Lipid Turnover in Oleaginous Yeasts

SUMMARY: When eight strains of the oleaginous yeasts Candida curvata, Lipomyces starkeyi, Rhodosporidium toruloides and Trichosporon cutaneum were starved of carbon after having accumulated lipid up to 34% of their biomass, the lipid was readily converted to new biomass in all cases except the two strains of L. starkeyi. When C. curvata D was grown in a two-stage chemostat with the second stage as a carbon-starvation vessel (but containing NH+ 4) biosynthesis of new biomass reached 1.9 ± 0.2 g per g lipid utilized. Experiments in a single-stage chemostat undergoing transition from lipid accumulation (nitrogen-limited medium) to carbon-starvation conditions showed that the lipid in C. curvata was rapidly mobilized. When the lipid was pre-labelled with 14C, a transitory pool of rapidly metabolizable non-lipid material appeared within 1.5 h of the initiation of starvation. Rates of lipid loss indicated that initiation of lipid degradation occurred immediately carbon was lost from the external medium.