.

To find out which bacteria are more effective as biodegraders, he put together a bacterial culture medium by mixing some household chemicals, tap water and yeast. He ground plastic bags into a powder and added it to the medium along with some dirt. The mixture was placed in a shaker at 30 degree for 3 months. Then he filtered out the remaining powder, transfer the culture into 3 flasks and also prepared a flask of boiled culture as the negative control. He placed strips of plastics cut out from bags into these flasks and compared the weights of the plastic strips after 6 weeks. He observed a 17% decrease, but that’s not good enough for him.

To identify the specific strain of bacteria responsible for degrading the plastic, Daniel grew the microbes on agar plates and found 4 different species. He did more tests using plastic strips and found that only the second strain was able to break down the plastic significantly.

Growing the strain with the others respectively indicated that the first strain and the second strain together resulted in 32% weight loss in plastic strips. Daniel hypothesized that strain no. 1 helped strain no. 2 reproduce. More tests revealed that the degrading species was Sphingomonas bacteria and the helper was Pseudomonas.

He did more tests using different bacterial concentrations, temperatures, and addition of sodium acetate as a carbon source for the bacteria. He found that at 37 degrees, with the optimal concentration and a little sodium acetate added, 43% degradation was achieved in 6 weeks. Although he did not actually do the test, but the plastic strips should be totally broken down in double that time. He also checked whether this could work on a larger scale by testing whole plastic bags. It worked, too.

A researcher in Ireland had shown that Pseudomonas broke down polystyrene, but Daniel Burd was the first to reasearch on polyethelene plastic bags.

There should not be any problem applying this method in the industry, all that is required includes a fermenter, a bacterial growth medium, the bugs and the plastic bags. Since the bacteria also produce heat during the process, little energy is needed to maintain the optimal temperature. The system produces only water and carbon dioxide, in the minuscular amount of 0.01% of the bacteria’s weight. If this works, it is a huge step forward in solving the problem of “white pollution.”

And all this coming from a 16-year-old teenager with an idea to do something that most of us just accept as it is. Now that’s the power of science!

Source: WCI student isolates microbe that lunches on plastic bags


Entry filed under: Science News. Tags: , , .

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19 Comments Add your own

  • […] June 27, 2008 blog post is taken from Alice’s Biotechnology Blog (and more) by Alice […]

  • 2. pratiksha  |  August 9, 2008 at 2:40 am

    i m pratiksha, persuing M.phil in biotechnology .
    i want to do research in d same field.Could you plese suggest me the further scope or work which i can continue.

    Pratiksha Sharma

  • 3. Alice  |  August 9, 2008 at 11:10 am

    Hello Pratiksha,

    I’m not sure if I’m in any position to give you suggestions, but I can throw out some ideas. Do you mean you want to do research in biodegradation of plastic? There are many topics you can look into, such as the mechanism of degradation, purification and characterization of the proteins responsible for degradation, expression of the proteins in bacteria that are easier to maintain, and ultimately, how to apply your research result to actually treat plastic in the industry.

    Hope this helps. Good luck on your studies!

  • 4. pratiksha  |  August 10, 2008 at 3:59 am


    i have received ur suggestions.thank u very much .
    Best Regards


  • 5. pratiksha  |  August 16, 2008 at 1:52 am


    thank u so much for your suggesions.
    can u send me the procedure to estimate degree of biodegradation of plastic/ polythenes. It would e benificial for me.

    Best Regards

  • 6. naresh kumar  |  October 22, 2008 at 4:15 am

    hai pratiksha this is naresh and my mail id is
    iam also doing my research in the same topic for my M.Tech project work.

  • 7. sandra zaki  |  November 15, 2008 at 1:27 pm

    iam sandra 4th year microbiology student science collage
    iam going to start my graduation project about the bio degradation of plastic and iam looking forward to have a support from you by giving me names of some microorganisms that had been show an ability to degrade plastic or any other complex synthetic polymers
    or even where to starte looking
    hope you can help me
    thank you very much

  • 8. sowmya  |  December 26, 2008 at 4:27 am

    i am planning to do work on plastic degrading microorganisms. i want ur suggestions. please guide for this.

    • 9. Alice  |  December 28, 2008 at 2:28 pm

      Hi sowmya,
      Do a search on scientific journal articles on this topic. There are many researches on this topic with different focus, such as industrial application, pollution clean-up, river rehabilitation, etc.

  • 10. nabamita  |  April 4, 2009 at 1:10 pm

    I have a seminar on biodegradation of plastics. I am a 3rd year engineering student of a reputed college. I belong to the biotechnology department and have to give a power point presentation on biodegradation of plastics. I am not being able to find any research papers on this topoic. Please can you hepl me

    • 11. Alice  |  April 4, 2009 at 5:58 pm

      Hi nabamita,

      I believe you can find journal articles on this topic easily. Know how to use your library. Every university may have a different system. It’s better to learn how to utilize your resources, the sooner the better.

      There are tons of papers out there on this topic (just like any other). See what I’ve digged up just by searching on Google here.

  • 12. sathya  |  July 6, 2009 at 3:24 am

    hello sir, plz give some idea for my project in plastic degradation by microorganisms

  • 13. Ravi  |  July 10, 2009 at 12:41 am

    I am joined phd recently i would like to work on the same topic i like to study under stressed condition microbes the degrading rate of plastic suggest something about this

  • 14. Guest Post: Free Market Ecology » A Taoistmonk's Life  |  June 24, 2012 at 3:50 pm

    […] If the dangers of non-biodegradable plastic threaten our oceans, then develop and market processes (that already exist today) to clean up these plastics. […]

  • 15. Alice  |  June 25, 2012 at 10:48 pm

    digestive enzymes of cockroach

    Interesting! Best of luck on your research. Thanks for visiting 🙂

  • 16. Carl Piaf  |  October 7, 2012 at 9:45 am

    I’m just waiting for this bacteria to mutate and head out into the global environment. That would reak havoc with much of our technology. I always wondered why this hadn’t already happened. Why hasn’t bacterial evolution already provided nature with an organism that fills the niche that human technology has provided. I expect that the plastic manufacturers are already at work combatting this “pest” that threatens their livelhood.

  • 17. African queen  |  March 19, 2014 at 12:53 pm

    is it the same species that also break down the plastic plates?

    • 18. Alice  |  March 19, 2014 at 9:33 pm

      I don’t know. But pay attention to this paragraph:

      A researcher in Ireland had shown that Pseudomonas broke down polystyrene, but Daniel Burd was the first to reasearch on polyethelene plastic bags.

      Given that there are so many different kinds of plastic used to manufacture plastic products, further research is probably required to find out which strains work the best on a certain type of plastic under what conditions.


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