St Andrews iGEM 2020
Our project Shinescreen focuses on engineering a novel and sustainable sunscreen using synthetic biology. We are taking the first steps to design a bacterial sunscreen which offers long term protection and is entirely coral friendly!
Design a novel system that synthesises shinorine and responds to environmental signals.
Conserve and Revitalise Coral Reefs
Oxybenzone and octinoxate in chemical sunscreens cause coral bleaching, impair polyp growth and increase their susceptibility to viruses.
We aim to create a smart sunscreen which uses bacteria as a source of sustainable and affordable UV protection.
Why Engineer a Reef-Safe Sunscreen?
Coral reefs are some of the most biodiverse habitats on the planet, supporting over 1 million species. Despite covering less than 1% of the ocean floor, they support a quarter of all marine species.
Coral reefs are also some of the most vulnerable habitats in the world. Reef building corals are ecosystem engineers, meaning that they are the basis for the habitat around them. Loss of these corals have devastating effects on the biodiversity of these habitats. Corals are uniquely vulnerable to a variety of stressors – their existence depends on their symbiotic relationship with photosynthetic algae called zooxanthellae, which provide the coral with energy. Stress can cause the expulsion of zooxanthellae, which leads to a phenomenon called coral bleaching.
Stresses that can cause coral bleaching include changes in water temperature, increasing acidification of the oceans and pollution. One type of pollution that has been of particular concern is the pollution of sunscreen chemicals. These have been shown to enhance the coral bleaching response, making corals more susceptible to other stressors such as climate change. These chemicals include oxybenzone and octinoxate, both of which are banned in the US state of Hawaii due to their effect on coral reefs. However, many of the alternatives to these chemicals are also suspected to be harmful to the marine environment.
We developed an in silico probiotic sunscreen containing a genetically designed bacterium that overexpresses a UV-protective compound, shinorine. Shinorine is a widespread mycosporine-like amino-acid (MAA) among cyanobacteria and algae. On application, the pre-cultured bacteria supported by a nutrient-rich medium would proliferate over the timespan of sun exposure, actively prolonging UV-protection over traditional sunscreens via live expression of our gene circuit, enhancing the effective shinorine concentration.
The gene circuit involves two parts: the shinogen, which expresses a four-enzyme gene cluster from the cyanobacterium Anabaena variabilis and the thanogen, a team-designed killswitch sensitive to glucose and green light. The shinogen and thanogen parts are divided across two plasmids in a two-plasmid delivery system designed to minimise the risk of horizontal gene transfer and post-segregational loss of the plasmid systems. Learn more about the design here.
Apart from gains in marine life protection, Shinescreen would be an advantage to patients experiencing skin conditions including eczema more sensitive to organic sunscreen irritation.
Further, the thanogen could operate independently from the shinorine-producing part, opening the possibility to a future generation of biosafe genetically engineered cosmetics.
Before and after a bleaching event in American Samoa. Credit: the ocean agency/xl Catlin Seaview Survey