As residents of a sunny seaside town, we were inspired to help preserve the local marine environment without discouraging tourists from enjoying its beauty. St Andrews is surrounded on three sides by the sea, and while it is too cold for coral reefs, a rich and biodiverse ecosystem lives in our waters. Through our research we discovered that while commercial sunscreens offer protection against UV radiation, chemical ingredients such as oxybenzone and octinoxate have damaging consequences to coral reef ecosystems (Downs et al., 2016; Schneider and Lim, 2019). These marine toxins contained in conventional sunscreens contribute to coral decline by leaching into aquatic environments and interfering with coral growth and reproduction. The biggest threat to coral conservation is undoubtedly rising ocean temperatures, but exposure to sunscreen chemicals can have a cumulative effect, making corals more vulnerable to other stressors (Wijgerde et al., 2020). In order to conserve coral reefs, more than one approach is required, including minimisation of exposure to sunscreen chemicals such as oxybenzone. It is estimated by the International Coral Reef Initiative (ICRI) that >14,000 tons of sunscreen are deposited into the ocean every year (Wood, 2018). Corals are ecosystem engineers, meaning that they create and maintain the ecosystem around them. Considering that 25% of all marine species depend on coral reef ecosystems, a loss such as this would lead to a devastating ecosystem collapse (EPA, 2018).
CREDIT: UMEED MISTRY / CORAL REEF IMAGE BANK
To help conserve coral reefs, the University of St Andrews iGEM team aims to develop the first sustainable and low-priced probiotic sunscreen. Our bacteria when present on the surface of the skin will produce a non-toxic, UV-absorbing compound called shinorine. Improving upon other shinorine-derived products, our product will provide prolonged protection against UV-A and UV-B compared to conventional and mineral-based alternatives. Protecting these vital coral reef ecosystems whilst also shielding the human population from the increasing threat of UV radiation is of overriding importance. Skin cancer affects millions of people annually with UV radiation also said to be responsible for 90% of skin aging. In fact, Cancer Research UK estimates that 86% of melanoma skin cancer cases in the UK are preventable (Cancer Research UK, 2015). An affordable, non-toxic sunscreen is therefore highly desirable.
Scientists have previously achieved production of the compound shinorine from species of marine bacteria and algae. Due to the nature of this extraction process, products containing this molecule retail at extortionate prices. We look to explore a novel and more economical approach to sustainable UV protection by implementing a pathway in a harmless Nissle E.coli strain to synthetically produce shinorine. When applied on the surface of the skin, shinorine and other UV protectant molecules overproduced by the bacteria in response to light will allow for the formation of a bioactive UV shield. The application of our probiotic is only temporary therefore the long-term survival of the bacteria must be prevented. To accommodate this, the bacteria in our sunscreen will only remain viable for a certain duration mediated by its ability to sense the surrounding gel and light intensity incident. Escape into the environment or permanent integration into the microbiome will be prevented.
Due to the Covid-19 pandemic and the ongoing restrictions in the United Kingdom, we have been unable to access the lab this summer. Instead, we have focussed on modelling, design of our gene circuit, and human practices. We are planning on a two-stage project, with lab work and development of a proof of concept next summer. The lack of lab access has allowed us to spend more time on the gene circuit than would have been possible in a normal iGEM summer project. As a result, we went through various iterations of our gene circuit, particularly our killswitch before reaching our final design, which we feel has been one of the (few) benefits of the current situation.
Our product would establish significant progress towards tackling important issues the world is facing: skin cancer and coral degradation. We believe our project has the potential to provide a solution that is as it would be more sustainable, low-priced, and longer-lasting than current available sunscreens.
CREDIT: THE OCEAN AGENCY / XL CATLIN SEAVIEW SURVEY
Cancer Research UK (2015) Melanoma skin cancer statistics, CRUK. Available at: https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/melanoma-skin-cancer (Accessed: 22 October 2020).
Downs, C. A. et al. (2016) ‘Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands’, Archives of Environmental Contamination and Toxicology. Springer US, 70(2), pp. 265–288. doi: 10.1007/s00244-015-0227-7.
EPA (2018) Basic Information about Coral Reefs. Available at: https://www.epa.gov/coral-reefs/basic-information-about-coral-reefs (Accessed: 22 October 2020).
Schneider, S. L. and Lim, H. W. (2019) ‘Review of environmental effects of oxybenzone and other sunscreen active ingredients’, Journal of the American Academy of Dermatology. Elsevier Inc, 80(1), pp. 266–271. doi: 10.1016/j.jaad.2018.06.033.
Wijgerde, T. et al. (2020) ‘Adding insult to injury: Effects of chronic oxybenzone exposure and elevated temperature on two reef-building corals’, Science of The Total Environment. The Authors, 733, p. 139030. doi: 10.1016/j.scitotenv.2020.139030.
Wood, E. (2018) Impacts of Sunscreens on Coral Reefs, Report by the International Coral Reef Initiative.