We are surrounded by plastic everyday, specifically PET (Polyethylene Terephthalate). Considered as the most common type of Polyester, PET is a plastic resin often used for packaging consumer products. We can also find it in our water bottles, plastic toys, and even in the fiber of our clothing. PET is a combination of two monomers known as ethylene glycol and purified terephthalic acid that, when combined, form the polymer PET. The problem with PET is that although it is a convenient material for humans to use, it does not easily biodegrade. As PET accumulates in the ecosystems around the world, it poses detrimental effects on habitats worldwide. That is why it is crucial that we find an efficient way to degrade PET.

Upon conducting our research on plastic degradation, shortly after deciding to focus on this topic, our team came across a joint collaboration research project from Keio University and the Kyoto Institute of Technology, two prestigious universities in Japan. Their paper explained their recent research on PET degradation into Terephthalic acid and ethylene glycol using a new bacterium originating from Japan called Ideonella Saikainesis. We were inspired by Ideonella Saikainesis because it was an effective PET degrader (containing PETase) from Osaka, Japan, our current location. Considering this, we realized that the production of PETase was based on unique Japanese research, so it was only apt to center our project around this as it showcases a special (and scientifically recent) aspect of the Japanese environment. Consequently, our aim and experimental idea were born: to optimize the use of PETase and hopefully add a new Biobrick to the iGEM catalog. Subsequently, when looking at past iGEM projects of Turkey 2014, University of Washington 2012 and Darmstadt 2012, all centered on plastic degradation, provided us with inspiration on the potential applications for our project in addition to lab protocol ideas.

We chose to optimize PETase as our goal, aiming to make a new type of biobrick available to future iGEM teams. We hoped that this will make experiments in the following years easier to conduct. However, in order to even get to that stage, we recognized that we needed a well thought out procedure. Our team is currently working on this step. Thus far we have determined that we will be using a western blot test to help us deal with the signal peptides. We also have three promoters (one on the slightly weaker side and two on the stronger side) taken from the list of Anderson promoters to test in order to determine how to make PETase most efficient.

However, before testing such promoters, we need to isolate and evaluate each promoters' effectiveness and efficiency. This information is essential before we proceed onto our next steps and think about real world applications. Questions we may ask ourselves following this first step include: “How long will the degradation take?” and “Will the byproducts of the degradation be harmful in any way to the environment or to people?”

Our aim, as stated above, is to find a faster, more efficient process to degrade plastic. Answers to such questions will be essential in seeking solutions to global environmental problems. In regards to the first question, to our current knowledge, 450 years is the timeframe for the natural biodegradation of PET. From our perspective, this time frame is inefficient when you consider how much PET is used daily. As a result, our experiment focuses on increasing the efficiency of the degradation of plastic through the manipulation of PETase. These are just some examples of the types of questions that we must first consider. Once our confidence in our research progresses, we can fully focus on individual procedural steps of our project such as the Western Blot test.

Abstract

In recent years, the production of Polyethylene Terephthalate (PET) has increased rapidly, as a result of low production costs and consumer demands. PET is one of the most common plastic polymers, comprised of repeating monomeric subunits of Terephthalic Acid and Ethylene Glycol. It is frequently used in the manufacture of plastic bottles and clothing fibres, especially in Japan. As avid users of PET-based products, our team decided to research how to optimise the degradation of PET, which takes an average of 450 years to degrade naturally. We were further inspired to pursue this goal with Keio University’s recent discovery of Ideonella sakainesis — a unique bacteria capable of PET degradation. Thus, we have focused our project on the synthesis of an optimal PETase biobrick, which would be included in the iGEM database. Ultimately, our goal is to find an ideal promoter to expedite the production and secretion of PETase.

References

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https://www.keio.ac.jp/en/press_releases/2016/cb96u90000005501-att/160330_2.pdf

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Yoshida, S., Hiraga, K., Takehana, T., Taniguchi, I., Yamaji, H., Maehada, Y., . . . Oda, K. (2016, March 11). Supplementary Materials for a Bacterium that Degrades and Assimilates Poly(ethylene terephthalate). Science, 351, 1196th ser. Retrieved June 30, 2016, from

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Yoshida, S., Hiraga, K., Takehana, T., Taniguchi, I., Yamaji, H., Maeda, Y., . . . Oda, K. (2016, March 11). A Bacterium that Degrades and Assimilates Poly(ethylene terephthalate). Science, 351(6278), 1196-1199. doi:10.1126/science.aad6359