The goal of our project is to reduce plastic pollution and fossil fuel consumption by creating a sustainable, carbon-negative plastic.
Describe how and why you chose your iGEM project.
Please see the 2023 Medals Page for more information.
This year, our team is working to produce the bioplastic polyhydroxybutyrate (PHB) from the microalgae C. reinhardtii. The goal of our project is to reduce plastic pollution and fossil fuel consumption by creating a sustainable, carbon-negative plastic. To accomplish this goal, we will engineer a recombinant C. reinhardtii strain, which expresses the genes PhaA, PhaB, and PhaC, optimized for C. reinhardtii, to facilitate PHB synthesis. Acetyl-CoA is the starting molecule for PHB. To increase acetyl-CoA availability, we want to knockout the pta-ackA gene that creates acetate. To ensure biosecurity, we are developing a toxin-antitoxin system to ensure our GE algae cannot escape from the lab.
Humanity as a whole is becoming more aware of the harms that fossil fuel consumption and plastic pollution have done to the planet, and there is an increasing social movement to right our wrongs and live sustainably. Bioplastics have the potential to create a two-fold impact, both in reducing oil consumption and reducing pollution. In fact, the United Nations’ Sustainable Development Goal 17 is Responsible Consumption and Production, and bioplastics could play a significant role in the circular economy. At the most recent Intergovernmental Negotiating Committee session in early June 2023, the committee devised a draft of "an international legally binding instrument on plastic pollution.” Such strong movement from the United Nations should, and does, serve as a signal to scientists, like our team, to develop effective plastic alternatives, such as an algae-based bioplastic.
Plastic pollution is a significant social and environmental concern. For example, plastics in landfills can persist for hundreds of years, leaching toxic chemicals into groundwater that can harm human and environmental health, and burning plastic waste creates harmful air pollution. Marine environments are especially harmed by plastic pollution. For example, many marine animals mistakenly eat plastic debris, which stays in their stomachs and can eventually cause the animal to starve to death.
As plastics linger in the water, they are broken down into microplastics, which can be carcinogenic and endocrine disruptors. When humans drink water contaminated by microplastics, they are unknowingly ingesting toxins. In Dr. Kosuth’s 2018 study “Anthropogenic contamination of tap water, beer, and sea salt,” microplastics were found in 94% of tap water samples from the United States. Dr. Palanisami of the University of Newcastle estimates that globally, people ingest an average of 5 grams of microplastics a week. Clearly, there is a significant body of evidence that change is needed in the plastics industry. A biodegradable bioplastic is one such solution.
Abdo, S. M., Ali, G. H. (2019) Analysis of polyhydroxybutrate and bioplastic production from microalgae. Bull Natl Res Cent. https://doi.org/10.1186/s42269-019-0135-5
Cassuriaga, A., et al. (2020). Polyhydroxybutyrate production and increased macromolecule content in Chlamydomonas reinhardtii cultivated with xylose and reduced nitrogen levels. International Journal of Biological Macromolecules. https://doi.org/10.1016/j.ijbiomac.2020.04.273
García, G., Sosa-Hernández, J. E., Rodas-Zuluaga, L. I., Castillo-Zacarías, C., Iqbal, H., & Parra-Saldívar, R. (2020). Accumulation of PHA in the Microalgae Scenedesmus sp. under Nutrient-Deficient Conditions. Polymers, 13(1), 131. https://doi.org/10.3390/polym13010131
Koch, M., Bruckmoser, J., Scholl, J., Hauf, W., Rieger, B., & Forchhammer, K. (2020). Maximizing PHB content in Synechocystis sp. PCC 6803: a new metabolic engineering strategy based on the regulator PirC. Microbial cell factories, 19(1), 231. https://doi.org/10.1186/s12934-020-01491-1
Mathiot, C., et al. (2019). Microalgae starch-based bioplastics: Screening of ten strains and plasticization of unfractionated microalgae by extrusion. Carbohydrate Polymers. https://doi.org/10.1016/j.carbpol.2018.12.057