8-15: Fermentation of Levoglucosan with Oleaginous Yeasts for Lipid Production

Pyroyzing lignocellulosic biomass results in levoglucosan (LG) in bio-oils that can be separated and utilized to improve the economics of pyrolysis. Existing LG utilization methods involve hydrolyzing LG into glucose prior to fermentation. This paper reports the lipid production with LG (without hydrolysis step) by oleaginous yeasts Rhodosporidium toruloides and Rhodotorula glutinis. Enzyme activity tests of LG kinases from these two yeasts indicated the pathway of the phosphorylation of LG to glucose-6-phosphate existed. The highest enzymatic activity obtained for R. glutinis was 0.22 U/mg of protein. The highest cell mass and lipid production by R. glutinis were respectively 6.8 g/L and 2.7 g/L from pure LG and 3.3 g/L and 0.78 g/L from a pyrolytic LG aqueous phase detoxified with ethyl acetate extraction, rotary evaporation and activated carbon. This corresponded to a lipid yield of 13.5 wt. % for pure LG and only 3.9 % for LG in pyrolysis oil.