iGEM 2022 - Crocin biosynthesis in the unconventional yeast Rhodotorula toruloides

Crocin is a carotenoid compound primarily responsible for the color of saffron. It has been shown to exhibit antioxidant, neuroprotective agent, as well as antiproliferative properties in cancer cells in vitro. The saffron plant requires specific climate conditions to grow and thrive. Additionally, the yield of crocin via extraction from saffron is rather low and the process is costly and labor consuming.

Hence, for many years scientists and research teams have tried to biosynthetically produce lab-based crocin. However, given the complex metabolic pathway required to produce crocin, success has been achieved only to a certain extent. Previous researchers have attempted to produce crocin and its precursors in organisms like Escherichia coli and Saccharomyces cerevisiae and have demonstrated and shown the various involved metabolic pathways. Nonetheless, the slow growth of plants, limited yield, and difficulty of constructing and optimising extensive synthetic pathways in microorganisms have limited the potential for industrial scale production. With climate change affecting the range of saffron cultivation and the demand for it increasing in the near future, a novel crocin biosynthesis method is essential.

To overcome these issues, we have decided to build upon the vast knowledge of previous research and of our team members , to focus on Rhodotorula toruloides, an unconventional yeast with a high potential for use in industrial biotechnology. Additionally, the yeast naturally produces β-carotene, which eliminates more than half of the reaction steps needed to be introduced to produce crocin in the organism. Based on literature review, only 3 new enzymatic reactions are needed to produce crocin in R. toruloides.

Crocin scarcity and cancer are global issues with subsequent local importance as Latvia has the 3rd highest cancer mortality rate in the European Union. A novel method for high quality crocin production is needed for extensive future research into the medical properties of the compound. Engineered yeasts could work for this goal and also create a geographically independent alternative source of the crocin since more that 90% of saffron globally is grown in regions heavily affected by climate change. Within our project we actively consulted with different stakeholders and took into consideration their insights about how we can contribute to the local community. Our team discussed these aspects with not only the scientific advisors we had but also the wider public during the Scientist’s Night. We consulted with the UL Student Business Incubator to determine the best ways to connect with the local start-up community. We learned about local events like Icebreakers’22 where science meets entrepreneurship and students can participate with a commercializable idea and receive support for the further development of it. The takeaway from all of the conversations we had was that synthetic biology can and should be used to create a sustainable way of crocin production, both for environmental reasons, scientific interest as well as business opportunity.