To realize the feasibility of biodiesel production from high-lipid cell culture, microbial lipid
production by the oleaginous yeasts was studied using glucose and sucrose as carbon
source. Among the tested strains, Cryptococcus sp. SM5S05 accumulated the highest levels
of intracellular lipids. The crude lipid contents of Cryptococcus sp. cultured in yeast malt
agar reached 30% on a dry weight basis. The accumulation of lipids strongly depended on
carbon/nitrogen ratio and nitrogen concentration. The highest content of lipids, measured
at a carbon/nitrogen ratio of 60e90 and at a nitrogen concentration of 0.2%, was 60e57%
lipids in the dry biomass. Batch cultures using corncob hydrolysate demonstrated that
there was minimal inhibitory effect with a reducing sugar concentration of 60 g l1 or
higher. Batch cultures of Cryptococcus sp. SM5S05 in the corncob hydrolysate medium with
60 g l1 glucose resulted in a dry biomass, lipid yields, and content of 12.6 g l1, 7.6 g l1, and
60.2%, respectively. The lipids contained mainly long-chain saturated and unsaturated
fatty acids with 16 and 18 carbon atoms. The fatty acid profile of Cryptococcus oils was quite
similar to that of conventional vegetable oil. The cost of lipid production could be further
reduced with corncob hydrolysate being utilized as the raw material for the oleaginous
yeast. The results showed that the microbial lipid from Cryptococcus sp. was a potential
alternative resource for biodiesel production.