Team:Austin UTexas/Implementation
Proposed Implementation
Overview of Proposed Implementation Scheme (1) Boat sprays OCTOphage in target area of plastic area or oil spill in waterway. (2) OCTOphage infects marine bacteria surrounding plastic or oil slick with packaged enzymes. (3)Bacteria is transduced with enzymes and begins producing them. (4)Host cell is lysed by OCTOphage and enzymes are released into solution. (5) Oil is dispersed to smaller droplets or plastic is degraded into carbon sources. Figure by team member Haris Tariq
With OCTOphage, we will be attempting to create a phage delivery system that can be used for delivering plastic degradation and oil emulsification genes to marine bacteria. By doing so, we hope to create an innovative solution for degrading plastic pollutants and cleaning oil spills in a fast and efficient way compared to existing methods. Currently, there is no method for cleaning nurdles (microplastics that are biproducts of plastic manufacturers) in waterways. For oil spills, current methods are very mechanical and time consuming or toxic to the environment. The goal is to have OCTOphage available to oil cleanup companies and possible government entities such as the Environmental Protection Agency for them to have a more innovative solution to cleaning these pollutants.
Current research in the lab is centered around testing the ability of OCTOphage to deliver our constructs and measuring the efficiency of the enzymes produced by the host cell. We can also model the phage population dynamics using our model to see how our system would behave in marine environments. After performing these initial tests and refining OCTOphage, we could apply it to a real world scenario.
Since we have two different types of enzymes, plastic degradation and oil emulsification, we would also have two different types of target scenarios. Our plastic degradation enzymes were designed to target nurdles made of PET plastic. In this scenario, we envision that the EPA would disperse our OCTOphage in marshlands using a boat to spray the phage into the water. The plastic degradation enzymes allow nurdles to be degraded into Terephthalic acid (TA) and Ethylene Glycol (EG) which can then be used as carbon sources by the surrounding marine bacteria. Using our solution in this way allows organizations like the EPA to clean up the plastic with one simple step of spraying the OCTOphage into the water. OCTOphage was specifically designed for marshlands because PET nurdles sink but the water is still shallow enough so that the temperature doesn’t get too cold for the enzymes. Marshes are commonly found near plastic manufacturing plants near the Gulf of Mexico and there is also currently no clean up solution for nurdles in water bodies, which is why we designed our project with this implementation in mind. Current nurdle clean up responsibility falls on environmentalists and local citizens, however by providing this solution to a government agency like the EPA we hope to alleviate that burden and provide a more efficient and long-term solution.
The second scenario of OCTOphage would target oil spills in the ocean. Similarly to the first scenario, we plan on using a boat to spray OCTOphage into the water where the oil spill as occurred. Using a boat in this scenario would allow for OCTOphage to be directly applied to the oil slick. The water with the oil would already contain a high concentration of marine bacteria that can use oil droplets as a carbon source, however these bacteria cannot access the oil for carbon when it is in a slick. OCTOphage would then deliver oil emulsification genes to these bacteria so that they could disperse the oil slick into smaller droplets of oil and breakdown the oil to use as a carbon source. This would allow the oil slick to gradually be cleaned up over time.
We envision companies using our project as possible control measures for when there is a spill. For example, a factory situated near a lake that has a minor oil spill could deploy boats that could spray the phage in the lake to minimize damage by the spill. Additionally, if there is a large spill in the ocean – such as the Gulf of Mexico – the EPA with the help of the US Navy could deploy multiple boats with our phage to the scene where they could spray the phage and minimize any damage to the environment.
As we planned our implementation for our project, we thoroughly considered possible safety hazards and environmental effects that OCTOphage may have. One main concern would be that our host cells that carry the engineered genes would propagate throughout the population and possibly mutate and become dangerous to the environment. However, we do not believe that this will be an issue because OCTOphage will lyse most of the host cells to release the enzymes into solution and more phage will just be continually added. In the case that there is a host cell that does not lyse, there will be no selective advantage for the cell to carry our engineered genes anyways. When the plastic is broken down into carbon sources, any of the neighboring bacteria is able to use them, so the host cell that produced the enzymes doesn’t actually receive any advantage. Other challenges we may need to consider before full implementation of OCTOphage is the enzyme kinetics given the specific conditions of salinity and temperature in the water bodies that we plan on targeting. The salinity and temperature can cause changes in the activity of PETase and possibly denature it. Likewise, the temperature could affect the ability of the phage’s infection. Another factor is the concentration of calcium in the water, which influences the ability of the phage to adsorb to the host cell. However, when conducting future research these parameters can be adjusted for and we do not anticipate these issues to cause significant problems in the implementation of the phage.