Improvement of lipid production in oleaginous yeast Rhodosporidium toruloides by ultraviolet mutagenesis.

The oleaginous yeast Rhodosporidium toruloides AS 2.1389 is viewed as desirable industrial microorganisms that can accumulate a high content of lipids for biodiesel production. In this study, we attempted to improve lipid accumulation in the yeast Rhodosporidium toruloides by UV irradiation mutagenesis and selection based on lithium chloride tolerance or ethanol-H2O2 tolerance. The biomass concentration, lipid yield and glucose consumption of mutant R. toruloides were determined. The transcription levels of lipid accumulation-related genes in the wild-type and mutant strains were also determined. The lithium chloride-tolerant strain R-ZL2 and the ethanol-H2O2-resistant strain R-ZY13 were generated by UV mutagenesis. The two mutant strains showed greater lipid productivity and lipid yield compared to the wild type. Transcriptional analysis revealed that IDP1, GPD1 and GND were expressed at significantly higher levels in the two high-lipid-producing mutants. In conclusion, lipid productivity and lipid yield in R. toruloides were successfully improved via UV mutagenesis and selection. We also identified some lipid accumulation-related genes for improving lipid productivity through genetic engineering.