Adaptive Evolution of Rhodosporidium toruloides with Ultra-centrifugal Fractionation Leads to a High Microbial Lipid Production using Crude Glycerol Feedstock.

Abstract

In situ reintegration of crude glycerol into lipid feedstock can increase the production efficiency and environmental tolerance for the biodiesel industry. In this study, a wild oleaginous yeast Rhodosporidium toruloides CGMCC 2.1389 was selected for its high cell growth and lipid accumulation in crude glycerol. Ultra-centrifugal fractionation was applied in a long-term adaptive evolution, and a stable R. toruloides XR20 strain was finally obtained. The lipid content and titer of the R. toruloides XR20 strain in flask increased by 100.1% and 75.8% compared with the parental strain. Record-breaking lipid titers using crude glycerol by R. toruloides XR20 were achieved by batch and fed-batch fermentation, reaching 24.5 ± 0.5 g/L and 42.5 ± 0.8 g/L, respectively. R. toruloides XR20 showed enlarged intracellular space, higher intracellular NADPH, and acetyl-CoA contents compared with the parental strain. The changes in the expression levels of the key genes favored lipid synthesis in R. toruloides XR20. This study constructed a robust high lipid-producing R. toruloides on crude glycerol, contributing to a glycerol-free biodiesel production process.