Carotenoids synthesis in rhodosporidium toruloides and their extraction by pulsed electric field technology
Toh, Shi Hui
Date of Issue2014
School of Chemical and Biomedical Engineering
This research demonstrates the potential of R. Toruloides as carotenoid producer grown on low-cost crude glycerol, a by-product of biodiesel plant, and applications of PEF treatment on to extract proteins and fatty acids biomass as an alternative, mild extraction technique. The conversion rate of crude glycerol to carotenoids by R. Toruloides was optimized and found that a concentration of 60g/L of glycerol was optimal for production. The carotenoids profile of R. Toruloides analyzed using High Performance Liquid Chromatography (HPLC). The later part of the research focuses on the investigation of PEF treatment on R. Toruloides to isolate the carotenoids, proteins and fatty acids. The compositions of fatty acids and carotenoids remained unchanged by PEF treatment. In both PEF treated and PEF untreated samples, the predominant fatty acids present analyzed by GC/MS were palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2). Use of PEF treatment to extract proteins and fatty acids were also investigated. The PEF treatment allowed little protein extraction yields (9.7 % of total protein at electric field = 10 kV/cm), however application of PEF treatment allowed higher lipid extraction yield (up to 50% of total lipids). When PEF treatment is applied, followed by heat drying at 60°C, the decanting and drying process of R. Toruloides was enhanced. There were no negative influences on the fatty acid and carotenoids distribution pattern caused by the higher temperature during drying process. Since carotenoids are present as stable intact oleosomes in R. Toruloides, this suggests the possibility of isolating carotenoids from the chromoplasts within a whole dehydrated R. Toruloides cell after PEF treatment.
DRNTU::Engineering::Chemical engineering::Biochemical engineering