Bioconversion of sugarcane molasses and waste glycerol on single cell oils for biodiesel by the red yeast Rhodotorula glutinis R4 from Antarctica

Abstract

In the context of the global energy crisis and the constant demand for biofuels, this work explored the biodiesel production from single-cell oils (SCO) produced by the Antarctic oleaginous yeast Rhodotorula glutinis R4 from low-cost local agro-industrial by-products (sugarcane molasses and waste glycerol). The lipid accumulation reached 46.8 % and 40.7 % at 120 h of culture using glycerol and molasses, respectively, which correspond to 5.72 and 8.68 g L−1 of final lipid concentration. R. glutinis R4 yielded 0.172 and 0.185 g of lipids per gram of substrate consumed grown in molasses or glycerol medium, respectively. These amounts being higher than the ones obtained in glucose medium (0.126 g g−1). At 120 h of culture, lipid volumetric productivities were 0.048 and 0.072 g L−1 h−1 using glycerol and molasses, respectively, and 0.043 g L−1 h−1 in the glucose yeast extract (GYM) medium. Oleic acid is the predominant fatty acid in the oils from R. glutinis R4, reaching 67.5 % with molasses, thus indicating that it is adequate for biodiesel synthesis. This is the first study where SCO produced by R. glutinis R4 were converted into biodiesel by acid transesterification with an efficiency above 90 %. The biodiesel produced by R. glutinis R4 grown on culture media containing molasses or waste glycerol is fully compliant with the international standards for biodiesel. SCO obtained from R. glutinis R4 using molasses and waste glycerol can be effectively used as sources of triacylglycerols for biodiesel production.