Evaluation of lipid production from xylose and glucose/xylose mixed sugar in various oleaginous yeasts and improvement of lipid production by UV mutagenesis

Abstract

Microbial lipids from oleaginous yeasts are recognized as promising alternative lipid sources. Although lipid productivity of oleaginous yeasts from glucose has been well-studied, knowledge of lipid productivity from xylose is limited. In this study, we aimed to evaluate and improve lipid productivity from xylose or glucose/xylose mixed sugar in various oleaginous yeasts. The xylose-based growth capability of 15 oleaginous strains belonging to Cryptococcus curvatus, Lipomyces starkeyi, Rhodosporidium toruloides, and Rhodotorula glutinis was tested. L. starkeyi strains showed relatively low growth capability. Ultraviolet mutagenesis combined with selection using cerulenin was applied for C. curvatus and R. toruloides strains. A mutant R. toruloides 8766 3-11C 2-53C exhibiting higher lipid productivity from xylose and glucose/xylose was obtained. The transcription levels of various lipid production-related genes were upregulated, whereas xylose metabolism-related genes were almost unchanged in the mutant. The results reveal the very diverse xylose-utilizing capability in the various oleaginous yeast species and strains. Promising target genes to improve lipid productivity from xylose through gene recombination were identified.