Investigating the metabolism of Chromochloris zofingiensis for the synthesis of astaxanthin, triacylglycerol and polyunsaturated fatty acids

• Applicant: Professorin Dr. Irmtraud Horst
• Subject Area: Biological Process Engineering ; Biochemistry ; Microbial Ecology and Applied Microbiology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 565000264

The carotenoid astaxanthin is a high-value product with very high antioxidant potential, which can be produced by several microorganisms including the microalgae Chromochloris zofingiensis. Astaxanthin is utilised as a dietary supplement, in the cosmetics industry and in aquaculture. Its effects are also being researched in medicine. However, chemically produced synthetic astaxanthin is not equivalent to the natural analogue. Under stress conditions such as nitrogen deficiency or high light, some microalgae produce astaxanthin and triacylglycerol (TAGs). For C. zofingiensis, it has been shown that astaxanthin is present in the cytosol as an esterified form in TAG droplets. In addition, polyunsaturated fatty acids (PUFAs) play a role in human nutrition. PUFAs are important because some of them are essential and cannot be produced by humans. At the beginning of the food chain, microalgae produce these fatty acids. The syntheses of astaxanthin, TAGs and PUFAs in C. zofingiensis are mutually dependend and also depend on the growth conditions. However, the relationships and mutual dependencies are not yet fully understood. The overall aim of this project is, therefore, gaining a better understanding of the fundamentals of astaxanthin, TAG and PUFA syntheses in C. zofingiensis at the metabolic level. It is important to understand the interdependencies of these pathways and on the respective growth conditions. Thus, it is necessary to determine the influence of nitrogen and sugar addition on the yield of astaxanthin, TAGs and PUFAs. This research is necessary for finding ways of establishing C. zofingiensis as an astaxanthin production organism alongside H. pluvialis. C. zofingiensis could be better suited for this purpose due to its ability to grow on glucose thus achieving high biomass concentrations in bioreactors. Therefore, one goal of this research is to understand the metabolism of C. zofingiensis in detail and to adapt it in such a way that the astaxanthin, TAG and PUFA yield per cell can be increased. This goal is to be achieved as part of a larger consortium in a follow-on project. To initiate this project, a six month research project is proposed in order to obtain detailed evidence and data for the dependency of nitrogen and carbon sources, carotenoid synthesis and astaxanthin esterification, TAG and PUFA synthesis. These findings will then help inform a larger consortium of the steps necessary for a deeper understanding of astaxanthin synthesis in C. zofingiensis.

• DFG Programme: Research Grants
• International Connection: United Kingdom
• Cooperation Partners: Dr. Matthew Davey; Dr. David Green; Dr. Puja Kumari; Dr. Michael Ross; Professorin Dr. Michele Stanley