Production of single cell oil from cane molasses by Rhodotorula kratochvilovae (syn, Rhodosporidium kratochvilovae) SY89 as a biodiesel feedstock

Abstract

Background: Single cell oil has long been considered an alternative to conventional oil sources. The oil produced can also be used as a feedstock for biodiesel production. Oleaginous yeasts have relatively high growth and lipid production rates, can utilize a wide variety of cheap agro-industrial wastes such as molasses, and can accumulate lipids above 20% of their biomass when they are grown in a bioreactor under conditions of controlled excess carbon and nitrogen limitation. Results: In this study, Rhodotorula kratochvilovae (syn, Rhodosporidium kratochvilovae) SY89 was cultivated in a nitrogen-limited medium containing cane molasses as a carbon source. The study aims to provide not only information on the production of single cell oil using R. kratochvilovae SY89 on cane molasses as a biodiesel feedstock, but also to characterize the biodiesel obtained from the resultant lipids. After determination of the sugar content in cane molasses, R. kratochvilovae SY89 was grown on the optimized cane molasses for 168 h. Under the optimized conditions, the yeast accumulated lipids up to 38.25 ± 1.10% on a cellular dry biomass basis. This amount corresponds to a lipid yield of 4.82 ± 0.27 g/L. The fatty acid profiles of the extracted yeast lipids were analyzed using gas chromatography, coupled with flame ionization detector. A significant amount of oleic acid (58.51 ± 0.76%), palmitic acid (15.70 ± 1.27%), linoleic acid (13.29 ± 1.18%) and low amount of other fatty acids were detected in the extracted yeast lipids. The lipids were used to prepare biodiesel and the yield was 85.30%. The properties of this biodiesel were determined and found to be comparable to the specifications established by ASTM D6751 and EN14214 related to biodiesel quality. Conclusions: Based on the results obtained, the biodiesel from R. kratochvilovae SY89 oil could be a competitive alternative to conventional diesel fuel.