Saving the Baltimore Inner Harbor
Is E. coli the answer?
Cleaning water polluted by plastics has always been a difficult issue. The plastic can be collected by machines, but that solution comes with some problems. One issue is storage: plastic takes up space, and that limits what you can do with this solution. A small machine meant to pick up plastic will have to be regularly emptied out. Another issue is the question of where the plastic goes after you collect it. First it has to be transported to a recycling center using energy, and once it gets there more energy and water is used in the recycling process. This system is very inefficient. Fortunately, the bacteria we designed could be part of a better solution.
We picked a safe strain of E.coli bacteria to work with. Into these bacteria, we inserted two genes that express enzymes allowing them to break down PET plastic into its component parts. The steps of this process are outlined in the diagram below.
Our bacteria could be put in a container inside a small machine pulled behind a boat; The plastic would be picked up by the machine and degraded by the bacteria, and the byproducts would be collected and stored. These byproducts could be used to make more plastic. Alternatively, the enzyme could be collected from the bacteria and used separately to degrade the plastic.
There are many other ways to implement this project in real life. Another option that we are considering is creating a simple recycling machine that you can use in your home. The design would be similar to a compost bin. You would have a container with the bacteria, to which you could add plastics to be broken down. The byproducts could be collected and reused.
If implemented with the proper safety precautions, such as a killswitch for the bacteria which would cause them to die if they escaped into the wild, this project could be one of the most promising solutions to the issue of plastics contaminating our water.