Sustainable biochemicals - Extraction of lipids and carotenoids from the oleaginous yeast Rhodotorula toruloides

Abstract

Oleaginous yeasts, with their high lipid accumulation, offer potential as sustainable alternatives to vegetable oils. They also have a unique capability for accumulating carotenoids together with lipids. Also, they have the ability to thrive on various waste and low-cost carbon sources. This thesis examined ways of converting lignocellulosic biomass into fatty acids and carotenoids using oleaginous yeasts and potential methods for extracting these valuable compounds efficiently, with the ultimate aim of establishing a foundation for their future incorporation as essential ingredients in the food and feed industries. Comprehensive investigations into the impact of conventional and supercritical carbon dioxide (SC-CO2) extraction methods on the composition of lipid and carotenoid extracts derived from the yeast species Rhodotorula toruloides revealed that SC-CO2 has promising capability for isolating these compounds, particularly carotenoids, unlike conventional extraction methods. A previously undetected adverse influence of including saponification in conventional methods on yield and composition of carotenoids was observed. This novel insight highlights the need for re-evaluating and refining existing lipid and carotenoid extraction methods. Further analysis of the lipid and carotenoid profiles of various R. toruloides strains yielded valuable insights, particularly concerning the hybrid strain CBS 6016T , for which predominant inheritance and expression of genetic traits from one parental strain (CBS 14), but not the other (CBS 349), was revealed. This research offers significant biotechnological potential. SC-CO2 extraction enhances eco-friendly lipid and carotenoid production in R. toruloides, while insights into hybrid strain CBS 6016T can aid genetic engineering for higher yields. Overall, this thesis opens the way toward greener, more efficient processes in the food, feed, and biotech sectors.