The project

The fine details of the project are yet to be completely finalised, however after our first meeting with Dr Badge, we had a brief outline of what we are planning on running with. To start, a bit about polystyrene....

Polystyrene - a useful product, with a problem..

The idea of trying to biodegrade polystyrene, which can be a highly visible waste product, was chosen because of the environmentally friendly aspect of the idea, something which is very important to the team.

Polystyrene, although wikipedia says different (http://en.wikipedia.org/wiki/Polystyrene), can in fact be degraded by naturally occurring bacteria, particularly a few specific strains of Pseudomonas sp. However this process takes a very long time, in part because polystyrene, unlike many plastics is resistant to photolysis (breakdown of a molecule by light).

As a result  polystyrene can remain in the environment for many years after its original function has been completed. In fact the the inertness of polystyrene is of benefit in landfills because it does not degrade and so contaminate groundwater. Additionally the rigid structure of polystyrene stabilises the landfill site. However landfill is seen increasingly as an unsustainable waste disposal method - as well as one that ignores the valuable hydrocarbons locked up in polystyrene…

You may be wondering why polystyrene is not recycled. It is recyclable bearing the recycling number "6", being a thermo or thermoset plastic, and the  majority of high density products such as CD cases are recycled. The problem arises with low density expanded polystyrene (EPS) used for packaging- this product is 98% air and so is not economically viable to recycle, as there is very little of the stryene monomer, per cubic meter.

Our project is therefore aimed at using the iGEM synthetic biology approach to engineer bacteria that can break down polystyrene in a safe, environmentally friendly and economical manner. The hope is that we can then link the degradation process to pathways of chemical or biological synthesis that can turn a waste product into a valuable and useful resource.

Sources used:
http://en.wikipedia.org/wiki/Polystyrene
http://www.earthresource.org/campaigns/capp/capp-styrofoam.html
http://www.ejnet.org/plastics/polystyrene/disposal.html