With all of the publicity about how plastics are piling up in landfills and the ocean there has been an assumption that the plastics are incapable of breaking down. During my undergrad as a Microbiology major at Cal Poly SLO I was interested in environmental microbiology. During this time I was given a link to an article about a Canadian teenager, Daniel Burd, who found an aerobic (grows in presence of oxygen) bacteria that can degrade plastic. Well this got me thinking, maybe the whole idea that plastics could be degraded actually made sense, I mean there are some really complex molecules in nature that can be broken down, why not the simple design of plastics. So I started planning an experiment, looking for anaerobic (grows without oxygen) bacteria that degrade plastic using a Winogradsky Column which consists of soil at the bottom of the column and liquid at the surface of the column, limiting the amount of air that can diffuse into the soil. I did this with the hope that if I could find plastic degrading bacteria I could make a microbial fuel cell which would essentially breakdown plastic and produce electricity at the same time. Yes, a little ambitious but worth a try. If you are interested in how I went through developing the procedure and results please feel free to read the following paragraphs. If you just want to get straight to business skip to the the next page!
With a vague idea of what Daniel Burd had done with his aerobic experiment I decided to design a similar experiment. In just a small sample of soil there are literally millions of bacteria, most are unable to be cultured in a lab. These bacteria and their relationships are so complicated that we may never be capable of understanding the exact ecology of a population of microbes in a spoonful of soil. With this general idea in mind it made sense to me that if put into an extreme environment, the microbes would adapt in order to survive. The nice thing with microbes is their ability to adapt quickly, turning on and off a variety of metabolic pathways to best utilize the resources available to them. That is exactly why microbes can be found almost everywhere on the planet. So my idea was to put soil microbes in an environment full of all the tasty elements they use to grow. I used Bushnell Hass Broth which is composed of Magnesium Sulfate, Calcium Chloride, Monopotassium Phosphate, Dipotassium Phosphate, Ammonium Nitrate, and Ferric Chloride. Or if you can see it better in terms of elements (Mg, S, O, Ca, Cl, K, N, H, Fe). You will notice that there is one KEY element missing from this solution, Carbon. Well lucky for us plastic is made up of Carbon (and Hydrogen) in long chains. Since Carbon is absolutely essential for microbes to grow (and all known life really) I was hoping that with all the other necessary ingredients available to them the microbes would use the Carbon found on the plastic to grow and luckily I was correct. So I will show you in just a few really simple steps how you can find plastic degrading bacteria from soil (I used landfill soil but I believe any soil would work).
Currently I am working on becoming a teacher and it is my personal belief that publishing this research for profit would really defeat the purpose.This would take away access to most people (who would have to fork over some serious cash just to look at it), especially when this could make a real, noticeable difference for a real environmental problem we face today. So I invite you to perform this experiment on your own, see what kind of results you get and collaborate our results. Please leave feedback for me in the comments, because this is my first instructable and I would like to make it the best it could possibly be. Thanks :)
Step 1: Materials
First you need your materials:
- At least 1 empty 2 liter Soda Bottle (cut the top off, see pictures below. I used 4)
- Bushnell Hass Broth (http://www.sigmaaldrich.com/catalog/product/FLUKA/B5051?lang=en®ion=US)
- Soil (try to dig down a few feet for a better chance of finding anaerobic bacteria)
- An accurate scale (preferably accurate to the thousand ex: 2.008g)
- Cut up strips of plastic bags
- Petri dishes and agar (I used TSA, Oatmeal agar, and Czapek agar just to have a nice variety)
- Sealable test tubes
- Sterile gloves
- Bunsen Burner
- Inoculating Loop